Potential assessment of transcritical CO2 secondary loop heat pump for electric vehicles. (April 2023)

• Record Type: Journal Article
• Authors: Wang, Haidan; Cao, Feng; Jia, Fan; Song, Yulong; Yin, Xiang
• Is Part Of: Applied thermal engineering. Volume 224(2023)
• Publication Date: 2023-04
• Subjects: Secondary loop system -- Transcritical CO2 system -- Heat pump technology -- Cruising range -- Electric vehicles; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2022.119921
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: The optimal coolant flow rate of the transcritical CO2 SL system exists. The SL system requires different gas coolers in cooling mode and heating mode. The SL system has little effect on driving range when thermal load is modest. Running an SL system in cooling mode is more detrimental to EVs. Abstract: The excellent heating performance and environmental advantages of the transcritical CO2 heat pump system make it a great fit for the electric vehicles (EVs). However, the high operating pressure leads to the possibility of excessive CO2 concentration in the cabin. To ensure the safety of passengers, a secondary loop (SL) system is proposed. In this study, we make a comparison between the traditional direct (TD) system and the SL system for an EV. The results show that the optimal coolant flow rate, with a range of 0.56 to 1.36 L/min in heating mode and 5.60 to 8.80 L/min in cooling mode, can increase the COP of the SL system in all working situations. In the heating mode, the COP of the SL system is 13.98% to 21.96% lower than that of the TD system, and the cruising range of the EV is reduced by 1.4 km ∼ 10.0 km. In cooling mode, the COP of the SL system is 16.95% to 22.45% lower than that of the TD system, and the cruising range has a reduction of 7.7 km ∼ 20.9 km. Results demonstrate that running the SL system in cooling mode rather than heating mode is more detrimental to EVs.