Numerical analysis of flow and temperature characteristics in a high multi-stage pressure reducing valve for hydrogen refueling station

Hydrogen refueling station is one of the most important parts for the hydrogen energy utilization. In this paper, a novel high multi-stage pressure reducing valve (HMSPRV) is proposed, which can be used for hydrogen stable decompression in hydrogen refueling station. In HMSPRV, the inner and outer porous shrouded valve core is used to replace piston valve core to achieve the first-stage throttling, and the porous orifice plate is chosen as the second-stage throttling component. Meanwhile, in order to verify the applicability of HMSPRV, the flow characteristics of two fluids are studied. Firstly, the choked flow, flow and temperature characteristics of superheated steam under different valve openings are carried out. Secondly, the flow characteristic of hydrogen is also conducted to validate the application of HMSPRV in hydrogen refueling station. The results show that, for superheated steam flow, with the increasing of valve openings, the maximum gradient of fluid pressure moves from the fitting surface where inner and outer porous shrouded to the orifice plate. The regulation of its amount is decreasing first and then increasing. With the increasing of valve openings, the maximum velocity, turbulent dissipation rate and pressure loss are all increasing gradually, while the temperature does not change significantly. For hydrogen flow, both the pressure changing process and velocity changing process are similar to superheated steam. It can be concluded that HMSPRV has good flow and temperature characteristics in complex conditions, and it does not prone to choked flow. Throttling effect of the multi-stage pressure reducing way is obvious. This work can benefit the further research work on hydrogen stable decompression in hydrogen refueling station.