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Journal Overview
REFRIGERATION AND AIR-CONDITIONING
Launched in 1990, Monthly
Indexed by:
China Academic Journal Comprehensive Evaluation Database
China Journal Full-text
Database:
Chinese Core Journal (Select) Database
Chinese Science and Technology Journal Database
Annual Report for Chinese Academic Journals Impact Factors
Telephone: 010-83560065，83510099
Domestic Unified Serial Number (CN):11-4519/TB
International Standard Serial Number (ISSN):1009-8402
Study on refrigerant substitution performance of commercial refrigerator and display cabinet
Li Mengjia;Tian Yafen;Liu Yefeng;Zhang Hua;Driven by the Kigali Amendment and stratogic goals of carbon peaking and carbon neutrality, R404A will be gradually phased out, while it's now being widely employed in commercial refrigeration equipments. R454C and R290, due to their low GWP and environmental friendliness, have become the most promising alternative refrigerants for commercial refrigeration. To compare the performance of these three different refrigerants in light commercial refrigeration equipment, different commercial refrigerators and display cabinets are tested in our environmental test laboratory. Critical parameters are compared including refrigerant charge amount, power consumption, material costs, and carbon emissions of R404A, R454C, and R290 systems. The results indicated that compared with the R404A system, the 24-hour power consumption of the R454C system can be reduced by about 5%, and the total carbon emissions can be reduced by about 15%. As for R290, the system charge is significantly reduced. The charge amounts for commercial refrigerators and display cabinets are only 20.6%-34.2% and 16.4%-23.6% of that of R404A, respectively, leading to a substantial reduction in refrigerant charging costs. Evenmore, the 24-hour power consumption can be reduced by 16.7%-35% and 11.9%-15.7% respectively. Furthermore, commercial refrigerators demonstrate superior carbon reduction performance, achieving a reduction in carbon emissions ranging from 25.3% to 43.7%.
Study on the migration of refrigerant and oil of R290 room air conditioner during startup process
Wang Che;Wu Jianhua;Li Jinbo;Du Yanjun;This study investigates the migration of refrigerant and oil of R290 room air conditioner during startup process under various operating conditions. Results show that the variation of superheated/subcooled degrees, as well as the variation of luminance of transparent tube with image processing at key locations of the system can be used to predict the change of phase of refrigerant and the durations. Besides, the variation of luminance can be also used to obtain the oil discharged from and returning to compressor. Large amount of liquid R290 would be sucked into the accumulator and the discharge become two-phase flow during startup. It lasts 30 seconds for rated cooling condition, while it takes 600 seconds for discharge to become superheated for ultra-low-temperature hea-ting condition. The storage of refrigerant in compressor. The high quality of vapor gas before expansion device contributed to the long-term superheated status for low-pressure side. Lots of oil are taken into system, and annular flow with high concentration of oil near expansion device is found. Crystal oil stain forms due to the extreme low temperature when liquid increases but oil can finally return to compressor after long time. The research is helpful for the optimal control and high reliability of the R290 room air conditioner during startup.
Experimental research on dissolution characteristics of new environmentally friendly refrigerant R491A in lubricating oils
Liu Jianchen;Dai Xiaoye;Shi Lin;To support the substitution of low GWP refrigerants in automotive air-conditioning systems, this study investigates the miscibility of the blended refrigerant R491A with two categories of compressor oils: polyester oils(POE) POE-68 and POE-100, and a polyalkylene glycol oil(PAG). Miscibility tests conducted from-20 ℃ to 20 ℃ showed that R491A formed a stable single phase with all three oils, with critical miscibility temperatures below-20 ℃. Using the equal-volume saturation method, the solubility of R491A in the three oils was measured from-20 ℃ to 60 ℃. The results indicate that solubility is jointly governed by temperature and pressure, increasing with pressure, and requiring higher pressures to reach the same solubility at elevated temperatures; pressure sensitivity is more pronounced in the low-temperature region. R491A exhibits superior solubility in the PAG oil compared with POE-68 and POE-100. These data provide essential thermodynamic support for oil circulation analysis, lubricant selection, and system design in the application of low GWP refrigerants in automotive air-conditioning systems.
Research progress on the thermophysical properties of low GWP refrigerant/lubricant mixtures
Wang Xiaopo;Jia Heyu;Zhou Xiongbo;A comprehensive literature review on the thermophysical properties of low-global warming potential(GWP) refrigerant and lubricant oil mixtures was carried out in this work. The studied refrigerants include natural refrigerants(e.g. CO2 and hydrocar-bons) and hydrofluoroolefins(e.g. R1234yf and R1234ze(E)). The thermophysical properties collected mainly include the solubility of refrigerant in oil, as well as the viscosity, surface tension, thermal conductivity, specific heat capacity, and density of refrigerant/oil mixtures. Analysis reveals that current studies on the solubility of refrigerant in oil are relatively thorough, a large number of experimental data have been reported in the litera-ture. However, data on other properties of the mixtures such as viscosity and surface tension remain insufficient. The lack of such properties limits the design and optimization of refrigeration systems. Future work should focus on experimental and theoretical investigations on the viscosity, density, surface tension, and specific heat capacity of mixtures containing low GWP refrigerants and oils.
Influence of refrigerant flow distribution characteristics on the performance of a heat recovery air-conditioning system
Zhang Jiahao;Wu Xi;Hu Guanghang;Nie Mingxu;Guan Hongfei;With the increasing demand for high-efficiency constant temperature air-conditioner in industry and commerce, the power consumption problem caused by the traditional electric heating outlet air temperature control method cannot be ignored. The condensing heat recovery air-conditioning system with double condensers in parallel is one of the solutions. In this paper, an experimental system is built, and the opening degree of electronic expansion valve(EEV) is taken as the basic research variable. Firstly, the refrigerant flow distribution characteristics under different opening degrees are quantified. Then the operating parameters and overall performance of the air-conditioning system are analyzed. The results show that the EEV opening in the range of 0 to 70% has a significant effect on the refrigerant flow distribution, condensation heat recovery capacity and temperature control of the treated air. The total refrigerant circulation flow and flow ratio of the system increase effectively, and the outlet air temperature of the treated air increases with the increase of condensation heat recovery capacity. When the opening exceeds 70 %, the change of EEV opening has little effect on the system performance. In the overall process of increasing EEV opening, the evaporation pressure of the air-conditioning sys-tem increases slightly, the condensation pressure decreases first and then increases, and the total heat transfer and coefficient of performance COPt of the system decre-ase. The thermal expansion valve can work normally only in the EEV opening range of 40% to 70%, and the superheat of the refrigerant can be controlled near 12 ℃. Based on the test data, the opening of EEV is controlled and optimized, and the flow distribution of refrigerant is finely regulated.
