ilk dresden new 8 kw chiller

Institute of Air-handling and Refrigeration (ILK Dresden)

Development of a small capacity

directly air-cooled water/LiBr absorption chiller

Chinese Solar Cooling Conference, Shanghai, 27.3.2015

ILK Dresden – R&D company

Founded in 1964

Re-established as independent

research institute in 1991

Employees: 145

Academics: 72 %

mean age: ~44

Laboratory area: ~3000 m²

Test rigs: ~56

Phys. / Chem. Laboratories: 25

2 27.03.2015 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik

Background and goal of the development

Problems in solar thermal cooling systems with small scale chillers

Complexity of the system

Interface problems because of different crafts (might be) involved

Possibly high error rate during installation

Auxiliary energy demand of the system

Limited applicability of evaporative systems but high re-cooling

sensibility of the cycle

Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 3 27.03.2015

Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 4

Challenges

Avoiding of an intermediate circuit:

- to minimize the auxiliary energy demand (as re-cooling circuit pump

usually consumes much electricity)

- for a better approach of external and internal temperatures since

temperature lift and driving temperature are limited

Air-cooled absorber needed

Water as refrigerant -> big free section needed

Air as heat transfer media -> big free section needed

?

27.03.2015

Distribution of the auxiliary energy demand

of a small scale water cooled absorption chiller

Nominal cooling capacity: 19,4 kW


35 %

22 % 25 %

27.03.2015

Auxiliary energy demand of the system

Auxiliary energy demand of the system with constant

speed pumps/fans as a function the cooling capacity


Distribution of auxiliary energy demand



Examples of air-cooled absorption chillers

H2O/LiBr, rotating HX,

intermediate circuit

NH3/H2O -> high working pressure!

Gas driven -> high driving temperature

Source Helioplus

Source: Rotartica

27.03.2015


Examples of air-cooled absorption chillers

H2O/LiBr, gas driven, intermediate

circuit

Q0=23 kW; zetta=1,1, Pel=1,8kW

(COPel=12,7)

27.03.2015

Source: Broad

Source: Broad

Balancing Single Lift vs. Double Dift

chilled water out: 13 °C


60

65

70

75

80

85

90

95

100

105

110

115

120

125

130

20 25 30 35 40 45 50

tL,e [°C]

t HW

,e [

°C]

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0,5

0,55

0,6

0,65

0,7

0,75

0,8

zre

al [-

]

durchgezogen - Double Lift / gestrichelt - Single LiftSolid lines – single effect/double lift; dashed lines – single-effect/single lift

Aimed specifications for the development

Condenser and Absorber directly air-cooled

Outdoor installation, frost save

Auxiliary energy consumption at nominal conditions < 60 Wel/kW0 („EER“ > 16)

Single effect / single lift


External Fluid Nominal Condition Operating Range

Chilled water temperature

(water w. 20 % Glycol) 18 °C / 13 °C (in/out) 6 °C … 20 °C (out)

Heating water temperature

(water w. 20 % Glycol) 95 °C / 87 °C (in/out) 75 °C … 105 °C (in)

Ambient air (for re-

cooling) 32 °C / 42 °C (in/out) 10 °C … 32°C (in)

Cooling capacity 8 kW

Test of components within functional model


Improved functional model

27.03.2015 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 13

First lab results


0,55

0,60

0,65

0,70

0,75

0,80

6

7

8

9

10

11

12

9 10 11 12 13 14 15 16 17

EER

th[-

]

coo

ling

po

wer

[kW

]

chilled water outlet temperature [°C]

cooling power and EERth

95 | var | var

95 | 25 | var95 | 30 | var95 | 35 | vardesign point (95 | 32 | 13)EER_th 95 | 25 | varEER_th 95 | 30 | varEER_th 95 | 35 | var

25

30

35

35

30

35

0,55

0,60

0,65

0,70

0,75

0,80

6

7

8

9

10

11

12

9 10 11 12 13 14 15 16 17

EER

th[-

]

coo

ling

po

wer

[kW

]



95 | var | var


0,55

0,60

0,65

0,70

0,75

0,80

6

7

8

9

10

11

12

9 10 11 12 13 14 15 16 17

EER

th[-

]

coo

ling

po

wer

[kW

]



95 | var | var


Restrictions of lab measurements

Limited space and height in lab

No free outflow of absorption chiller outlet air

-> increased air-side counter pressure

-> higher fan speed for same air flow rate needed

-> increased power consumption of fan

=> no meaningful results regarding EERel

Difficulty to maintain even temperature

distribution

27.03.2015 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 15

Conclusion and Outlook

Thermal design point reached

No useful results regarding electrical efficiency yet

Field test planned in summer 2015

Results expected regarding

Electrical efficiency

Operational experience

Outdoor installation


Vacuum ice slurry technology for high density cold

storage, e.g. in PV driven cooling systems

High energy density (93 kWh/m³)

Higher efficiency than conventional ice bank

storage through high evaporation temperature

No glycol circuit needed

Ice slurry is pumpable

Capacity range: 50 … 500 kW

Matching solar radiation and cooling demand

Efficient cooling, cold storage or heating using vacuum ice slurry 17

ILK Dresden Department of Applied Energy Engineering

Bertolt-Brecht-Allee 20; 01309 Dresden; Germany

Dr.-Ing. Mathias Safarik

Tel.: +49 351 4081-700

E-Mail: [email protected]

Thanks for your attention!

Questions?

ilk dresden new 8 kw chiller

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