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- Wang, Anci, et al.
(författare)
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Performance optimization of electric vehicle battery thermal management based on the transcritical CO2 system
- 2023
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 266
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Tidskriftsartikel (refereegranskat)abstract
- Thermal management of electric vehicles, especially battery thermal management, is critical to driving range and operational safety. To find a vehicle thermal management system with higher energy efficiency and environmental protection, an environmentally-friendly and efficient battery and cabin parallel cooling thermal management system was evaluated with CO2 as the working fluid. First, different control strategies of the evaporation temperature were compared regarding the battery cooling performance. Then, the effect of the battery cooling evaporation temperature on the coefficient of performance (COP) was explored. It was found that the maximum COP increased by 8.38% as the evaporation temperature decreased from 17 to 5.8 °C. Besides, it was found that the optimal battery cooling evaporation temperature range is 10.2–11 °C when the battery heating power is 0.4 kW. The vapor quality at the cold plate outlet should be lower than 0.95. Finally, the battery cooling performance under variable operating conditions was investigated. The influence of operating parameters on the battery cooling evaporation temperature and CO2 outlet vapor quality was also analyzed. Simulation results showed that the optimum evaporation temperature range varied significantly under different working conditions. The vapor quality at the cold plate outlet decreased slightly with the evaporation temperature.
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| 2. |
- Wang, Anci, et al.
(författare)
-
Principle and performance optimization analysis of a frost-free control for electric vehicle heat pumps
- 2023
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 226
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Tidskriftsartikel (refereegranskat)abstract
- To avoid the attenuation of the electric vehicle driving range caused by the performance degradation of the heat pump during frost, a frost-free control strategy was developed which enables frost-free operation without adding any additional dehumidifying and drying components. Simulation analyses of the frost-free control principle and performance characteristics are carried out. Thermodynamic and response characteristics of evaporation temperature to valve openings of different heat pumps are compared. The results show that excessive pressure drops in evaporators severely hinder the realization of frost-free operation. Then, the effect of evaporator designs on frost-free operation is further investigated. A new comprehensive evaluation parameter (η) that can unify pressure drop and heat transfer is proposed. When η is between 0 and −2, the heat exchanger meets the requirements of frost-free control. In addition, the upper humidity range for frost-free operation at different temperatures is calibrated. When the ambient temperature is 0/-5/-10/-15/-25 °C, the corresponding maximum humidity that can achieve frost-free operation is 87/86/85/84/82 %, respectively. In low temperature and high humidity regions, the frost-free operation can be guaranteed by increasing the evaporator airflow volume rate and reducing the supply air temperature.
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