摘要
针对竖直多波纹板片内R134a的流动沸腾进行实验研究,采用高速相机捕捉并分析两相流型的衍变规律,分析干度对换热系数、压降的影响。结果表明:板片内部的汽液相于其所处平面沿水平方向存在交替分布特征;随着干度上升,板片左上角部分流域出现相对停滞的液膜区,其面积随着干度的增加而扩大;波纹板片内的主导换热机制由核态沸腾逐渐转变为对流沸腾。当干度x较低时(x<0.4),换热系数随干度的增加缓慢增加;随后换热系数随干度的上升速率加快(0.4<x<0.6),并于x=0.6时达到最大值;高干度时(x>0.7),板片内出现局部干涸现象,换热系数迅速下降。当质量通量相同时,板片的摩擦压降随干度的增加而增加,而饱和压力的上升会使得摩擦压降有所降低,最大降幅为20.4%。
The flow boiling of R134a in a vertical multi-corrugated plate heat exchanger was investigated experimentally.The transition of two-phase flow pattern was captured and analyzed by a high-speed camera,meanwhile the effects of dryness on heat transfer coefficient and pressure drop were analyzed.The results show that the vapor and liquid phase show an interval distribution along the horizontal direction.With the increase of dryness,a relatively stagnant liquid film region is observed in the upper-left corner of the test section,and its area expands with the increase of dryness,and the heat transfer mechanism gradually changes from nuclear boiling to convective boiling.Under the low dryness(x<0.4),the heat transfer coefficient increases slowly with the increase of dryness,then it rises rapidly(0.4<x<0.6)to the peak value(x=0.6),and decreases rapidly due to local dry-out at the high dryness(x>0.7).The friction pressure drop increases with the dryness at the same mass flux.However,the rise of saturation pressure can lead to a lower pressure drop,and the maximum decrease is 20.4%.
作者
陈庆虎
方奕栋
劳伟超
黄钰期
许霖杰
CHEN Qinghu;FANG Yidong;LAO Weichao;HUANG Yuqi;XU Linjie(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering,Shanghai 200093,China;College of Energy Engineering,Zhejiang University,Hangzhou 310027,Zhejiang Province,China)
出处
《化学工程》
CAS
CSCD
北大核心
2024年第8期55-59,89,共6页
Chemical Engineering(China)
关键词
板式换热器
流动沸腾
流型
换热特性
plate heat exchanger
flow boiling
flow pattern
heat transfer characteristic
