Modeling And Thermodynamic Analysis Of Hydrogen Filling Process Of The Fuel Cell Vehicle

Fuel cell vehicles are an indispensable part of the development of hydrogen energy in China and an important direction of the use of hydrogen energy.In order to popularize the use of fuel cell vehicles,the construction of hydrogen refueling stations is crucial.In order to meet the hydrogen filling requirements of on-board hydrogen cylinders of hydrogen fuel cell vehicles and reduce the cost of the operation process of the hydrogen refueling station,it is necessary to study the hydrogen filling process of the on-board hydrogen cylinders in the hydrogen refueling station.In view of the core of the hydrogen refueling station——the cascade hydrogen storage system composed of multiple hydrogen storage tanks,the influence of these thermodynamic parameters on the specific energy consumption and utilization rate of the hydrogen filling process was studied from the aspects of the volume ratio,pressure ratio and capacity of the hydrogen storage tanks.In addition,the influence of volume ratio and stage change of on-board hydrogen storage system on hydrogen filling process is also studied.The main research contents and results of this paper are as follows:(1)The thermodynamic model of the hydrogen filling process of fuel cell vehicles is established and verified.The results show that the pressure and temperature rise obtained by simulation and experiment increase with time,and the error of the final state pressure and temperature rise is 0.43%and 0.85%respectively,indicating the correctness of the model.(2)Several on-board hydrogen cylinder with different volumes were used,and the effects of the number of stages and volume ratio of the on-board hydrogen storage system on the specific energy consumption and utilization rate of the hydrogen filling process were analyzed.The results show that the specific energy consumption of hydrogen filling process is reduced by 8.1%and the utilization rate is increased by 32%from 1 to 5 stages.With the increase of the number of stages,the decline trend of specific energy consumption tends to be flat,and the rise trend of utilization rate also tends to be flat.The volume ratio and filling sequence of on-board hydrogen cylinder have little effect on the specific energy consumption and utilization rate of the filling process.(3)Several hydrogen storage tanks in the hydrogen refueling station with different pressure levels and volumes are used to analyze the impact of volume ratio,pressure ratio and capacity change of the cascade hydrogen storage system on the specific energy consumption and utilization rate of the hydrogen filling process.The research shows that the specific energy consumption and utilization ratio decrease with the increase of the volume ratio of the low pressure storage tank during the change of the volume ratio.When the volume ratio is 4:3:2,the specific energy consumption and utilization ratio are the lowest.In addition,the volume change does not change the result of the volume ratio change.In the process of pressure ratio change,the specific energy consumption and hydrogen utilization rate of hydrogen refueling station are decreasing with the increasing of nominal pressure ratio of medium pressure stage to high pressure stage.In addition,the volume change only slightly changes the result of pressure ratio change.Therefore,the lowest specific energy consumption ratio can be found by fixing the utilization ratio and changing the pressure ratio.For example,if the total mass of hydrogen in the station is 600kg,the hydrogen utilization rate is required to be no less than 12%,and the optimal pressure of each level is 50.2MPa,65MPa,and 86.7MPa respectively.