Research And Design Of 70MPa High Pressure Hydrogen Pressure Reducing Valve

Hydrogen energy's reproducibility,diverse production methods,no pollution,high energy conversion rate,high energy density,and various storage methods make countries around the world regard the hydrogen energy industry as an important part of their national energy strategies.Applying hydrogen energy to vehicle fuel is an important part of the energy strategy.A hydrogen fuel cell vehicle during driving,the high-pressure hydrogen in the high-pressure hydrogen storage bottle flows through the pipeline,is decompressed in the high-pressure hydrogen decompression valve,and finally flows into the hydrogen fuel cell to generate electricity.If the high-pressure hydrogen decompression valve malfunctions,the high-pressure hydrogen cannot be decompressed to the pre-pressure of thuje hydrogen fuel cell,which will affect the service life and energy conversion effect of the hydrogen fuel cell,and may even break through the hydrogen fuel cell,resulting in a safe driving direct impact.Therefore,research on high-pressure hydrogen pressure reducing valve is very important for the development of hydrogen fuel cell vehicles.Based on the above background,this paper details the current status of valve research and the current status of high-pressure hydrogen pressure reducing valve flow fields at home and abroad.After analysis,a two-dimensional simplified model of the internal flow field of the two-stage high-pressure hydrogen pressure reducing valve is established,and the fluid mechanics calculation software Fluent is used to study it.First,the two-dimensional simplified model is established according to the fluid mechanics theory.The first-stage decompression adopts the form of a poppet valve and the second-stage decompression adopts the form of a flat valve.A new iterative calculation method and a method to reduce the sub-relaxation factor and improve the convergence are proposed from the perspective of solving the difficulty of converging the calculation of the high-pressure difference,small flow and minimum spool size models.From the simulation calculation results,iterative calculation method can make the calculation converge;reducing the sub-relaxation factor can improve the convergence and make the result more accurate.Then,based on the model established above,the effects of inlet size,first-stage spool opening and second-stage spool opening on the flow rate of the two-stage high-pressure hydrogen pressure reducing valve are studied.And find the key parameters of high pressure hydrogen pressure reducing valve suitable for hydrogen fuel cell bus.At the same time,the effects of the opening of the first-level spool and the opening of the second-level spool on the pressure distribution,temperature field,velocity field and energy loss of the two-stage high-pressure hydrogen pressure reducing valve were studied from the cloud diagram and the distribution diagram in the X direction.Through analysis,it is determined that the maximum speed and minimum temperature of the valve will not cause damage to the valve on the basis of decompression,and great energy loss occurs at the spool.Finally,based on the above analysis,three-dimensional modeling of the two-stage high-pressure hydrogen pressure-reducing valve is established,and its components and working mechanism of pressure-reducing are introduced in detail.Through the static analysis of the stem of the two-stage valve core structure,the selection basis of the spring stiffness coefficient is obtained.MATLAB is used to study the dynamic characteristics of the stem to provide a reference for the selection of the sealing ring.