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Experimental investigation on low-temperature performance of the CO2 indirect heat pump integrated system with air and waste heat sources for electric vehicles.

Author(s) : TENG H., LI M., XIONG S., LIU Z., LU C., FENG X., CHEN H., CHANG W., JIANG Y.

Type of article: IJR article

Summary

To mitigate the efficiency degradation of system caused by insufficient air-side heat absorption capacity in lowtemperature, this study proposes a CO2 indirect-loop (IL) heat pump (HP) integrated system featuring singlestage compression series indoor heat exchanger and waste heat source utilization for electric vehicle (EV) application scenarios. The study first reveals the performance variation patterns of IL system compared to direct loop (DL) system. At an ambient temperature of -20 ◦C, the coefficient of performance (COP) of the IL system decreases by average of 5.7%-8.9% due to secondary heat exchange (evaporation temperature difference of 5 ◦C), but its outlet air temperature uniformity improves by 9.9%-12.9%. Meanwhile, for every 1 ◦C increases in the water-cooled condenser (WCC) outlet temperature the system's COP decreases by 1.8%. The dual heat source architecture significantly enhances the system's low-temperature adaptability. Experimental data indicate that, under conditions of -20 ◦C ambient temperature and 45 ◦C supply air temperature, the dual source heat pump (DSHP) mode achieves COP that is 25.4%-38.9% higher than that of the air source-only mode. Further research revealed that when waste heat power is sufficient and inlet coolant temperature exceeds the ambient temperature, the introduction of an air source may actually lead to a reduction in the average heat source grade on the evaporation side, resulting in the waste heat-only mode outperforms the DSHP mode in terms of performance. This research not only reveals the energy efficiency enhancement mechanism through the synergy between air source and waste heat source and provides novel insights for low-temperature performance optimization. 

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Details

  • Original title: Experimental investigation on low-temperature performance of the CO2 indirect heat pump integrated system with air and waste heat sources for electric vehicles.
  • Record ID : 30034899
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 186
  • Publication date: 2026/06
  • DOI: http://dx.doi.org/https://doi.org/10.1016/j.ijrefrig.2026.106917

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