电动车辆热管理系统中CO_(2)工质替代方案对续航里程的影响

Impact of CO_(2) Refrigerant Substitution Scheme in the Thermal Management System of Electric Vehicles on Driving Range

针对电动车辆热管理系统传统制冷剂面临淘汰以及电动车辆冬季“续航里程”焦虑问题,对具有极佳制热能力的天然工质二氧化碳制冷剂(R744)作为工质的热管理系统进行了能效寻优与续航影响评估。搭建跨临界R744系统实验平台,基于GT-suite开发了包含R134a制冷剂和R744制冷剂在内的高精度动态整车热系统模型,该模型涵盖了热管理系统、电池热电系统、动力系统、座舱热模型和控制器,以评估真实驾驶条件下的热管理系统能耗和续航表现。实验与模拟结果显示,电池冷却器的进口冷却液温度对最优排气压力几乎没有影响,冷却液流量的增大使得最优压力增长约0.2~0.3 MPa,环境温度是影响最优排气压力最明显的因素。此外,定义了热管理能耗系数用以定量评估热管理系统能量消耗对整车能耗的影响,对比分析发现:在40℃时,R744系统的能耗系数较R134a高出0.066,续航里程减小了7.02%,而在-25℃环境下,R744的能耗系数比R134a低0.27,续航里程增加了44.52%。综合全年平均续航里程、运行成本和环保性因素,R744系统在严寒、寒冷和温和气候区更具优势,而R134a则更适合炎热及夏热冬暖地区的应用。

To address the phase-out of traditional refrigerants in electric vehicle thermal management systems and the concern of winter driving range anxiety,an evaluation of energy efficiency optimization and driving range impact is conducted on a thermal management system that uses the excellent heating capabilities of the natural refrigerant carbon dioxide(R744).An experimental platform for a transcritical R744 thermal management system is set up,and a detailed dynamic whole-vehicle thermal system model incorporating R134a and R744 is developed using GT-suite.This model encompasses the thermal management system,battery thermal-electric system,power system,cabin thermal model,and controller to evaluate energy consumption and driving performance under real-world driving conditions.Experimental and simulation findings reveal that the inlet coolant temperature of the battery cooler has minimal impact on the optimal exhaust pressure,while increasing the coolant flow rate raises the optimal pressure by approximately 0.2—0.3 MPa,with ambient temperature significantly influencing the optimal exhaust pressure.Furthermore,a thermal management energy consumption factor is defined to quantitatively evaluate the system’s energy consumption impact on overall vehicle energy usage.Comparative analysis reveals that at 40℃,the energy consumption factor of the R744 system is 0.066 higher than that of R134a,leading to a 7.02%reduction in driving range.Conversely,at-25℃,the energy consumption factor of R744 is 0.27 lower than that of R134a,resulting in a 44.52%increase in driving range.Considering factors such as average annual driving range,operating costs,and environmental considerations,the R744 system proves more advantageous in cold,cool,and mild climate zones,while R134a is better suited for hotter and temperate regions.