R&D of a Hydraulic Hydrogen Compression System for Refuelling Stations

Abstract The article presents a hydraulic hydrogen compression solution designed to serve as a booster compressor. It can be adapted to changing parameters of the inlet pressure of hydrogen and allows stabilising the hydrogen accumulation process in the high-pressure storage. The main results of this study were obtained using a numerical model developed to explore the thermodynamic processes that occur during the hydraulic compression of hydrogen. The modelling was carried out using COMSOL Multiphysics® 6.0 software with the CFD and heat transfer modules. The compression chamber in the form of a cylinder with a volume of 1.14 l and wall thickness of 5 mm was used in the computational model. The aim of these simulations was to investigate the temperature change limits of hydrogen, cylinder walls and working fluid, as well as to estimate the actual value of pressure inside the cylinder. The considered process of pressure increase in the cylinder chamber was modelled as a continuous change of volume filled with working fluid with discrete time step of 0.01 s, taking into account the increase of temperature inside the cylinder. The derived modelling results for different durations of compression stroke ts from 0.5 to 20.0 s were presented. The curves of energy consumption and temperature rise during the compression process were calculated for initial hydrogen pressures P1 = 3.0, 10.0, 15.0 and 20.0 MPa and compression ratio Kc = 5.0. The results of simulation of thermodynamic processes and their analysis allowed estimating energy consumption in the system of hydraulic compression and determining conditions which would lead to the increase in efficiency of hydrogen compression operation systems under consideration.