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预测水平管束降膜流动模态是确定不同流量下传热传质系数的关键步骤。本文对几种表面增强管的外表面降膜流动进行了研究,流动模态转变边界可以通过流体Re数与Ga数之间的函数关系式描述。测试流体包括水、乙二醇、50%乙二醇水溶液和45%溴化锂溶液,通过测试得到了不同管表面的降膜流动转变关系式并进行了比较。研究结果表明,管表面结构对滴状向滴柱状以及滴柱状向柱状的转变点的Re数影响较大,而对柱状向柱帘状以及柱帘状向帘状转变的Re数影响较小。
It is a key step to determine the heat and mass transfer coefficient under different flow rates to predict the falling film flow pattern of horizontal tube bundles. In this paper, the falling film flow on the outer surface of several surface-enhanced tubes was studied. The boundary of the flow mode transition can be described by the functional relationship between the Reynolds number and the Ga number. The test fluid includes water, ethylene glycol, 50% ethylene glycol and 45% lithium bromide solution. The relations of falling film flow transition on different pipe surfaces were obtained and compared. The results show that the influence of the tube surface structure on the Re number of the droplet to the drop column and the droplet column to columnar transition point is greater, while the Re number of the columnar columnar curtain to the curtain shade curtain has less influence.