| The advantages of hydrogen as a clean and renewable energy source are abundant source,high calorific value,good safety,etc.Having the ability to independently develop large-scale hydrogen liquefaction equipment is the key task of hydrogen energy into energy strategy.From the perspective of improving the shaft seal performance of hydrogen liquefaction hydrogen turbo-expander,the dry gas seal is used as the research object to analyze the steady state performance.The geometry of the stationary and rotating rings of the dry gas seal is determined according to the structure of the expander,providing the prerequisites for the subsequent modelling.The sealing requirements of the expander are comprehensively analyzed,the seal operating characteristics are described and sealing insulation measures are proposed to ensure reliable sealing at low temperatures and to reduce leakage rate.In the refrigeration cycle of the hydrogen liquefaction process,the n-sec hydrogen conversion is ignored and the low temperature properties are calculated according to standard hydrogen and the variation of hydrogen properties with temperature at different pressures are analyzed.The SRK equation was chosen as the hydrogen actual gas equation of state and its applicability was verified by comparing the commonly used hydrogen actual gas equation of state with the NIST REFPROP database at the studied operating conditions.Based on the isothermal assumption,the gas film flow simulation was carried out to analysis the flow pattern of the gas film under the study conditions,and the laminar flow model was chosen.The effect of operating parameters such as rotating speed,pressure and geometric parameters such as groove depth and film thickness on the gas pressure,opening force and leakage was analyzed.The results show that opening force and leakage rate increases with the increase of the rotating speed,pressure and groove depth.The effect on the opening force is less than the effect on the leakage rate.The opening force decreases with the film thickness increasing while leakage rate increases.Simulation of the gas film flow fields considering temperature variation was carried out to study the temperature distribution of the gas film under different working conditions.The effect of frictional heat on the gas film pressure was analyzed.A seal isothermal model is compared with the thermal model and values of pressure distribution along the radius are similar,but there is a significant difference in the gas film pressure in the groove region,so in order to simulate the gas film flow field more realistically,the temperature variation needs to be considered.The effect of changes in rotating speed and pressure on end faces temperature rise under specific conditions is analyzed.The higher the rotating speed,the higher the end faces temperature rise,so that the end faces temperature rise can be reduced by decreasing the rotating speed,but the inlet pressure change has little effect on the end faces temperature rise.Analysis of the fluid-solid coupling of stationary and rotating rings,considering the deformation of stationary and rotating rings in the axial direction under the pressure of the flow field,which is distributed in the ring and has a certain conical deformation,the maximum deformation occurs at the inner and outer radius of the end faces.The centrifugal force generated by the rotation of the rotating ring reduces the deformation of the rotating ring greater than the deformation of the rotating ring.The effect of the rotating speed on the deformation of the rotating ring is large,the effect of pressure on the deformation of the stationary ring is large. |
