A novel pump-thermal synergistic pressurization process for an efficient liquid hydrogen refueling station system

Abstract

The traditional 70 MPa liquid hydrogen (LH2) refueling stations (HRSs) require LH2 pumps with high outlet pressures, leading to high initial investment, energy consumption, and difficulty in developing an LH2 pump meeting requirements. Existing LH2 HRSs using thermal compression eliminate the need for pressurization equipment but result in significant waste due to low-pressure hydrogen venting. Therefore, we have pioneered a novel pump-thermal synergistic pressurization process for an efficient LH2 HRS system. The process utilizes a 45 MPa LH2 pump and an electric heating method, allowing easily controllable heat input. This study constructs a thermodynamic model for this system that includes the dynamic operational processes of all core components. Based on the established model, the outlet parameters of the LH2 pump, characteristic parameters of the pressure vessel, the refueling process, and the operation of the entire system are investigated. By dynamic simulation of the whole HRS system with pump and thermal compression, it is found that the specific energy consumption for hydrogen refueling is reduced to 0.55 kWh/kg, with the pump consuming 0.2 kWh/kg while thermal compression consuming 0.35 kWh/kg. After optimizing control strategies, the cycle venting of the pressure vessel and the residual hydrogen gas after re-heating and pressurization account for only 11.6%, and further utilization through the pump pressurization cycle can achieve high utilization with no residuals. This system effectively reduces the initial investment and energy consumption for LH2 HRSs. It simplifies the structure, facilitating the retrofit of existing stations and promoting the construction and application of HRSs.