Solubility, Miscibility, and Liquid Viscosity of Lubricants with CO2 … · 2017-10-02 ·...

Solubility, Miscibility, and Liquid Viscosity of Lubricants with CO2

and Propane

Chris SeetonSeeton C&PUniversity of Illinois at Urbana-Champaign

Chicago 2003 – ASHRAE Winter Meeting

Viscosity – Temperature ChartASTM D 341-93 (1998)

1251151059585756555453525155-5-15

10000

20001000500

200

10060

3020

810

654

3

2

1 -0.63743

-0.43743

-0.23743

-0.03743

0.16257

0.36257

0.56257

2.403378

Kin

emat

ic V

isco

sity

, cS

t


Viscosity Naphthene Mineral Oil

-15 -5 5 15 25 35 45 55 65 75 85 95 105 115 125

1

2

3

456

108

2030

60100

200

50010002000

10000

-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%


Viscosity and Vapor PressureNaphthene Mineral Oil / Propane

1251151059585756555453525155-5-15

10000

20001000500

200

10060

3020

810

654

3

2

1-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%

10%

20% propane

SolubilityNaphthenic Mineral Oil 32 / Propane

1201009080706050403020100-10-20-30-40 1100

10

20

30

40

50

Temperature (C)

Pres

sure

(bar

)

15% Propane

5%

10%Pure Propane

20%

30%

Viscosity – Temperature ChartDaniel Chart


1251151059585756555453525155-5-15

10000

20001000

500

200

10060

4020

810

654

3

2

1-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%

10%

P =

2 b

ar

P =

4 b

ar

P =

5 b

ar

P =

6 b

ar

20% propane

P =

15

bar

Naphthenic Mineral Oil 32 / PropaneDaniel Chart

Assume:Evaporator = -6°C

Suction Pressure = 4 bar6°C Superheat10°C Suction Line HX 20°C Rise in Compressor

Bearing Lubrication Temp.30°C

Pure Lubricant Viscosity62 cSt

Mixture Viscosity 22 cSt


1251151059585756555453525155-5-15

10000

20001000

500

200

10060

4020

810

654

3

2

1-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%

10%

P =

2 b

ar

P =

4 b

ar

P =

5 b

ar

P =

6 b

ar

20% propane

P =

15

bar

POE-55 / R-134aDaniel Chart

-40 -20 0 20 40 60 80 100

10000

20001000

500200100

60

3020

810

654

3

2

1.25 -1

-0 .8

-0 .6

-0 .4

-0 .2

0

0 .2

0 .4

0 .6

2 .3 6 7 6 3 5

Kin

emat

ic V

isco

sity

, cS

t 100%POE-55

90%

80%

70%

P =

1 b

ar

P =

3 b

ar

P =

5 b

ar

P =

2 b

ar


Suction Pressure = 2.3 bar6°C Superheat10°C Suction Line HX 20°C Rise in Compressor




Viscosity ComparisonISO 32 Lubricants with Propane

0

10

20

30

40

50

60

AB MO POE PAG POE/R134a

Vis

cosi

ty (c

St)

Test Condition: -6°C Evaporating, 6°C Superheat, 10°C Suction Line HX, 20°C Compressor Heating

DensityNaphthenic Mineral Oil 32 / Propane

Density of Naphthene Mineral Oil / Propane

0.68

0.7

0.72

0.74

0.76

0.78

0.8

0.82

0.84

0.86

0.88

0.9

0.92

0.94

-25 -15 -5 5 15 25 35 45 55 65 75 85 95 105

Temperature (C)

Den

sity

(g/c

c)

0% Pure MO

5%

10%

20%

30%Propane

15%

DensityPolyalkylene Glycol 46 / Propane

Density of Polyalkylene Glycol / Propane

0.640.660.680.7

0.720.740.760.780.8

0.820.840.860.880.9

0.920.940.960.98

11.021.04

-25 -15 -5 5 15 25 35 45 55 65 75 85 95 105

Temperature (C)

Den

sity

(g/c

c)

0% Pure PAG

5%

10%

20%

30% Propane

15%

Propane Miscibility

POE, AB, and MO showed excellent solubility with propanePAG showed a saturated pressure close to pure propane for 30% compositions– Could be a sign of possible immiscibility– More testing is necessary

Vapor Pressure90% by weight 220 Lubricant Concentration

1009080706050403020100-10-20 1201100

10

20

30

40

50

60

Temperature (C)

Pre

ssur

e (b

ar)

Pure CO2

PAO-220

AB-220

PAG-220POE-220

SolubilityPAO > AB > PAG > POE

( ) 2TF

TEDPlog ++=

Modified Clausius-Clapeyron

Mixture Viscosities – 90% LubricantPAG > PAO > POE > AB

120100806040200-20

1.25

2

3

456

108

2030

60100200

50010002000

10000

-1

-0 .8

-0 .6

-0 .4

-0 .2

0

0 .2

0 .4

0 .6

2 .4 0 3 3 7 7 9

Abso

lute

Vis

cosi

ty, m

Pa*

sec

PA G-220

PA O-220

POE-220

A B-220

Pure Lubricants

PA GPA OPOEMOA B

POE-55 / CO2Daniel Chart

-40 -20 0 20 40 60 80 100

10000

20001000

500200100

60

3020

810

654

3

2

1.25 -1

-0 .8

-0 .6

-0 .4

-0 .2

0

0 .2

0 .4

0 .6

2 .3 6 7 6 3 5

Kin

emat

ic V

isco

sity

, cS

t 100%POE-55

95%

90%

85%

P =

10

bar

P =

15

bar

P =

35

barP =

25

bar

Assume:Evaporator = 0°C

Suction Pressure = 35 bar10°C Superheat10°C Internal Heat Exchanger 20°C Rise in Compressor



Mixture Viscosity 5.5 cSt

Miscibility in CO2

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0W t % L u b r i c a n t i n C O 2

- 4 0

- 3 5

- 3 0

- 2 5

- 2 0

- 1 5

- 1 0

- 5

0

5

1 0

1 5

2 0

2 5

3 0

tem

pera

ture

/ o C

P O EP O EP A GP A G

P A OP A O

MM

A BA B

MiscibleImmiscible

POE Miscible

CO2 Miscibility

Based on miscibility data design concerns should be based on the cycle operation for the AB, MO, PAO, and PAG lubricantsIt is expected that the POE lubricant will not experience these miscibility problems– HOWEVER, serious design considerations must be

weighed to account for the reduction in the mixture viscosity

Lubricants with CO2 - Conclusions

POE Lubricant type showed good miscibility– Severe viscosity reduction possibly limits its use to low

temperature cascade systems

PAG, PAO, MO and AB are only partially soluble in CO2– Transcritical AC systems Ø evaporators, receivers, Int. HX – Transcritical Heat Pump systems Ø evaporators, receivers,

compressor sump

However, the PAG type lubricant seems to give the best lubricity for transcritical applications

– PAG maintained the highest mixture lubricity in this study

High efficiency oil separators may make MO a viable lubricant in some cascade systems

Prototype AC Compressorfailed @ 10 hrsRepeatable

POE-220

Influence of CO2- Roller BearingLubrication

Polyol Ester 32 / PropaneDaniel Chart






Viscosity and Vapor PressurePolyol Ester / Propane

-15 -5 5 15 25 35 45 55 65 75 85 95 105 115 125

1

2

3

456

108

2030

60100

200

50010002000

10000

-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%

10%

P =

2 b

ar

P =

4 b

ar

P =

5 b

ar

P =

6 b

ar

20% propane

Polyalkylene Glycol 46 / PropaneDaniel Chart






Viscosity and Vapor PressurePolyalkylene Glycol / Propane

-15 -5 5 15 25 35 45 55 65 75 85 95 105 115 125

1

2

3

456

108

2030

60100

200

50010002000

10000

-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%

10%

P =

2 b

ar

P =

4 b

ar

P =

5 b

ar

P =

6 b

ar

20% propane

Alkylbenzene 32 / PropaneDaniel Chart






Viscosity and Vapor PressureAlkylbenzene / Propane

-15 -5 5 15 25 35 45 55 65 75 85 95 105 115 125

1

2

3

456

108

2030

60100

200

50010002000

10000

-0 .6 3 7 4 3

-0 .4 3 7 4 3

-0 .2 3 7 4 3

-0 .0 3 7 4 3

0 .1 6 2 5 7

0 .3 6 2 5 7

0 .5 6 2 5 7

2 .4 0 3 3 7 8

Kin

emat

ic V

isco

sity

, cS

t

0%

10%

P =

2 b

ar

P =

4 b

ar

P =

5 b

ar

P =

6 b

ar

20% propane

Solubility, Miscibility, and Liquid Viscosity of Lubricants with CO2 … · 2017-10-02 ·...

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