进水温度对新型复合气提降膜蒸发器性能的影响

Effect of water inlet temperature on performance of evaporator combined with Vapor-lift effect

就提出的基于气提效应的新型复合降膜蒸发器展开了深入研究,讨论了进水温度发生变化时,该复合降膜蒸发器的水力特性和传热传质性能的变化情况。研究表明:随着进水温度的增加,输送单元的输送液体流量和输送高度比(泵送高度与驱动吸程之比)均得到提高;而蒸发换热单元的降落液膜厚度则随进水温度的增加而减薄,从而使得传热性能增强;且随着进水温度的增加,其对传热性能的提高逐渐减弱。在相同的输送流量下,进水温度从30℃增加到90℃时,其传热系数提高66.8%～69.3%。

This paper is concerned with the theoretical analysis to obtain the effect of water inlet temperature on the performance of the proposed falling film evaporator combined with vapor-lift effect. Results indicate that the transported liquid flow rate and transportation height ratio(ratio of the pumping height to the driving suction depth)increase with higher water inlet temperature.However,higher water inlet temperature results in the decreasing of falling film thickness which leads to higher heat transfer coefficient.Moreover,the enhancement on the heat transfer performance decreases with increasing water inlet temperature.Theoretical analysis shows when transporting the same water flow rate,the water inlet temperature increases from 30℃to 90℃,and the heat transfer coefficient increases by 66.8 9%5 to 69.3%.