车用燃料电池阴极系统特性

为了提高车用燃料电池效率，利用物质守恒定律、理想气体方程以及二维插值法，建立了含有双螺杆压缩机的阴极系统模型，讨论了根据压缩机转速、压缩比计算其流量和功耗的方法，分析了环境因素对压缩机的影响以及阴极流体特性、过氧比特性.研究结果表明:在设定条件下，随过氧比变化，系统输出功率和效率的变化规律一致，最优过氧比为2.5，电能利用效率随过氧比增大呈单调下降趋势；工作温度升高能够提高系统输出功率，但会使系统电能利用效率有微弱降低，工作温度由60 ℃升到80 ℃时，系统输出功率增长5.03%，电能利用效率降低0.57%. 

Characteristics of Cathode System in Fuel Cells for Electric Vehicles

To improve the efficiency of fuel cells for vehicles, a cathode system model with a twin screw compressor was built by mass conservation, ideal gas law, and two-dimensional interpolation method. The methods to compute the air flow rate and the power of the compressor were discussed according to its rotational speed and pressure ratio. Based on the cathode system model, the influences of ambient factors on the cathode flow property and oxygen excess ratio (OER) were studied. Simulation results show that the output power and the efficiency change with the change of OER in the same way under the set conditions, and the optimal value of OER is 2.5, while the electrical efficiency decreases with OER increasing. In addition, elevated stack temperature will result in an increase in output power and a slight decrease in electrical efficiency. When the temperature elevates from 60 ℃ to 80 ℃, the output power increases by 5.03% and the electrical efficiency decreases by 0.57%.