1

An Experimental Investigation and Modelling of the Viscosity Refrigerant/oil Solutions.

V. P. Zhelezny1*, V.V. Sechenyh1, Yu. V. Semenyuk1, A. J. Grebenkov2, O. V. Beliayeva2

1 Odessa State Academy of Refrigeration, 1/3 Dvoryanskaya Str., 65026 Odessa, Ukraine

2 Joint Institute for Power and Nuclear Research – Sosny, 99 Akademik Krasin Str., 220109

Minsk, Belarus

* Corresponding author. Tel.: + 380 487 663146. Fax: + 380 482 238931.

E-mail address: vzhelezny@mail.ru

Abstract

This paper presents experimental data for the viscosity of solutions of refrigerant

R600a (isobutane) with mineral compressor oils Azmol, Reniso WF 15A, and R245fa

(1,1,1,3,3-pentafluoropropane) with polyolester compressor oil Planetelf ACD 100 FY on the

saturation line. The experimental data were obtained for solution of R600a with mineral

compressor oil Azmol in the temperature range from 294.7 to 338.1 К and the concentration

range 0.04399 Rw 0.3651, the solution of R600a with mineral compressor oil Reniso WF

15A at the temperatures from 285.8 to 348.4 К and the concentration range 0.03364 Rw

0.2911, the solution of R245fa with polyolester compressor oil Planetelf ACD 100 FY at the

temperatures from 309 to 348.2 and the concentration range 0.06390 Rw 0.3845. The

viscosity was measured using a rolling ball method. The method for prediction of dynamic

viscosity for refrigerant/oil solutions is reported.

Keywords: Experimentation; Isobutane; Solution; R245fa; Oil; Viscosity.

2

Nomenclature

a, b, c, d, e Coefficients in Eq. (4, 6-9)

C Viscosimeter constant, m2 s-2

m Mass, kg

T Temperature, K

t Reduced temperature

w Weight concentration

x Mole fraction

Greek symbols

Universal function of reduced temperature

Parameter in Eq. (3) depends on refrigerant mole fraction

Dynamic viscosity, Pa s

Density, kg m-3

Time, s

Subscripts and superscripts

Pseudocritical property

B Ball

ROS Refrigerant oil solution

OIL Property of oil

R Property of the pure refrigerant

0 Coefficient in Eq. (3) depends on refrigerant mole fraction

3

1. Introduction

Lately, ecological factors and ecological safety issues prevail over other requirements

laid for refrigerants. Heat pumps, refrigeration installations and air conditioners are retrofitted

by ozone-safe refrigerants with low global warming potential (GWP). Among such

refrigerants natural refrigerant R600a and halogen derivative refrigerant R245fa find wide

application [1–3]. The latter is regarded as the most prospective refrigerant for replacing

ozone depleting refrigerant R11.

Well known fact that the real working fluid in a vapor-compression refrigeration systems

represents a solution consisting of the refrigerant and the compressor oil admixtures. Thus,

the properties of refrigerant/oil solutions (ROS) should be used [4] when estimating an

efficiency of the compressor system or analyzing heat transfer processes in evaporator and

condenser.

The dependence of the viscosity for the ROS on the temperature and the concentration

has a complicated behaviour. However, the accurate experimental data for the viscosity of

the ROS still remains limited. It should be mentioned that the prediction methods for ROS

viscosity available in literature do not provide an appropriate level of accuracy [5]. Therefore,

the purpose of the present paper is to perform experimental study of the viscosity for the

solutions of widely used refrigerants and compressor oils.

2. Experimental section

In order to study the viscosity of the ROS, an experimental apparatus was designed. A

schematic outline of the experimental setup is given in Fig. 1.

Fig. 1.

4

The main element of the experimental setup is a measuring cell, which represents a

glass tube (15) filled up with a solution to be investigated and a small steel ball inside. (16).

There are two marks on the tube in order to register time taken by the ball passing a certain

distance. The measuring cell is placed inside flow thermostat (14). The auxiliary thermostat is

equipped with basic (3) and regulated (2) heaters, stirrer (4), pump (7) and heat exchanger

(5). Constant temperature in the auxiliary thermostat is kept up by automatic control system

which consists of contact thermometer (6), amplifier (1) and heater (2). During the process

of experiment the temperature was measured with the help of laboratory mercury expansion

thermometers (13) with scale factor of 0.1 K. The thermometers were placed in immediate

vicinity of the experimental cell.

The thermostat temperature stability has been estimated to be within ±0.05 К. The flow

thermostat is fixed at a slewing table which allows changing an angle of slope of the

measuring cell in order to provide measurements in a wide range of the viscosity values of

the investigated solutions. Cathetometer (18) is used for visual observations of the ball

movement.

Filling of the measuring cell with compressor oil is done with the help of an injector. The

quantity of refrigerant required for a given concentration of the solution is condensed in the

cell from a heated balloon (12). Afterwards, when valve V3 is closed the balloon is cooled by

liquid nitrogen in order to condense the vapour of the refrigerant, which has resided in

connecting pipes. Masses of solution components are determined using the results of

weighing of the injector and the balloon before and after filling. Weighing is provided with the

help of an analytical balance with an uncertainty of 5·10–7 kg.

The sylphon (17) performs a function of a separator between the investigating solution

and the oil of the piston pressure gauge (20). The latter is used for making, maintaining and

measuring the pressure of the investigated sample in the viscometer. In the given

experiments the pressure in the measuring cell was established in a value by 1–2 bar higher

5

than the saturated vapor pressure of the investigated solution of the given concentration.

Thus, the possibility of vapor phase formation in the cell was avoided.

According to the results of the additional experiment, in the temperature range from 30

to 350 K the increase of pressure by 10 bar leads to negligibly small growth of viscosity in the

ROS liquid phase. Therefore, measurement the viscosity of the ROS may quite reasonably

be referred to the saturated liquid state.

Before experimental investigation of the viscosity for the ROS, calibration tests were

carried out in order to define values of the viscometer constant with different angles of the

measuring cell slope. In addition, the compressor oils, which were components of the

investigated ROS and were preliminarily measured on an Ubbelohde viscosimeter, and then

were used as reference fluids. The data for the viscosity of the compressor oils were

reported in [5].

The concentration of the liquid phase of the ROS is estimated by the following formula:

RR

R OIL

mw

m m

(1)

where Rm and OILm are the mass of refrigerant filled into the cell and that of oil

correspondingly. Relative uncertainty of determination of mass concentration does not

exceed 0.01–0.05 %.

In order to clean the investigated sample of water admixtures and permanent gases the

compressor oil was heated to T= 388 K and then vacuumized for 60 s. The cleaning

procedure was repeated several times. The purity of the compressor oils was checked by an

Abbe refractometer. Thermodynamic and physical-chemical properties of the compressor

oils are listed in Table 1.

Table 1.

6

The compressor oil Azmol was manufactured by «Azmol» company (Ukraine).

Compressor oils Planetelf ACD 100FY and Reniso WF 15A were produced by «TOTAL

Lubricants» and «FUCHS» respectively. The purity of the R600a and R245fa was 99.8 wt.

% and 99.9 wt. %.

3. Calculation and discussion

In the framework of the rolling ball method which was used in the experiments, the

dynamic viscosity for the liquid phase of the ROS is calculated by the formula:

( )ROS B ROSC (2)

where C is the viscometer constant, B is the density of the material which the ball is made

of ( 7810B kg m-3), ROS is the density of the ROS in the saturated liquid phase (data for

the density of the ROS were taken from [6-8] ), is the time taken for the ball passing a

fixed distance between marks on the glass tube. The total uncertainty of the measurements

in viscosity in the experiment was estimated to be 1.5 to 4%. The experimental data are

listed in Table 2-4.

Table 2-4.

The experimental data for the viscosity of the ROS were described using the following

equation:

0

Rt x

R O S Rx t (3)

7

where R O S is the dynamic viscosity of the ROS on a saturation line, 0 Rx is the

coefficient depended on mole fraction of the refrigerant, Rx is the parameter depended

mole fraction of the refrigerant, t is universal function of reduced temperature for the

refrigerants, 1 / Ct T T is the reduced temperature, CT is the pseudocritical temperature

of the ROS.

The pseudocritical temperature for the ROS in the concentration range 0.3 1Rw

can be calculated by method reported in [9], the pseudocritical temperature for the ROS in

concentration range 0 0.3Rw was calculated by method based on minimization of the

deviations for the experimental data obtained from calculated value by the Eq.(3). The

concentration dependence for the pseudocritical temperature of the ROS in the concentration

range 0 1Rw was fitted by Eq. (4).

0.52 3c R R RT a b x c x d x (4)

where a, b, c, and d are the coefficients. The values of the coefficients of the Eq.(4) are

listed in Table 5.

For determination the value for the universal function t the data for the dynamic

viscosity for different refrigerants [10] in the range 0.08 0.4t and data for the viscosity

of the compressor oils [5] in the range 0.4 0.65t were taken and then analyzed (as is

shown in Fig. 2 ).

Fig. 2.

Based on performed analysis the following universal dependence t was obtained:

2

2 3

0.61538 16.155 33.098

1 10.591 33.506 24.077

t tt

t t t

. (5)

8

As a result of fitting of the experimental data on the dynamic viscosity in the liquid phase of

the ROS, the concentration dependence for the parameter 0 Rx can be determined as:

0 exp2

R RR 2

R R

a + cx + exx

1 + bx + dx

with 0 Rx 1 (6)

where a, b, c, and d are the coefficients. The values of the coefficients of the Eq.(4) are

listed in Table 5. The concentration dependences of coefficient Rx can be calculated by

the following equations:

for the ROS R600a/Azmol with 0 Rx 1

exp exp1.5R R R R Rx a+bx +cx +d x +e x (7)

for the ROS R600a/Reniso WF 15A with 0 Rx 1

exp1.5 2R R R R Rx a+bx +cx +dx +e x (8)

for the ROS R245fa/Planetelf ACD 100 FY with 0 Rx 1

3 0.5= expR R R R Rx a+bx +cx +d x +ex (9)

where a, b, c, d, e are coefficients listed in Table 5.

As is seen, the Eq.3 has only 2 coefficients. The both coefficients can be calculated

from the experimental data. Thus, Eq.(3) can be applied to prediction of the dynamic

viscosity of the refrigerants in the range 0.08 0.4Rw (scaling area) and for the

compressor oils in the range 0.4 0.65Rw . As is shown in Fig.3, the relative deviations of

the values for the dynamic viscosity for the refrigerants and the compressor oils [5, 10] from

data calculated by Eq.3 lie in the range from 1.5 to 3.7%.

9

Fig. 3.

Deviations of the experimental data obtained from the values calculated by Eq.3 (see Figs. 4

-6) lie in the range from 1.5 to 4.5%.

Figs. 4-6.

The modified Daniel plot [11] developed using Eqs.3-9 are presented on Figs.7-9

Figs. 7-9.

5. Conclusion

The new accurate experimental information on dynamic viscosity of the refrigerant

solution of R600a with compressor mineral oil Azmol, the refrigerant solution of R600a with

compressor mineral oil Reniso WF 15A and the solution of refrigerant R245fa with

polyolester oil Planetelf ACD 100 FY have been obtained. The simple correlation for

prediction the dynamic viscosity for the refrigerant/oil solutions in the wide range of

concentrationsand temperatures based on limited empirical information has been proposed.

As can be seen the experimental data for the ROS have been successfully described by the

correlation. The experimental data obtained can be applied when designing evaporators,

compressors, heat exchangers and other important parts of refrigeration systems.

10

References

[1] Pearson F. Refrigerants past, present and future. In Proceedings 21st International

Congress of Refrigeration, IIR/IIF, 2003; Washington DC, USA. p. 1-12.

[2] Khlieva OYa, Kosoy BV, Stepanova VP, Zhelezny VP. The End and New the Beginning:

Alternative Refrigerants for the New Heat Pump Generation. Abstracts 5-th International

Conference “Problems of Industrial Heat Engineering”, May 22-27 2007; Kiev, Ukraine. p.

234-235.

[3] Kuijpers L. The impact of the Montreal and Kyoto protocol on new developments in

refrigeration and a/c. In Proceedings IIR conference "Emerging Trends in Refrigeration & Air-

conditioning", 1998; New Delhi, India. p. 1-14.

[4] Meltzer LZ. Lubricants for freon refrigerating machines, Moscow: Pischevaya

promishlennost, 1969. p.121-158 (in Russian).

[5] Zhelezny VP, Sechenyh VV, Semenyuk YV, Ancherbak SN, Tsvetkov ON. Experimental

investigation of thermophysical properties of compressor oils: Mogul ONF 46, Planetelf ACD

100 FY, Azmol, Lunaria FR 32, XC 15, XC 40. Bulletin of the International Academy of

Refrigeration. 2007; 2; 23-30. (in Russian).

[6] Zhelezny PV, Procenko DA, Zhelezny VP, Ancherbak SN. An experimental investigation

and modelling of the thermodynamic properties of isobutane-compressor oil solutions: Some

aspects of experimental methodology. Int J Refrigeration 2007; 30; 433-445.

[7] Zhelezny VP, Semenyuk YuV, Ancherbak SN, Grebenkov AJ, Beliayeva OV. An

Experimental investigation and modeling of the solubility, density and surface tension of

1,1,1,3,3,- pentafluoropropane (R245fa)/ synthetic polyolester compressor oil solutions. J

Fluor Chemistry 2007; 128; 1029-1038.

[8] Nichenko SV; Semenyuk YuV, Zhelezny VP; Density and surface tension for the solution

R600a/Reniso WF 15. Refrigeration Eng Technology. 2008, in press (in Russian).

[9] Zhelezny PV, Zhelezny VP, Skripov PV. Determination of the pseudocritical parameters

for refrigerant/oil solutions. Fluid Phase Equilib 2003; 212; 285-302.

11

[10] McLinden MO, Klein SA, Lemmon EW and Peskin APG, 2003, NIST Standard

Reference Database 23, NIST Thermodynamic Properties of Refrigerants and Refrigerants

Mixtures Database (REFPROP), Version 7.1 (Gaithersburg: National Institute of Standard

and Technology).

[11] Daniel G, Anderson M, Schmidt W, Tokumitsu M. Performance of selected synthetic

lubricants in industrial heat pumps. Heat Recov Systems 1982; 2; 359-368.

[12] Skripov PV, Starostin AA, Volosnikov DV, Zhelezny VP. Comparison of thermophysical

properties for oil/refrigerant mixtures by use the pulse heating method, Int J Refrigeration

2003; 26; 721-728.

12

Fig. 1. Scheme of experimental apparatus.

1 – contact thermometer amplifier; 2 – regulated heater; 3 – basic heater; 4 – stirrer; 5 – heat

exchanger; 6 – contact thermometer; 7 – pump; 8 – fore pump; 9 –inlet valve; 10 – cryogenic

trap; 11 – thermocouple gage head; 12 – balloon with refrigerant; 13 – laboratory mercury

thermometer; 14 – flow thermostat; 15 – quartz glass tube; 16 – steel rolling ball; 17 –

sylphon delimiter; 18 – cathetometer; 19 – pressure gauge; 20 – piston pressure gauge; 21 –

water cooler.

13

0,1 0,2 0,3 0,4 0,6

4

5

6

8

9

10

11

12

ln

t

R290 R600 R600a R125 R134a R245fa R23 Planetelf ACD 100FY Reniso WF 15A Azmol XC 15 Mogul ONF 46 XC 40

Fig. 2. Dependence of logarithm of dynamic viscosity on reduced temperature t for

refrigerants and compressor oils.

0,1 0,2 0,3 0,4 0,6-4

-3

-2

-1

0

1

2

3

4

100( [5

,10

]-ca

lc)/ ca

lc,

%

t

R290 R600 R600a R125 R134a R245fa R23 Planetelf ACD 100FY Reniso WF 15A Azmol XC 15 Mogul ONF 46 XC 40

Fig. 3. Deviations of data on dynamic viscosity of refrigerants [10] and compressor oils [5]

from calculated values by Eq. 3.

14

290 300 310 320 330 340

-4

-2

0

2

4

100( e

xp-

calc)/ ca

lc, %

T, K

xR=0

xR=0.2473

xR=0.4202

xR=0.6043

xR=0.8042

Fig. 4. Deviations of experimental data on dynamic viscosity of the ROS R600a/Azmol from

calculated values by Eq. 3.

280 290 300 310 320 330 340 350

-4

-2

0

2

4

100( e

xp-

calc)/ ca

lc, %

T, K

xR=0

xR=0.1604

xR=0.3242

xR=0.4863

xR=0.6927

Fig. 5. Deviations of experimental data on dynamic viscosity of the ROS R600a/Reniso WF

15A from calculated values by Eq. 3.

15

310 320 330 340 350-4

-2

0

2

4

100( ex

p-

calc)/ ca

lc, %

T, K

xR=0

xR=0.3128

xR=0.5424

xR=0.7167

xR=0.8064

Fig. 6. Deviations of experimental data on dynamic viscosity of the ROS R245fa/Planetelf

ACD 100 FY from calculated values by Eq. 3.

260 270 280 290 300 310 320 330 340 350

1

10

100

7 bar6 bar

4 bar

3 bar

2 bar

1 bar

60%

50%

40%

30%

20%

10%

Kin

emat

ic v

isco

sity

, mm

2 s-1

T, K

0%

Fig. 7. Modified Daniel plot ( v P T )for the ROS R600a/Azmol

16

260 270 280 290 300 310 320 330 340 350

1

10

100

7 bar6 bar

4 bar3 bar

2 bar

1 bar

60%

50%

40%

30%

20%

10%

Kin

emat

ic v

isco

sity

, mm

2 s-1

T, K

0%

Fig. 8. Modified Daniel plot ( v P T ) for the ROS R600a/Reniso WF 15A.

260 270 280 290 300 310 320 330 340 350

1

10

100

1000

5 bar4 bar

3 bar2 bar

1 bar

0.5 bar

60%

50%

40%

30%

20%

10%

Kin

emat

ic v

isco

sity

, mm

2 s-1

T, K

0%

Fig. 9. Modified Daniel plot ( v P T ) for the ROS R245fa/Planetelf ACD 100 FY.

17

Figure Captions:

Fig. 1. Scheme of experimental apparatus for study of ROS viscosity.

1 – contact thermometer amplifier; 2 – regulated heater; 3 – basic heater; 4 – stirrer; 5 – heat

exchanger; 6 – contact thermometer; 7 – pump; 8 – fore pump; 9 –inlet valve; 10 – cryogenic

trap; 11 – thermocouple gage head; 12 – balloon with refrigerant; 13 – laboratory mercury

thermometer; 14 – flow thermostat; 15 – quartz glass tube; 16 – steel rolling ball; 17 –

sylphon delimiter; 18 – cathetometer; 19 – standard pressure gage; 20 – piston pressure

gauge; 21 – water cooler.

Fig. 2. Dependence of logarithm of dynamic viscosity on reduced temperature t for

refrigerants and compressor oils.

Fig. 3. Deviations of data on dynamic viscosity of refrigerants [10] and compressor oils [5]

from calculated values by Eq. 3.

Fig. 4. Deviations of experimental data on dynamic viscosity of the ROS R600a/Azmol from

calculated values by Eq. 3.

Fig. 5. Deviations of experimental data on dynamic viscosity of the ROS R600a/Reniso WF

15A from calculated values by Eq. 3.

Fig. 6. Deviations of experimental data on dynamic viscosity of the ROS R245fa/Planetelf

ACD 100 FY from calculated values by Eq. 3.

Fig. 7. Modified Daniel plot ( v P T ) for the ROS R600a/Azmol

Fig. 8. Modified Daniel plot ( v P T ) for the ROS R600a/Reniso WF 15A.

Fig. 9. Modified Daniel plot ( v P T ) for the ROS R245fa/Planetelf ACD 100 FY.

18

Tables

Table 1. Thermodynamical and physical-chemical properties of the compressor oils

Property Reniso WF

15A Azmol

Planetelf ACD

100 FY

Colour – 0.5* 1* –

Density at 288 K kg m-3 889** 881** 976**

Density at 293 K kg m-3 885** 877** 972**

Dynamic viscosity

at 313 K

at 373 K

mPa s

mPa s

13.2**

2.66**

9.27**

2.20**

100**

10.1**

Acid number mg KOH/g 0.02* 0.02* < 0.1*

Flash point K 437* 426* 543*

Floc point

temperature K

214**

(9% in R-600а)

186**

(5% in R-600а)

249**

(5% in R-245fa)

Pour point

temperature K – 223* 240*

Molecular weight g mol-1 319** 415** 894**

Pseudocritical

temperature*** K 776*** 767*** 807***

* - Manufacturer's data

** - Data were obtained in the Department of Engineering Thermal Physics of Odessa State

Academy of Refrigeration

*** - The pseudocritical temperature for compressor oils was experimentally determined by

the method of pulse heating (Skripov et al., 2003).

19

Table 2. Experimental data on dynamic viscosity of the ROS R600a/Azmol on the saturation

liquid phase.

,T K 310 , Pa s , kg 3m ,T K 310 , Pa s , kg 3m

Rx = 0 310.5 3.44 815.3

293.4 20.3 876.9 313.3 3.14 813.5

298.1 16.4 873.7 316.2 3.07 811.5

303.2 13.3 870.2 318.3 2.89 810.0

308.3 11.0 866.8 320.2 2.80 808.7

313.1 9.24 863.5 323.3 2.66 806.5

318.7 7.72 859.6 325.3 2.56 805.0

323.5 6.65 856.4 325.9 2.49 804.6

328.6 5.76 852.9 328.1 2.41 803.0

333.3 5.10 849.6 329.2 2.38 802.2

338.2 4.51 846.3 332.2 2.30 799.9

343.1 4.04 842.9 Rx = 0.6043

347.3 3.66 840.0 303.4 2.29 786.2

Rx = 0.2473 308.3 2.14 782.5

303.1 6.85 839.8 314.1 1.90 778.1

20

305.7 5.77 838.3 318.7 1.86 774.5

308.2 4.95 836.8 323.6 1.68 770.6

317.4 4.57 831.0 328.6 1.51 766.4

323.0 3.76 827.4 333.5 1.48 762.1

328.4 3.43 823.8 337.8 1.31 758.3

333.2 3.03 820.5 Rx = 0.8042

337.4 2.86 817.5 294.7 1.12 792.4

338.1 2.78 817.0 301.0 1.00 787.9

Rx = 0.4202 303.6 0.998 786.0

303.1 4.21 820.2 305.7 0.946 784.5

305.7 3.84 818.5 308.3 0.933 782.5

308.2 3.58 816.9 313.1 0.868 778.9

21

Table 3. Experimental data on dynamic viscosity of the ROS R600a/Reniso WF 15A in the

saturated liquid phase.

,T K 310 , Pa s , kg 3m ,T K 310 , Pa s , kg 3m

Rx = 0 293.2 6.21 852.2

292.8 34.1 886.1 298.4 5.06 847.9

298.5 25.3 882.3 303.4 4.55 843.7

303.0 20.5 879.3 308.3 4.07 839.7

307.8 16.5 876.1 318.4 3.05 831.2

313.8 13.0 872.2 323.2 2.79 827.2

318.6 10.8 869.0 328.2 2.48 823.0

323.2 9.21 865.9 333.0 2.28 819.0

328.6 7.66 862.4 338.4 1.99 814.4

333.2 6.68 859.3 343.3 1.83 810.3

338.2 5.80 856.0 Rx = 0.4863

342.2 5.21 853.4 289.2 3.49 827.5

348.4 4.47 849.3 293.2 3.15 823.9

353.2 3.99 846.1 298.2 2.83 819.5

Rx = 0.1604 303.4 2.63 814.8

293.1 14.6 874.0 308.4 2.36 810.3

22

298.1 11.8 870.2 313.2 2.12 806.0

303.3 9.91 866.2 317.7 1.97 801.9

308.4 8.11 862.3 323.2 1.67 796.9

313.2 6.93 858.6 327.2 1.56 793.3

318.2 6.05 854.8 333.5 1.41 787.5

323.2 5.10 851.0 Rx = 0.6927

328.2 4.60 847.1 285.8 1.91 771.0

333.2 4.08 843.3 289.3 1.77 767.7

338.2 3.46 839.5 293.2 1.64 764.0

343.2 3.27 835.6 298.2 1.53 759.3

348.2 2.76 831.7 303.3 1.39 754.4

Rx = 0.3242 308.2 1.30 749.7

287.0 7.43 857.3 313.2 1.18 744.8

23

Table 4. Experimental data on dynamic viscosity of the ROS R245fa/Planetelf ACD 100 FY

in the saturated liquid phase.

,T K 310 , Pa s , kg 3m ,T K 310 , Pa s , kg 3m

Rx = 0 323.1 17.5 975.5

308.2 133 960.9 328.0 14.6 972.3

313.0 100 957.4 333.3 12.4 968.8

318.0 77.2 953.7 338.2 10.4 965.4

323.0 60.4 950.1 343.3 9.21 961.9

328.0 47.9 946.4 348.1 7.96 958.4

333.2 38.6 942.7 Rx = 0.7167

338.1 32.7 939.1 307.0 12.7 1009

343.2 26.5 935.4 313.3 10.8 1004

348.2 22.2 931.8 317.9 9.30 1001

353.1 18.9 928.2 323.3 8.27 997.6

Rx = 0.3128 327.7 7.53 994.5

309.9 54.3 963.6 333.2 6.30 990.5

313.3 45.2 961.5 338.6 5.52 986.4

318.3 37.3 958.3 343.7 5.04 982.4

323.5 29.8 954.8 Rx = 0.8064

24

328.1 26.1 951.8 312.8 5.59 1029

333.4 20.4 948.2 318.1 4.93 1025

338.3 17.5 944.7 323.0 4.33 1021

343.0 14.9 941.4 328.0 4.11 1018

347.9 12.9 937.8 333.4 3.54 1013

Rx = 0.5424 338.4 3.35 1009

308.3 27.5 984.7 342.7 3.03 1005

313.2 24.5 981.7 348.1 2.75 1000

317.8 20.5 978.9

25

Table 5. Coefficients in Eqs. (4, 6-9).

Refrigerant oil solution a b c d e

Сoefficients in Eq.(4)

R600a/Azmol 587998 -700085 131199 146692 –

R600a/Reniso WF 15A 602091 -1217374 1149306 -367696 –

R245fa/Planetelf ACD

100 FY 651265 -1209867 1005760 -264527 –

Сoefficients in Eq. (6)

R600a/Azmol 6.9841 4.8285 63.686 -4.2000 -59.590

R600a/Reniso WF 15A 8.0316 3.1276 54.599 -1.2433 -43.005

R245fa/Planetelf ACD

100 FY 11.236 0.85745 40.015 -0.049810 -36.905

Сoefficients in Eq. (7)

R600a/Azmol -267.98 304.24 -168.04 14.434 252.24

Сoefficients in Eq. (8)

R600a/Reniso WF 15A 17.699 69.308 -113.93 74.595 -17.535

Сoefficients in Eq. (9)

R245fa/Planetelf ACD

100 FY 49.930 32.181 28.166 -46.282 15.763