A first study of the potential of integrating an ejector in hydrogen fuelling stations for fuelling high pressure hydrogen vehicles

Abstract

This present study evaluates the potential of entraining the low-pressure hydrogen to fuel cell vehicles during fuelling processes, which is expected to promote the development of the hydrogen fuel automotive industry. A computational fluid dynamics model is developed to evaluate the potential of the proposed hydrogen fuelling process. A flow behaviour analysis is performed to show the detailed flow structure in the critical and sub-critical processes for the hydrogen ejector. The critical suction pressure and critical back pressure are assessed under various inlet pressures of the primary nozzle. The results show that the high-pressure hydrogen accelerates in the primary nozzle, leading to the decrease of the static pressure, which generates the suction effect in the downstream of the nozzle exit to entrain the hydrogen from the low-pressure tank. The entrainment ratio declines along with the increasing back pressure or decreasing inlet pressure of the suction chamber. This study suggests that the integration of an ejector instead of a reduction valve into the hydrogen fuelling station improves the energy efficiency by utilizing less hydrogen from the high-pressurized hydrogen storage during vehicle fuelling.