Thermodynamic study on a new transcritical CO2 ejector expansion refrigeration system with two-stage evaporation and vapor feedback

By the stability analysis of the basic transcritical CO2 ejector expansion refrigeration cycle (EERC), the paper proposed a new system which introduces another evaporator downstream the ejector to increase the gas quality into the separator and a vapor feedback valve to decrease the exceed gas into the compressor. The two new components stand for two different cycles: two-stage evaporation cycle and vapor feedback cycle. The theoretical analysis of the new system is carried out based on the first and second laws of thermodynamics to show the effect of the parameters on the system performance, such as entrainment ratio, high-side pressure, outlet temperature of gas cooler, etc. The results by the first law show that, compared with basic EERC the new system can be used in wider range of working conditions, and the COP of the two-stage evaporation cycle is 28.6% higher and the vapor feedback cycle is lower slightly. By exergy analysis at optimum high-side pressure, it is found that the exergy destruction of ejector is the greatest part. The simulation results also give the working ranges of the two cycles, which can help to analyze the system control. Hence, the improvement in the system is a promising method to reduce the restrain in basic EERC system but more study is still needed.

[1]  A. A. Kornhauser,et al.  Improvements to the ejector expansion refrigeration cycle , 1996, IECEC 96. Proceedings of the 31st Intersociety Energy Conversion Engineering Conference.

[2]  Masafumi Nakagawa,et al.  Supersonic two-phase flow of CO2 through converging–diverging nozzles for the ejector refrigeration cycle , 2009 .

[3]  Piotr A. Domanski,et al.  Theoretical Evaluation of the Vapor Compression Cycle With a Liquid-Line/Suction-Line Heat Exchanger, Economizer, and Ejector (NISTIR 5606) , 1995 .

[4]  Min-Soo Kim,et al.  Experimental study on the improvement of CO2 air conditioning system performance using an ejector , 2011 .

[5]  Shengming Liao,et al.  A correlation of optimal heat rejection pressures in transcritical carbon dioxide cycles , 2000 .

[6]  Somchai Wongwises,et al.  Experimental study on R-134a refrigeration system using a two-phase ejector as an expansion device , 2008 .

[7]  Predrag Stojan Hrnjak,et al.  Experimental validation of a prototype ejector designed to reduce throttling losses encountered in transcritical R744 system operation , 2008 .

[8]  H. Kursad Ersoy,et al.  Performance improvement of the vapour compression refrigeration cycle by a two‐phase constant area ejector , 2009 .

[9]  Mortaza Yari,et al.  Performance analysis and optimization of a new two-stage ejector-expansion transcritical CO2 refrigeration cycle , 2009 .

[10]  F. A. Manjili,et al.  Performance of a new two-stage multi-intercooling transcritical CO2 ejector refrigeration cycle , 2012 .

[11]  Eckhard A. Groll,et al.  Transcritical CO2 refrigeration cycle with ejector-expansion device , 2005 .

[12]  Masafumi Nakagawa,et al.  Performance of Two Phase Ejector in Refrigeration Cycle. , 1998 .

[13]  Pei-Xue Jiang,et al.  Particular characteristics of transcritical CO2 refrigeration cycle with an ejector , 2007 .

[14]  Ma Yitai,et al.  Thermodynamic analysis of transcritical CO2 refrigeration cycle with an ejector , 2011 .

[15]  Alan A. Kornhauser,et al.  The Use of an Ejector as a Refrigerant Expander , 1990 .

[16]  Jianlin Yu,et al.  Applying mechanical subcooling to ejector refrigeration cycle for improving the coefficient of performance , 2007 .

[17]  Masafumi Nakagawa,et al.  Experimental analysis on the effect of internal heat exchanger in transcritical CO2 refrigeration cycle with two-phase ejector. , 2011 .

[18]  Jahar Sarkar,et al.  Optimization of ejector-expansion transcritical CO2 heat pump cycle , 2008 .

[19]  Jahar Sarkar,et al.  Ejector enhanced vapor compression refrigeration and heat pump systems—A review , 2012 .

[20]  Alan A. Kornhauser,et al.  Performance tests of a two phase ejector , 1995 .

[21]  S. M. Liaoa,et al.  A correlation of optimal heat rejection pressures in transcritical carbon dioxide cycles , .

[22]  H. Laborit,et al.  [Experimental study]. , 1958, Bulletin mensuel - Societe de medecine militaire francaise.