The phase separation concept condensation heat transfer in horizontal tubes for low-grade energy utilization
The phase separation concept condensation heat transfer in horizontal tubes for low-grade energy utilization
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DOI：
10.1016/j.energy.2014.03.075
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发表时间：
2014-05
期刊：
影响因子：
9
通讯作者：
Jian Xie;Jinliang Xu;Feng Xing;Wang Zixuan;Huan Liu
中科院分区：
文献类型：
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作者：
Jian Xie;Jinliang Xu;Feng Xing;Wang Zixuan;Huan Liu
本文采用相分离概念，研究了内径为14.81 mm，换热长度为1200 mm的水平管内的凝结换热。中空网筒是由两层网筛表面包裹而成。外层的孔径为76 μm。本发明构造了一种多尺度冷凝管。重点研究了分层流和环状流的调制，通过将液体保持在网状圆筒内，增加蒸汽覆盖管壁面积，强化分层流的传热。对于环状流，汽核中的液滴被网筛表面捕获，以增加管壁附近的汽相空隙率，从而增强帽状传递。实验结果表明，该管的传热系数可达到光管的2倍以上。总热阻最大降低45.6%。对于沿着整个管长方向的冷凝流，随着蒸汽质量流量Gxin的增大，换热强化率增大。压力分析解释了增加的传热趋势。管内液体流动部分抑制了强化传热率的提高。
This paper reports condensation heat transfer in a horizontal tube with a 14.81 mm inside diameter and a 1200 mm heat transfer length, by using the phase separation concept. The hollow mesh cylinder was formed by packaging two layers of mesh screen surface. The outer layer had the pore size of 76 μm. This invention constructs a multiscale condenser tube. The modulation of stratified flow and annular flow was focused on. Liquid was held within the mesh cylinder to increase the vapor covered tube wall surface to enhance the heat transfer for stratified flows. For annular flows, liquid droplets in the vapor core were captured by the mesh screen surface to increase the vapor void fractions near the tube wall, enhancing the hat transfer. The measurements showed that the heat transfer coefficients could be more than two times of those in the bare tube. The total thermal resistance was decreased by 45.6%, maximally. The heat transfer enhancement ratios were increased with the vapor mass fluxes,Gxin, for the condensation flow along the whole tube length. A pressure analysis explained the increased heat transfer trend. The increment of heat transfer enhancement ratios was suppressed with a liquid flow part in the tube.