燃料电池用高速单螺杆压缩机的仿真研究

Simulation of high speed single screw compressor in fuel cell

根据容积式压缩机的流量和转速成准线性关系的特性,指出高转速压缩机能够在小容积下提供相对较大的空气流量,符合车载燃料电池的基本要求.对高转速单螺杆压缩机的压缩过程建立了数学模型,模型以螺槽、星轮以及壳体所围成的容腔作为控制容积,应用质量守恒定律和热力学第一方程,同时考虑了冷却剂的换热效果以及气体泄漏.在该模型基础上,分析了在高工作转速下压缩空气物性参数、压缩机容积效率和能量利用率的变化规律.仿真结果表明,随着工作转速的增大,空气压缩机的排气量/体积比明显提高,在保持排气量稳定的前提下,可以通过提高压缩机转速来减小设备体积,从而满足燃料电池对压缩机的质量和体积要求;伴随着对流换热效果的减弱,压缩机的能量利用率有所下降.

According to the volume compressor＇s quasi-linear relationship between flow rate and rotational speed, it was pointed out that the high speed compressor which provides large flow rate under small package can satisfy the basic demand of fuel cells on vehicles. A mathematical model for high speed single screw compressor was established. The compressing process was modeled on the assumption of the working chamber as a control volume, to which the conservation equations of mass and energy were applied, while the heat exchange and air leakage were taken into consideration. According to the model, the physical properties of compressed air, the compressor＇s volume efficiency and energy dissipation under different rotational speed were calculated. Simulation results show that the ratio of mass flow to device volume obviously increases with increase of the rotational speed. On the assumption of fixed mass flow, increasing the compressor＇s rotational speed can decrease the device＇s volume. However more energy is dissipated because the heat transfer effect is weakened.