| With the increasing depletion of fossil fuels,hydrogen energy becomes a new energy that is vigorously developed worldwide,and hydrogen-fuel-cell vehicles have become an inevitable choice for today’s new-energy market.In the process of marketization of hydrogen energy,a large number of hydrogen refueling stations need to be built to ensure the mileage of hydrogen-fuel-cell vehicles.When the hydrogen is being injected into the vehicle,through processes such as pressurization,storage and filling,the temperature of the hydrogen will increase significantly due to the compression and throttling expansion effect.High temperature will affect the hydrogen storage tank of the hydrogen refueling station,being a threat to the safety of vehiclemounted gas cylinders.Therefore,it is necessary to design and develop a hydrogen heat exchanger with good heat transfer,compact structure,which is safe and controllable in the high-pressure environment during the hydrogenation process.Based on this,the main contents of this article are as follows:First part of this thesis will illustrate the simulation process of hydrogen booster system,storage system and refueling system.Taking technological features of hydrogen station into consideration,from hydrogen supply source,pressurization system,storage system to the filling system,based on the hydrogen refueling station process specifications required in SAE J 2601-2016,with the steady-state and dynamic simulation functions in the Aspen HYSYS process simulation software,the process was designed and built.Through simulation analysis,the physical properties and heat load of the inlet and outlet fluids of the heat exchangers in each process unit are obtained.According to the simulation data,the standard heat exchanger process parameters of the hydrogen refueling station is tested---the flow rate is 6.64m3/h and the heat load is29.7k W.The heat exchange network is also established for combining hydrogen refueling stations and heat exchangers.Secondly,based on the standard heat exchanger process parameters,the matrix structure of the cross-flow narrow channel heat exchanger is adopted,and the structure of the matrix is analyzed and optimized.The main optimized structural parameters are the diameter,number of holes,and arrangement of the hydrogen channels,center distance between horizontal and vertical holes,hydrogen flow length.Solid Works software was used to establish the three-dimensional model of the heat exchanger substrate with different hydrogen horizontal hole center distances and vertical hole center distances under three hydrogen apertures of 10 mm,8mm and 6mm.(1)Perform finite element analysis and simulation based on the static analysis module in ANSYS Workbench.Analyze the stress linearization at the maximum stress in the heat exchange matrix.The optimal hydrogen hole horizontal hole center distance and staggered hole vertical,hole center distance under the three hydrogen diameters,and the hydrogen flow cross-sectional size of the heat exchanger matrix are determined and defined.(2)FLUENT was used to simulate the flow field of these three optimization schemes,observe the temperature change trend of the hydrogen flow section,obtain the hydrogen flow length when the heat exchange demand is met,and determine the length of the heat exchanger matrix in the hydrogen flow direction.According to the optimization principle---as small as possible,the heat exchanger matrix structure with a hydrogen hole diameter of 6 mm was determined as the final optimization plan.Finally,to verify the exchanger meets the requirements,the overall structure mechanics simulation and flow field simulation with hydrogen distribution structure and cold fluid side head are carried out.As a result,it meets the requirements and the hydrogen is uniformly distributed in the pores.The experiment demonstrates that this small cross-flow narrow-channel heat exchanger structure can meet the needs of hydrogen heat exchange in a 70 MPa hydrogen refueling station. |
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