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Pseudo-optimal discharge pressure analysis of transcritical CO2 electric vehicle heat pumps due to temperature glide


Wang, A and Cao, F and Yin, X and Jia, F and Fang, J and Wang, X, Pseudo-optimal discharge pressure analysis of transcritical CO2 electric vehicle heat pumps due to temperature glide, Applied Thermal Engineering, 215 Article 118856. ISSN 1359-4311 (2022) [Refereed Article]

Copyright Statement

Copyright (2022) Elsevier Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License, ( which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

DOI: doi:10.1016/j.applthermaleng.2022.118856


Performance improvement of electric vehicle heat pumps can enhance thermal comfort and reduce the power consumption of electric vehicles, hence stimulating their development. In this paper, the cyclic characteristics of an electric vehicle heat pump were studied under different operating modes and working conditions. Different from the optimal discharge pressure of conventional CO2 systems which was determined by the variation gradient characteristics of the transcritical isotherm, the discharge pressure of electric vehicle heat pumps at the peak COP value was defined as a pseudo-optimal discharge pressure and was determined by the obvious temperature glide at the outlet of the gas cooler. This pseudo-optimal discharge pressure existed at both transcritical and subcritical states. The difference in the pseudo-optimal discharge pressure between the subcritical or transcritical states was first evaluated. Then an in-depth analysis of the influence of key parameters on the pseudo-optimal discharge pressure was studied to develop an accurate prediction method since the traditional prediction methods were not applicable. The results showed that pseudo-optimal discharge pressure increased with the ambient temperature, inlet air temperature, and supply air temperature. This study provides valuable information for the comprehensive performance optimization of an electric vehicle thermal management system.

Item Details

Item Type:Refereed Article
Keywords:CO2 heat pump, pseudo-optimal discharge pressure, temperature glide, performance optimization, electric vehicle
Research Division:Engineering
Research Group:Mechanical engineering
Research Field:Energy generation, conversion and storage (excl. chemical and electrical)
Objective Division:Energy
Objective Group:Energy storage, distribution and supply
Objective Field:Energy systems and analysis
UTAS Author:Wang, X (Professor Xiaolin Wang)
ID Code:150847
Year Published:2022
Deposited By:Engineering
Deposited On:2022-07-02
Last Modified:2022-08-11

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