卧式螺旋管内流动换热壁温分布特性

Wall temperature distribution characteristics of flow and heat transfer inside horizontal helically-coiled tube

螺旋管是一种高效换热管型,在卧式螺旋管内流动时受到重力和离心力的作用,工质流动方向时刻改变,产生二次回流,从而表现出了不同于其他管型的流动与传热特性。以卧式螺旋管为研究对象,选取底部截面、上升段截面、顶部截面三个具有代表性的位置截面,采用逐渐增大热通量法研究了其在单相对流和过冷沸腾条件下壁温的分布特性。为螺旋管换热器的设计与应用提供了参考依据。

Helically-coiled tube is a kind of high-efficiency heat transfer tube. When fluid flows in horizontal helically-coiled tube it will be affected by gravity and centrifugal forces,and the flow direction changes from time to time,resulting in secondary flow and thus behaving different flow and heat transfer characteristics from those in other tubes.In order to explore the temperature distribution characteristics of the inner tube wall when fluid flows in single phase and under subcooled boiling,the inner tube wall temperatures on the bottom,the rising part and the top cross sections selected in a horizontal helicallycoiled tube are experimentally studied by means of increasing the heat flux gradually.Factors which result in these characteristics are explained in detail.The completed work has significance of reference for the design and engineering applications of helically-coiled tube heat exchangers.