Browse > Article
http://dx.doi.org/10.6110/KJACR.2011.23.7.505

Comparison of Performance in CO2 Cooling System with an Ejector for Various Operating Conditions  

Kang, Byun (Graduate School of Chosun University)
Cho, Hong-Hyun (Department of Mechanical Engineering, Chosun University)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.23, no.7, 2011 , pp. 505-512 More about this Journal
Abstract
Recently, many researchers have analyzed the performance of the transcritical $CO_2$ refrigeration cycle in order to identify opportunities to improve the system energy efficiency. The reduction of the expansion process losses is one of the key issues to improve the efficiency of the transcritical $CO_2$ refrigeration cycle. In this study, the analytical study on the performance characteristics of $CO_2$ cycle with an ejector carried out with a variation of outdoor temperature, gascooler inlet air velocity, evaporator inlet air velocity, and evaporator inlet air temperature. As a result, the system performance could be improved over 85% by using an ejector for various operating condition because of the reduction of compressor work. Moreover, the cooling capacity increased about 18% for variable outdoor condition. Therefore, the high performance of an ejector system could be maintained for wide operating conditions and system reliability could be improved compared to that of a basic system.
Keywords
Carbon dioxide; Transcritical system; Ejector; COP;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Wang, C. C., Lee., S. W., and Sheu, W. J., 2001, A Comparative Study of Compact Enhanced Fin-and-Tube Heat Exchanges, International Journal of Heat and Mass Transfer, Vol. 44, pp. 3565-3573.   DOI   ScienceOn
2 ASHRAE 1983, Methods of testing for seasonal efficiency of unitaty air-conditioner and heat pumps, ASHRAE Standard, p. 116.
3 Nakagawa, M., Marasigan, A. R., Matsukawa, T., Kurashina, A., 2010, Experimental investigate performance of two-phase ejector for $CO_2$ refrigeration cycle with and without heat exchanger, Proceedings of 9 th IIR Gustav Lorentzen Conference, Sydney.
4 Gnielinski, V., 1976, New equations for heat and mass transfer in turbulent pipe and channel flow, International Chemical Engineering, Vol. 16, pp. 59-68.
5 Churchill, S. W., 1977, Friction-factor equation span all fluid flow regimes, Chemical Engineering, Vol. 7, pp. 91-92.
6 Ortiz, T. M., Li, D., Groll, A. E., 2003. Evaluation of the Performance Potential of CO2 as a Refrigerant in Air-to-Air Conditioner and Heat Pumps：System Modelling and Analysis, ARTI final report No. 21CR/610-10030.
7 Yoon, S. H., 2002, Studies on the Characteristics of Evaporation and supercritical Gas Cooling Heat Transfer of Carbon Dioxide, Ph. D. thesis, Seoul University, Seoul, Korea.
8 Sarkar, J., 2008, Optimization of ejector-expansion transcritical $CO_2$ heat pump cycle, Energy, Vol. 33, pp. 1399-1406.   DOI   ScienceOn
9 Deng, J., Jiang, P., Lu, T., Lu, W., 2007, Particular characteristics of transcritical $CO_2$ refrigeration cycle with an ejector, Applied Thermal Engineering, Vol. 27, pp. 381-388.   DOI   ScienceOn
10 Li, D., Groll, A., 2005, Transcritical $CO_2$ refrigeration cycle with ejector-expansion device, International Journal of Refrigeration, Vol. 28, pp. 766-773.   DOI   ScienceOn