摘要
为研究半椭圆管在水平降膜蒸发时各参数对液膜厚度的影响与液膜分布规律,搭建了单根水平降膜液膜厚度拍摄实验台,用图像差值法研究了热流密度、喷淋温度、布液高度、喷淋密度对液膜厚度的影响,并比较了相同工况下不同管型的液膜厚度。研究结果表明:随着热流密度增加,平均液膜厚度减小;随着喷淋温度增加,液膜厚度减小;随着布液高度的增加,平均液膜厚度逐渐减薄,在布液高度很小的时候,换热管上部容易积液;随着喷淋密度的增加,平均液膜厚度逐渐变厚;对于截面周长相同的圆管,椭圆管和半椭圆管,在相同工况下,所有管型的换热管的液膜厚度在周向角上都存在一个最薄点,最薄点出现在90°附近,且半椭圆管的平均液膜厚度最薄。
To study the distribution of liquid film and how parameters influencing the thickness of the falling film outside horizontal semi-elliptical tube,an experimental platform was set up for taking photos of thickness of falling liquid film.Image subtraction method was applied to study the effects of the difference of heat flux,spray temperature,height of liquid distributor and spray density on the thickness of the liquid film.The film thickness of different tube types under the same condition was also compared.The results show that the average liquid film thickness decreases with the heat flux increasing;the average liquid film thickness decreases with the spray temperature increasing;the average liquid film thickness decreases gradually with the height of liquid distributor increasing,when the height of liquid distributor is small,the upper part of tube is easy to accumulate liquid.The average liquid film thickness increases gradually with the increase of spray density.Under the same conditions,for circular,elliptical and semi-elliptical tubes with the same section perimeter,there is a thinnest point of liquid film thickness in circumferential direction at 90°nearby,and the average liquid film thickness of semi-elliptical tube is the thinnest in all tube types.
作者
胡昊
周亚素
王树信
徐新帆
张晓阳
HU Hao;ZHOU Ya-su;WANG Shu-xin;XU Xin-fan;ZHANG Xiao-yang(College of Environmental Science and Engineering,Donghua University,Shanghai 201620,China)
出处
《化学工程》
CAS
CSCD
北大核心
2020年第8期18-23,35,共7页
Chemical Engineering(China)
关键词
半椭圆管
水平降膜
液膜厚度
热流密度
喷淋温度
布液高度
喷淋密度
semi-elliptical tube
horizontal falling film
film thickness
heat flux
spray temperature
liquid distribution height
spray density
