performance characteristics of fixed volume ratio compressors

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Purdue University

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International Compressor Engineering Conference School of Mechanical Engineering

1982

Performance Characteristics of Fixed Volume RatioCompressors

J. R. Sauls

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Sauls, J. R ., "Performance Characteristics of Fixed Volume Ratio Compressors" (1982).International Compressor EngineeringConference. Paper 394.hp://docs.lib.purdue.edu/icec/394
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CONCLUSIONSA procedu re for an alyzing the performance of anid ealized fixed volum e ra tio compressor has beenpresen ted. The analysis ex plains the chara cte r-i s t ic 'S hapes of fixed volum e ra tio compressorpower and effic iency curves and can be used to study the effect of built-in volu m e ra tio andla te open ing unl oader s on unloaded perf ormance .An eXpression for adiabatic efficiency was dev-eloped and i t was shown tha t the idealized fixedvo lu m e ra tio compressor efficiency varieswith press ure rat io . The losses in efficiency arethe penalty paid for use of a fixed vo lum e ra tio concep t. I t is suggested that the eff icie ncycom pute d including these losses (equation 20)is a pr oper reference per fo rmance le vel and compar ison of actual performance wit h th is reference is a good measure of desi gn quality.REFERENCES[1 ] Sulla ir Corp., "Packaged RefrigerationScrew Compressors, Engineering Dat a" ,

September, 1972.

31 0300 290

270260

"'"' 240"""' 23 0 "'"' 22 0:z:"'

210 "'. 2DO"'ll 190 ISO 170160150140130 20

FIGURE lROTARY SCREW COMPRESSORPOWER CHARACTER ISTICS

DATA FROM REFERENCE ( l)

I 3II

III

I/I 2I /------1---r;

I I II I 1

I I I/ I /I I II / II 2

I / II /

I II /

I II.-1----1

II

40 60 so 100 EVAPORATOR PRE SS URE

I T COND 66 .02 T COND 105.03T CONO 122.0

V I. 2.6

110 120

...>z

205

120 11511 0 105 1009590as80 7570 65 so5550

p

FIGURE 2ISENTROPIC POWER RAT IO VS Pl

REFR IGERANT R-22

20

K : 1.135EQUATION 7

P3 261 .7 PSIA!TSAT122.0 DEGl

I ~ P3:225.5 P$1AI (T SATI0 5.0 DEGI~ P3172 .9 P$1A(TSAT 86. 0DEG I40 60 BO 100 120 1


7/8

pP,

FIG URE 5SYSTEM r .2'1COMPRESSOR v1 3.5 k = .1 35

FIG UR E 6POWER RATIO VS P l

CONDENSER PR ES SU RE = 172 .9 PSI ACONDENSER TEM PE RATU RE= 86. 0DEG.

120115110 10510095;: 90

z 85.... eo

7670 65so55 50 20

120115 110105100 95

... 90>.85zi ; eo

757065605650 20

RE FR IG ERA NT R-2 2

40

K:1.1 35 6

5I - vi=1.52-v l 2 .0

5-y j; :4. 06 - vi ' 5.0 ISENTROP E(E QN7)

6o eo 1oo 12o J4oPl- PSIA

FIGU RE 7POWER RAT IO VS P lRE FR IG ERA NT R- 22

K= 1. 135

3 2I 1 I

I I I

/ I I/ // /

II,

I I II I II I, ,

I I

/ II / I

I I/ , ', ,

I I,,

I T- CONO 86 .0 2 T- CONO 105.03 T- COND =122. 0"i- 2.6

40 60 eo 100 12 0 140Pl-PS IA

pP,

...>.:::.:

"'

...>:z....30"

206

FIG UR E 8

6, 0 3o

5, 0kO3.0 2.0LO

0 1.0 V/ V1

fiGURE 9PA RT LOAD PERFOR MA NC E

5:1 PRE SS UR E RAT IO P 1 =50 .0 PS IA

K l . l3 510610 096 9086 80 7510 65so-555045 4035 4- 1=.o30 25200. 0 o.a 0,4 0.6 o.e 1.0

100959085 8075 70 666055 5045 4035 30 2520

FRJ.CTJONOF SW EP TVOLUME

FI GU RE 10PART LOAD PERFO RM ANCE 41 PRESSU RE RAT IO

Pl= 50. 0PSI AK =1. 13 5

4

I - ; ' 4. 02- Vi'!il:s -v i= s .o 4- " 8. 0

o.o 0.2 0. 4 0.6 0. 8 I oFF IAC TIO N OF SW EP TVOLUME


8/8

858075 70 656055

FIG URE IIPART LOAD PERFORMANCE

2 50.. 45"'

l

.....;..""

1.00.9

i:; o.a"' 0.7 "i: 0. 6l:; 0.5 ": 0.4

performance characteristics of fixed volume ratio compressors

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