Hydrogen decompression analysis by multi-stage Tesla valves for hydrogen fuel cell

Hydrogen fuel cell is an ideal power source for electric vehicles. For a hydrogen fuel cell electric vehicle, the hydrogen is reserved in a high pressure level to promote the recharge mileage while relatively low-pressure hydrogen is demanded for proper functioning of the fuel cell stack, so that decompression of hydrogen is needed before hydrogen flowing into the fuel cell. With a reverse flow through Tesla valves, there appears a large pressure drop between the inlet and outlet, which can be used for hydrogen decompression nicely. However, a single-stage Tesla valve cannot meet the pressure drop requirement, so multi-stage Tesla valves are utilized. In this paper, numerical simulations of reversed hydrogen flow through multi-stage Tesla valves are carried out. The stage number of multi-stage Tesla valves and the inlet/outlet pressure ratio are both studied, and the distributions of temperature, pressure, and velocity inside multi-stage Tesla valves are all investigated. Results show that as the stage number increases or the inlet/outlet pressure ratio decreases, the pressure and the velocity inside multi-stage Tesla valves decrease, and the less the stage number, the more possibility for the velocity higher than local acoustic speed. Besides, a power-law relationship between the flow rate, the stage number and pressure ratio is summarized. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.