Performance Enhancement of a Novel Compression/Ejection Trans-Critical CO 2 Heat Pump System Coupled with Composite Heat Sources

Yuxiang Zhang, Xiao Zhang, Xiang Qin (), Min Zhao and Yuhui Chen
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Yuxiang Zhang: School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
Xiao Zhang: School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
Xiang Qin: School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, China
Min Zhao: School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
Yuhui Chen: School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China

Energies, 2025, vol. 18, issue 21, 1-20

Abstract: The efficient utilization of renewable heat sources is important for the performance enhancement of trans-critical CO 2 heat pump systems and for promoting the transformation of energy structures. A composite-heat-source matching ratio is introduced in this article to assess the impact of a high-temperature heat source and low-temperature heat source on the performance of a novel compression/ejection trans-critical CO 2 heat pump (CTHP) system coupled with the use of composite heat sources theoretically. The research results show that the maximum reduction in the optimum gas cooler outlet pressure ( P opt,out,gc ) is 3.13% with the increase in evaporating temperature ( T e ), and the maximum reduction is 1.67% with the rise in the composite-heat-source matching ratio, which means that the composite-heat-source matching ratio is equally significant on the optimum high-pressure side compared to the T e . The correlations of optimum high pressure and other optimum cycle parameters for the CTHP system, considering the composite-heat-source matching ratio, were obtained, which provide useful guidelines for optimizing the system design and selecting the appropriate operating conditions. Overall, this article will be helpful for the further development and optimization of the CTHP system, which is of great importance for increasing the utilization rate of renewable heat sources such as geothermal or air-source for urban buildings and accelerating the electrification and low-carbon transformation of terminal energy consumption.

Keywords: trans-critical CO 2 heat pump; ejector; heat sources; performance enhancement (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: 2025
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