Pressure analysis on two-step high pressure reducing system for hydrogen fuel cell electric vehicle

Hydrogen fuel cell electric vehicle (FCEV) can achieve zero exhaust emission and zero pollution. In order to make FCEV reach a farther travel distance, greater demands are put on its pressure reducing system. In this paper, a two-step high pressure reducing system for FCEV is proposed. The system is made up of two parts, a new high multi-stage pressure reducing valve (HMSPRV) and a multi-stage muffler. As a new system, its feasibility has to be verified. Since the valve opening condition has a great effect on hydrogen flow, pressure reduction and energy consumption, different valve opening conditions are taken as the research point. The flow field analysis of the new HMSPRV is conducted on three aspects: pressure field, velocity field and energy consumption. It can be found that both the pressure reducing and velocity increasing gradients mainly reflect at those throttling components for all valve openings. For energy consumption, in the comprehensive study of flow vortexes and turbulent dissipation rate, it can be found that the larger of the valve opening, the larger of energy consumption. Then, a thermo-fluid-solid coupling analysis is conducted on the new HMSPRV, and it is concluded that the new system meets strength requirement. Furthermore, as the second step of the high pressure reducing system, the flow and pressure fields of multi-stage muffler are investigated. The five-stage muffler is exactly designed to complete the whole pressure reducing process. This study can provide technological support for achieving pressure regulation in the hydrogen transport system of FCEV when facing complex conditions, and it can also benefit the further research work on energy saving and multi-stage flow of pressure reducing devices.