相变材料辅助的燃料电池客车冷启动特性研究

Research on cold start characteristics of fuel cell bus assisted by phase change material

随着燃料电池在客车上的应用不断深入,其低温环境下冷启动问题逐渐凸显。为了提高燃料电池客车的启动速度,使电池更快地工作在合理的温度范围内同时降低冷启动过程的能耗,将相变材料(PCM)引入电堆冷启动系统,利用PCM可吸收电堆工作废热的特性,在冷启动时将废热放出加热电堆。基于仿真平台搭建电堆冷启动系统模型,对比分析了正温度系数热敏电阻(PTC)独立加热、PCM独立加热和PCM-PTC联合加热的温升变化和能耗特性。3种加热方式均使80 k W电堆从–20℃升高到10℃,PTC的功率为12 k W,PCM采用石蜡/膨胀石墨复合相变材料(CPCM)。在联合加热方式下,分析了PCM质量对冷启动时间、节能率和潜热利用率的影响。结果表明:PCM-PTC联合加热方式较PTC独立加热节省约33.46%能耗,启动时间缩短了37.40%,较PCM独立加热启动时间缩短了61.00%;随着PCM质量的增加,冷启动时间缩短,系统节能率增加,但是PCM的潜热利用率却在下降。PCM辅助的冷启动系统为燃料电池发动机在低温环境下快速启动和节能提供了思路。

With the deepening application of fuel cells in passenger cars,the problem of cold start in low temperature environment becomes more and more prominent.In order to increase the start speed of fuel cell bus,make the battery work faster in a reasonable temperature range and reduce the energy consumption of cold start process,phase change material(PCM) is introduced into the cold start system of electric reactor.PCM can absorb the waste heat of electric reactor,then the waste heat is released to heat electric reactor during cold start.Based on the simulation platform,the cold start system model of electric reactor is established,and the temperature rise and energy consumption characteristics of positive temperature coefficient thermistor(PTC) independent heating,PCM independent heating and PCM-PTC combined heating are compared and analyzed.The results show that,all the three heating methods can increase the 80 kW reactor from –20 ℃ to 10 ℃,and the power of PTC is 12 kW.The PCM adopts paraffin/expanded graphite composite phase change material(CPCM).The effects of PCM mass on cold start time,energy saving rate and latent heat utilization rate are analyzed under combined heating mode.The results show that,compared with PTC independent heating,PCM-PTC combined heating saves about 33.46%energy consumption and reduces the starting time by 37.40%,and reduces the starting time by 61.00% compared with the PCM independent heating.With the increase of PCM mass,the cold start time shortenes and the system energy saving rate increases,but the latent heat utilization rate of PCM decreases.PCM-assisted cold start system provides an idea for fast start and energy saving of fuel cell engine in low temperature environment.