蒸汽流量对蒸汽直接接触冷凝的影响  

Effect of vapor injection rate on direct contact condensation of vapor

作　　者：唐继国 阎昌琪 孙立成[2] 莫政宇[2] 

机构地区：[1]哈尔滨工程大学核科学与技术学院核安全与仿真技术国防重点学科实验室,哈尔滨150001 [2]四川大学水利水电学院水力学与山区河流开发保护国家重点实验室,成都610207

出　　处：《航空动力学报》2016年第7期1610-1616,共7页Journal of Aerospace Power

基　　金：国家自然科学基金(51376052,11175050,51106101);四川大学科研基金(YJ201432)

摘　　要：为研究蒸汽流量对蒸汽直接接触凝结及汽泡表面变化过程的影响,利用高速摄像仪记录一定过冷度、不同蒸汽流量条件时过冷水中蒸汽的凝结过程.实验结果表明:蒸汽流量小于0.36m^3/h时,汽泡表面始终较光滑;当蒸汽流量升至0.74m^3/h时,汽泡表面上出现波动,汽泡最终逐渐分裂成数个小汽泡;当蒸汽流量大于1.13m^3/h时,汽泡表面上的波动非常剧烈,汽泡不稳定性增强,并最终破碎成大量微汽泡.且随蒸汽流量增,这些微汽泡的直径减少,喷射速度增加.蒸汽流量超过1.13m^3/h后,汽泡在凝结时,其相对半径迅速减小,半径变化率迅速增加.汽泡表面剧烈的波动会极大的增加汽泡有效换热面积,导致蒸汽与过冷水间的传热和传质过程被极具的加强.In order to investigate the effect of vapor injection rate on the direct contact condensation and evolution of vapor bubble surface, a high-speed video camera was employed to record the process of vapor condensation in the cold bulk at a certain liquid subcooling and different vapor injection rates. Experimental results showed that the bubble surface was rela tively smooth throughout the whole slow process of bubble condensation when the vapor in jection rate was less than 0.36m3/h. As the vapor injection rate increased to 0.74m3/h, sur face wave appeared on the bubble surface and the bubble was split up into some tiny bubbles finally. When the vapor injection rate was larger than 1.13m3/h, surface wave on the bubble was very violent. The bubble instability was enhanced and the bubble would collapse into many microbubbles. Furthermore, with the increase of the vapor injection rate, the diameter of these microbubbles decreased and the average velocity increased. When the vapor injection rate exceeded 1.13m3/h, the bubble relative radius decreased and the change rate of bubble radius increased rapidly. The strong surface wave on the bubble could increase the bubble cffective area of heat transfer significantly, resulting in a substantial enhancement of heat and mass transfer between vapor and cold bulk.

关 键 词：直接接触凝结 汽泡表面 汽泡破裂 微汽泡 蒸汽流量 

分 类 号：V129[航空宇航科学与技术—人机与环境工程] TK124[动力工程及工程热物理—工程热物理]