| Electric vehicles are gradually replacing fuel vehicles as a future mode of transportation for its characteristics of environmentally friendly and high energy efficiency.The key component-the power battery needs to work at proper temperature and demands temperature uniformity between modules.With the trend of increasing energy density of power battery,increasing number of modules and the development of fast-charging technology,the demand for heat dissipation has risen rapidly.The efficiency of the air-based cooling system is too low to the cooling demand of the power battery while the liquid-based system is complex,expensive and electrically conductive,the refrigerant-based system will be the future of the battery thermal management for its high-efficiency,good temperature uniformity,low cost and weight.A refrigerant-based battery thermal management system based on the novel honeycomb shaped single-sided roll-bond cooling plate according to the thermal management demand the power battery and the cabin.To solve the disadvantages of flow maldistribution and limited heat transfer areas of the straight channel,a novel honeycomb shaped single-sided roll-bond cooling plate was designed to effectively enhance heat transfer and improve efficiency.The experimental bench was built and the uncertainty of system parameters of the experimental bench was analyzed to provide conditions and accurate data for testing and simulation model under variable conditions.Based on the testing results,the optimal refrigerant charging amount of the battery cooling system was 1600 g.The speed control of the compressor in the refrigerant-based cooling system is very important.The superheat of the cold plate outlet also has a greater impact on the temperature uniformity.The system can respond to the thermal management requirements quickly in about 150 seconds,which shows fast response characteristic according to the testing results.The average temperature of the surface of cooling plates can be controlled between the proper temperature range of 15-20℃ and meet the temperature uniformity requirement of 4℃ under the given conditions while the maximum heat power was designed up to 6k W.Through the exergy analysis of the system,it is found that the battery cooling plates account for a large proportion of the total exergy loss.The impacts of inlet structure and the width of the flow channel on system performance was analyzed.The effects of opening of electronic expansion valve,compressor speed,supply air volume and ambient temperature on the thermodynamic performance parameters of cabin cooling system were analyzed.After calibration and verification based on the experimental data,the model can simulate the novel refrigerant-based system and components accurately and the maximum relative error of the thermodynamic parameters simulation is about 5%.In order to achieve the temperature uniformity of the cooling plates,temperature of the cooling plate surface and the temperature difference both increase as the heating power increases.The refrigerant-based cooling system with novel cooling plate can meet the thermal management demand under given extreme operating conditions and WLTP conditions.The dual-evaporator of the refrigerant-based system is highly coupled.The start-stop of the cabin cooling system will cause large disturbance to the temperature of the battery cooling plate surface.With the increasing of the supply air volume to the cabin during the start-stop process,the temperature fluctuation of the battery cold plate becomes larger.The impacts of the cabin on the battery cooling system was greatly eliminated through cascade control strategy,and the maximum temperature fluctuation was reduced from 4.5 ℃ to 1.9 ℃. |
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