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采用特殊的管子形状和表面是最为常用、有效的强化换热手段。该文以滴形管凝结换热作为研究对象,阐述了烟气中水蒸气凝结换热过程的特点及强化换热的条件。对液滴在圆管和滴管不同位置处的受力进行分析,说明不同管形对液膜层厚度的影响程度。通过回收天然气锅炉排烟余热实验,研究滴形管的凝结换热性能,分析影响换热性能的因素,并与圆形管进行比较。结果表明:烟气通过滴形换热管的压损小于圆管,温差大于圆管,冷却水温升高于圆管,换热系数高于圆管。采用滴形管对于强化凝结换热是一种行之有效的方法。
Using a special tube shape and surface is the most commonly used, effective means of strengthening the heat exchanger. In this paper, the condensation heat transfer of the drop tube is taken as the research object, and the characteristics of the condensation heat transfer and the conditions of heat transfer enhancement are discussed. The force of the droplet at different positions of the tube and the dropper is analyzed to show the influence of different tube shapes on the thickness of the liquid film. Through the experiment of reclaiming waste heat from exhaust gas of natural gas boiler, the condensation heat transfer performance of drop tube was studied. The factors affecting the heat transfer performance were analyzed and compared with that of round tube. The results show that the pressure loss of the flue gas through the drop-shaped heat exchange tube is smaller than that of the round tube, the temperature difference is larger than that of the round tube, the temperature of the cooling water rises above the round tube, and the heat transfer coefficient is higher than that of the round tube. The use of drop tube for enhanced condensation heat is an effective method.