A-501-18

RefRigeRant REpoRT 18

Refrigerant Report

Contents

Essential revisions/supplements vs. 17th edition

Page

33

4

667

88

99

111111

131516

17171819

202021222223

24

272728293132

36

38

40

This edition supersedes all previous issues.

General aspects on refrigerant developmentsIntroduction

Alternative refrigerants (overview)

Environmental aspectsGlobal Warming and TEWI factor Eco-Efficiency

HCFC refrigerantsR22 as transitional refrigerant

HFC and HFO refrigerantsR134a as a substitute for R12 and R22 ■ Lubricants for HFCsAlternatives to R134aR152a – an alternative to R134a (?)"Low GWP" HFO refrigerants R1234yf and R1234ze(E)

Refrigerant blendsService blends as substitutes for R502 Service blends as substitutes for R12 (R500)

HFC Alternatives for R502 and R22R404A and R507A as substitutes for R502 and R22R407A, R407B and R407F as substitutes for R502 and R22 R422A as substitute for R502 and R22

HFC Alternatives for R22R407C as substitute for R22R410A as substitute for R22 R417A, R417B, R422D and R438A as substitutes for R22R427A as substitute for R22R32 as substitute for R22

HFO/HFC blends as alternatives to HFCs

Halogen free refrigerantsNH3 (Ammonia) as alternative refrigerantR723 (NH3/DME) as an alternative to NH3

R290 (Propane) as substitute for R502 and R22Propylene (R1270) as an alternative to PropaneCO2 as an alternative refrigerant and secondary fluid

Special applications

Refrigerant properties

Application ranges ■ Lubricants

General aspects on refrigerant developments

Introduction

Stratospheric ozone depletion as well asatmospheric greenhouse effect due to refrig-erant emissions have led to drastic changesin the refrigeration and air conditioning tech-nology since the beginning of the 1990s.

This is especially true for the area of com-mercial refrigeration and A/C plants withtheir wide range of applications. In formeryears the main refrigerants used for thesesystems were ozone depleting types, namelyR12, R22 and R502; for special applicationsR114, R12B1, R13B1, R13 and R503 wereused.

With the exception of R22 the use of thesechemicals is not allowed any more in indus-trialised countries. In the European Union,however, an early phase-out was alreadyenforced in several steps (see page 8). The main reason for this early ban of R22contrary to the international agreement is theozone depletion potential although it is onlysmall.Since 2010, phase-out regulations got effec-tive in other countries as well, in the USA forinstance.

Due to this situation enormous conse-quences result for the whole refrigerationand air conditioning sector. BITZER thereforecommitted itself to taking a leading role inthe research and development of environ-mentally benign system designs.

After the chlorine-free (ODP = 0) HFC refrig-erants R134a, R404A, R407C, R507A andR410A have become widely established formany years in commercial refrigeration, air-conditioning and heat pump systems, mean-while new challenges have come up. Theyconcern primarily the greenhouse effect. Theaim is a clear reduction of direct emissionscaused by refrigerant losses and indirectemissions by particularly efficient systemtechnology.

In this area, applicable legal regulations arealready in force, such as the EU Regulationon F-Gases No. 517/2014 (see BITZERbrochure A-510) and a series of regulationsalready ratified or in preparation as part ofthe EU ErP Ecodesign Directive. Similar reg-ulations are also in preparation or havealready been implemented in North Americaand other regions.

Even though indirect emissions caused byenergy production are considerably higherthan direct (CO2-equivalent) emissionscaused by HFC refrigerants, refrigerants with

high global warming potential (GWP) will infuture be subject to use restrictions or bans.This will affect primarily R404A and R507A,for which alternatives with lower GWP arealready being offered. However, in order toachieve the legal objectives, substitutes forfurther refrigerants and increased use of nat-urally occurring substances (NH3, CO2,hydrocarbons) will become necessary.

This requires comprehensive testing of theserefrigerants, suitable oils and accordinglyadjusted systems.

Therefore a close co-operation exists withscientific institutions, the refrigeration and oilindustries, component manufacturers as wellas a number of innovative refrigeration andair conditioning companies.

A large number of development tasks havebeen completed. For alternative refrigerantssuitable compressors are available.

Besides the development projects BITZERactively supports legal regulations and selfcommitments concerning the responsibleuse of refrigerants as well as measures toincrease system and components’ efficiency.

The following report deals with potentialmeasures of a short to medium-term changetowards technologies with reduced environ-mental impact in medium and large sizecommercial refrigeration and air-conditioningsystems. Furthermore, the experience whichexists is also dealt with and the resultingconsequences for plant technology.

❄ ❄ ❄

Serveral studies confirm that the vapourcompression refrigeration plants normallyused in the commercial field are far superiorin efficiencyto all other processes down to acold space temperature of around -40°C.

The selection of an alternative refrigerant andthe system design receives special signifi-cance, however. Besides the request forsubstances without ozone depletion poten-tial (ODP=0) especially the energy demandof a system is seen as an essential criteriondue to its indirect contribution to the green-house effect. On top of that there is thedirect global warming potential (GWP) due torefrigerant emission.

Therefore a calculation method has beendeveloped for the qualified evaluation of asystem which enables an analysis of thetotal influence on the greenhouse effect.

In this connection the so-called "TEWI" fac-tor (Total Equivalent Warming Impact) has

been introduced. Meanwhile, another, moreextensive assessment method has been de-veloped under the aspect of "Eco-Efficiency".Hereby, both ecological (such as TEWI) andeconomical criteria are taken into account(see also page 7).

Therefore it is possible that the assessmentof refrigerants with regard to the environmentcan differ according to the place of installa-tion and drive method.

Upon closer evaluation of substitutes for theoriginally used CFC and HCFC as well as forHFCs with higher GWP, the options with single-substance refrigerants are very limited.They include, for example, R134a, whosecomparably low GWP will allow its use for alonger time to come. Furthermore thisincludes the hydro fluoro olefins (HFO)R1234yf and R1234ze(E) with a GWP < 10,which so far have been available to only alimited extent and for which no long-termexperience is available as yet.

Direct alternatives (based on fluorinatedhydrocarbons) for almost all refrigerants ofhigher volumetric refrigerating capacity andpressure level than R134a can only be "for-mulated" as blends. However, taking intoaccount thermodynamic properties, flamma-bility, toxicity and global warming potential,the list of potential candidates is very limited.Blends of reduced GWP include in additionto R134a, R1234yf and R1234ze(E) primarilythe refrigerants R32, R125 and R152a.

Besides halogenated refrigerants, Ammonia(NH3) and hydrocarbons are considered assubstitutes as well. The use for commercialapplications, however, is limited by strictsafety requirements.

Carbon dioxide (CO2) becomes more impor-tant as an alternative refrigerant and second-ary fluid, too. Due to its specific characteris-tics, however, there are restrictions to ageneral application.

The illustrations on the next pages show astructural survey of the alternative refriger-ants and a summary of the single or blendedsubstances which are now available. Afterthat the individual subjects are discussed.

Refrigerant properties, application rangesand lubricant specifications are shown onpages 38 to 41.

For reasons of clarity the less or only re-gionally known products are not specified inthis issue, which is not intended to imply anyinferiority.

3

Alternative refrigerants – overview

4

Alternative Refrigerants

SingleSubstances

e.g. R134aR125R32R143aR152a

HFC– chlorine free –

"Low GWP"Refrigerants

Blends

e.g. R404AR507AR407-SeriesR410AR417A7BR422A/DR427A

SingleSubstances

R234yfR1234ze(E)

Blends

R1234yf/R1234ze(E)/HFC

SingleSubstances

e.g. NH3R290R1270R600aR170R744

Blends

e.g. R600a/R290

R290/R170

R723

Halogen free

SingleSubstances

e.g. R22R123R124R142b

Blends

predominantlyR22-Based

HCFC/HFC– partly chlorinated –

Medium and LongTerm Refrigerants

Transitional/ServiceRefrigerants*

Fig. 1 Structural classification of refrigerants

* Service refrigerants contain HCFC as blend component. They are therefore subject to the same legal regulations as R22 (see page 8). As a result of the continued refurbishment of older installations, the importance of these refrigerants is clearly on the decline. For some of them, production has already beendiscontinued. However, for development-historic reasons of service blends, these refrigerants will continue to be covered in this Report.

Former AlternativesRefrigerants

ASHRAE Trade name Composition DetailedClassification (with blends) Information

R134aR152a

– pages

R437A ISCEON MO49 Plus DuPont R125/134a/600/601 9...11, 16, 38...41

R404A various R143a/R125/R134aR502/R22 R507A various R143a/125 pages

R422A ISCEON MO79 DuPont R125/134a/600a 17...19, 38...41

R407A Mexichem, Arkema R32/125/134aR407C various R32/125/134aR407F Performax LT Honeywell R32/125/134aR410A various R32/125R417A ISCEON MO59 DuPont R125/134a/600 pages

R417B Solkane 22L Solvay R125/134a/600 18...23, 38...41

R422D ISCEON MO29 DuPont R125/134a/600aR427A Forane 427A Arkema R32/125/143a/134aR438A ISCEON MO99 DuPont R32/125/134a/600/601a

R114 R236fa – – pagesR12B1 R227ea – – 36, 38...41

R410A various R32/125 pagesR13B1 – ISCEON MO89 DuPont R125/218/290 37, 38...41

R13 R23 – – pagesR503 R508A KLEA 508A Mexichem R23/116 37, 38...41R508B Suva 95 DuPont R23/116

HFC refrigerants 09.14

Fig. 2 Substitutes for CFC and HCFC refrigerants (chlorine free HFCs)

1

R22

R12(R500) 4

Alternative refrigerants – overview

5

Current AlternativesRefrigerants

ASHRAE Trade name Composition Detailled Classification (with blends) Information

R1234yf various –R1234ze(E) various – R513A Opteon® XP10 DuPont R1234yf/134a pages 24…26 ,R450A Solstice N-13 Honeywell R1234ze(E)/134a 38…41– ARM-42 Arkema R1234yf/152a/134a– AC5X Mexichem R32/1234ze(E)/134a

R449A Opteon® XP40 DuPont R32/125/1234yf/134aR448A Solstice N-40 Honeywell R32/125/1234yf/1234ze(E)/134a pages 24…26 ,– ARM-32b Arkema not disclosed 38…41– LTR4X Mexichem R32/125/1234ze(E)/134a

– DR-91 DuPont not disclosed– Solstice N-20 Honeywell R32/125/1234yf/1234ze(E)/134a pages 24…26– ARM-32c Arkema not disclosed

R32 various –– Opteon® XL41 DuPont R32/1234yfR447A Solstice L-41 Honeywell R32/125/1234ze(E) pages 24…26– ARM-71a Arkema not disclosed– HPR1D Mexichem R32/1234ze(E)/CO2

Explanation of Fig. 2 to 4 Flammable Large deviation in refrigerating capacity and Service refrigerant AzeotropeToxic pressures to the previous refrigerant with zero ODP

HFO and HFO/HFC Blends

Current AlternativesRefrigerants

ASHRAE Trade name Formula DetailedClassification Information

R290/600a – C3H8/C4H10 pagesR600a – C4H10 29, 38...41

R717 – NH3

R723 – NH3 + R-E170 pagesR290 – C3H8 27...31, 38...41R1270 – C3H6

R600a – C4H10pages36, 38...41

no direct alternatives available

R23 R170 – C2H6pages37, 38...41

Various R744pages32...35, 38...41

Halogen free refrigerants 09.14

Fig. 4 Alternatives for HCFC and HFC refrigerants (halogen free refrigerants)

3

3

3

4 51

1

1

1

1

1

1

1

1

1

1

1

2

2

1 2 5

R404A/R507A*

R22/R407C*

R410A

R134a

Fig. 3 "Low GWP" Refrigerants and blends

* Due to the large number of different HFO/HFC blends and the potential changes in development products, the above list for R404A/R507A and R22/R407C alternatives onlycontains non-flammable blends of GWP < 1500. On pages 24 to 26, HFO/HFC blends are extensively discussed. Further options are also dealt with.

R134a

R124

R404AR507AR22

R410AM089

1

1

1

1

1

6

Fig. 6 Comparison of TEWI figures (example)

TEW

I x 1

03

Refrigerant charge [m]10kg 25kg 10kg 25kg

recoverylosses

300

200

100

RL

RL

RL

RL

ENERGY

ENERGY

ENERGY

ENERGY

Comparisonwith 10% higher

energy consumption

LL

RL = Impact of

leakageLL = Impact of

lossesLL LL

LL

+10%

+10%

Global Warming andTEWI Factor

As already mentioned in the introduction amethod of calculation has been developed,with which the influence upon the globalwarming effect can be judged for the opera-tion of individual refrigeration plants (TEWI = Total Equivalent Warming Impact).

All halocarbon refrigerants, including thenon-chlorinated HFCs belong to the cat-egory of the greenhouse gases. An emis-sion of these substances contributes to theglobal warming effect. The influence is how-ever much greater in comparison to CO2which is the main greenhouse gas in theatmosphere (in addition to water vapour).Based on a time horizon of 100 years, theemission from 1 kg R134a is for exampleroughly equivalent to 1430 kg of CO2(GWP100 = 1430). It is already apparent from these facts thatthe reduction of refrigerant losses must beone of the main tasks for the future.

On the other hand, the major contributor toa refrigeration plant’s global warming effectis the (indirect) CO2 emission caused byenergy generation. Based on the high per-centage of fossil fuels used in power sta-tions the average European CO2 release isaround 0.45 kg per kWh of electrical energy.A significant greenhouse effect occurs overthe lifetime of the plant as a result of this.

TEWI = TOTAL EQUIVALENT WARMING IMPACT

TEWI = ( GWP x L x n ) + ( GWP x m [ 1- α recovery ] ) + ( n x Eannual x β )

Leakage Recovery losses

direct global warming potential

Energy consumption

indirect globalwarming potential

GWP = Global warming potentialL = Leakage rate per yearn = System operating timem = Refrigerant chargeα recovery = Recycling factorEannual = Energy consumption per yearβ = CO2-Emission per kWh

[ CO2-related acc. to IPCC IV ][ kg ][ Years ][ kg ]

[ kWh ](Energy-Mix)

ExampleMedium temperature R134a

SST -10 °CSCT +40 °Cm 10 kg // 25 kgL[10%] 1 kg // 2,5 kgCAP 13,5 kW E 5 kW x 5000 h/ab 0.45 kg CO2/kWha 0.75n 15 yearsGWP 1430 (CO2 = 1)

time horizon 100 years

As this is a high proportion of the total bal-ance it is also necessary to place an in-creased emphasis upon the use of highefficiency compressors and associatedequipment as well as optimized systemcomponents, in addition to the demand for alternative refrigerants with favourable (thermodynamic) energy consumption.

When various compressor designs arecompared, the difference of indirect CO2emission (due to the energy requirement)can have a larger influence upon the totaleffect as the refrigerant losses.

A usual formula is shown in Fig. 5, the TEWIfactor can be calculated and the various areasof influence are correspondingly separated.

In addition to this an example in Fig. 6(medium temperature with R134a) showsthe influence upon the TEWI value with vari-

Fig. 5 Method for the calculation of TEWI figures

Environmental aspects

ous refrigerant charges, leakage losses andenergy consumptions.

This example is simplified based on anoverall leak rate as a percentage of therefrigerant charge. As is known the practi-cal values vary very strongly whereby thepotential risk with individually constructedsystems and extensively branched plants is especially high.

Great effort is taken worldwide to reducegreenhouse gas emissions and legal regulations have partly been developedalready. Since 2007, the "Regulation oncertain fluorinated greenhouse gases" – which also defines stringent requirementsfor refrigeration and air-conditioning sys-tems – has become valid for the EU. Meanwhile, the revised Regulation No.517/2014 entered into force and willbecome applicable as of January 2015.

7

Environmental aspects

Eco-Efficiency

As mentioned above, an assessment basedon the specific TEWI value takes into accountthe effects of global warming during theoperating period of a refrigeration, air-con-ditioning or heat pump installation. Hereby,however, the entire ecological and economi-cal aspects are not considered.

But apart from ecological aspects, whenevaluating technologies and making invest-ment decisions, economical aspects arehighly significant. With technical systems,the reduction of environmental impact fre-quently involves high costs, whereas lowcosts often have increased ecological con-sequences. For most companies, the in-vestment costs are decisive, whereas theyare often neglected during discussionsabout minimizing ecological problems.

For the purpose of a more objective as-sessment, studies* were presented in 2005and 2010, using the example of supermar-ket refrigeration plants to describe a con-cept for evaluating Eco-Efficiency. It isbased on the relationship between addedvalue (a product's economic value) and theresulting environmental impact.

With this evaluation approach, the entire lifecycle of a system is taken into account interms of:

❏ ecological performance in accordancewith the concept of Life Cycle Assess-ment as per ISO 14040,

❏ economic performance by means of a Life Cycle Cost Analysis.

This means that the overall environmentalimpact (including direct and indirect emis-sions), as well as the investment costs,operating and disposal costs, and capitalcosts are taken into account.

The studies also confirm that an increase ofEco-Efficiency can be achieved by investingin optimized plant equipment (minimizedoperating costs). Hereby, the choice of re-frigerant and the associated system tech-nology plays an important role.

Eco-Efficiency can be illustrated in graphicrepresentation (see example in Fig. 8). Forthis, the results of the Eco-Efficiency evalu-ation are shown on the x-axis in the systemof coordinates, whilst the results of the lifecycle cost analysis are shown on the y-axis.This representation shows clearly that asystem exhibits an increasingly better Eco-

Efficiency, the higher it lies in the top rightquadrant – and conversely, it becomes lessefficient in the bottom left sector.

The diagonals plotted into the system ofcoordinates represent lines of equal Eco-Efficiency. This means that systems or pro-cesses with different life cycle costs andenvironmental impacts can quite possiblyexhibit the same Eco-Efficiency.

Fig. 8 Example of an Eco-Efficiency evaluation

increasing Eco-E

fficiency

Co

st a

dva

ntag

e

E n v i r o n m e n t a l a d v a n t a g e

decreasing Eco-E

fficiency

Fig. 7 Concept of Eco-Efficiency

Life-Cycle-Cost Analysis

(including investment

costs, cost of operation,

capital costs)

Eco-Efficiency

considers

economical and ecological

aspects

Concept of Eco-Efficiency

Life Cycle Assessment

according to ISO 14040

* Study 2005: Compiled by Solvay Management Support GmbH and Solvay Fluor GmbH, Hannover,together with the Information Centre on HeatPumps and Refrigeration (IZW), Hannover.

Study 2010: Compiled by SKM ENVIROS, UK, commissioned by and in cooperation with EPEE(European Partnership for Energy and Environment).

Both projects were supported by an advisory groupof experts from the refrigeration industry.

8

HCFC Refrigerants

Fig. 9 R12/R22 – comparison of discharge gas temperatures ofa semi-hermetic compressor

Fig. 10 R12/R22/R502 – comparison of pressure levels

With regard to components and systemtechnology a number of particularities areto follow as well. Refrigerant R22 has ap-proximately 55% higher refrigerating cap-acity and pressure levels in comparison to R12**. The significantly higher dischargegas temperature is also a critical factorcompared to R12 (Fig. 9) and R502**.

Similar relationships in terms of thermalload are found in the comparison with HFCrefrigerants R134a, R404A/R507A (pages 9and 17).

Resulting design criteria

Particularly critical – due to the high dis-charge gas temperature – are low tempera-ture plants especially concerning thermalstability of oil and refrigerant, with the dan-ger of acid formation and copper plating.Special measures have to be adoptedtherefore, such as two stage compression,controlled refrigerant injection, additionalcooling, monitoring of discharge gas tem-perature, limiting the suction gas superheatand particularly careful installation.

BITZER can supply a widespread range ofreciprocating, screw and scroll compres-sors for R22.

* Not allowed for new equipment in Germany andDenmark since January 1st, 2000 and in Swedenas of 1998.

Since January 1st, 2001 restrictions apply to theother member states of the EU as well. The meas-ures concerned are defined in the ODS Regulation1005/2009 of the EU commision on ozone deplet-ing substances amended in 2009. This regulationalso governs the use of R22 for service reasonswithin the entire EU.

Since 2010, phase-out regulations in other countries, such as the USA, are valid.

** Already banned in most countries.

Disc

harg

e ga

s te

mp.

[˚C

]

Evaporation [˚C]

80

170

-40 0 10-30 -20 -10

90

160

150R12tc +60

R22tc +60tc +50

tc +50

tc +40

tc +40

100

110

120

130

140

Pres

sure

[ba

r]

Temperature [˚C]

1

25

0 60

6

15

4

10

20

-40 -20

R12

R22

R502

2

4020

R22 as transitional refrigerant

Although chlorine free substitutes likeR134a and R404A/R507A (Figs. 1 and 2)have extensively made their way as substi-tutes, in many international fields R22 is stillused in new installations and for retrofittingof existing systems.

Reasons are relatively low investment costs,especially compared with R134a systems,but also in its large application range, fa-vourable thermodynamic properties and low energy requirement. Additionally thereis world wide availability of R22 and theproven components for it, which is not yetguaranteed everywhere with the chlorinefree alternatives.

Despite of the generally favourable proper-ties R22 is already subject to various re-gional restrictions* which control the useof this refrigerant in new systems and forservice purposes due to its ozone deple-tion potential – although being low.

9

HFC and HFO refrigerants

Fig. 11/1 R134a/R12 – comparison of performance data of a semi-hermetic compressor

Fig. 11/2 R134a/R22 – comparison of performance data of a semi-hermetic compressor

Rela

tion

R134

a to

R12

(=10

0%)

Evaporation [˚C]

80

110

0 10

90

100

COP

Q o

85

95

105

-30 -20 -10

t c 50˚C

tc 50˚C

tc 40˚C

toh 20˚C

t c 40˚C

Rela

tion

R134

a to

R22

(=10

0%)

Evapration [˚C]

50

110

10 20

70

COP

Q o

60

80

100

-20 -10 0

toh 20˚C

90

t c 40˚C

t c 50˚C

tc 50˚C

tc 40˚C

R22. There are also limitations in the appli-cation with low evaporating temperatures tobe considered. Comprehensive tests have demonstratedthat the performance of R134a exceedstheoretical predictions over a wide range ofcompressor operating conditions. Temperature levels (discharge gas, oil) areeven lower than with R12 and, therefore,substantially lower than R22 values. Thereare thus many potential applications in air-conditioning and medium temperature re-frigeration plants as well as in heat pumps.Good heat transfer characteristics in evapo-rators and condensers (unlike zeotropicblends) favour particularly an economicaluse.

R134a is also characterized by a compara-bly low GWP (1430). In view of future userestrictions (e.g. EU F-Gas Regulation), thisrefrigerant will continue to be applicable fora longer time to come.

Lubricants for R134a and other HFCs

The traditional mineral and synthetic oils arenot miscible (soluble) with R134a and otherHFCs described in the following and aretherefore only insufficiently transportedaround the refrigeration circuit.Immiscible oil can settle out in the heatexchangers and prevent heat transfer tosuch an extent that the plant can no longerbe operated. New lubricants were devel-oped with the appropriate solubility andhave been in use for many years. Theselubricants are based on Polyol Ester (POE)and Polyalkylene Glycol (PAG).

They have similar lubrication characteristicsto the traditional oils, but are more or lesshygroscopic, dependent upon the refriger-ant solubility. This demands special care during manufac-turing (including dehydrating), transport,storage and charging, to avoid chemicalreactions in the plant, such as hydrolysis.

PAG based oils are especially critical withrespect to water absorption. Moreover, theyhave a relatively low dielectric strength andfor this reason are not very suitable forsemi-hermetic and hermetic compressors.They are therefore mainly used in car A/C

R134a as substitute forR12 and R22

R134a was the first chlorine free (ODP = 0)HFC refrigerant that was tested compre-hensively. It is now used world-wide inmany refrigeration and air-conditioning unitswith good results. As well as being used asa pure substance R134a is also applied asa component of a variety of blends (see"Refrigerant blends", from page 13).

R134a has similar thermodynamic properties to R12:

Refrigerating capacity, energy demand,temperature properties and pressure levelsare comparable, at least in air-conditioningand medium temperature refrigerationplants. This refrigerant can therefore beused as an alternative for most former R12applications.

For some applications R134a is even pre-ferred as a substitute for R22, an impor-tant reason being the limitations to the useof R22 in new plants and for service. How-ever, the lower volumetric refrigerating cap-acity of R134a (see Fig. 11/2) requires alarger compressor displacement than with

10

HFC and HFO refrigerants

Fig. 12 R134a/R12/R22 – comparison of pressure levels

Pres

sure

[ba

r]

Temperature [˚C]

1

25

0 60

6

15

4

10

20

-40 -20

R12

R22

R134a

2

4020

Supplementary BITZER informationconcerning the use of R134a(see also http://www.bitzer.de)

❏ Semi-hermetric reciprocating com-pressors KP-104 “ECOLINE Series”

❏ Technical Information KT-620“HFC Refrigerant R134a”

❏ Technical Information KT-510“Polyolester oils for reciprocatingcompressors”

❏ Special edition“A new generation of compact screwcompressors optimised for R134a”

systems with open compressors, wherespecific demands are placed on lubricationand optimum solubility is required becauseof the high oil circulatation rate. In order toavoid copper plating, no copper containingmaterials are used in these systems either. The rest of the refrigeration industry prefersester oils, for which extensive experienceis already available. The results are positivewhen the water content in the oil does notmuch exceed 100 ppm.

Compressors for factory made A/C andcooling units are increasingly being chargedwith Polyvinyl Ether (PVE) oils. Althoughthey are even more hygroscopic than POE,on the other hand they are very resistant tohydrolysis, thermally and chemically stable,possess good lubricating properties andhigh dielectric strength. Unlike POE they donot tend to form metal soap and thus thedanger of capillary clogging is reduced.

Resulting design and construction criteria

Suitable compressors are required forR134a with a special oil charge, and adapt-ed system components.

The normal metallic materials used in CFCplants have also been proven with esteroils; elastomers must sometimes be match-ed to the changing situation. This is espe-cially valid for flexible hoses where therequirements call for a minimum residualmoisture content and low permeability.

The plants must be dehydrated with partic-ular care and the charging or changing oflubricant must also be done carefully. Inaddition relatively large driers should beprovided, which have also to be matched tothe smaller molecule size of R134a.

Meanwhile, many years of very positiveexperience with R134a and ester oilshave been accumulated. For this re-frigerant, BITZER offers an unequalledwide range of reciprocating, screw, andscroll compressors.

Converting existing R12 plants

At the beginning this subject had been dis-cussed very controversially, several conver-sion methods were recommended and ap-plied. Today there is a general agreementon technically and economically matchingsolutions.

Here, the characteristics of ester oils arevery favourable. Under certain conditionsthey can be used with CFC refrigerants,they can be mixed with mineral oils and tol-erate a proportion of chlorine up to a fewhundred ppm in an R134a system.

The remaining moisture content has, how-ever, an enormous influence. The essentialrequirement therefore exists for very thor-ough evacuation (removal of remainingchlorine and dehydration) and the installa-tion of generously dimensioned driers.Doubtful experience has been found, withsystems where the chemical stability wasalready insufficient with R12 operation e.g.with bad maintenance, small drier capacity,high thermal loading. The increased deposi-tion of oil decomposition products contain-ing chlorine often occurs here. These prod-ucts are released by the working of thehighly polarized mixture of ester oil andR134a and find their way into the compres-sor and regulating devices. Conversionshould therefore be limited to systemswhich are in a good condition.

Restrictions for R134a in mobile air-conditioning (MAC) systems

In future, a new EU Directive on "Emissionsfrom MAC systems" will ban the use ofR134a in new systems. Several alternativetechnologies are already being developed.See the pertaining explanations on pages11, 12 and 35.

11

Alternatives to R134a

For mobile air-conditioning systems (MAC)with open drive compressors and hoseconnections in the refrigerant circuit, therisk of leakages is considerably higher thanwith stationary systems. With a view to re-ducing direct emissions in this applicationarea, an EU Directive (2006/40/EC) has therefore been passed. Within the scope ofthe Directive, and starting 2011, type appro-vals for new vehicles will only be granted ifthey use refrigerants with a global warmingpotential (GWP) of less than 150. Conse-quently, this excludes R134a (GWP = 1430)which has been used so far in thesesystems.

Meanwhile, alternative refrigerants and newtechnologies were developed and tested.This also involved a closer examination ofthe use of R152a.

For quite some time the automotive indus-try has agreed on so-called "Low GWP"refrigerants. The latter is dealt with as fol-lows.

The CO2 technology which was preferredfor this type of application for a long timehas not yet been introduced for differentreasons (see pages 12 and 35).

R152a – an alternative to R134a (?)

Compared to R134a, R152a is very similarwith regard to volumetric cooling capacity(approx. -5%), pressure levels (approx. -10%) and energy efficiency. Mass flow,vapour density and thus also the pressuredrop are even more favourable (approx. -40%).

R152a has been used for many years as acomponent in blends but not as a singlesubstance refrigerant till now. Especiallyadvantageous is the very low global warm-ing potential (GWP = 124).

R152a is flammable – due to its low fluorine content – and classified in safetygroup A2. As a result, increased safetyrequirements demand individual designsolutions and safety measures along withthe corresponding risk analysis.

For this reason, the use of R152a in MACsystems is rather unlikely.

“Low GWP” HFO refrigerants R1234yf and R1234ze(E)

The ban on the use of R134a in mobile air-conditioning systems within the EU has trig-gered a series of research projects. Apartfrom the CO2 technology (page 35), newrefrigerants with very low GWP values andsimilar thermodynamic properties as R134ahave been developed.

In early 2006, two refrigerant mixtures wereintroduced under the names "Blend H"(Honeywell) and "DP-1" (DuPont). INEOSFluor followed with another version underthe trade name AC-1. In the broadestsense, all of these refrigerants were blendsof various fluorinated molecules.

During the development and test phase itbecame obvious that not all acceptance cri-teria could be met, and thus further exami-nations with these blends were discontinued.Consequently, DuPont* and Honeywell*bundled their research and developmentactivities in a joint venture which focused on2,3,3,3-tetrafluoropropene (CF3CF = CH2).This refrigerant, designated R1234yf, be-longs to the group of hydro fluoro olefins(HFO). These refrigerants are unsaturatedHFCs with a chemical double bond.

The global warming potential is extremelylow (GWP100 = 4). When released to theatmosphere, the molecule rapidly disinte-grates within a few days, resulting in a verylow GWP. This raises certain concernsregarding the long-term stability in refrigera-tion circuits under real conditions. However,extensive testing has demonstrated therequired stability for mobile air-conditioningsystems.

R1234yf is mildly flammable as measuredby ASTM 681, but requires significantlymore ignition energy than R152a, forinstance. Due to its low burning velocityand the high ignition force, it received aclassification of the new safety group "A2L"according to ISO 817.

In extensive test series, it has been shownthat a potentially increased risk of therefrigerant flammability in MAC systems canbe avoided by implementing suitable con-

HFC and HFO refrigerants

12

From the group of hydro fluoro olefins,another substance under the nameR1234ze(E) is available, which until nowhas been used predominantly as blowingagent for polyurethane foam and propel-lant. R1234ze(E) differs from R1234yf byhaving a different molecular structure. Itsthermodynamic properties also providefavourable conditions for the use as refrig-erant. Its global warming potential is alsovery low (GWP100 = 7).

Often there is a degree of uncertainty con-cerning flammability. In safety data sheets,R1234ze(E) is declared as non-flammable.However, this only applies to transport andstorage. When used as a refrigerant, ahigher reference temperature of 60°C forflammability tests is valid. At this tempera-ture, R1234ze(E) is flammable and there-fore classified in the same safety groupA2L as R1234yf.

R1234ze(E) is sometimes called an R134asubstitute, but its volumetric refrigeratingcapacity is more than 20% below that ofR134a or R1234yf. Moreover, the boilingpoint (-18°C) considerably limits its use forlower evaporation temperatures. Therefore,the preferred use of positive displacementcompressors is for high temperature appli-cations. For further information, see page36, "Special applications".

Further applications for HFO refrigerants

The use of R1234yf in other mobile air-conditioning applications is also being con-sidered, as well as in stationary A/C andheat pump systems. However, this musttake into account the charge limitations forthe A2(L) refrigerants (e.g. EN378), whichwill restrict their use accordingly. Additionalconcerns are those regarding the long-term stability in refrigeration circuits, giventhe usually very long life cycles of suchsystems.

For applications requiring the use of refrig-erants of safety group A1 (neither flammablenor toxic), R134a alternatives of lower GWPbased on HFO/HFC blends have alreadybeen developed. They have been tested forsome time in real systems.

R1234yf, as well as R1234ze(E), describedbelow, are also used as base componentsin HFO/HFC blends. In view of legal regula-tions for the reduction of F-Gas emissions(e.g. EU F-Gas Regulation), these blendshave been developed as "Low GWP" alter-natives to R404A/R507, R22/R407C andR410A. Some of these refrigerants havealready been tested with regard to refriger-ating capacity and efficiency as parts ofthe "Alternative Refrigerants Evaluation Program" (AREP) initiated by AHRI andhave also been used in trial systems. Forfurther information on HFO/HFC blends,see page 24.

structive measures. However, some investi-gations (e.g. by Daimler-Benz) also show anincreased risk. This is why various manu-facturers have intensified again the devel-opment of alternative technologies.

Toxicity investigations have shown verypositive results, as well as compatibilitytests of the plastic and elastomer materialsused in the refrigeration circuit.Some lubricants show increased chemicalreactivity which, however, can be sup-pressed by a suitable formulation and/oraddition of "stabilizers".

Operating experiences gained from labora-tory and field trials to date allow a positiveassessment, particularly with regard to per-formance and efficiency behaviour. For theusual range of mobile air-conditioning oper-ation, refrigerating capacity and coefficientof performance (COP) are within a range of5% compared with that of R134a. There-fore, it is expected that simple systemmodifications will provide the same per-formance and efficiency as with R134a.

The critical temperature and pressure levelsare also similar, while the vapour densitiesand mass flows are approximately 20%higher. The discharge gas temperature withthis application is up to 10 K lower.

With a view to the relatively simple conver-sion of mobile air-conditioning systems, thistechnology prevailed up to now over thecompeting CO2 systems.

However, as already explained before, dueto the flammability of R1234yf, investiga-tions focus on other technical solutions.They include, among others, CO2 systems.

HFC and HFO refrigerants

13

Refrigerant blends

Refrigerant blends

Refrigerant blends have been developed forexisting as well as for new plants with pro-perties making them comparable alternativesto the previously used substances.

It is necessary to distinguish between threecategories:

1. Transitional or service blendsMost of these blends contain HCFC R22as the main constituent. They are primarilyintended as service refrigerants forolder plants with view on the use ban ofR12, R502 and other CFCs. Corresponding products are offered byvarious manufacturers, the practical ex-perience covering the necessary steps of conversion procedure are available.

However, the same legal requirementsapply for the use and phase-out regula-tions of these blends as for R22 (seepage 8).

2. HFC blends These are substitutes for the refrigerantsR502, R22, R13B1 and R503. Above all,R404A, R507A, R407C and R410A, arebeing used to a great extent. One group of these HFC blends also con-tains hydrocarbon additives. The latterexhibit an improved solubility with lubri-cants, and under certain conditions theyallow the use of conventional oils. In manycases, this opens up possibilities for theconversion of existing (H)CFC plants tochlorine-free refrigerants (ODP = 0) with-out the need for an oil change.

3. HFO/HFC blends as successor generation of HFC refriger-ants. It concerns blends of new "LowGWP" refrigerants (e.g. R1234yf) withHFCs. The fundamental target is an addi-tional decrease of the global warmingpotential (GWP) as compared to estab-lished halogenated substances (see page 24).

Two and three component blends alreadyhave a long history in the refrigeration trade.

A difference is made between the so called"azeotropes" (e.g. R502, R507A) with ther-modynamic properties similar to single sub-stance refrigerants, and "zeotropes" with"gliding" phase changes (see also next sec-tion). The original development of "zeo-tropes" was mainly concentrated on specialapplications in low temperature and heatpump systems. Actual system constructionremained, however, the exception.

A somewhat more common earlier practicewas the mixing of R12 to R22 in order toimprove the oil return and to reduce thedischarge gas temperature with higherpressure ratios. It was also usual to add R22to R12 systems for improved performance,or to add hydrocarbons in the extra lowtemperature range for a better oil transport.

This possibility of specific "formulation"of certain characteristics was indeed thebasis for the development of a new genera-tion of blends.

In section "Introduction" (page 3), it wasalready explained that no direct single-sub-stance alternatives (on the basis of fluori-nated hydrocarbons) exist for the previouslyused and current refrigerants of higher volu-metric refrigeration capacity than R134a.This is why they can only be "formulated"as blends. However, taking into accountthermodynamic properties, flammability,toxicity and global warming potential, thelist of potential candidates is strongly limited.

For the previously developed CFC andHCFC substitutes, the range of substanceswas still comparably large, due to the factthat substances of high GWP could also beused. However, for formulating blends withsignificantly reduced GWP, in addition toR134a, R1234yf and R1234ze(E), primarilyrefrigerants R32, R125 and R152a can beused. Most of them are flammable. Theyalso exhibit considerable differences withrespect to their boiling points, which is whyall "Low GWP" blends of high volumetricrefrigerating capacity have a substantialtemperature glide (see following section).

BITZER has accumulated extensiveexperience with refrigerant blends.Laboratory and field testing was com-menced at an early stage so that basicinformation was obtained for the opti-mizing of the mixing proportions andfor testing suitable lubricants. Basedon this data, a large supermarket plant– with 4 BITZER semi-hermetics in par-allel – could already be commissionedin 1991.The use of these blends in the mostvaried systems has been state-of-the-art for many years – generally withgood experiences.

General characteristics of zeotropicblends

As opposed to azeotropic blends (e.g.R502, R507A), which behave as single sub-stance refrigerants with regard to evapora-tion and condensing processes, the phasechange with zeotropic fluids occurs in a"gliding" form over a certain range of tem-perature.

This "temperature glide" can be more orless pronounced, it is mainly dependentupon the boiling points and the percentageproportions of the individual components.Certain supplementary definitions are alsobeing used, depending on the effective val-ues, such as "near-azeotrope" or "semi-azeotrope" for less than 1 K glide.

This means in practice already a smallincrease in temperature in the evaporationphase and a reduction during condensing.In other words, based on a certain pressurethe resulting saturation temperatures differin the liquid and vapour phases (Fig. 13).

To enable a comparison with single sub-stance refrigerants, the evaporating andcondensing temperatures have been oftendefined as mean values. As a consequencethe measured subcooling and superheatingconditions (based on mean values) areunreal. The effective result – related to dewand bubble temperature – is less in eachcase.

14

Fig. 13 Evaporating and condensing behavior of zeotropic blends Fig. 14 Pressure level of R404A in comparison to R502

Pres

sure

Enthalpy

Temperature glideMean condensing temperatureMean evaporating temperature

Δtgtcmtom

CC1

DD1

A A1

B B1

Isotherms

Δtg

Δtgtcm

tom

Bubble

Line

Dew

line

Pres

sure

[ba

r]

Temperature [˚C]

-40 40 60-20 0 20

25

15

1

20

10

2

4

6

R404A

R502

Refrigerant blends

These factors are very important whenassessing the minimum superheat at thecompressor inlet (usually 5 to 7 K) and thequality of the refrigerant after the liquid receiver.

With regard to a uniform and easily com-prehensible definition of the rated com-pressor capacity, the revised standardsEN12900 and AHRI540 are applied. Evapo-rating and condensing temperatures refer to saturated conditions (dew points).

❏ Evaporating temperature according topoint A (Fig. 13).

❏ Condensing temperature according topoint B (Fig. 13).

In this case the assessment of the effectivesuperheat and subcooling temperatures willbe simplified.

It must however be considered that theactual refrigerating capacity of the systemcan be higher than the rated compressorcapacity. This is partly due to an effectivelylower temperature at the evaporator inlet.

A further characteristic of zeotropic refriger-ants is the potential concentration shiftwhen leakage occurs. Refrigerant loss inthe pure gas and liquid phases is mainlynon-critical. Leaks in the phase changeareas, e.g. after the expansion valve, withinthe evaporator and condenser/receiver areconsidered more significant. It is therefore recommended that solderedor welded joints should be used in thesesections.

Extended investigations have in the mean-time shown that the effect of leakage leadsto less serious changes in concentrationthan was initially thought. It is in any casecertain that the following substances ofsafety group A1 (see page 38) which aredealt with here cannot develop any flam-mable mixtures, either inside or outside thecircuit. Essentially similar operating condi-tions and temperatures as before can onlybe obtained by supplementary chargingwith the original refrigerant in the case of asmall temperature glide.

Further conditions/recommendations con-cerning the practical handling of blendsmust also be considered:

❏ The plant always has to be charged withliquid refrigerant. When vapour is takenfrom the charging cylinder shifts in con-centrations may occur.

❏ Since all blends contain at least oneflammable component, the entry of air into the system must be avoided. A critical shift of the ignition point can occur under high pressure and evacu-ating when a high proportion of air is present.

❏ The use of blends with a significant tem-perature glide is not recommended forplants with flooded evaporators. A largeconcentration shift is to be expected inthis type of evaporator, and as a resultalso in the circulating refrigerant massflow.

15

Service blends

Service blends with thebasic component R22* as substitutes for R502

As a result of the continued refurbishmentof older installations, the importance ofthese refrigerants is clearly on the decline.For some of them, production has alreadybeen discontinued. However, for develop-ment-historic reasons of service blends,these refrigerants will continue to be cov-ered in this Report.

These refrigerants belong to the group of"Service blends" and are offered under thedesignations R402A/R402B* (HP80/ HP81– DuPont), R403A/R403B* (formerlyISCEON 69S/69L) and R408A* (“Forane”FX10 – Arkema).

The basic component is in each case R22,the high discharge gas temperature ofwhich is significantly reduced by the addi-tion of chlorine free substances with lowisentropic compression exponent (e.g.R125, R143a, R218). A characteristic fea-ture of these additives is an extraordinarilyhigh mass flow, which enables the mixtureto achieve a great similarity to R502.

R290 (Propane) is added as the third com-ponent to R402A/B and R403A/B to improve

miscibility with traditional lubricants ashydrocarbons have especially good solu-bility characteristics.

For these blends two variations are offeredin each case. When optimizing the blendvariations with regard to identical refrigerat-ing capacity as for R502 the laboratorymeasurements showed a significantly in-creased discharge gas temperature (Fig.15), which above all, with higher suctiongas superheat (e.g. supermarket use) leadsto limitations in the application range.

On the other hand a higher proportion ofR125 or R218, which has the effect of re-ducing the discharge gas temperature tothe level of R502, results in somewhat high-er cooling capacity (Fig. 16).

With regard to material compatibility theblends can be judged similarly to (H)CFCrefrigerants. The use of conventional refrig-eration oil (preferably semi or full synthetic) isalso possible due to the R22 and R290proportions.

Apart from the positive aspects there arealso some disadvantages. These sub-stances can also only be seen as alterna-tives for a limited time. The R22 proportionhas (although low) an ozone depletion poten-tial. The additional components R125,

R143a and R218 still have a high globalwarming potential (GWP).

Resulting design criteria/Converting existing R502 plants

The compressor and the components whichare matched to R502 can remain in the sys-tem in most cases. The limitations in theapplication range must however be con-sidered: Higher discharge gas temperatureas for R502 with R402B**, R403A** andR408A** or higher pressure levels withR402A** and R403B**.

Due to the good solubility characteristics ofR22 and R290 an increased danger exists,that after conversion of the plant, possibledeposits of oil decomposition productscontaining chlorine may be dissolved andfind their way into the compressor and reg-ulating devices. Systems where the chemi-cal stability was already insufficient withR502 operation (bad maintenance, low driercapacity, high thermal loading) are particu-larly at risk.

* When using blends containing R22 legal regu-lations are to be observed, see also page 8.

** Classification according to ASHRAE nomenclature.

Fig. 15 Effect of the mixture variation upon the discharge gas temperature (example: R22/R218/R290)

Fig. 16 Comparison of the performance data of a semi-hermetic compressor

Disc

harg

e g

as te

mp.

[˚C

]

Content of R218 [%]

170

0 6020 40

165

150

115

120

130

140

R403

A

R403

B

R502

totctoh

R22

-35°C40°C20°C

145

155

135

125

160

Com

paris

on o

f per

form

ance

[%] 110

105

100

95

90

85

to

tc

toh

-35°C

40°C

20°C

115

Qo COP

R50

2

R40

2A (H

P80)

R40

2B (H

P81)

R40

3B (6

9L)

R40

3A (6

9S)

R40

8A (F

X10)

R40

3B (6

9L)

R40

3A (6

9S)

R40

8A (F

X10)

R50

2

R40

2A (H

P80)

R40

2B (H

P81)

16

Before conversion generously dimensionedsuction gas filters and liquid line driersshould therefore be fitted for cleaning andafter approximately 100 hours operation anoil change should be made; further checksare recommended.

The operating conditions with R502 (in-cluding discharge gas temperature andsuction gas superheat) should be noted sothat a comparison can be made with thevalues after conversion. Depending uponthe results regulating devices should possi-bly be reset and other additional measuresshould be taken as required.

Supplementary BITZER informationconcerning the use of retrofit blends(see also http://www.bitzer.de)

❏ Technical Information KT-650 “Retrofitting of R12 and R502refrigerating systems to alterna-tive refrigerants”

Service blends as substitutes for R12 (R500)

Although as experience already shows,R134a is also well suited for the conversionof existing R12 plants, the general use forsuch a "retrofit" procedure is not alwayspossible. Not all compressors which havepreviously been installed are designed forthe application with R134a. In addition aconversion to R134a requires the possibilityto make an oil change, which is for exam-ple not the case with most hermetic typecompressors.

Economical considerations also arise, espe-cially with older plants where the effort inconverting to R134a is relatively high. Thechemical stability of such plants is alsooften insufficient and thus the chance ofsuccess is very questionable.Therefore "Service blends" are also avail-able for such plants as an alternative toR134a and are offered under the designa-tions R401A/R401B (MP39/MP66 – DuPont),R409A (“Forane” FX56 – Arkema, Solvay).

Service blends

The main components are the HCFC re-frigerants R22, R124 and/or R142b. Either HFC R152a or R600a (Isobutane) is used as the third component. Operationwith traditional lubricants (preferably semior full synthetic) is also possible due to themajor proportion of HCFC.

A further service blend was offered underthe designation R413A (ISCEON49 –DuPont), but replaced by R437A by the endof 2008. However, for development-historicreasons of service blends, R413A will con-tinue to be covered in this Report. The con-stituents of R413A consist of the chlorinefree substances R134a, R218, and R600a.In spite of the high R134a content the useof conventional lubricants is possible be-cause of the relatively low polarity of R218and the favourable solubility of R600a.

R437A is a blend of R125, R134a, R600and R601 with similar performance andproperties as R413A. This refrigerant alsohas zero ODP.

However, due to the limited miscibility ofR413A and R437A with mineral and alkyl-benzene oils, oil migration may result insystems with a high oil circulation rateand/or a large liquid volume in the receiver –for example if no oil separator is installed.

If insufficient oil return to the compressor isobserved, the refrigerant manufacturer rec-ommends replacing part of the original oilcharge with ester oil. But from the compres-sor manufacturer's view, such a measurerequires a very careful examination of thelubrication conditions. For example, if in-creased foam formation in the compressorcrankcase is observed, a complete changeto ester oil will be necessary. Moreover,under the influence of the highly polarizedblend of ester oil and HFC, the admixture ofor conversion to ester oil leads to increaseddissolving of decomposition products anddirt in the pipework. Therefore, generouslydimensioned suction clean-up filters must be provided. For further details, see the refrigerant manu-facturer's "Guidelines".

Resulting design criteria/Converting existing R12 plants

Compressors and components can mostlyremain in the system. However, when us-ing R413A and R437A the suitability mustbe checked against HFC refrigerants. Theactual "retrofit" measures are mainly re-stricted to changing the refrigerant (possiblyoil) and a careful check of the superheatsetting of the expansion valve. A significant temperature glide is presentdue to the relatively large differences in theboiling points of the individual substances,which demands an exact knowledge of thesaturation conditions (can be found fromvapour tables of refrigerant manufacturer) inorder to assess the effective suction gassuperheat.

In addition the application range must alsobe observed.Different refrigerant types are required forhigh and low evaporating temperatures ordistinct capacity differences must be con-sidered (application ranges see page 40).This is due to the steeper capacity charac-teristic, compared to R12.

Due to the partially high proportion of R22especially with the low temperature blends,the discharge gas temperature with somerefrigerants is significantly higher than withR12. The application limits of the compres-sor should therefore be checked beforeconverting.The remaining application criteria are simi-lar to those for the substitute substancesfor R502 which have already been men-tioned.

* By using R22 containing blends the legal require-ments are to be followed, see also page 8.

Supplementary BITZER informationconcerning the use of retrofit blends(see also http://www.bitzer.de)

❏ Technical Information KT-650“Retrofitting of R12 and R502 refrigerating systems to alternativerefrigerants”

17

HFC Alternatives for R502 and R22

R404A and R507A assubstitutes for R502and R22

These blends are chlorine free substitutes(ODP = 0) for R502 as well as for R22 inmedium and low temperature ranges.

A composition which was already launchedat the beginning of 1992 is known underthe trade name "Suva" HP62 (DuPont).Long term use has shown good results.Further blends were traded as "Forane"FX70 (Arkema) and "Genetron" AZ50 (AlliedSignal/Honeywell) or "Solkane" 507 (Solvay). In the mean time HP62 and FX70 havebeen listed in the ASHRAE nomenclature as R404A and AZ50 as R507A.

The basic components belong to the HFCgroup, where R143a belongs to the flam-mable category. Due to the combinationwith a relatively high proportion of R125 theflammability is effectively counteracted andalso in the case of leakage.

A feature of all three ingredients is the verylow isentropic compression exponent whichresults in a similar, with even a tendency tobe lower, discharge gas temperature toR502 (Fig. 17). The efficient application ofsingle stage compressors with low evapo-rating temperatures is therefore guaranteed.

Fig. 17 R404A/R502 – comparison of discharge gas temperatures of a semi-hermetic compressor

Fig. 18 Comparison of performance data of a semi-hermetic compressor

Disc

harg

e ga

s te

mp.

of R

404A

– re

lativ

e di

ffere

nce

to R

502

[K]

Evaporating [˚C]

-20-40 -30 -20 -10

tc 55°C

tc 40°C

toh 20°C

-10

0

+10

Com

paris

on o

f per

form

ance

[%]

100

95

90

80

to

tc

toh

-35°C

40°C

20°C

105

Qo

85

COP

R50

2

R40

4A

R50

7A

R50

2

R40

4A

R50

7A

Due to the similar boiling points for R143aand R125, with a relatively low proportionof R134a, the temperature glide with theternary blend R404A within the relevantapplication range is less than one Kelvin.The characteristics within the heat ex-changers are not therefore very different aswith azeotropes. The results obtained so farfrom heat transfer measurements showfavourable conditions.

R507A is a binary substance combinationwhich even gives an azeotropic characteris-tic over a relatively wide range. The condi-tions therefore tend to be even better.

The performance found in laboratory tests(Fig. 18) gives hardly any difference be-tween the various substances and show alarge amount of agreement with R502. Thisalso explains the high market penetration ofthese substitutes – they are essentially"standard" in commercial refrigeration sys-tems in Europe and North America.

Questions concerning material compatibilityare manageable; experience with otherHFCs justifies a positive assessment. POEoils can be used as lubricants; the suitabilityof various alternatives is being investigatedas well (see pages 9/10).

The relatively high global warming potential(GWP100 = 3922…3985) which is mainlydetermined by the R143a and R125 is

something of a hitch. It is however improvedcompared to R502 and with regard to thefavourable energy demand also leads to areduction of the TEWI value. Other improve-ments are possible in this respect due tofurther developed system control.

Nevertheless, due to their high globalwarming potential (GWP), the use of R404Aand R507A will no longer be allowed in theEU in new installations from 2020. This hasalready been settled in the F-Gas Regula-tion No. 517/2014 to be applied from 2015.However, the concurrent requirement onthe phase-down in connection with a strictquota system will lead to an earlier phase-out in many applications. For more detailedinformation, please refer to BITZERbrochure A-510.

In the US there are also initiatives (EPA rec-ommendation) to phase out R404A andR507A from 2016. Other regions will proba-bly follow.

Alternatives with lower GWP are the HFCblends dealt with in the following (frompage 18) as well as HFO/HFC blends beingdeveloped and evaluated (from page 24).

Halogen free refrigerants or cascade systems using different refrigerants are also an option for specific applications(from page 27).

18

R407A/R407B/R407F as substitutes for R502 and R22

Alternatively to the earlier described substi-tutes additional mixture versions have beendeveloped based on R32 which is chlorinefree (ODP = 0) and flammable like R143a. The refrigerant R32 is also of the HFC typeand initially seen as a candidate for R22alternatives (page 20). However, due to ex-tent of blend variations comparable thermo-dynamic characteristics to R404A/R507Acan also be obtained.

Such kind of refrigerants were at first in themarket under the trade name KLEA 60/61(ICI) and are listed as R407A/R407B* in theASHRAE nomenclature.

Honeywell has developed another blendwith the trade name Performax LT (R407Faccording to ASHRAE nomenclature) andintroduced it into the market. The R32share is ten percentage points higher thanthe one in R407A while the R125 propor-tion is lower accordingly.

The necessary conditions, however, foralternatives containing R32 are not quite asfavourable compared to the R143a basedsubstitutes as dealt with earlier. The boilingpoint of R32 is very low at -52°C, in addi-

tion the isentropic compression exponent iseven higher than with R22. To match thecharacteristics at the level of R404A andR507A therefore requires relatively high pro-portions of R125 and R134a. The flamma-bility of the R32 is thus effectively suppressed,at the same time the large differences in theboiling points with a high proportion ofR134a leads to a larger temperature glide.

The main advantage of R32 is the extra-ordinarily low global warming potential(GWP100 = 675) so that even in combina-tion with R125 and R134a it is significantlylower than with the R143a based alterna-tives mentioned above (R407A: GWP100 =2107, R407F: GWP100 = 1825).

With that they also comply with the require-ment of the new EU F-Gas Regulationwhich from 2020 will only allow refrigerantsof GWP < 2500.

Measurements made with R32 containingblends do show certain capacity reductionscompared to R404A and R507A, with lowevaporating temperatures, the COP howev-er shows less deviation and is even higherin medium temperature applications (Fig. 20).

* Meanwhile, R407B is no longer available in the mar-ket. Due to the historical development of HFCblends this refrigerant will, however, still be consid-ered in this Report.

Resulting design criteria

The system technology can be based onthe experience with R502 over a wide area.On the thermodynamic side, a heat ex-changer between the suction and liquid lineis recommended as this will improve therefrigerating capacity and COP.

BITZER offers the whole program ofreciprocating, scroll and screw com-pressors for these blends.

Converting existing (H)CFC plants

Experience gained in investigative programsshows that qualified conversions are pos-sible. However, major expenditure may benecessary depending on the system de-sign.

Supplementary BITZER informationconcerning the use of HFC blends(see also http://www.bitzer.de)

❏ Technical Information KT-651 "Retro-fitting of R22 systems to alternativerefrigerants"

❏ Technical Information KT-510 “Polyolester oils for reciprocatingcompressors”

HFC Alternatives for R502 and R22

Fig. 19 R407A, R407F/R404A – comparison of discharge gas temperature of a semi-hermetic compressor

Fig. 20 Comparison of performance data of a semi-hermetic compressor

Disc

harg

e ga

s te

mp.

of R

407A

/F –

rela

tive

diffe

renc

e to

R40

4A [K

]

Evaporation [˚C]

-40 -30 -20 00

10

R407A

40°Ctc

R407F

20

30

40

50

-10

Com

paris

on o

f per

form

ance

[%]

Qo

100

95

90

75

totctoh

-10°C

45°C

20°C

105

80

COP

R40

4A

R40

7A

R40

7F

R40

4

R40

7A

R40

7F

19

Whether these favourable conditions areconfirmed in real applications is subject to the system design.

An important factor is the significant tem-perature glide which can have a negativeinfluence upon the capacity/temperaturedifference of the evaporator and condenser.With regard to the material compatibility,R32 blends can be assessed similarly toR404A and R507A; the same applies to thelubricants.

Despite the relatively high proportion ofR125 and R134a in the R32 blends the dis-charge gas temperature is higher than withthe R143a based alternatives. This is inparticular valid for R407F. As a result cer-tain limitations occur in the applicationrange as well as the requirement for addi-tional cooling of compressors when operat-ing at high pressure ratios.

2-stage compressors can be applied veryefficiently where especially large lift condi-tions are found. An important advantagethereby is the use of a liquid subcooler.

Resulting design criteria

The experience with R404A/R507A andR22 can be used for the plant technologyin many respects, considering the tempera-ture glide as well as the difference in the thermodynamic properties.

Converting existing R22 plants

Practical experiences show that qualifiedconversions are possible. Compared to R22the volumetric refrigeration capacity is near-ly similar while the refrigerant mass flow isonly slightly higher. These are relativelyfavourable conditions for the conversion ofmedium and low temperature R22 systems.

The main components can remain in thesystem provided that they are compatiblewith HFC refrigerants and ester oils. How-ever, special requirements placed on theheat exchanger with regard to the signifi-cant temperature glide must be considerd.A conversion to ester oil is also necessary,which leads to increased dissolving ofdecomposition products and dirt in thepipework. Therefore, generously dimen-sioned suction clean-up filters must be pro-vided.

R422A as substitute for R502 and R22

Amongst other aims, R422A (ISCEONMO79 – DuPont) was developed in order toobtain a chlorine-free refrigerant (ODP = 0)for the simple conversion of existing mediumand low temperature refrigeration systemsusing R502 and R22.

For this, it was necessary to formulate arefrigerant with comparable performanceand energy efficiency to that of R404A,R507A, and R22, which also permits theuse of conventional lubricants.

This pertains to a zeotropic blend of thebasic components R125 and R134a with asmall addition of R600a. Due to its relativelyhigh R134a percentage, the temperatureglide (Fig. 34) lies higher than for R404A,but lower than other refrigerants with thesame component blends – such as R417Aand R422D (see page 22).

The adiabatic exponent, compared toR404A and R507A, is smaller and thereforethe discharge gas and oil temperatures ofthe compressor, too. Under extreme lowtemperature conditions this can be advan-tageous. In cases of low pressure ratio and

suction gas superheat this can be negativedue to increased refrigerant solution if esteroil is used.

The material compatibility is comparable tothe blends mentioned previously, the sameapplies to the lubricants, as well. On ac-count of the good solubility of R600a, con-ventional lubricants can also be used underfavourable circumstances.

In particular, advantages result during theconversion of existing R502 and R22 sys-tems as mentioned above. However, forplants with high oil circulation rates and/orlarge liquid charge in the receiver, it is possible for oil migration to occur – for example if no oil separator is installed.

If insufficient oil return to the compressor isobserved, the refrigerant manufacturer rec-ommends replacing part of the original oilcharge with ester oil. But from the com-pressor manufacturer's view, such a meas-ure requires a very careful examination ofthe lubrication conditions. For example, ifincreased foam formation in the compres-sor crankcase is observed, a completechange to ester oil* will be necessary. Un-der the influence of the highly polarizedblend of ester oil and HFC, the admixture ofor conversion to ester oil leads to increaseddissolving of decomposition products anddirt in the pipework. Therefore, generouslydimensioned suction clean-up filters mustbe provided. For further details, see the refrigerant man-ufacturer's "Guidelines".

From a thermodynamic point of view a heatexchanger between suction and liquid lineis recommended, thereby improving thecooling capacity and coefficient of perform-ance. Besides this the resulting increase inoperating temperatures leads to more fa-vourable lubricating conditions (lower solu-bility).

* General proposal for screw compressors and liquidchillers when used with DX evaporators with internal-ly structured heat exchanger pipes. Furthermore, anindividual check regarding possible additional meas-ures will be necessary.

BITZER compressors are suitable forR422A. An individual selection is pos-sible upon demand.

Conversion of R404A/R507A systemsLarger differences in thermodynamic prop-erties (e.g. mass flow, discharge gas tem-perature) and the temperature glide ofR407A/F may require the replacement ofcontrol components and if necessary retro-fitting of additional compressor coolingwhen existing systems are converted. In newly built systems a specific design ofcomponents and system must be made.

BITZER offers a comprehensive programof semi-hermetic reciprocating compres-sors for R407A und R407F.

Supplementary BITZER informationconcerning the use of HFC blends(see also http://www.bitzer.de)

❏ Technical Information KT-651“Retrofitting of R22 systems to alternative refrigerants”

HFC Alternatives for R502 and R22

20

Fig. 21 R407C/R22 – comparison of performance data of a semi-hermetic compressor

Fig. 22 R407C/R22 – comparison of pressure levels

Rela

tion

R407

C to

R22

(=10

0%)

Evaporation [˚C]

80

110

10 20

90

100

85

95

105

-20 -10 0

COP

Q o

tc 40˚C

tc 50˚C

t c 50˚C

t c 40˚C

toh 20˚C

Pres

sure

[ba

r]

Temperature [˚C]

-40 40 60-20 0 20

25

15

1

20

10

2

4

6

R22

R407C

With that R407C also complies with therequirement of the new EU F-Gas Regula-tion which from 2020 will only allow refrig-erants with GWP < 2500.

The high temperature glide is a disadvan-tage for usual applications which requiresappropriate system design and can have anegative influence on the efficiency of theheat exchangers (see explanations onpages 13/14).

Due to the properties mentioned, R407C ispreferably an R22 substitute for air-condi-tioning systems and (within certain limita-tions) also for medium temperature refriger-ation. In low temperature refrigeration, be-cause of the high proportion of R134a, asignificant drop in refrigerating capacity andCOP is to be expected. There is also thedanger of an increased R134a concentra-tion in the blend in evaporators, with con-sequential reduction in performance andmalfunctioning of the expansion valve (e.g.insufficient suction gas superheat).

Material compatibility can be assessed assimilar to that of the blends discussed pre-viously; the same applies to the lubricants.

* Previous trade names are not used any more.

R407C as substitutefor R22

Blends of the HFC refrigerants R32, R125and R134a are seen as the favourite can-didates for shortterm substitution for R22 –their performance and efficiency are verysimilar (Fig. 21). At first two blends of thesame composition have been introducedunder the trade names AC9000* (DuPont)and KLEA66* (ICI). They are listed in theASHRAE nomenclature as R407C. In themeantime there are also further blend vari-eties (e.g. R407A/R407F) with somewhatdiffering compositions, whose propertieshave been optimized for particular applica-tions (see page 18).

Unlike the R502 substitutes with identicalblend components (see pages 18/19), theR22 substitutes under consideration con-tain higher proportions of R32 and R134a. A good correspondence with the propertiesof R22 in terms of pressure levels, massflow, vapour density and volumetric refriger-ating capacity is thus achieved. In addition,the global warming potential is relatively low(GWP100 = 1774), which is a good presup-position for favourable TEWI values.

HFC Alternatives for R22

HFC alternatives for R22

As the HCFC refrigerant R22 (ODP = 0.05)is accepted only as a transitional solution, anumber of chlorine-free (ODP = 0) alternati-ves have been developed and tested exten-sively. They are already being used on alarge range of applications.

Experience shows, however, that none ofthese substitutes can replace the refrigerantR22 in all respects. Amongst others thereare differences in the volumetric refrigerat-ing capacity, restrictions in possible appli-cations, special requirements in systemdesign or also considerably differing pres-sure levels. So various alternatives comeunder consideration according to the par-ticular operating conditions.

Apart from the single-component HFCrefrigerant R134a, these are mainly blends(different compositions) of the componentsR32, R125, R134a, R143a, and R600(a).The following description mainly concernsthe development and potential applicationsof these. The halogen-free substitutes NH3,propane and propylene as well as CO2should also be considered, however, spe-cific criteria must be applied for their use(described from page 27).

21

HFC Alternatives for R22

Fig. 23/1 R410A/R22 – comparison of performance data of a semi-hermetic compressor

Fig. 23/2 R410A/R22 – comparison of pressure levels

Rela

tion

R410

A to

R22

(=10

0%)

Evaporation [˚C]

80

150

10 20-20 -10 0

toh 20˚C

COP

Q o

tc 40˚C

tc 50˚C

tc 50˚C

tc 40˚C

90

140

130

120

110

100

Pres

sure

[ba

r]

Temperature [˚C]

-40 40 60-20 0 20

25

15

20

10

2

4

6

3

35

30

R22

R410A

Resulting design criteria

With regard to system technology, previousexperience with R22 can only be utilized toa limited extent. The distinctive temperatureglide requires a particular design of themain system components, e.g. evaporator,condenser, expansion valve. In this contextit must be considered that heat exchangersshould preferably be laid out for counter-flow operation and with optimized refriger-ant distribution. There are also special re-quirements with regard to the adjustment ofregulating devices and service handling.

Furthermore, the use in systems with flood-ed evaporators is not recommended as thiswould result in a severe concentration shiftand layer formation in the evaporator.

BITZER can supply a widespread rangeof semi-hermetic reciprocating, screwand scroll compressors for R407C.

Converting existing R22 plants

Because of the above mentioned criteria,no general guidelines can be defined. Each case must therefore be examinedindividually.

R410A as substitutefor R22

In addition to R407C, there is a near azeo-tropic blend being offered with the ASHRAEdesignation R410A. It is widely used already,mainly in air conditioning applications.

An essential feature indicates nearly 50%higher volumetric cooling capacity (Fig.23/1) in comparison to R22, but with theconsequence of a proportional rise in sys-tem pressures (Fig. 23/2).

At high condensing temperatures, energyconsumption/COP initially seems to be lessfavourable than with R22. This is mainlydue to the thermodynamic properties. Onthe other hand, very high isentropic efficien-cies are achievable (with reciprocating andscroll compressors), whereby the differ-ences are lower in reality.

Added to this are the high heat transfercoefficients in evaporators and condensersdetermined in numerous test series, withresulting especially favourable operatingconditions. With an optimized design, it isquite possible for the system to achieve abetter overall efficiency than with otherrefrigerants.

Because of the negligible temperature glide(< 0.2 K), the general usability can be seensimilar to a pure refrigerant.

The material compatibility is comparable tothe previously discussed blends and thesame applies for the lubricants. However,the pressure levels and the higher specificloads on the system components need tobe taken into account.

Resulting design criteria

The fundamental criteria for HFC blendsalso apply to the system technology withR410A, however the extreme high pressurelevels have to be considered (43°C con-densing temperature already correspondsto 26 bar abs.).

Compressors and other system compo-nents designed for R22 are not suitable forthis refrigerant or only to a limited extent.

The availability of suitable compressors andsystem components has been secured inthe meantime.

When considering to cover usual R22 appli-cation ranges, the significant differences inthe thermodynamic properties (e.g. pres-sure levels mass and volume flow, vapourdensity) must be evaluated.

22

R427A as a substitute for R22

This refrigerant blend was introduced someyears ago under the trade name ForaneFX100 (Arkema). In the meantime it is listedin the ASHRAE nomenclature as R427A.

The R22 substitute is offered for the con-version of existing R22 systems for which a “Zero ODP” solution is requested. This re-frigerant is an HFC mixture with base com-ponents R32/R125/R143a/R134a.

In spite of the blend composition based onpure HFC refrigerants, the manufacturerstates that a simplified conversion proced-ure is possible.

This is positively influenced by the R143aproportion. Accordingly, when convertingfrom R22 to R427A, all it takes is a re-placement of the original oil charge withester oil. Additional flushing sequences arenot required, as proportions of up to 15%of mineral oil and/or alkyl benzene have nosignificant effect on oil circulation in thesystem.

However, it must be taken into account thatunder the influence of the highly polarizedmixture of ester oil and HFC increased dis-solving of decomposition products and dirtin the pipework is caused. Therefore, gen-erously dimensioned suction clean-up filtersmust be provided.

Regarding refrigerating capacity, pressurelevels, mass flow and vapor density R427Ais relatively close to R22. During retrofitessential components such as expansionvalves can remain in the system.Due to the high proportion of blend compo-nents with low adiabatic exponent the dis-charge gas temperature is considerablylower than with R22 which has a positiveeffect at high compression ratios.

A refrigerant also belonging to the categoryof HFC/HC blends was introduced in 2009under the trade name ISCEON MO99(DuPont) – ASHRAE classification R438A.This formulation was selectively designedfor a higher critical temperature for applica-tions in hot climate areas. The base com-ponents are R32, R125, R134a, R600 andR601a.

Like R407C, all four substitute refrigerantsare zeotropic blends with a more or less sig-nificant temperature glide. In this respect thecriteria described in connection with R407Care also valid.

Apart from similar refrigeration capacitythere are fundamental differences in thermo-dynamic properties and in oil transport be-haviour. The high proportion of R125 caus-es with R417A/B and R422D a higher massflow than with R407C, a lower dischargegas temperature and a relatively high super-heating enthalpy. These properties indicatethat there are differences in the optimizationof system components and a heat exchangerbetween liquid and suction lines is of advan-tage.

Despite the predominant proportion of HFCrefrigerants the use of conventional lubri-cants is possible to some extent becauseof the good solubility properties of thehydrocarbon constituent. However, in sys-tems with a high oil circulation rate and/or a large volume of liquid in the receiver oilmigration may result.

In such cases, additional measures arenecessary. For further information on oilreturn and lubricants, see the previous sec-tion on "R422A as substitute for R502 andR22" (page 19).

BITZER compressors are suitable for thedescribed refrigerants.An individual selection is possible upondemand.

This also requires considerable construc-tional changes to compressors, heat ex-changers, and controls, as well as meas-ures of tuning vibrations.

In addition, safety requirements are con-cerned also affecting the quality and dimen-sions of piping and flexible tube elements(for condensing temperatures of approx.60°C/40 bar).

Another criterion is the relatively low criticaltemperature of 73°C. Irrespective of thedesign of components on the high pressureside, the condensing temperature is thuslimited.

For R410A, BITZER offers a series ofsemi-hermetic reciprocating compres-sors and scroll compressors.

R417A/417B/422D/438Aas substitutes for R22

The same as for R422A (page 19), one of theaims for these developments was to providechlorine-free refrigerants (ODP = 0) for thesimple conversion of existing R22 plants.

R417A was introduced to the market sever-al years ago, and is also offered under thetrade name ISCEON MO59 (DuPont). Thissubstitute for R22 contains the blend com-ponents R125/R134a/R600, and thereforediffers considerably from e.g. R407C with acorrespondingly high proportion of R32.

Meanwhile, a further refrigerant based onidentical components, but with a higherR125 content, has been offered under the trade name Solkane 22L (Solvay) –ASHRAE classification R417B. Due to itslower R134a content, the volumetric refrig-erating capacity as well as the pressure lev-els are higher than with R417A. This resultsin different performance parameters andemphasis in the application range.

The same applies to a further blend with thesame main components, but R600a as hy-drocarbon additive. It is offered under tradename ISCEON MO29 (DuPont) and listed asR422D in the ASHRAE nomenclature.

HFC Alternatives for R22

23

HFC R32

R32 as substitute for R22

As described earlier R32 belongs to the HFCrefrigerants group but initially was mainly usedas a component of refrigerant blends only. Anessential barrier for the application as a puresubstance so far is the flammability classifica-tion in safety group A2L. This requires adequatecharge limitations and/or additional safetymeasures, especially with installations insidebuildings. In addition there are very high pres-sure levels and discharge gas temperatures(compression index higher than with R22 andR410A).

On the other hand R32 has favorable thermo-dynamic properties, e.g. very high evaporatingenthalpy and volumetric refrigerating capacity,low vapor density (low pressure drop in pipe-lines), low mass flow and favorable power in-put for compression. Besides that the globalwarming potential is low (GWP100 = 675).

Looking at these favorable properties andtaking into account the additional and strivedfor emission reductions, R32 will increasingly

Abb. 24 R32/R410A – comparison of performance and operating data of a scroll compressor

Rela

tive

com

paris

on [%

]

Qo

100

90

80

60

totcΔtoh

5°�C50°�C10 K110

70

COP

120

40

50

pc qm

Disc

harg

e ga

s te

mpe

ratu

re [°

�C]

Qo Refrigerating capacityCoefficient of performanceCondensing pressureRefrigerant mass flow

COPpcqm

60

80

100

120

R32

R41

0A

R32

R41

0A

also be used as a refrigerant in factory pro-duced systems (A/C units and heat pumps)with low refrigerant charges. Concerning safe-ty requirements the regulations (e.g. accord-ing to EN 378) for A2 refrigerants are still validalthough it was proven in flammability teststhat the necessary ignition energy is very highand the flame speed is low. Based on theseproperties R32 (like R1234yf and R1234ze)has been put into the new safety group A2Laccording to ISO 817.

To what extent the safety demands for A2Lrefrigerants (as opposed to A2) can be re-lieved in future can not finally be judged to-day. Therefore, individual risk analyses are re-quired.

BITZER scroll compressors of seriesGSD6/GSD8 can be delivered for labora-tory tests with R32. A customizeddesign is available upon request.

It must be taken into account that this isalso a zeotropic blend with a distinct tem-perature glide. Therefore the criteria asdescribed in context with R407C are validhere as well.

BITZER compressors are suitable forR427A. An individual selection is pos-sible upon demand.

Supplementary information concerningthe use of HFC blends(see also http://www.bitzer.de)

❏ Technical information KT-651 “Retrofitting R22 systems to alternative refrigerants”

24

HFO/HFC blends

HFO/HFC blends as alternatives to HFCs

Due to the decision with the use of the"Low GWP" refrigerant HFO-1234yf (seepages 11/12) in automotive air-conditioningsystems, the development of alternativesfor other mobile applications and stationarysystems has meanwhile also been initiated.

The primary goals are the formulation ofblends with significantly reduced GWPwhile maintaining similar thermodynamicproperties to those of the HFCs used pre-dominantly today.

The base components are the refrigerantsR1234yf and R1234ze(E), which belong tothe group of hydro fluoro olefins (HFO) witha chemical double bond. Due to their com-bination of properties, they are characteri-zed as preferred candidates. However, bothrefrigerants are flammable (safety groupA2L). Moreover, their volumetric refrigerat-ing capacity is low. That of R1234yf isapproximately at the level of R134a andthat of R1234ze(E) is even more than 20%lower.

The list of additional potential refrigerantsfrom the HFO group is relatively long. How-ever, there are only few substances thatmeet the requirements in terms of thermo-dynamic properties, flammability, toxicity,chemical stability, compatibility with materi-als and lubricants. They include, for exam-ple, low-pressure refrigerants such asR1336mzzZ (DuPont DR-2) and R1233zd(E)which, however, are primarily an option forchillers with large centrifugal compressorsor can be used with positive displacementcompressors in high temperature applica-tions. Furthermore, R1233zd(E) has a (very)low ozone depleting potential (ODP), whichmay lead to restrictions in its use.

On the other hand, currently there are nosuitable candidates of similar volumetricrefrigerating capacity as R22/R407C,R404A/R507A and R410A with prospectsfor commercial application. Direct alterna-tives for these refrigerants of significantlylower GWP must therefore be "formulated"as a blend of R1234yf and/or R1234ze(E)with HFC refrigerants, and possible smallproportions of hydrocarbons.

However, due to the properties of the HFCrefrigerants suitable as blend components,flammability and GWP are related diametri-cally to one another. In other words:Blends as alternatives to R22/R407C ofGWP < approx. 900 to 1000 are flamma-ble. This is also true with alternatives forR404A/R507A and R410A in blends ofGWP < approx. 1300 to 1400. The reasonfor this is the high GWP of each of the re-quired non-flammable components.For R134a alternatives, the situation ismore favorable. Due to the already relative-ly low GWP of R134a, a blend with R1234yfand/or R1234ze(E) enables a formulation ofnon-flammable refrigerants with a GWP ofapprox. 600.

Currently there are two directions of devel-opment:❏ Non-flammable HFC alternatives

(blends) with GWP values according tothe above mentioned limits – safetygroup A1. Regarding safety require-ments these refrigerants can then beutilized the same way as currently usedHFCs

❏ Flammable HFC alternatives (blends)with GWP values below the above men-tioned possible limits – according tosafety group A2L (for refrigerants of lowflammability). See also explanations onpage 11.

Among others this group of refrigerants isthen subject to charge limitations accord-ing to today's requirements for A2 refriger-ants.

To what extent the safety requirements forA2L refrigerants (compared to A2) can berelieved, can only be assessed by individ-ual risk analyses.

Non-flammable R134a alternatives

As mentioned before, the most favorablestarting situation for developing non-flam-mable blends exists for R134a alternatives.

For them, GWP values of approx. 600 canbe achieved. This is less than half com-pared with R134a (GWP100 = 1430). Inaddition to that, this type of blend versionscan have azeotropic properties, which iswhy they can be used like pure refrigerants.

For quite some time a blend has been test-ed on a large scale in real systems – thiswas developed by DuPont, and is calledOpteon® XP-10. Results available todayare promising.

This is also true for an R134a alternativedesignated Solstice N-13 and offered byHoneywell which, however, differs regard-ing the blend composition.

Meanwhile the refrigerants are listed in theASHRAE nomenclature under R513A(DuPont) and R450A (Honeywell).

The same category also includes the refrig-erant blends ARM-42 (ARKEMA) as well asAC5X (Mexichem).

All options have refrigerating capacity, powerinput, and pressure levels similar to R134a.As a result components and system tech-nology can be taken over. Just minorchanges like e.g. superheat adjustment ofthe expansion valves is necessary.

Polyolester oils are suitable lubricantswhich must meet special requirements,e.g. for the utilization of additives.

Very favorable perspectives arise in super-market applications in the medium tem-perature range in a cascade with CO2 forlow temperature, just as in liquid chillerswith higher refrigerant charges where theuse of flammable or toxic refrigerants wouldrequire comprehensive safety measures.

Alternatives for R22/R407C,R404A/R507A and R410A

Since the available HFO molecules(R1234yf und R1234ze) show a consider-ably smaller volumetric refrigerating capaci-ty compared to the above mentioned HFCrefrigerants, for the particular alternativesrelatively large HFC proportions with highvolumetric refrigerating capacity must beadded. The potential list of candidates israther limited. R32 with relatively low GWPis one option. However, a negative aspectis its flammability (A2L), resulting also in aflammable blend upon adding fairly largeproportions in order to increase the volu-metric refrigerating capacity while maintai-ning a favorable GWP.

25

HFO/HFC blends

Current "Low GWP" Alternatives for HFC refrigerantsHFC refrigerant

ASHRAE Trade Name Composition GWP Safety GroupNumber (with blends) (AR4)

R513A Opteon® XP10 DuPont R1234yf/134a 631 A1R450A Solstice N-13 Honeywell R1234ze(E)/134a 601 A1

R134a – AC5X Mexichem R32/1234ze(E)/134a 620 A1(GWP 1430) R1234yf various – 4 A2L

R1234ze(E) various – 7 A2L– ARM-42 Arkema R1234yf/152a/134a < 150 A2L

R449A Opteon® XP40 DuPont R32/125/1234yf/134a 1397 A1R448A Solstice N-40 Honeywell R32/125/1234yf/1234ze(E)/134a 1386 A1– ARM-32b Arkema not disclosed ~ 1400 A1– LTR4X Mexichem R32/125/1234ze(E)/134a 1295 A1

R404A/R507A R452A Opteon® XP44 DuPont R32/125/1234yf 2140 A1(GWP 3922/3985) – ARM-35 Arkema not disclosed ~ 2150 A1

– Opteon® XL40 DuPont R32/1234yf 246 A2L– Solstice L4F Honeywell not disclosed 145 A2L – ARM-20a/20b Arkema not disclosed < 150 / ~ 250 A2L – ARM-25 Arkema not disclosed < 150 A2

– DR-91 DuPont not disclosed 949 A1 – Solstice N-20 Honeywell R32/125/1234yf/1234ze(E)/134a 975 A1 R22/R407C – ARM-32c Arkema not disclosed ~ 1350 A1(GWP 1810/1774) – DR-3 DuPont R32/1234yf 148 A2LR444B Solstice L-20 Honeywell R32/152a/1234ze(E) 294 A2L

R32 various – 675 A2L– Opteon® XL41 DuPont R32/1234yf 466 A2LR410A R447A Solstice L-41 Honeywell R32/125/1234ze(E) 582 A2L (GWP 2088) – ARM-71a Arkema not disclosed < 500 A2L– HPR1D Mexichem R32/R1234ze(E)/CO2 407 A2L

Actual Alternatives Components / Mixture components "Low GWP" alternativesHFC Refrigerants

Safety GWP R1234yf R1234ze(E) R32 R152a R134a R125 CO2 R290Group A2L A2L A2L A2 A1 A1 A1 A3

GWP 4 7 675 124 1430 3500 1 3

A1 ~ 600 ✔ ✔ ✔ ✔R134a A2L < 150 ✔ ✔ ✔ ✔(GWP 1430) A2L < 10 ✔ ✔

A1 < 2500 ✔ ✔ ✔ ✔A1 < 1400 ✔ ✔ ✔ ✔ ✔R404A/R507A A2L < 250 ✔ ✔ ✔ ✔(GWP 3922/3985) A2L < 150 ✔ ✔A2 < 150 ✔ ✔ ✔

A1 900..1400 ✔ ✔ ✔ ✔ ✔R22/R407C A2L < 250 ✔ ✔ ✔(GWP 1810/1774) A2L < 150 ✔ ✔

A2 < 150 ✔ ✔ ✔

R410A A2L < 750 ✔(GWP 2088) A2L < 500 ✔ ✔ ✔ ✔

Abb. 25/2 "Low GWP" Alternatives for HFC refrigerants

3

1

1

2

3

4

2

The relatively low GWP allows the use of R134a also longer term Significantly lower refrigerating capacity than reference refrigerantA number of refrigerants listed above are declared by the manufacturer as development products. This is subject for possible changes in composition and product nameAR4: according to IPCC IV

➔➔

2 2

1

3

3

Abb. 25/1 Potential mixture components for "Low GWP" alternatives (Examples)

1

2

3

Refrigerating capacity, mass flow, discharge gas temperature similar to R404AOnly low percentage – due to temperature glide (CO2) and flammability (R290)Significantly lower refrigerating capacity than reference refrigerant

4

26

HFO/HFC blends

On the other hand, when formulating as anon-flammable blend a relatively large pro-portion of refrigerants with high fluoric con-tent (e.g. R125) must be added whichallows the flammability to be suppressed. A drawback here is the relatively high GWPof these chemicals. This results in GWPvalues of more than approx. 900 for non-flammable R22/R407C alternatives andmore than approx. 1300 with options forR404A/R507A. Compared to R404A/R507A, however, this means a reductiondown to a third.

The future drastic phase-down of F-Gases,e.g. as part of the EU F-Gas Regulation,leads already today to a demand for R404A/R507A substitutes with GWP values clearlybelow 500. Although this is possible withan adequate composition of the blend(high proportions of HFO, R152a, possiblyalso hydrocarbons), the disadvantage willbe its flammability (safety groups A2L orA2). In this case, the application will havehigher safety requirements and the need ofan adequately adjusted system technology.

For R410A there is no non-flammable alter-native on the horizon. Either R32 (see page23) as pure substance or blends of R32and HFO can be used for this. Due to itshigh volumetric refrigerating capacity thisrequires a very high proportion of R32,which is why only GWP values in the rangefrom approx. 400 to 600 can be achieved.With a higher HFO proportion, the GWPcan be reduced even further, but at the costof a clearly reduced refrigerating capacity.

All blend options described above show amore or less distinct temperature glide dueto significant boiling point differences. Thesame criteria apply as described in contextwith R407C.

Beyond that the discharge gas temperatureof most R404A/R507A alternatives is con-siderably higher compared to the corre-sponding HFC blends.

In single stage low temperature systemsthis may lead to restrictions in the com-pressor application range or require specialmeasures for additional cooling.

In transport applications or in low tempera-ture systems with smaller condensing units,the compressors used can often not meetthe required operating ranges, due to thehigh discharge gas temperatures. This iswhy refrigerant blends on basis of R32 andHFO with a relatively high proportion ofR125 have also been developed. The GWPis slightly above 2000, but below the limitof 2500 set in the EU F-Gas Regulationfrom 2020. The main advantage of suchblends is their moderate discharge gastemperature, which allows the operationwithin the typical application limits of R404A.

Fig. 25/1 shows an overview of the poten-tial blend components for the alternativesdescribed above. With some refrigerantsthe mixture components for R22/R407Cand R404A/R507A substitutes are identicalbut their distribution in percent is different.

Meanwhile suitable blend versions for labo-ratory tests, some of them also for fieldtests or real applications are being offeredprimarily by DuPont, Honeywell, Arkemaand Mexichem. A series of refrigerants arestill to be considered development pro-ducts, which for various reasons are notyet distributed commercially. Until nowtrade names are mainly used althoughsome HFO/HFC blends are already listed inthe ASHRAE nomenclature.

Fig. 25/2 lists a range of currently availablerefrigerants or refrigerants declared asdevelopment products. For some of themthe blend components are also given. Dueto the large number of different versionsand the potential changes in developmentproducts, BITZER has so far tested onlysome of the new refrigerants. This is whyin the tables on pages 38/39 (Fig. 33/34)for the time being only refrigerant proper-ties of non-flammable alternatives forR134a and R404A/R507A (GWP < 1500)are listed which have already received anASHRAE number.

For testing the "Low GWP" refrigerantsAHRI (USA) has initiated a test programentitled "Alternative Refrigerants EvaluationProgram (AREP)". It was established to

investigate and evaluate a series of theproducts including halogen-free refrige-rants. A part of them is also listed in Fig.25/2. The first phase of the project hasbeen completed, and further investigationsincluding those in special applications havealready been initiated.

From a compressor manufacturer’s pointof view there should be an aim for limitingthe product variety currently becomingapparent and to reduce the future offer toa few "standard refrigerants". It will not bepossible for component and equipmentmanufacturers nor for installers and servi-ce companies to deal in practice with alarger range of alternatives.

BITZER is strongly involved in variousprojects dealing with HFO/HFC blendsand has already gained important know-ledge in the use of these refrigerants.Semi-hermetic reciprocating compres-sors of the ECOLINE series and CS. andHS. Screw compressors can be usedwith the new refrigerant generation inlaboratory and field tests. Scroll com-pressors of series GSD6/GSD8 havebeen released for laboratory tests withR32 or R32/HFO blends. An individual compressor selection ispossible on demand.For further information see brochure A-510, section 6 and brochure No. 378 20 386.

27

Halogen free refrigerants

NH3 (Ammonia) as alternative refrigerant

The refrigerant NH3 has been used for morethan a century in industrial and larger re-frigeration plants. It has no ozone depletionpotential and no direct global warming po-tential. The efficiency is at least as good aswith R22, in some areas even more favour-able; the contribution to the indirect globalwarming effect is therefore small. In addition it is incomparably low in price.Summarized, is this then an ideal refrigerantand an optimum substitute for R22 or analternative for HFCs!? NH3 has indeed verypositive features, which can also be mainlyexploited in large refrigeration plants.

Unfortunately there are also negative as-pects, which restrict the wider use in thecommercial area or require costly andsometimes new technical developments.

A disadvantage with NH3 is the high isen-tropic exponent (NH3 = 1.31 / R22 = 1.19 /R134a = 1.1), that results in a dischargetemperature which is even significantly hig-her than that of R22. Single stage compres-sion is therefore already subject to certainrestrictions below an evaporating tempera-ture of around -10°C.

The question of suitable lubricants is also notsatisfactorily solved for smaller plants insome kinds of applications. The oils usedpreviously were not soluble with the refriger-ant. They must be separated with complextechnology and seriously limit the use of"direct expansion evaporators" due to thedeterioration in the heat transfer.

Special demands are made on the thermalstability of the lubricants due to the highdischarge gas temperatures. This is espe-cially valid when automatic operation is considered where the oil should remain foryears in the circuit without losing any of itsstability.

NH3 has an extraordinarily high enthalpydifference and as a result a relatively smallcirculating mass flow (approximately 13 to15% compared to R22). This feature which

is favourable for large plants makes thecontrol of the refrigerant injection more diffi-cult with small capacities.

A further criteria which must be consideredis the corrosive action on copper contain-ing materials; pipe lines must therefore be made in steel. Apart from this the de-velopment of motor windings resistant toNH3 is also hindered. Another difficulty arises from the electrical conductivity of the refrigerant with higher moisture content.

Additional characteristics include toxicityand flammability, which require special safe-ty measures for the construction and oper-ation of such plants.

Resulting design and construction criteria

Based on the present "state of technology",industrial NH3 systems demand totally diffe-rent plant technology, compared to usualcommercial systems.

Due to the insolubility with the lubricatingoil and the specific characteristics of therefrigerant, high efficiency oil separatorsand also flooded evaporators with gravity or pump circulation are usually employed.Because of the danger to the public and tothe product to be cooled, the evaporatoroften cannot be installed directly at the coldspace. The heat transport must then takeplace with a secondary refrigerant circuit.

Two stage compressors or screw compres-sors with generously sized oil coolers, mustalready be used at medium pressure ratios,due to the unfavorable thermal behaviour.

Refrigerant lines, heat exchangers and fit-tings must be made of steel; larger sizepipe lines are subject to examination by acertified inspector.

Corresponding safety measures and alsospecial machine rooms are required de-pending upon the size of the plant and therefrigerant charge.

The refrigeration compressor is usually of"open" design, the drive motor is a separ-ate component.

These measures significantly increase the expenditure involved for NH3 plants,especially in the medium and smaller cap-acity area.

Efforts are therefore being made world-wideto develop simpler systems which can alsobe used in the commercial area.

A part of the research programs is dealingwith part soluble lubricants, with the aim ofimproving oil circulation in the system. Sim-plified methods for automatic return of non-soluble oils are also being examined as analternative.

BITZER is strongly involved in theseprojects and has a large number ofcompressors operating. The experi-ences up to now have revealed thatsystems with part soluble oils are diffi-cult to govern. The moisture content inthe system has an important influenceon the chemical stability of the circuitand the wear of the compressor. Be-sides, high refrigerant solution in the oil(wet operation, insufficient oil tempera-ture) leads to strong wear on the bear-ings and other moving parts. This isdue to the enormous volume changewhen NH3 evaporates in the lubricatedareas.These developments are being continued.The emphasis is also on alternativesolutions for non-soluble lubricants.

Besides to this various equipment manufac-turers have developed special evaporators,where the refrigerant charge can be signifi-cantly reduced.

In addition to this there are also develop-ments for the "sealing" of NH3 plants. Thisdeals with compact liquid chillers (chargebelow 50 kg), installed in a closed containerand partly with an integrated water reser-voir to absorb NH3 in case of a leak. Thistype of compact unit can be installed inareas which were previously reserved forplants with halogen refrigerants due to thesafety requirements.

28

Halogen free refrigerants

Fig. 26/1 Comparison of discharge gas temperatures Fig. 26/2 NH3/R22 – comparison of pressure levels

Disc

harg

e ga

s te

mpe

ratu

re [

˚C]

Evaporation [˚C]

-40 10-20 040

60

140

100

80

tc

Δtohη

40°C10K0.8

R290

R134a

R404A

-10-30

120R22

NH3

R723

160

180

Pres

sure

[ba

r]

Temperature [˚C]

1

25

0 60

6

15

4

10

20

-40 -20

2

4020

R22NH3

R723 (NH3/DME) as an alternative to NH3

The previously described experiences withthe use of NH3 in commercial refrigerationplants with direct evaporation caused fur-ther experiments on the basis of NH3 un-der the addition of an oil soluble refrigerantcomponent. The main goals were an im-provement of the oil transport characteristicsand the heat transmission with conventionallubricants along with a reduced dischargegas temperature for the extended applica-tion range with single stage compressors.

An assessment of the use of NH3 compactsystems – in place of systems using HFCrefrigerants and conventional technology –is only possible on an individual basis,taking into account the particular applica-tion. From the purely technical view-pointand presupposing an acceptable pricelevel, it is anticipated that a wider range ofproducts will become available.

The product range from BITZER todayincludes an extensive selection of opti-mized NH3 compressors for varioustypes of lubricants:

❏ Single stage open reciprocatingcompressors (displacement 19 to152 m3/h with 1450 rpm) for air-con-ditioning, medium temperature andBooster applications

❏ Open screw compressors (displace-ment 84 to 1015 m3/h – with parallel operation to 4060 m3/h – with 2900rpm) for air-conditioning, mediumand low temperature cooling.Options for low temperature cooling:– Single stage operation– Economiser operation– Booster operation

The result of this research project is a re-frigerant blend of NH3 (60%) and dimethylether "DME" (40%), developed by the "Insti-tut fuer Luft- und Kaeltetechnik, Dresden",Germany (ILK), that has been applied in aseries of real systems. As a largely inorgan-ic refrigerant it received the designationR723 due to it its average molecular weightof 23 kg/kmol in accordance to the stan-dard refrigerant nomenclature.

DME was selected as an additional compo-nent for its properties of good solubility andhigh individual stability. It has a boiling pointof -26°C, a relatively low adiabatic expo-nent, is non toxic and is available in a hightechnical standard of purity.In the given concentration NH3 and DMEform an azeotropic blend characterised bya slightly rising pressure level in comparisonto pure NH3. The boiling point lies at -36.5°C (NH3 -33.4°C), 26 bar (abs.) ofcondensing pressure corresponds to58.2°C (NH3 59.7°C).

The discharge gas temperature in air-con-ditioning and medium temperature rangesdecrease by about 10 to 25 K (Fig. 26/1)and thereby allows for an extension of theapplication range to higher pressure ratios.On the basis of thermodynamic calculations

Conversion of existing plants

The refrigerant NH3 is not suitable for theconversion of existing (H)CFC or HFC plants;they must be constructed completely newwith all components.

Supplementary BITZER informationconcerning the application of NH3(see also http://www.bitzer.de)

❏ Technical Information KT-640“Application of Ammonia (NH3)as an alternative refrigerant”

29

Halogen free refrigerants

a single-digit percent rise in cooling capaci-ty results when compared to NH3. Thecoefficient of performance is similar and iseven more favourable at high pressureratios, which experiments have confirmed.Due to the lower temperature level duringcompression an improved volumetric andisentropic efficiency is also to be expected,at least with reciprocating compressors incase of an increasing pressure ratio.

Due to the higher molecular weight of DME,mass flow and vapour density increase withrespect to NH3 by nearly 50% which is oflittle importance to commercial plants, es-pecially in short circuits. In classical indus-trial refrigeration plants, however, this is asubstantial criterion with regard to pressuredrops and refrigerant circulation. Also fromthese considerations it can be clearly seenthat in commercial applications and especi-ally in water chillers, R723 has its preferredutilisation.

The material compatibility is comparable tothat of NH3. Although non-ferrous metals(e.g. CuNi alloys, bronze, hard solders) arepotentially suitable, provided that the watercontent in the system is at a minimum (< 1000 ppm), a system design that cor-responds with typical ammonia practise is recommended nonetheless.

As lubricant mineral oils or (preferred) poly-alpha olefin can be used. As mentioned be-fore the portion of DME creates improvedoil solubility and a partial miscibility. Besidesthis the relatively low liquid density and anincreased concentration of DME in the oil,positively influences the oil circulation. PAGoils would be fully or partly miscible withR723 for typical applications but are notrecommended for reasons of the chemicalstability and high solubility in the compres-sor crankcase (strong vapour developmentin the bearings).

Tests have shown that the heat transfer co-efficient at evaporation and high heat flux isimproved in systems with R723 and mineraloil than when using NH3 with mineral oil.

Further characteristics are toxicity and flam-mability. By means of the DME content, theignition point in air diminishes from 15 to6% but. Despite of this, the azeotrope still

R290 (Propane) as substitute for R502 and R22

R290 (propane) can also be used as a sub-stitute refrigerant. As it is an organic com-pound (hydrocarbon) it does not have anozone depletion potential and a negligibledirect global warming effect. To take intoconsideration however, is a certain contri-bution to summer smog.

The pressure levels and the refrigeratingcapacity are similar to R22 and the tem-perature behaviour is as favourable as withR134a.

There are no particular material issues. Incontrast to NH3 copper materials are alsosuitable, so that semi-hermetic and herme-tic compressors are possible. The mineraloils usually found in a HCFC system can beused here as a lubricant over a wide appli-cation range.

Refrigeration plants with R290 have been inoperation world-wide for many years, main-ly in the industrial area – it is a "proven"refrigerant.

Meanwhile R290 is also used in smallercompact systems with low refrigerant char-ges like residential A/C units and heatpumps. Furthermore, a rising trend can beseen in its use with commercial refrigerationsystems and chillers.

Propane is offered also as a mixture withIsobutane (R600a) or Ethan (R170). Thisshould obtain a good performance matchwith halocarbon refrigerants. Pure Isobu-tane is mostly intended as a substitute forR12 in small plants (preferably domesticrefrigerators).

The disadvantage of hydrocarbons is thehigh flammability, and therefore been classi-fied as refrigerants of "Safety Group A3".With the normal refrigerant charge found incommercial plants this means that the sys-tem must be designed according to “flame-proof” regulations.

The use of semi-hermetic compressors inso called "hermetically sealed" systems is inthis case subject to the regulations for haz-ardous zone 2 (only seldom and short termrisk). The demands for the safety technology

remains in the safety group B2, but mayreceive a different classification in case of arevised assessment.

Resulting layout criteria

The experiences made with the NH3 com-pact systems described above can be usedin the plant technology. However, adjust-ments in the component layout are neces-sary under consideration of the higher massflow. Besides a suitable selection of theevaporator and the expansion valve a verystable superheat control must be ensured.Due to the improved oil solubility “wet ope-ration” can have considerable negative re-sults when compared to NH3 systems withnon-soluble oil.

With regards to safety regulations the samecriteria apply to installation and operationas in the case of NH3 plants.

Suitable compressors are special NH3 ver-sions which possibly have to be adapted tothe mass flow conditions and to the con-tinuous oil circulation. An oil separator isusually not necessary with reciprocatingcompressors.

Bitzer NH3 reciprocating compressorsare suitable for R723 in principle. Anindividual selection of specificallyadapted compressors is possible ondemand.

30

Halogen free refrigerants

Fig. 27 R290/R1270/R22 – comparison of performance data of a semi-hermetic compressor

Fig. 28 R290/R1270/R22 – comparison of pressure levels

Rela

tion

R290

and

R12

70 to

R22

(=10

0%)

Evaporation [˚C]

80

120

-40 0 10-30 -20 -10

90

110

100

Q o (R290)

COP (R1270)

COP (R290)

Q o (R1270)

tc 40˚Ctoh 20˚C

Pres

sure

[ba

r]

Temperature [˚C]

1

25

0 60

6

15

4

10

20

-40 -20

2

4020

R22

R1270

R290

include special devices to protect againstexcess pressures and special arrangementsfor the electrical system. In addition meas-ures are required to ensure hazard free ven-tilation to effectively prevent a flammablegas mixture occurring in case of refrigerantleakage.

The design requirements are defined bystandards (e.g. EN378) and may vary in dif-ferent countries. For systems applied withinthe EU an assessment according to the EC Directive 94/9/EC (ATEX) may becomenecessary as well.

With open compressors this will possiblylead to a classification in zone 1. Zone 1demands, however, electrical equipment inspecial flame-proof design.

Resulting design criteria

Apart from the measures mentioned above,propane plants require practically no specialfeatures in the medium and low tempera-ture ranges compared with a usual (H)CFCand HFC system. When sizing componentsconsideration should however be given tothe relatively low mass flow (approximately55 to 60% compared to R22). An advan-tage in connection with this is the possibili-ty to greatly reduce the refrigerant charge.

On the thermodynamic side an internal heatexchanger between the suction and liquidline is recommended as this will improvethe refrigerating capacity and COP.

Owing to the particularly high solubility ofR290 (and R1270) in common lubricants,BITZER R290/R1270 compressors arecharged with a special oil of a high viscosityindex and particularly good tribologicalproperties.

In connection to this, an internal heatexchanger is also an advantage as it leadsto higher oil temperatures thus to lower solubility with the result of an improved viscosity.

Due to the very favourable temperaturebehaviour (Fig. 26/1), single stage com-pressors can be used down to approxi-mately -40°C evaporation temperature.R290 could then also be considered as analternative for some of the HFC blends.

A range of semi-hermetic reciprocatingcompressors and CS. compact screws isavailable for R290. Due to the individualrequirements a specifically equippedcompressor version is offered. Inquires and orders need a distinstiveindication to R290. The handling of the

order does include an individual agree-ment between the contract partners.Open reciprocating compressors arealso available for R290, together with acomprehensive program of flame-proofaccessories which may be required.

Conversion of existing plants with R22or HFC

Due to the flame-proof protection measuresrequired for an R290 plant, it would appearthat a conversion of existing plants is onlypossible in exceptional cases.

They are limited to systems, which can bemodified to meet the corresponding safetyregulations with an acceptable effort.

Supplementary BITZER informationconcerning the use of R290

❏ Technical Information KT-660“Application of Propane and Propy-lene with semi-hermetic compressors”

31

Halogen free refrigerants

that there is a danger of polymerization athigh pressure and temperature levels. Testscarried out by hydrocarbon manufacturersand stability tests in real applications showthat reactivity in refrigeration systems ispractically non-existent. Doubts have occa-sionally been mentioned in some literatureregarding propylene’s possible carcinogeniceffects. These assumptions have been dis-proved by appropriate studies.

Resulting design criteria

With regard to system technology, experi-ence gained from the use of propane canwidely be applied to propylene. However,component dimensions have to be altereddue to higher volumetric refrigerating cap-acity (Fig. 27). The compressor displace-ment is correspondingly lower and thereforealso the suction and high pressure volumeflows. Because of higher vapour density themass flow is almost the same as for R290.As liquid density is nearly identical the sameapplies for the liquid volume in circulation.

Propylene (R1270) as an alternative to Propane

For some time there has also been in-creasing interest in using propylene(propene) as a substitute for R22 or HFC.Due to its higher volumetric refrigeratingcapacity and lower boiling temperature(compared to R290) applications in mediumand low temperature systems, e.g. liquidchillers for supermarkets, are of particularinterest. On the other hand, higher pressurelevels (> 20%) and discharge gas tempera-tures have to be taken into consideration,thus restricting the possible applicationrange.

Material compatibility is comparable withpropane, as is the choice of lubricants.

Propylene is also easily inflammable andbelongs to the A3 group of refrigerants. Thesame safety regulations are therefore to beobserved as with propane (page 30).

Due to the chemical double bond propyleneis relatively reaction friendly, which means

As with R290 the use of an internal heatexchanger between suction and liquid lines isof advantage. However, due to R1270’s high-er discharge gas temperature restrictions arepartly necessary.

A range of semi-hermetic reciprocatingcompressors and CS. compact screws isavailable for R1270. Due to the individualrequirements a specifically equipped com-pressor version is offered. Inquires and orders need a distinstive indi-cation to R1270. The handling of the orderdoes include an individual agreementbetween the contract partners. Openreciprocating compressors are also avail-able for R1270, together with a compre-hensive program of flame-proof acces-sories which may be required.

Supplementary BITZER information con-cerning the use of R1270

❏ Technical Information KT-660“Application of Propane and Propylenewith semi-hermetic compressors”

32

Fig. 29/1 R744(CO2) – pressure/enthalpy diagram

200100 300 400 500 6000

20

40

60

80

100

120

140

160

Enthalpy [kJ/kg]

Pres

sure

[bar

]

31.06°C

2Transcritical process

Subcritical process

R744 (CO2)

Fig. 29/2 R744(CO2)/R22/R404A – comparison of pressure levels

0

80

0 80

60

50

70

-60 4020

40

30

20

10

-40 -20 60

Critical temperature 31.06 ˚C

CO2

R404A

R22

Pres

sure

[bar

]

Temperature [°C]

temperature differences in evaporators,condensers, and gas coolers. Moreover, the necessary pipe dimensions are verysmall, and the influence of the pressuredrop is comparably low. In addition, whenused as a secondary fluid, the energy de-mand for circulation pumps is extremely low.

In the following section, a few examples ofsubcritical systems and the resulting designcriteria are described. An additional sectionprovides details on transcritical applications.

Subcritical applications

From energy and pressure level points ofview, very beneficial applications can beseen for industrial and larger commercialrefrigeration plants. For this, CO2 can beused as a secondary fluid in a cascade sys-tem and if required, in combination with afurther booster stage for lower evaporatingtemperatures (Fig. 30/1).

The operating conditions are always sub-critical which guarantees good efficiencylevels. In the most favourable applicationrange (approx. -10 to -50°C), pressures are still on a level where already availablecomponents or items in development, e.g.for R410A, can be matched with accept-able effort.

Safety Refrigerants", CO2 became less pop-ular and since the 1950’s had nearly disap-peared.

The main reasons for that are its relativelyunfavourable thermodynamic characteristicsfor usual applications in refrigeration andair-conditioning.The discharge pressurewith CO2 is extremely high and the criticaltemperature at 31°C (74 bar) is very low.Depending on the heat source temperatureat the high pressure side transcritical oper-ations with pressures beyond 100 bar arerequired. Under these conditions, the ener-gy efficiency is often lower compared to theclassic vapour compression process (withcondensation), and therefore the indirectglobal warming effect is suitably higher.

Nonetheless, there is a range of applica-tions in which CO2 can be used very eco-nomically and with favourable Eco-Efficien-cy. For example, these include subcriticallyoperated cascade plants, but also transcrit-ical systems, in which the temperature glideon the high pressure side can be used ad-vantageously, or the system conditions permit subcritical operation for long periods.In this connection it must also be notedthat the heat transfer coefficients of CO2are considerably higher than of other re-frigerants – with the potential of very low

Carbon Dioxide R744 (CO2) as an alternative refrigerant and secondary fluid

CO2 has had a long tradition in the refri-geration technology reaching far into the19th century. It has no ozone depletingpotential, a negligible direct global warmingpotential (GWP = 1), is chemically inactive,non-flammable and not toxic in the classi-cal sense. That is why CO2 is not subject-ed to the stringent demands regardingcontainment as apply for HFCs (F-GasRegulation), and flammable or toxic re-frigerants. However, compared to HFCsthe lower practical limit in air has to beconsidered. For closed rooms this mayrequire special safety and detection systems.

CO2 is also low in cost and there is no nec-essity for recovery and disposal. In ad-dition, it has a very high volumetric refriger-ating capacity, which depending on oper-ating conditions equates to approx. 5 – 8times more than R22 and NH3.

Above all, the safety relevant characteristicswere an essential reason for the initial wide-spread use. The main focus for applicationswere marine refrigeration systems, for ex-ample. With the introduction of the "(H)CFC

Halogen free refrigerants

33

Resulting design criteria

For the high temperature side of such acascade system, a compact cooling unitcan be used, whose evaporator serves onthe secondary side as the condenser forCO2. Chlorine-free refrigerants are suitablesuch as NH3, HCs or HFCs, HFO andHFO/HFC blends.

With NH3 the cascade heat exchangershould be designed so that the dreadedbuild-up of ammonium carbonate is pre-vented in the case of leakage. This tech-nology has been applied in breweries for a long time.

A secondary circuit for larger plants withCO2 could be constructed utilising, to awide extent, the same principles for a lowpressure pump circulating system, as isoften used with NH3 plants. The essentialdifference exists therein, that the condens-ing of the CO2 results in the cascade cool-er, and the receiver tank (accumulator) onlyserves as a supply vessel.

The extremely high volumetric refrigeratingcapacity of CO2 (latent heat through thechanging of phases) leads to very low massflow rates and makes it possible to usesmall cross sectional pipe and minimal en-ergy needs for the circulating pumps.

For the combination with a further compres-sion stage, e.g. for low temperatures, thereare different solutions.

Fig. 30/1 shows a variation with an addition-al receiver where one or more Booster com-pressors will pull down to the necessaryevaporation pressure. Likewise, the dischargegas is fed into the cascade cooler, condens-es and then carried over to the receiver (MT).The feeding of the low pressure receiver (LT)is achieved by a level control device.Instead of classical pump circulation thebooster stage can also be built as a so-called LPR system. The circulation pump is thus not necessarybut the number of evaporators is then limit-ed with a view to an even distribution of theinjected CO2.

In the case of a system breakdown where ahigh rise in pressure could occur, safetyvalves can vent the CO2 to the atmospherewith the necessary precautions.As an alternative to this, additional coolingunits for CO2 condensation are also usedwhere longer shut-off periods can bebridged without a critical pressure increase.

For systems in commercial applications adirect expansion version is possible as well.

Supermarket plants with their usually widelybranched pipe work offer an especiallygood potential in this regard. The mediumtemperature system is then carried out in aconventional design or with a secondarycircuit and for low temperature applicationcombined with a CO2 cascade system (forsubcritical operation). A system example isshown in Fig. 30/2.

For a general application, however, not allrequirements can be met at the moment. Itis worth considering that system technolo-gy changes in many respects and speciallyadjusted components are necessary tomeet the demands.

The compressors, for example, must beproperly designed because of the highvapour density and pressure levels (par-ticularly on the suction side). There are also specific requirements with regard tomaterials. Furthermore only highly dehy-drated CO2 must be used.

High demands are made on lubricants aswell. Conventional oils are mostly not misci-ble and therefore require costly measuresto return the oil from the system. On theother hand, a strong viscosity reductionwith the use of a miscible and highly solublePOE must be considered.

Fig. 30/2 Conventional refrigeration system combined with CO2 low temperature cascade

CO Cascade2HFC (NH3 / HC)*

* only with secondary system

Fig. 30/1 Casacde system with CO2 for industrial applications

CO2

LT MT

LC

PC

CPR

MT LT

NH3 / HC /HFC

Simplifiedsketch

Simplifiedsketch

Halogen free refrigerants

34

sure" is determined as a function of gascooler outlet temperature by means of bal-ancing between the highest possible en-thalpy difference and simultaneous mini-mum compression work. It must be adapt-ed to the relevant operating conditionsusing an intelligent modulating controller(see system example, Fig. 31).

As described above, under purely thermo-dynamic aspects, the transcritical operat-ing mode appears to be unfavourable interms of energy efficiency. In fact, this istrue for systems with a relatively high tem-perature level of the heat sink on the high-pressure side. However, additional meas-ures can be taken for improving efficiency,such as the use of parallel compression(economiser system) and/or ejectors orexpanders for recovering the throttling loss-es during expansion of the refrigerant.Apart from that, there are application areasin which a transcritical process is advanta-geous in energy demand. These includeheat pumps for sanitary water, or dryingprocesses. With the usually very high tem-perature gradients between the dischargetemperature at the gas cooler intake andthe heat sink intake temperature, a very lowgas temperature outlet is achievable. This ispositively influenced by the temperatureglide curve and the relatively high meantemperature difference between CO2 vapourand secondary fluid. The low gas outlet tem-perature leads to a particularly high enthalpydifference, and therefore to a high systemCOP.

Low-capacity sanitary water heat pumpsare already manufactured and used in largequantities. Plants for medium to highercapacities (e.g. hotels, indoor swimmingpools) are still in the development and intro-ductory phase.Apart from these specific applications, thereis also a range of developments for theclassical areas of refrigeration and air-con-ditioning. This also covers supermarket

refrigeration plants, for example. Meanwhileinstallations with parallel compounded com-pressors are in operation to a larger scale.They are predominantly booster systemswhere medium and low temperature circuitsare connected together (without heatexchanger). The operating experience andthe determined energy costs show promis-ing results. However, the investment costsare still considerably higher than for classi-cal plants with HFCs and direct expansion.

On the one hand, the reasons for thefavourable energy costs lie in the highdegree of optimized components and thesystem control, and also in the previouslydescribed advantages regarding heat trans-fer and pressure drop. On the other hand,these installations are preferably used in cli-mate zones permitting very high runningtimes in subcritical operation due to theannual ambient temperature profile.

For increasing the efficiency of CO2 super-market systems and for using them inwarmer climate zones, the technologiesdescribed above using parallel compressionand/or ejectors are increasingly used.

Insofar, but also in view of the very de-manding technology and the high require-ments placed on the qualification of plan-ners and service personnel, CO2 technologycannot be regarded as a general replace-ment for plants using HFC refrigerants.

Resulting design criteria

Detailed information on this topic would gobeyond the scope of this publication. In anycase, the system and control techniquesare substantially different from conventionalplants. Already when considering pressurelevels as well as volume and mass flowratios specially developed components,controls, and safety devices as well as suitably dimensioned pipework must beprovided.

For subcritical CO2 applicationsBITZER offers two series of specialcompressors.

Supplementary BITZER informationconcerning compressor selection forsubcritical CO2 systems

❏ Brochure KP-120Semi-hermetic reciprocating compres-sors for subcritical CO2 application(LP/HP standstill pressures up to30/53 bar)

❏ Brochure KP-122Semi-hermetic reciprocating compres-sors for subcritical CO2 application(LP/HP standstill pressures up to 100 bar)

❏ Additional publications on request

Transcritical applications

Transcritical processes are characterized inthat the heat rejection on the high pressureside proceeds isobar but not isotherm.Contrary to the condensation process dur-ing subcritical operation, gas cooling (de-superheating) occurs, with correspondingtemperature glide. Therefore, the heatexchanger is described as gas cooler. Aslong as operation remains above the criti-cal pressure (74 bar), only high-densityvapour will be transported. Condensationonly takes place after expansion to a lowerpressure level – e.g. by interstage expan-sion in an intermediate pressure receiver.Depending on the temperature curve of theheat sink, a system designed for transcriti-cal operation can also be operated subcrit-ically, whereby the efficiency is better underthese conditions. In this case, the gascooler becomes the condenser.

Another feature of transcritical operation isthe necessary control of the high pressureto a defined level. This "optimum pres-

Halogen free refrigerants

35

The compressor technology is particularlydemanding. The special requirements resultin a completely independent approach. For example, this involves design, materials(bursting resistance), displacement, crankgear, working valves, lubrication system, aswell as compressor and motor cooling.Hereby, the high thermal load severely limitsthe application for single-stage compres-sion. Low temperature cooling requires 2-stage operation, whereby separate highand low pressure compressors are particu-larly advantageous with parallel compound-ed systems.

The criteria mentioned above in connectionwith subcritical systems apply to an evenhigher degree for lubricants.

Further development is necessary in manyareas, and for most applications, transcriti-cal CO2 technology cannot yet be regardedas state-of-the-art.

For transcritical CO2 applications,BITZER offers a wide range of specialcompressors.Their use is aimed at specific applica-tions, therefore individual examinationand assessment are required. * See page 11 for further information.

CO2 in mobileair-conditioning systems

Within the scope of the long-discussedmeasures for reducing direct refrigerantemissions, and the ban on the use ofR134a in MAC systems* within the EU, the development of CO2 systems has beenpursued intensively since several years.

At the first glance, efficiency and thereforethe indirect emissions from CO2 systemsunder typical ambient conditions appear tobe relatively unfavourable. But it must beconsidered that present R134a systemsare less efficient than stationary plants ofthe same capacity. The reasons for this liein the specific installation conditions andthe relatively high pressure losses in pipe-work and heat exchangers. With CO2,

pressure losses have significantly less influ-ence. Moreover, system efficiency is furtherimproved by the high heat transfer coeffi-cients in the heat exchangers.

This is why optimized CO2 air-condition-ing systems are able to achieve efficienciesthat are comparable to those of R134a.Regarding the usual leakage rates of suchsystems, a more favourable balance isobtained in terms of TEWI.

From today's viewpoint, it is not yet pos-sible to make a prediction as to whetherthe CO2 technology can in the long runprevail in this application. Certainly, thisalso depends on experiences with "LowGWP" refrigerants (page 11) which in themeantime are partially introduced by theautomotive industrie. Hereby, other aspectssuch as operating safety, costs, and globallogistics will play an important role.

Fig. 31 Example of a transcritical CO2 Booster System

LTMT

CO2 Booster System

Suplementary BITZER information concerning compressor selection for transcritical CO2-systems

❏ Brochure KP-130Semi-hermetic reciprocating compres-sors for transcritical CO2 application

❏ Additional publications upon request

Simplifiedsketch

Halogen free refrigerants

36

Special applications

R124 and R142b as substitutes forR114 and R12B1

Instead of the refrigerants R114 andR12B1 predominately found in the past inhigh temperature heat pumps and cranecabin A/C installations, the HCFC R124and R142b can be used as alternatives innew installations.With these gases it is also possible to uselong proven lubricants, preferably mineraloils and alkyl benzenes with high viscosity.

Because of the Ozone Depleting Potential,the use of these refrigerants must only beregarded as an interim solution. In the EUmember states, the application of HCFCs is no longer allowed. For R124 and R142bthe same restrictions are valid as for R22(page 8). The flammability of R142b shouldalso be considered with the resulting safetyimplications (safety group A2).

Resulting design criteria/Converting existing plants

In comparison to R114 the boiling tempera-tures of the alternatives are lower (approx. -10°C) which results in larger differences inthe pressure levels and volumetric refriger-ating capacities. This leads to stronger limi-tations in the application range concerninghigh evaporation and condensing tempera-tures.A conversion of an existing installation willin most cases necessitate the exchangingof the compressor and regulating devices.Owing to the lower volume flow (higher vol-umetric refrigerating capacity), possibleadjustments to the evaporator and the suc-tion line will be required.

Over the previous years BITZER com-pressors have been found to be wellsuited with R124 and R142b in actualinstallations. Depending on perform-ance data and compressor type modifi-cations are necessary, however. Per-formance data including further designinstructions are available on request.

Chlorine free substitutes for special applications

Due to the limited markets for systems withextra high and low temperature applica-tions, the requirements for the developmentof alternative refrigerants and system com-ponents for these areas has not been sogreat.

In the meantime a group of alternatives forthe CFC R114 and Halon R12B1 (high tem-perature), R13B1, R13 and R503 (extra lowtemperature) were offered as the replace-ments. With closer observations it has beenfound that the thermodynamic properties ofthe alternatives differ considerably from thepreviously used substances. This can causecostly changes especially with the conver-sion of existing systems.

Alternatives for R114 and R12B1

R227ea and R236fa are considered suitablesubstitutes even though they may no longerbe used in new installations in the EU from2020, due to their relatively high GWP.

R227ea cannot be seen as a full replace-ment. Recent research and field tests haveshown favourable results, but with normalsystem technology the critical temperatureof 102°C limits the condensing temperatu-res to about 85..90°C.

R236fa provides the more favourable con-ditions at least in this regard – the criticaltemperature is above 120°C. A disadvan-tage, however, is the smaller volumetricrefrigerating capacity. This is similar to R114and with that 40% below the performance ofR124 which is widely used for extra hightemperature applications today.

Refrigerant R600a (Isobutane) will be aninteresting alternative where the safety reg-ulations allow the use of hydrocarbons(safety group A3). With a critical tempera-ture of 135°C, condensing temperatures of100°C and more are within reach.

The volumetric refrigerating capacity isalmost identical to R124.

The "Low GWP" refrigerant R1234ze(E) canalso be regarded as a potential candidatefor extra high temperature applications.Compared to R124, its cooling capacity ishigher by 10 to 20% and its pressure levelby about 25%. At an identical refrigeratingcapacity, the mass flow differs only slightly.Its critical temperature is 107°C, whichwould enable an economical operation upto a condensing temperature of about90°C. However, like R1234yf, R1234ze(E) ismildly flammable and therefore classified inthe new safety group A2L. The correspon-ding safety regulations must be observed.

However, until now no sufficient operatingexperience is available, which is why anassessment of the suitability of this refriger-ant for long-term use is not yet possible.

For high temperature heat pumps in theprocess technologie and special applica-tions in the field of high temperaturesDuPont has presented an HFO basedrefrigerant called DR-2.

The critical temperature is at 171°C, theboiling temperature at 33.4°C. This enablesan operation at condensing temperaturesfar above 100°C for which only purpose-built compressors and system componentscan be used.

DR-2 has a GWP < 10 but is not flammableaccording to tests carried out so far. There-fore a classification in safety group A1 canbe expected.

A more detailed evaluation is not yet possi-ble with respect to the chemical stability ofthe refrigerant and of the lubricants at thevery high temperatures and the usually verylong operating cycles of such systems. The special applications also include sys-tems for power-heat coupling – the so-called "Organic Rankine Cycle" (ORC),which become increasingly important. Inaddition to DR-2 as a potentially suitableoperating fluid, a series of other substancesare also possible, depending on the tem-perature level of the heat source and theheat sink. They include R245ca (GWP100 = 1030) hav-ing a critical temperature of 154°C, whichlike DR-2 is also suitable as refrigerant forchillers with large centrifugal compressors. In addition Solvay offers suitable refriger-

37

Special applications

Fig. 32 R13B1/HFC alternatives – comparison of discharge gas temperatures of a 2-stage compressor

Basis R13B1

Disc

harg

e ga

s te

mpe

ratu

re –

rela

tive

diffe

renc

e to

R13

B1 [K

]

40

30

20

10

0

-10

-30

-20

R41

0A

ISC

EON

MO

89

to

tc

Δtoh

-70°C

40°C

20 K

A comprehensive description of ORCsystems would go beyond the scope ofthis Refrigerant Report. Further informa-tion is available upon request

Alternatives for R13B1

Besides R410A, ISCEON MO89 (DuPont)can be regarded as potential R13B1 sub-stitute. With R410A a substantially higherdischarge gas temperature is to be con-sidered when compared to R13B1 whichrestricts the application range even in 2-stage compression systems to a greaterextent.

ISCEON MO89 is a mixture of R125 andR218 with a small proportion of R290. Dueto the properties of the two main compo-nents, density and mass flow are relativelyhigh and discharge gas temperature is verylow. Liquid subcooling is of particular ad-vantage.

Both of the mentioned refigerants have rel-atively high pressure levels and are there-fore limited to 40 through 45°C condensingtemperature with the usually applied 2-stagecompressors. They also show less capacity

ants containing the base componentR365mfc for ORC applications. A productwith the trade name Solkatherm SES36already presented several years ago con-tains perfluoropolyether as a blend compo-nent. It is an azeotrope having a criticaltemperature of 178°C. Meanwhile twozeotropic blends containing R365mfc andR227ea have been developed whose criti-cal temperatures are 177°C and 182°C,due to different mixing ratios. They areavailable under the trade names SolkathermSES24 and SES30. In ORC systems zeotropic behavior may beadvantageous. In the case of single-phaseheat sources and heat sinks the tempera-ture difference at the so-called "pitch point"can be raised by the gliding evaporationand condensation. This leads to improvedheat transmission due to the higher drivingaverage temperature difference.

As an expander for ORC systems screwand scroll compressors can be adaptedin their construction accordingly. Forseveral years BITZER has been involvedin various projects and has alreadygained important knowledge with thistechnology and experience in designand application.

than R13B1 at evaporating temperaturesbelow -60°C.In addition to this, the steep fall of pressurelimits the application at very low tempera-tures and may require a change to a cas-cade system with for example R23 in thelow temperature stage.

Lubrication and material compatibility areassessed as being similar to the other HFCblends.

Alternatives for R13 and R503

The situation is more favourable with thesesubstances as R23 and R508A/R508B canalready replace R13 and R503. RefrigerantR170 (Ethane) is also suitable when thesafety regulations allow the use of hydro-carbons (safety group A3).

Due to the partly steeper pressure curve ofthe alternative refrigerants and the higherdischarge gas temperature of R23 com-pared with R13, differences in performanceand application ranges for the compres-sors must be considered. Individual adap-tation of the heat exchangers and controlsis also necessary.

As lubricants for R23 and R508A/B, polyolester oils are suitable, but these must bematched for the special requirements atextreme low temperatures.

R170 has also good solubility with conven-tional oils, however an adaptation to thetemperature conditions will be necessary.

BITZER has carried out investigationsand also collected experiences withseveral of the substitutes mentioned,performance data and instructions areavailable on request.Due to the individual system technolo-gy for these special installations, con-sultation with BITZER is necessary.

Refrigerant Properties

38

R22R124R142b

R134aR152aR125R143aR32

R227eaR236fa

R23

R404AR507A R407AR407FR422A

R437A

R407CR417AR417BR422DR427AR438A

R410A

ISCEON MO89

R508AR508B

R1234yfR1234ze(E)R513A (XP10)R450A (N-13)

R448A (N-40)R449A (XP40)

R717R723R600aR290R1270

R170

R744

AR4: according to IPCC IV – time horizon 100 years – also basis for EU F-Gas Regulation 517/2014

N/A Data not yet published.

Alternative refrigerant has larger deviation in refrigerating capacity and pressure

Alternative refrigerant has larger deviation below -60°C evaporating temperature

Also proposed as a component in R290/600a-Blends (direct alternative to R12)

Classification according to EN378-1 and ASHRAE 34

According to EN 378-1: 2008 + A2: 2012,Annex E

0.0550.0220.065

0

0

0

0

1810609

2310

1430124

35004470675

32209810

14800

39223985210718253143

1805

177423462920272921382264

2088

3805

1321413396

47

631601

13861397

08333

3

1

Composition(Formula)

Substitute /Alternative

for

ODP

[R11=1,0]

GWP(100a)

[CO2=1,0]

Practicallimit

[kg/m3]

Safetygroup

Application range

5

HFC Blends

Halogen free Refrigerants

HFO and HFO/HFCBlends

0.30.11

0.066

0.250.0270.39

0.0560.061

0.590.59

0.68

0.520.530.330.290.29

0.08

0.310.150.070.260.280.08

0.44

N/A

0.230.2

0.058N/A0.35N/A

N/AN/A

0.00035N/A

0.0110.0080.008

0.008

0.07

A1A1A2

A1A2A1A2

A2L

A1A1

A1

A1A1A1A1A1

A1

A1A1A1A1A1A1

A1

N/A

A1A1

A2LA2LA1A1

A1A1

B2B2A3A3A3

A3

A1

09.14

CHClF2CHClFCF3CCIF2CH3

CF3CH2FCHF2CH3CF3CHF2CF3CH3CH2F2

CF3-CHF-CF3CF3-CH2-CF3

CHF3

R143a/125/134aR143a/125R32/125/134aR32/125/134aR125/134a/600a

R125/134a/600/601

R32/125/134aR125/134a/600R125/134a/600R125/134a/600aR32/125/143a/134aR32/125/134a/600/601a

R32/125

R125/218/290

R23/116R23/116

CF3CF=CH2CF3CH=CHFR1234yf/134aR1234ze(E)/134a

R32/125/1234yf/1234ze(E)/134aR32/125/1234yf/134a

NH3NH3/R-E170C4H10C3H8C3H6

C2H6

CO2

R502 (R12 )

R114 , R12B1

R12 (R500)

R13 (R503)

R503

R134a

R404A,R507A

R22 (R13B1 )

R22

R22 (R502)

R404A (R22)R404A (R22)R134aR404A (R22)R404A (R22)

R23

various

R12B1, R114R114

R12 (R22 )

mainly used aspart componentsfor blends

seepage 40

seepage 40

seepage 40

seepage 40

seepage 41

R13B1

Refrigerant type

HCFC-Refrigerants

3

3

4

5

6

5 6

4

5

1

1

1

1

1

1

2

2

2

These statements are valid subject to reservations; they are based on information published by various refrigerant manufacturers.Fig. 33 Refrigerant properties (continued on Fig. 34)

1

HFC Single-component Refrigerants

Refrigerant Properties

39

-41-11-10

-26-24-48-48-52

-16-1

-82

-47-47-46-46-49

-33

-44-39-45-45-43-42

-51

-55

-86-88

-30-18-29-24

-45-46

-33-37-12-42-48

-89

-57

Rounded values

Total glide from bubble to dew line – based on 1 bar (abs.) pressure.Real glide dependent on operatingconditions.Approx. values in evaporator:H/M 70%; L 60% of total glide

Reference refrigerant for these values is stated in Fig. 33 under the nomina-tion “Substitute for” (column 3)Letter within brackets indicates operating conditionsH High temp (+5/50°C)M Medium temp (-10/45°C)L Low temp (-35/40°C)

R22R124R142b

R134aR152aR125R143aR32

R227eaR236fa

R23

R404AR507A R407AR407FR422A

R437A

R407CR417AR417BR422DR427AR438A

R410A

ISCEON MO89

R508AR508B

R1234yfR1234ze(E)R513A (XP10)R450A (N-13)

R448A (N-40)R449A (XP40)

R717R723R600aR290R1270

R170

R744

09.14

Fig. 34 Refrigerant properties

Refrigeranttype

3

3

4

5

6

6

1

2

Boilingtemperature

[°C]

Temperatureglide[K]

Criticaltemperature

[°C]

Cond. temp.at 26 bar(abs) [°C]

Refr.capacity

[%]

Dischargegas temp.

[K]

Schmierstoff(Verdichter)

1 2 1 1 3 3

000

00000

00

0

0.70

6.66.42.5

3.6

7.45.6 3.44.57.16.6

<0.2

4.0

00

000

0.4

6.15

00000

0

0

96122137

101113667378

102>120

26

7371838372

95

878775818780

72

70

1314

9511098

106

8482

1331311359792

32

31

63105110

8085515642

96117

1

5554565756

75

586858626463

43

50

-3-3

82927885

6058

6058

1147061

3

-11

80 (L)

97 (M)N/AN/AN/AN/A

105 (M)107 (M)

98 (M)104 (M)100 (M)

108 (M)

100 (H)97 (H)95 (M)90 (M)90 (M)88 (M)

140 (H)

99 (M)

102 (M)88 (M)

94 (M)97 (M)

100 (M)105 (M)N/A 89 (M)

112 (M)

+35

-8N/AN/AN/AN/A

-34-34-19-11-39

-7

-8-25-37-36-20-27

-4

-14

-7-6

+12+12

+60+35N/A-25-20

seepage 41

5

5

5

5

5

5

5

5

5

5

5

5 5

4 4

55

5

HFC Blends

Halogen free Refrigerants

HFO and HFO/HFC Blends

HCFC-Refrigerants

HFC Single-component Refrigerants

Valid for single stage compressors

Data on request (operating conditionsmust be given)

Triple point at 5,27 bar

Stated performance data are average valuesbased on calorimeter tests.

40

-100-80-60-40-2002040

R124 ● R142b

R401A ● R409A

R401B

R22

R402B

R402A ● R403B ● R408A

Evaporation CApplication with limitations

2-stage

2-stage

Evaporation C-100-80-60-40-2002040

R227ea ● R236fa

R134a ● R513A ● R450A

R407C ● R417A

R410A

R23 ● R508A ● R508B

Condensing temperature limitedApplication withlimitations

Compressors for high pressure 42 bar

CASCADE

2-stage

2-stage

2-stage

1

2

ISCEON MO89

R437A

R404A ● R507A

R407A ● R407F ● R417BR422A ● R422D R448A ● R449A

● R427A ● R438A

12

2

2

Transitional/Service refrigerants

Fig. 35 Application ranges for HCFC’s and Service Blends

HFC and HFO refrigerants

Fig. 36 Application ranges for HFC refrigerants and blends (ODP = O)

Application ranges

41

R290 ● R1270

-100-80-60-40-2002040

R600a

R170

Evaporation C

NHR723*

3

CO2

Application with limitations

CASCADE

2-stage

– see pages 32...35 –

2-stage

2-stage

* see information on pages 28/29

(H)CFC

NH ● R7233

Service blends with R22

HFC + blends

Hydrocarbons VG VG VG

AD

+VG

+VG

VG

Especially critical with moisture

Possible higher basic viscosity

Possible specialAD

formulation

Good suitability

Application with limitations Not suitable

Further information see pages 10/11 and explanations for the particular refrigerants.

VG VG

Suitability dependant on system design

HFC/HC blends

HFO+HFO/HFC blends

Min

eral

oil

(MO

)

Alky

l-be

nzen

e(A

B)

Min

eral

oil

+ al

kyl-

benz

ene

Poly

-alp

ha-

olef

in (P

AO)

Poly

oles

ter (

POE)

Poly

viny

l-et

her

(PVE

)

Poly

-gl

ycol

(PAG

)

ydro

cH c min

eral

oil

rack

ed

Traditional oils New lubricants

Application ranges ■ Lubricants

Halogen free refrigerants

Fig. 37 Application ranges for halogen free refrigerants

Lubricants

Fig. 38 Lubricants for compressors

42

Notes

Notes

43

Subject to change // 80050203 // 09.2014

Bitzer Kühlmaschinenbau GmbHEschenbrünnlestraße 15 // 71065 Sindelfingen // Germany

Tel +49 (0)70 31 932-0 // Fax +49 (0)70 31 932-147 bitzer@bitzer.de // www.bitzer.de