Correlation and prediction of phase equilibria for mixtures of low-GWP refrigerants with lubricants

doi:10.11949/0438-1157.20250592

Abstract

Abstract:

The mixture formed by refrigerants and lubricating oils is present in various components of the refrigeration system, and its phase equilibrium characteristics are of significant importance for the design optimization of thermodynamic cycles and components. Using the PC-SAFT state equation based on statistical associating fluid theory, the gas-liquid phase equilibrium of binary mixtures of seven low-GWP refrigerants such as R1234yf, R600a, R744, etc., with lubricating oils PEC4—PEC9 was calculated. The results show that the PC-SAFT model has good consistency with experimental results, and the average pressure deviation is mostly within 6%. Meanwhile, to further expand the model's predictive performance for complex multicomponent mixture phase equilibrium, a BP neural network model was used to train the binary interaction parameters of the PC-SAFT state equation, and the predicted binary interaction parameters were used for the phase equilibrium calculation of binary systems lacking experimental data, such as R1233zd(E)/PEC lubricating oil, multicomponent complex systems R744/POE lubricating oil, and R290/POE lubricating oil. The k_ij predicted by the neural network model was used to predict these complex multicomponent systems, with an average pressure deviation of 8.99%, indicating its applicability to practical engineering calculations.

Key words: refrigerant, lubricant oil, phase equilibria, mixtures, PC-SAFT, BP neural network

摘要：

制冷剂与润滑油所形成的混合物存在于制冷系统各部件中，其相平衡特性对热力循环及部件的设计优化具有重要意义。采用基于统计缔合流体理论的PC-SAFT状态方程，对R1234yf、R600a、R744等7种低GWP制冷剂与润滑油PEC4~PEC9的二元混合物气液相平衡进行计算，结果显示PC-SAFT模型与实验结果一致性较好，计算的平均压力偏差绝大部分在6%以内。同时，为进一步拓展模型对复杂多元混合物相平衡的预测性能，采用BP神经网络模型对PC-SAFT状态方程的二元交互参数进行训练，并将预测得到的二元交互参数用于缺乏实验数据的二元体系R1233zd（E）/PEC润滑油、多组分的复杂体系R744/POE润滑油和R290/POE润滑油的相平衡计算。采用神经网络模型预测得到的k_ij 对多组分复杂体系进行预测对比，平均压力偏差为8.99%，可用于实际工程计算。

关键词: 制冷剂, 润滑油, 相平衡, 混合物, PC-SAFT, BP神经网络

CLC Number:

TK 121

Huirong WANG, Lingling SUN, Wenduan QI, Yixian HU, Yanpo SHAO, Zhi YANG, Yanxing ZHAO. Correlation and prediction of phase equilibria for mixtures of low-GWP refrigerants with lubricants[J]. CIESC Journal, 2025, 76(11): 5828-5841.

王慧荣, 孙玲玲, 戚文端, 胡熠暹, 邵艳坡, 杨智, 赵延兴. 低GWP制冷剂与润滑油混合物的相平衡关联与预测[J]. 化工学报, 2025, 76(11): 5828-5841.

Figures/Tables 20

Fig.1 Topology of BP neural network

Table 1 Experimental data set on the phase equilibria of low-GWP refrigerants with PECs lubricants

制冷剂	润滑油	实验数据点数(等温组数)	温度/K	压力/MPa	文献
R1233zd(E)	PEC4	42 (6)	298~343	0.037~0.37	[7]
	PEC6	36 (6)	298~343	0.043~0.249	[7]
	PEC8	42 (6)	298~343	0.05~0.277	[7]
R1234yf	PEC4	63 (7)	293~348	0.066~2.071	[19]
	PEC5	63 (7)	293~348	0.079~2.087	[19]
	PEC6	63 (7)	293~348	0.075~2.079	[10]
	PEC7	63 (7)	293~348	0.078~2.04	[10]
	PEC8	63 (7)	293~348	0.083~2.088	[10]
	PEC9	49 (7)	293~348	0.179~1.689	[5]
R1234ze(E)	PEC4	56 (7)	293~353	0.054~1.81	[19]
	PEC5	72 (8)	283~353	0.045~1.80	[20]
	PEC6	56 (8)	283~353	0.05~1.795	[21]
	PEC7	64 (8)	283~353	0.054~1.897	[22]
	PEC8	56 (8)	283~353	0.06~1.86	[21]
	PEC9	56 (8)	283~353	0.059~1.856	[22]
R1243zf	PEC4	56 (8)	278~343	0.081~0.974	[23]
	PEC5	56 (8)	278~343	0.081~0.975	[23]
	PEC6	56 (8)	278~343	0.088~0.973	[6]
	PEC7	53 (8)	278~343	0.091~0.98	[24]
	PEC8	56 (8)	278~343	0.09~0.981	[6]
	PEC9	51 (8)	278~343	0.099~0.992	[24]
R600a	PEC4	49 (7)	293~348	0.054~1.013	[25]
	PEC5	49 (7)	293~348	0.070~1.031	[26]
	PEC6	49 (7)	293~348	0.048~0.995	[25]
	PEC7	49 (7)	293~348	0.056~0.967	[26]
	PEC8	49 (7)	293~348	0.047~0.994	[25]
	PEC9	49 (7)	293~348	0.089~0.989	[5]
RE170	PEC4	64 (8)	283~353	0.057~1.836	[27]
	PEC5	64 (8)	283~353	0.060~1.808	[27]
	PEC6	64 (8)	283~353	0.071~1.807	[28]
	PEC7	56 (7)	293~348	0.074~1.831	[29]
	PEC8	64 (8)	283~353	0.082~1.807	[28]
	PEC9	56 (7)	293~348	0.078~1.897	[29]
R744	PEC4	83 (8)	243~343	0.754~9.555	[4]
	PEC5	51 (7)	283~333	0.887~6.387	[30]
	PEC6	91 (8)	243~343	0.767~9.821	[31]
	PEC7	55 (8)	283~348	0.834~7.501	[32]
	PEC8	56 (5)	273~343	0.25~9.70	[33]
	PEC9	32 (7)	283~333	1.145~7.321	[32]

Table 2 Extended experimental data set for the phase equilibria of refrigerants with PECs lubricants

制冷剂	润滑油	文献	实验数据点数(等温组数)	温度/K	压力/MPa
R32	PEC5	[3]	28 (4)	303~363	0.007~1.795
	PEC9	[34]	28 (4)	303~363	0.203~1.937
R125	PEC5	[3]	30 (4)	303~363	0.073~1.897
	PEC9	[34]	28 (4)	303~363	0.093~2.104
R134a	PEC5	[3]	28 (4)	303~363	0.052~1.065
	PEC9	[34]	28 (4)	303~363	0.104~1.218
R143a	PEC5	[3]	28 (4)	303~363	0.088~1.843
	PEC9	[34]	28 (4)	303~363	0.135~1.974
R152a	PEC5	[3]	24 (4)	303~363	0.058~0.904
	PEC9	[34]	28 (4)	303~363	0.151~1.022

Table 3 PC-SAFT parameters for refrigerants and PECs lubricants

流体	m	σ/Å	（ε/k）/K	MW/(g/mol)	μ/D	文献
R1233zdE	3.2449	3.3483	198.5	130.5	1.12	[36]
R1234yf	2.834	3.364	168.2	114.04	2.24	[14]
R1234zeE	3.294	3.165	171.2	114.04	1.13	[14]
R1243zf	2.544	3.457	178.242	96.05	2.43	本文^①
R600a	2.2616	3.7574	216.53	58.123	0	[15]
RE170	2.3071	3.2528	211.06	46.069	0	[15]
R744	2.5968	2.5503	151.24	44.01	0	[39]
R32	2.472	2.797	161.7	52.02	1.978	[35]
R125	3.147	3.12	153.7	120.02	1.563	[35]
R134a	3.262	3.002	162.1	102	2.058	[14]
R143a	2.516	3.268	160.184	84.04	2.34	本文^①
R152a	2.628	3.128	179.001	66.05	2.262	本文^①
PEC4	9.949	3.825	254.602	416.51	0	[12]
PEC5	10.533	3.972	261.81	472.61	0	[38]
PEC6	11.28	4.07	266.545	528.72	0	[12]
PEC7	12.104	4.141	269.99	584.83	0	[38]
PEC8	12.611	4.244	275.966	640.93	0	[12]
PEC9	12.893	4.364	284.83	697.05	0	[38]

Table 4 Pressure deviations of refrigerants with PECs binary mixtures calculated by PC-SAFT

工质	AARD(p)/%
工质	PEC4	PEC5	PEC6	PEC7	PEC8	PEC9	均值
R1233zdE	3.38	—	1.99	—	2.49	—	2.62
R1234yf	2.02	1.68	2.33	2.09	4.12	1.67	2.32
R1234zeE	1.48	1.95	2.11	2.6	2.74	3.27	2.36
R1243zf	3.54	4.28	4.59	4.76	5.15	5.18	4.58
R600a	0.69	1.15	1.86	1.59	2.84	3.69	1.97
RE170	3.56	3.02	4.49	3.54	5.92	4.39	4.15
R744	4.37	3.6	5.35	8.25	6.55	3.98	5.35
均值	2.72	2.61	3.24	3.80	4.26	3.70

Fig.2 Comparison of calculated pressures with experimental values using the PC-SAFT model

Fig.3 Comparison of solubility of refrigerants in different PECs at 303.15 K with experimental values

Fig.4 Comparison of the solubility for different refrigerants in PEC5 with experimental values

Fig.5 Regressed binary interaction parameters for PC-SAFT based on experimental values

Table 5 Coefficients of the linear regression obtained based on the experimental values of the refrigerant and PECs binary mixtures kij

工质	$k i j = α 1 + α 2 M W + α 3 T$			R²
工质	$α 1$	$α 2$	$α 3$	R²
R1233zdE	-0.03876	7.99×10^-5	2.59×10^-5	0.95618
R1234yf	-0.07829	1.38×10^-4	1.05×10^-4	0.99144
R1234zeE	-0.11221	1.80×10^-4	1.85×10^-4	0.99768
R1243zf	-0.0891	1.20×10^-4	8.07×10^-5	0.99686
R600a	0.03475	-2.65×10^-5	5.84×10^-6	0.52775
RE170	-0.04461	7.68×10^-5	7.57×10^-5	0.89349
R744	-0.04398	2.34×10^-4	1.32×10^-4	0.93748

Table 5 Coefficients of the linear regression obtained based on the experimental values of the refrigerant and PECs binary mixtures kij

工质	$k i j = α 1 + α 2 M W + α 3 T$			R²
工质	$α 1$	$α 2$	$α 3$	R²
R1233zdE	-0.03876	7.99×10^-5	2.59×10^-5	0.95618
R1234yf	-0.07829	1.38×10^-4	1.05×10^-4	0.99144
R1234zeE	-0.11221	1.80×10^-4	1.85×10^-4	0.99768
R1243zf	-0.0891	1.20×10^-4	8.07×10^-5	0.99686
R600a	0.03475	-2.65×10^-5	5.84×10^-6	0.52775
RE170	-0.04461	7.68×10^-5	7.57×10^-5	0.89349
R744	-0.04398	2.34×10^-4	1.32×10^-4	0.93748

Fig.6 Comparison of kij obtained from linear regression with experimental calculated values

Fig.7 Pearson correlation analysis of input parameters in BP neural network prediction model

Fig.8 Comparison of the predicted model training results and the experimental values calculated for the kij

Fig.9 Comparison of the solubility in PEC calculated based on the BP prediction model for different refrigerants with experimental values

Table 6 Comparison of calculated pressure deviations based on the PC-SAFT equation with different binary interaction parameters

工质/润滑油	AARD(p) /% @303.15K
工质/润滑油	实验计算	线性回归	BP预测	实验计算	线性回归	BP预测
R1233zdE/PEC4	4.19	4.26	4.32	3.36	4.01	3.54
R600a/PEC6	2.71	4.24	3.02	1.86	3.42	2.11
R744/PEC8	9.02	9.58	9.12	5.94	8.44	6.42

Table 7 Comparison of R1233zdE / PEC binary interaction parameters obtained by linear regression and BP prediction

温度/K	PEC5
温度/K	线性回归	BP预测	线性回归	BP预测	线性回归	BP预测
298.15	0.00674	0.00554	0.01571	0.01629	0.02469	0.02096
303.15	0.00687	0.00623	0.01584	0.01748	0.02482	0.022
313.15	0.00713	0.00716	0.0161	0.01892	0.02508	0.02372
323.15	0.00739	0.00774	0.01636	0.01916	0.02534	0.02487
333.15	0.00765	0.00832	0.01662	0.01851	0.02559	0.02549
343.15	0.00791	0.00912	0.01688	0.01742	0.02585	0.02586

Table 8 PC-SAFT parameters of R290 and multivariate POE lubricant oils employed in this work

工质及润滑油	m	σ/Å	(ε/k)/K	MW/(g/mol)	文献
R290	2.002	3.6184	208.11	44.096	[15]
POE22	8.3216	4.677	321.08	540.6	[43]
POE68	11.1356	4.7572	301.87	760	[44]
POE75	7.0401	4.3303	270.4842	417.682	本文^①

Fig.10 Comparison of kij calculated based on BP neural network prediction and experimental values

Fig.11 Comparison of the solubility of refrigerants in POE calculated based on the BP prediction model and experimental values

Table 9 Comparison of calculated pressure deviations based on the PC-SAFT equation with different binary interaction parameters

工质/润滑油	AARD(p) /% @Average
工质/润滑油	实验计算	线性回归	k_ij =0	BP预测
R744/POE68	5.91	11.66	—	7.14
R290/POE22	5.92	16.64	33.81	7.99
R290/POE75	2.14	28.76	44.15	11.83

References 45

[1]	Daniel G, Anderson M J, Schmid W, et al. Performance of selected synthetic lubricants in industrial heat pumps[J]. Journal of Heat Recovery Systems, 1982, 2(4): 359-368.
[2]	侯树鑫, 段远源, 王晓东. 氢氟烃+润滑油混合物气液相平衡模型[J]. 工程热物理学报, 2008, 29(6): 927-930.
	Hou S X, Duan Y Y, Wang X D. Gas liquid equilibrium model of hydrofluorocarbon+lubricating oil mixture[J]. Journal of Engineering Thermophysics, 2008, 29(6): 927-930.
[3]	Wahlström Å, Vamling L. Solubility of HFC32, HFC125, HFC134a, HFC143a, and HFC152a in a pentaerythritol tetrapentanoate ester[J]. Journal of Chemical & Engineering Data, 1999, 44(4): 823-828.
[4]	Pernechele F, Bobbo S, Fedele L, et al. Solubility of carbon dioxide in pentaerythritol tetrabutyrate (PEC4) and comparison with other linear chained pentaerythritol tetraalkyl esters[J]. International Journal of Thermophysics, 2009, 30(4): 1144-1154.
[5]	Sun Y J, Di G L, Wang J, et al. Phase behavior of R1234yf and R600a in pentaerythritol tetranonanoate[J]. International Journal of Refrigeration, 2020, 109: 135-142.
[6]	Luo Y, Wang X D, Wang X P. Solubilities of 3,3,3-trifluoropropene in pentaerythritol tetrahexanoate and pentaerythritol tetraoctanoate from 278.15 K to 343.15 K at pressures to 1 MPa[J]. Fluid Phase Equilibria, 2023, 566: 113699.
[7]	Sun Y J, Wang S B, Zheng H Q, et al. Measurement of phase equilibrium for R-1233zd(E) with three pure esters between 298.15 and 343.15 K[J]. Journal of Chemical & Engineering Data, 2024, 69 (1): 194-203.
[8]	Yokozeki A. Solubility of refrigerants in various lubricants[J]. International Journal of Thermophysics, 2001, 22(4): 1057-1071.
[9]	Teodorescu M, Lugo L, Fernández J. Modeling of gas solubility data for HFCs-lubricant oil binary systems by means of the SRK equation of state[J]. International Journal of Thermophysics, 2003, 24(4): 1043-1060.
[10]	Sun Y J, Wang X P, Wang D B, et al. Measurement and correlation for phase equilibrium of HFO1234yf with three pentaerythritol esters from 293.15K to 348.15K[J]. The Journal of Chemical Thermodynamics, 2017, 112: 122-128.
[11]	García J, Paredes X, Fernández J. Phase and volumetric behavior of binary systems containing carbon dioxide and lubricants for transcritical refrigeration cycles[J]. The Journal of Supercritical Fluids, 2008, 45(3): 261-271.
[12]	Fouad W A, Vega L F. Molecular modeling of the solubility of low global warming potential refrigerants in polyol ester lubricants[J]. International Journal of Refrigeration, 2019, 103: 145-154.
[13]	Albà C G, Llovell F, Vega L F. Searching for suitable lubricants for low global warming potential refrigerant R513A using molecular-based models: solubility and performance in refrigeration cycles[J]. International Journal of Refrigeration, 2021, 128: 252-263.
[14]	Heithorst B. Influence of fluid properties on lubricant return for low-GWP refrigerants[D]. München, Beyern: Technische Universität München, 2023.
[15]	Gross J, Sadowski G. Perturbed-chain SAFT: an equation of state based on a perturbation theory for chain molecules[J]. Industrial & Engineering Chemistry Research, 2001, 40(4): 1244-1260.
[16]	Gross J, Vrabec J. An equation-of-state contribution for polar components: dipolar molecules[J]. AIChE Journal, 2006, 52(3): 1194-1204.
[17]	Rehner P, Bauer G, Gross J. FeOs: an open-source framework for equations of state and classical density functional theory[J]. Industrial & Engineering Chemistry Research, 2023, 62(12): 5347-5357.
[18]	Abbasi F, Abbasi Z, Bozorgmehry Boozarjomehry R. Estimation of PC-SAFT binary interaction coefficient by artificial neural network for multicomponent phase equilibrium calculations[J]. Fluid Phase Equilibria, 2020, 510: 112486.
[19]	Wang X P, Sun Y J, Gong N. Experimental investigations for the phase equilibrium of R1234yf and R1234ze(E) with two linear chained pentaerythritol esters[J]. The Journal of Chemical Thermodynamics, 2016, 92: 66-71.
[20]	Sun Y J, Wang X P, Gong N, et al. Solubility of trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze (E)) in pentaerythritol tetrapentanoate (PEC5) in the temperature range from 283.15 to 353.15 K[J]. International Journal of Refrigeration, 2014, 48: 114-120.
[21]	Wang X P, Sun Y J, Kang K. Experimental investigation for the solubility of R1234ze(E) in pentaerythritol tetrahexanoate and pentaerythritol tetraoctanoate[J]. Fluid Phase Equilibria, 2015, 400: 38-42.
[22]	Sun Y J, Wang X P, Gong N, et al. Solubility of trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) in pentaerythritol ester heptanoic acid (PEC7) and in pentaerythritol tetranonanoate (PEC9) between 283.15K and 353.15K[J]. Fluid Phase Equilibria, 2015, 387: 154-159.
[23]	Jia H Y, Zhang Y J, Wang X P. Solubility prediction of refrigerants in PEC lubricants based on back-propagation neural network combined with genetic algorithm[J]. Journal of Molecular Liquids, 2024, 404: 124926.
[24]	Luo Y, Liu Z, Lu C, et al. Vapor-liquid equilibrium measurements of 3,3,3-trifluoropropene with pentaerythritol tetraheptanoate and pentaerythritol tetranonanoate[J]. Journal of Chemical Thermodynamics, 2022, 174: 106874.
[25]	Sun Y J, Wang X P, Wang D B, et al. Absorption of isobutane in three linear chained pentaerythritol esters between 293.15 and 348.15K[J]. International Journal of Refrigeration, 2017, 76: 118-125.
[26]	Sun Y J, Wang X P, Gong N, et al. Solubility measurement and correlation of isobutane with two pentaerythritol tetraalkyl esters between (293.15 and 348.15) K[J]. Journal of Chemical & Engineering Data, 2015, 60(5): 1504-1509.
[27]	Sun Y J, Wang X P, Gong N, et al. Solubility of dimethyl ether in pentaerythritol tetrabutyrate and in pentaerythritol tetrapentanoate. Comparison with other pentaerythritol tetraalkyl esters[J]. The Journal of Chemical Thermodynamics, 2015, 87: 23-28.
[28]	Sun Y J, Wang X P, Gong N, et al. Solubility of dimethyl ether in pentaerythritol tetrahexanoate (PEC6) and in pentaerythritol tetraoctanoate (PEC8) between (283.15 and 353.15) K[J]. Journal of Chemical & Engineering Data, 2014, 59(11): 3791-3797.
[29]	Sun Y J, Wang X P, Lang H X, et al. Phase equilibrium behavior for methoxymethane + pentaerythritol tetraheptanoate and methoxymethane + pentaerythritol tetranonanoate systems[J]. Journal of Chemical & Engineering Data, 2016, 61(10): 3504-3509.
[30]	Fandiño O, López E R, Lugo L, et al. Solubility of carbon dioxide in two pentaerythritol ester oils between (283 and 333) K[J]. Journal of Chemical & Engineering Data, 2008, 53(8): 1854-1861.
[31]	Bobbo S, Pernechele F, Fedele L, et al. Solubility measurements and data correlation of carbon dioxide in pentaerythritol tetrahexanoate (PEC6)[J]. Journal of Chemical & Engineering Data, 2008, 53(11): 2581-2585.
[32]	Fandiño O, López E R, Lugo L, et al. Solubility of carbon dioxide in pentaerythritol ester oils. New data and modeling using the PC-SAFT model[J]. The Journal of Supercritical Fluids, 2010, 55(1): 62-70.
[33]	Fedele L, Pernechele F, Bobbo S, et al. Solubility of carbon dioxide in pentaerythritol tetraoctanoate[J]. Fluid Phase Equilibria, 2009, 277(1): 55-60.
[34]	Wahlström Å, Vamling L. Solubility of HFCs in pentaerythritol tetraalkyl esters[J]. Journal of Chemical & Engineering Data, 2000, 45(1): 97-103.
[35]	Vinš V, Hrubý J. Solubility of nitrogen in one-component refrigerants: prediction by PC-SAFT EoS and a correlation of Henry's law constants[J]. International Journal of Refrigeration, 2011, 34(8): 2109-2117.
[36]	Peng S Z, Wang E Q, Qing K, et al. Prediction of vapor-liquid equilibrium and pvTx properties of mixtures containing HFOs, HFCs, HCs, and CO₂ using polar PC-SAFT model[J]. Fluid Phase Equilibria, 2024, 580: 114049.
[37]	Zhao Y X, Dong X Q, Gong M Q, et al. Evaluation of PR, NRTL, UNIFAC, and PCSAFT on the VLE of binary systems containing ammonia[J]. Industrial & Engineering Chemistry Research, 2017, 56(8): 2287-2297.
[38]	Razzouk A, Mokbel I, García J, et al. Vapor pressure measurements in the range 10^-5 Pa to 1Pa of four pentaerythritol esters: density and vapor-liquid equilibria modeling of ester lubricants[J]. Fluid Phase Equilibria, 2007, 260(2): 248-261.
[39]	占涛涛, 陈于航, 杨枚洁, 等. PC-SAFT状态方程参数化及其热物性计算精度对S-CO₂循环性能分析的影响[C]//中国工程热物理学会工程热力学与能源利用学术会议.珠海, 2022.
	Zhan T T, Chen Y H, Yang M J, et al. The Parameterization of PC-SAFT state equation and its impact on the calculation accuracy of thermophysical properties in S-CO₂ cycle performance analysis[C]//Chinese Society of Engineering Thermophysics Conference on Engineering Thermodynamics and Energy Utilization. Zhuhai, 2022.
[40]	Tang Q X, Wang H R, Yang Z, et al. Evaluation and prediction on the VLE of binary systems containing HFO refrigerants and PEC lubricants[J]. Journal of Chemical & Engineering Data, 2025, 70(4): 1551-1561.
[41]	Sugii T, Ishii E, Müller-Plathe F. Solubility of carbon dioxide in pentaerythritol hexanoate: molecular dynamics simulation of a refrigerant-lubricant oil system[J]. The Journal of Physical Chemistry. B, 2015, 119(37): 12274-12280.
[42]	García J, Youbi-Idrissi M, Bonjour J, et al. Experimental and PC-SAFT volumetric and phase behavior of carbon dioxide+ PAG or POE lubricant systems[J]. The Journal of Supercritical Fluids, 2008, 47(1): 8-16.
[43]	Czubinski F F, Sanchez C J N, da Silva A K, et al. Phase equilibrium and liquid viscosity data for R-290/POE ISO 22 mixtures between 283 and 353 K[J]. International Journal of Refrigeration, 2020, 114: 79-87.
[44]	Marcelino Neto M A, Barbosa J R. Phase and volumetric behaviour of mixtures of carbon dioxide (R-744) and synthetic lubricant oils[J]. The Journal of Supercritical Fluids, 2009, 50(1): 6-12.
[45]	Sun Y J, Wang X P, Wang S B, et al. Viscosity measurement and correlation of saturated solutions of R-290 with three lubricants[J]. International Journal of Refrigeration, 2023, 155: 1-6.