170kW燃料电池系统引射器关键结构参数影响研究

Research on the Influence of Key Structural Parameters of Ejectors for a 170kW Fuel Cell System

采用引射器实现大功率燃料电池系统中氢气的循环利用是未来的主流方向,然而突出的问题是引射器在低功率工况下性能表现较差,难以满足覆盖宽功率范围的要求。本文针对170 kW级大功率燃料电池用引射器,建立了引射器内流动三维数值模拟模型,分析了在宽工况下引射器关键结构参数,即喷嘴出口直径D和等容混合室直径D对引射性能的影响规律,进而探讨了适用宽功率工况的引射器最佳结构参数组合。结果表明:选用较小的D能够形成较大的流动压差,防止二次流倒流,提升引射器低功率工况下的性能。当D/D在2.5~3.0时,引射器性能最佳,覆盖功率范围由70~170 kW拓宽至40~170 kW,引射器适应的功率范围拓宽近43%。研究结果为170kW以上大功率燃料电池系统用引射器设计提供了重要参考。

Hydrogen re-circulation driven by ejectors in high-power fuel cell systems is promising in the fu‐ture.However,the outstanding problem is that the performance of ejectors is significantly poor under low power con‐ditions,which results in the inefficiency of the ejector working in the wide power range of fuel cell systems.In this paper,a three-dimensional numerical model is established for the ejector used in a 170 kW fuel cell system.The in‐fluence of two key geometric parameters including throat diameter of the primary nozzle(D)and mixing chamber di‐ameter(D)is analyzed under a wide range of working conditions.Moreover,the optimal combination of geometric parameters applicable for a wide power range is discussed.The results show that a large pressure difference is gener‐ated in the ejector due to a small D,thereby preventing the backflow of the secondary flow.Hence the performance of the ejector can be improved under low power conditions.Furthermore,the best performance is obtained when DDis 2.5~3.0,which leads to an increase in the power range from 70~170 kW to 40~70 kW(i.e.an increase of near‐ly 43%).The research results provide an important reference for the design of ejectors used in fuel cell systems with power above 170 kW.