Parameter Sensitivity Study for Typical Expander-Based Transcritical CO 2 Refrigeration Cycles

Bo Zhang, Liu Chen, Lang Liu, Xiaoyan Zhang, Mei Wang, Changfa Ji and Song Ki-Il
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Bo Zhang: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China
Liu Chen: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China
Lang Liu: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China
Xiaoyan Zhang: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China
Mei Wang: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China
Changfa Ji: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China
Song Ki-Il: Energy School, Xi’an University of Science and Technology, Yanta Road, Xi’an 710054, China

Energies, 2018, vol. 11, issue 5, 1-20

Abstract: A sensitivity study was conducted for three typical expander-based transcritical CO 2 cycles with the developed simulation model, and the sensitivities of the maximum coefficient of performance (COP) to the key operating parameters, including the inlet pressure of gas cooler, the temperatures at evaporator inlet and gas cooler outlet, the inter-stage pressure and the isentropic efficiency of expander, were obtained. The results showed that the sensitivity to the gas cooler inlet pressure differs greatly before and after the optimal gas cooler inlet pressure. The sensitivity to the intercooler outlet temperature in the two-stage cycles increases sharply to near zero and then keeps almost constant at intercooler outlet temperature of higher than 45 °C. However, the sensitivity stabilizes near zero when the evaporator inlet temperature is very low of −26.1 °C. In two-stage compression with an intercooler and an expander assisting in driving the first-stage compressor (TEADFC) cycle, an abrupt change in the sensitivity of maximum COP to the inter-stage pressure was observed, but disappeared after intercooler outlet temperature exceeds 50 °C. The sensitivity of maximum COP to the expander isentropic efficiency increases almost linearly with the expander isentropic efficiency.

Keywords: parameter sensitivity; CO 2 transcritical cycle; refrigeration; expander; COP (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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