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为研究壁面过冷度对含不凝性气体蒸汽流动冷凝换热能力的影响,分别进行水冷却与空气冷却条件下空气-蒸汽混合气在水平管内的流动冷凝实验,分析空气入口质量分数,混合气入口流速以及管外冷却剂体积流量变化时,管内局部换热系数随壁面过冷度的变化规律。结果表明:在环状流及波状流范围内,局部换热系数随壁面过冷度的增加而增大;在分层流范围则随壁面过冷度的增加而减小;空气含量与混合气流速的增加,会使得环状流和波状流下壁面过冷度增大对冷凝换热能力的促进作用更为显著。
In order to study the influence of wall undercooling on the condensing heat transfer capacity of steam containing non-condensable gases, the air-steam mixture in the horizontal tube under water-cooling and air-cooling conditions were respectively tested for the flow condensation. The air inlet mass fraction, Gas inlet flow rate and volume flow of coolant outside the tube, the local tube heat transfer coefficient with the wall undercooling law. The results show that the local heat transfer coefficient increases with the increase of the degree of undercooling in the annular and wavy flows, decreases with the increase of the degree of supercooling in the stratified flow, When the velocity increases, the effect of increasing the supercooling degree of the annular flow and wavy flow on the condensation heat transfer is more significant.