【摘要】 在金属管内壁喷涂低导热涂层有利于减少低温预冷总耗时，但其作用机制尚未探明。以竖直管路低温预冷为对象，忽略预冷过程气液两相流体间热质传递作用的直接求解，将流体–管壁间的沸腾传热转化为随管壁温变化的热边界函数，分别对光管与低导热涂层管预冷规律开展了计算预示与对比分析。研究发现，管内壁涂层的低导热率并非是实现预冷提速的主控机制，涂层反而会引入额外的传热热阻，延缓管壁降温速率；而莱顿弗罗斯特点附近区域的固–液间歇接触是造成低热导率涂层管能够快速降温的核心机制。在固–液间歇接触作用下，涂层管可减少预冷耗时约12%。为强化预冷速率，宜采用涂层更厚、热导率更低、浸润性更好的涂层材料。更多还原

【Abstract】 Applying low thermal conductivity coating at the interior surface of a metal pipe is beneficial to decreasing the overall time consumption of a cryogenic chilldown process.However,the underlying mechanism responsible for this effect remains to be elucidated.In this study,a vertical pipeline was selected as the subject.The direct solution of heat and mass transfer between gasliquid two-phase fluid during chill-down process was ignored,but the boiling heat transfer between the fluid and wall was transformed into a thermal boundary function which varied with the inner wall temperature.The chilldown processes of a bare pipe case and a low-thermal-conductivity coated pipe were calculated and compared.It was observed that the low thermal conductivity effect did not account for the accelerated chilldown process.Instead,the coating could introduce additional thermal resistance,which could potentially decrease the heat transfer rate.Actually,the intermittent solidliquid contact near Leidenfrost point could primarily account for the fast childown effect associated with the low thermal conductivity coating layer.Under this intermittent contact mechanism,the chill-down time of the coated pipe is reduced by approximately 12% when compared to a none coating pipe event.To further enhance the chilldown effect,it is recommended to employ the coating material with a thicker layer,lower thermal conductivity,and superior wettability.更多还原