摘要
对常压下竖直环隙流道内沸腾换热启动阶段壁温的瞬态变化特性和流动不稳定性进行了实验研究。结果表明环隙流道壁温变化经历跃升回落、各截面平均温度基本不变和快速上升三个阶段，存在强烈的流动不稳定性和壁温波动，并伴随着局部干湿交替现象。产生流动不稳定性的主要原因是流道中间歇生成长聚合汽泡，引起介质的突然加速、停滞或倒流。影响壁温波动的主要因素有环隙宽度、加热热流密度、初始水温、进出口附近大容积液体的过冷度及加热面吸附的不凝性气体等。
An experimental investigation on transient of wall temperature in start-up process of pool boiling heat transfer in narrow annuli under atmospheric pressure was carried out. The results showed that the variation of wall temperature can be divided into three stages: ascending steeply, average value on each cross section maintaining approximately constant or varying slowly, and then increasing rapidly. The wall temperature and fluid flow oscillated intensely, even appears partial alternate drying and wetting at the lower part of heated wall. The existence of large coalesced bubble which leads to geyser boiling is a necessary condition for the occurrence of flow instability, since that induces the fluid flow suddenly accelerating and then coming to a standstill or even reverse flowing. The main factors that affect wall temperature oscillation are gap width, heat flux, initial temperature, subcooling of bulk liquid at/near inlet and outlet and non-condensable gas absorbed on heated wall etc.
出处
《核动力工程》
EI
CAS
CSCD
北大核心
2000年第4期289-293,303,共6页
Nuclear Power Engineering
关键词
沸腾换热
壁温
流动不稳定性
竖直环隙流道
Boiling heat transfer
Narrow annuli
Start-up
Wall temperature
Flow instability
