| As a viable energy carrier for fuel cell vehicles(FCV),hydrogen provides a clean and efficient solution for transportation.The storage and fast filling is one of the core issues impeding the commercial development of FCV.Hydrogen is fed from refueling station to on-board hydrogen storage system(HSS).The temperature rise rapidly due to the negative of the Joule-Thomson effect during the process of fast filling.Then high temperature can cause the composite material to fail,ultimately leading to safety issues.Safe and fast refueling is an urgent problem to be solved in hydrogen station at present,especially the high pressure filling technology of 70 MPa tank is not mature.Considering the safety reasons,the SAE-J2579 have restricted the maximum wall temperature inside the hydrogen vessel below 85 ℃ and the maximum fueling pressure has to limited below 125% of the designed pressure.Therefore,this paper studies the temperature rise during the fast filling process.The research includes:(1)Firstly,the mechanism of temperature rise in the cylinder from the perspective of thermodynamics and the harm of high temperature on the tank are analyzed.Secondly the system of fast filling was built and the experiment of 35 MPa cylinder was carried out under the condition of ensuring safety as a data foundation.(2)Computational Fluid Dynamics(CFD)is used to predict the temperature distribution within a tank during refueling by COMSOL.Building the model includes the selection of physical field,meshing,turbulence model,gas model and boundary condition setting etc.(3)On the one hand,the accuracy of the simulation model was verified by comparing to the experimental data.On the other hand,the independence of the grid was also verified in the process of model construction.Only half of the geometric model was used to minimize the calculation time without affecting the results.In addition the influence of several key parameters(such as initial pressure,ambient temperature,filling rate,etc.)on the temperature rise in the tank was studied.During the process of refueling,the temperature in the tank increased with the increase of initial pressure,ambient temperature and the filling rate.(4)Some reasonable and effective filling strategy is preliminarily designed according to the analysis of the simulation results.Three filling strategies are proposed in this paper: the filling rate in the first half is greater than the latter half;the hydrogen pre-cooled can be done;the coupling control of cooling temperature and filling speed.Finally,the dual goals of temperature and filling time can be achieved while minimizing energy consumption. |
