Heat Transfer Analysis Of Frost Dew Formation On The Surface Of Low Temperature Valve Dropper

With the continuous expansion of global production scale of cryogenic engineering products,the demand for cryogenic valves in the cryogenic market is also growing.At the same time,the technical performance and structural requirements of cryogenic valves in the market are also increasing.Low temperature valves are affected by many factors such as ambient temperature,air relative humidity,inflow speed and medium temperature in the valves,which may cause condensation and frosting on the cold surface of the valves.When condensation and frosting occur on the cover and drip disc of cryogenic valve,the service life of cryogenic valve will be reduced,and leakage of valve may occur,resulting in accidents.The research background and significance of this topic were introduced,and the research status of frost condensation on the cold surface of cryogenic valves was expounded.The main influencing factors of the formation of frost on the surface of low temperature valve were summarized and the formation of frost on the surface of low temperature valve was discussed.In order to solve the problem of frost and dew condensation on the surface of long neck valve cover and drip disc during the operation of cryogenic valve,the paper takes 6 "1500LB cryogenic ball valve as the research object,and conducts the following research by means of theoretical analysis,numerical simulation and experimental verification.The physical model of the long-neck valve cover and drip tray of the low-temperature valve was simplify,combined the law of conservation of energy and Fourier's law,and derived the differential equation of heat conduction and the solution conditions to obtain the change rule with time of the temperature of the valve cover and the drip tray at different positions.The ANSYS Workbench and Fluent software were used to numerical simulation the temperature field of the cryogenic valve and the surface of the two-dimensional model of the drip tray.The deformation of the frost layer and the factors affecting the frost layer growth on the surface of the low temperature valve were analyzed.The temperature of the stem at the upper surface of the gland ball valve packing gland,the temperature of the root of the drip pan,the temperature of the flange root in the bonnet and the temperature of the valve body cavity were tested,and the temperature with time of each component was analyzed.The correctness of the theoretical analysis and numerical simulation results of the unsteady temperaturefield of the long neck valve cover and the drip tray was verifiedThrough the theoretical analysis of the heat transfer process of the long-neck valve cover and drip tray of the low-temperature valve,it is found that the temperature variation of the valve cover and the drip tray at different positions has a monotonically decreasing exponential function distribution.The numerical simulation of the formation process of the two-dimensional model of the drip tray was carried out.It was found that the ambient temperature,relative humidity of the air had a great influence on the frost layer growth of the low temperature valve surface,and the influence of the incoming air velocity was small.