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针对传统的满液型蒸发换热器,将蒸发器中的水平加热管束按叉排方式紧凑排列形成窄缝空间,在大气压和低压运行条件下,利用窄缝空间沸腾强化换热机理,可以将在低壁温/低热负荷条件下的自然对流换热转化为核态沸腾换热,能有效提高满液式蒸发器的换热性能。和传统的满液型蒸发换热器相比,这种紧凑式蒸发器平均换热系数能提高一倍以上。紧凑蒸发器的管距、管位置,工作压力都对蒸发器的换热性能有显著影响,管距的影响是最大的。不同的压力条件下存在一个对应的最佳管距。在此管距下,蒸发换热器的强化换热性能达到最大。最佳管距对应的管束水力当量直径近似等于池内沸腾时的气泡脱离直径。随着压力减小,最佳管距逐渐增大。同时,紧凑式管束布置引起的窄缝空间内沸腾强化换热强化效果也逐步降低。
In view of the traditional flooded evaporative heat exchanger, the horizontally heated tube bundles in the evaporator are arranged in a narrow arrangement in a narrow-row space. Under atmospheric pressure and low-pressure operating conditions, the use of narrow space boiling enhances the heat exchange mechanism, Under the condition of low wall temperature and low heat load, the natural convective heat transfer transforms into nucleate boiling heat exchange, which can effectively improve the heat transfer performance of the flooded evaporator. Compared with the traditional flooded evaporative heat exchangers, the average heat transfer coefficient of this compact evaporator can be more than doubled. The tube pitch, tube position and working pressure of the compact evaporator all have a significant impact on the heat transfer performance of the evaporator, and the influence of the tube pitch is the greatest. Under different pressure conditions there is a corresponding optimal tube spacing. Under this tube pitch, the enhanced heat transfer performance of the evaporative heat exchanger is maximized. The optimal tube diameter corresponds to the diameter of the tube bundle equivalent to the diameter of the bubble when boiling in the pool. As the pressure decreases, the optimal tube spacing increases. At the same time, the effect of enhancing heat transfer by boiling in a narrow space caused by the compact tube bundle arrangement is also gradually reduced.