Simulation of the optimal heat rejection pressure for transcritical CO2 expander cycle

Junlan YANG, Yitai MA, Minxia LI, Hua TIAN

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PDF(186 KB)
Front. Energy ›› 2010, Vol. 4 ›› Issue (4) : 522-526. DOI: 10.1007/s11708-010-0027-8
RESEARCH ARTICLE

Simulation of the optimal heat rejection pressure for transcritical CO2 expander cycle

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Abstract

In order to optimize and control transcritical CO2 refrigeration cycle, a mathematical model was developed to simulate the system performance. The simulation results show that a maximum COP exists at the optimal heat rejection pressure not only for throttle valve cycle but also for expander cycle. Also, the optimal heat rejection pressures of the throttle valve cycle are greater than those of the expander cycle under the same condition. In order to further obtain correlation of the optimal heat rejection pressure for transcritical CO2 expander cycle, it is necessary to analyze the impact degree of compressor efficiency, expander efficiency, gas cooler outlet temperature and evaporation temperature. Based on the simulation results, the values of the optimal heat rejection pressure for the expander cycle were regressed in terms of gas cooler outlet temperature and evaporation temperature at given compressor efficiency and expander efficiency. Finally, two types of polynomial correlations were obtained. One is cubic form, with an average deviation of less than 0.5% and the other is simplified form, with an average deviation of less than 1%. It is, therefore, convenient to use either correlation to simulate the performance of transcritical CO2 expander cycle.

Keywords

transcritical CO2 cycle / optimal heat rejection pressure / simulation / expander

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Junlan YANG, Yitai MA, Minxia LI, Hua TIAN. Simulation of the optimal heat rejection pressure for transcritical CO2 expander cycle. Front Energ Power Eng Chin, 2010, 4(4): 522‒526 https://doi.org/10.1007/s11708-010-0027-8

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Acknowledgements

This research was supported by the National Natural Science Foundation of China (Grant No. 50506019) and the Development of Science and Technology Foundation of Colleges and Universities in Tianjin (No. 20071116).

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg
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