Simulation Of Heat Transfer In Cryogenic Treatment And Design Of A Test System For Cryogenic Valves

With the development of modern science and technology, industry, LNG/LPG exploration and space technology, cryogenic valves have been widely used in many applications. The crystal lattice structure and mechanical properties of material at low temperatures are quiet different with those at ambient temperatures. Cryogenic treatment is an effective method to stabilizing crystal lattice and structural dimension, and to improving abradability and corrosion resistance of material. Cryogenic treatment of metal material becomes one of the key techniques for cryogenic valve industry.Firstly, our work focuses on the process of cryogenic treatment of valve components, especially cooling down time. After an analysis and comparison of the empirical coefficients of boiling heat transfer, a revised empirical equation has been proposed for the case of stainless steel plate block. Based on the empirical equation, numerical simulation with ANSYS has been conducted to demonstrate the cooling down process of valve components during the cryogenic treatment. The simulation results can be used as the reference to predicting the total cooling time for the valve components.In order to verify the simulation model and empirical coefficients of boiling heat transfer, experiments have been done on a stainless steel disc block treated by liquid nitrogen. Based on cooling process curve and comparison with simulation results, revisions have been made to the critical heat flux and minimum film coefficient of heat transfer. The simulation with revised parameters agrees well with experimental results, which may lead to more accurate prediction of cooling down time.