低压条件下紧凑式顺排管束满液型蒸发换热器的强化换热特性研究

提出了一种新型紧凑式顺排光滑管束组成的满液式蒸发换热器。在低压条件下对水平光滑顺排管束的小空间内沸腾强化换热特性进行了实验研究,确认了管距、管位置和运行压力对强化换热性能的影响。实验表明存在一个能得到最大强化换热效果的最佳管距,这一最佳管距接近沸腾气泡的脱离直径。压力对强化换热效果也有重要影响:随着压力降低,强化换热效果也逐步减弱。实验结果对高效节能型蒸发换热器设计提供了设计基础。

ENHANCEMENT BOILING HEAT TRANSFER OF COMPACT IN-LINE BUNDLE EVAPORATOR UNDER LOW PRESSURE CONDITIONS

A new type compact flooded-type evaporators consisted of in-line bundle with smooth tubes for various sub-atmospheric pressures were proposed. The effects of tube spacing, tube position and operating pressure on the boiling heat transfer enhancement were systematically investigated. The experimental results show that the compact in-line tube bundles have a significant enhanced heat transfer than those of the common tube bundles, and there is an optimum tube spacing that provides a most enhanced heat transfer effect. This optimum tube spacing is quite close to the bubble departure diameter. The operating pressures have a remarkable influence on the boiling heat transfer enhancement in the compact bundles. The heat transfer enhancement effect decreases with the decrease of the operating pressure. The experimental data are practical for designing a highly effective low-pressure flooded-type evaporator.