Simulation And Performance Prediction Of Filling Process In On-board Hydrogen Storage Tank

In order to safely fuel as much hydrogen gas as possible into the hydrogen fuel cell vehicle within a shortest time,and to meet the consumers’ requirements for filling time and mileage,the refueling process of on-board hydrogen storage tank is studied in this paper.Firstly,on the basis of the mass conservation equation and energy conservation equation,a theoretical model for filling process of on-board hydrogen storage tank is established.For continuous improvement of the simplified geometric model of the tank wall structure,single-zone（hydrogen zone）lumped parameter model,dual-zone（hydrogen zone,tank wall zone）lumped parameter model and triple-zone（hydrogen zone,liner zone and shell zone）lumped parameter model are proposed respectively.The similarities and differences of the heat transfer conditions among the U.S.Naval gas charging model,the MC method based refueling model and our models are analyzed and compared.Under adiabatic and diathermic conditions,four models of single-zone single-temperature（hydrogen temperature）,dual-zone single-temperature（hydrogen temperature）,dual-zone dual-temperature（hydrogen temperature and wall temperature）,and triple-zone triple-temperature（hydrogen temperature,liner temperature and shell temperature）conditions are summarized.The models in each condition are built in MATLAB/Simulink software to simulate the hydrogen filling process,and the numerical solutions are obtained.Comparing the numerical solutions with the analytical solutions calculated by analytical methods,the validity of the model is verified.At the same time,the prediction of hydrogen temperature and tank wall temperature is realized to ensure the safety of hydrogen refueling process.Secondly,based on the single-zone lumped parameter model,the analytical solution of the filling time is obtained,and the effects of the initial hydrogen temperature,the initial hydrogen pressure,the inlet temperature and the final hydrogen pressure on the filling time are investigated,the prediction of filling time are realized.In addition,for the expected filling time,when the hydrogen temperature reaches the limit value of 85°C,the corresponding critical initial hydrogen temperature,critical initial hydrogen pressure,and critical inlet temperature can be determined.If the actual initial hydrogen temperature is higher than the critical initial temperature,the actual initial hydrogen pressure is lower than the critical initial pressure,and the actual inflow temperature is higher than the critical inflow temperature,the filling time will exceed the expected value,otherwise the filling time will be lower than the expected value.Finally,the dual-zone dual-temperature lumped parameter model is used to calculate the value of state of charge（SOC）during the filling process of on-board hydrogen storage tank in this paper.The calculated values are compared with the experimental data.The results show a good agreement.It’s proved that the SOC value during the filling process of on-board hydrogen storage tank can be calculated by the dual-zone dual-temperature model.Meanwhile,the influence of mass flow rate and inflow temperature on SOC is researched.According to the analytical solution of SOC,when the type of hydrogen storage tank,mass flow rate and inflow temperature are known,the SOC value at the end of the hydrogen refueling process can be predicted.In this paper,the heat transfer of on-board hydrogen storage tank is deeply analyzed.The hydrogen temperature,filling time and SOC during hydrogen refueling process can be predicted.The study results can provide a certain theoretical basis to make hydrogen refueling strategy and ensure the safety of the refueling process.