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本文研究了空气隙膜蒸馏的传热过程,给出了其主要的传热计算公式。实验结果表明热腔内进液流量的增加,使传热强化,膜通量增加,但提高膜通量最有效的方式还是提高进液的温度。针对膜蒸馏热腔内切向旋转入流的特点,本文认为采用近似对流外掠平板的经验公式更加合适,并根据实验结果拟合出热腔对流换热的经验公式,计算结果与实验结果吻合较好。空气隙厚度大于3mm后,由于空气隙内自然对流换热的影响,空气隙传递的热量反而增加,并且进液温度越高,自然对流换热对总热流密度的影响越大。根据实验结果给出了水蒸气在冷壁表面凝结换热的表面传热系数计算公式。
In this paper, the heat transfer process of air gap membrane distillation is studied, and the main heat transfer calculation formula is given. The experimental results show that the increase of liquid flow in the hot chamber increases the heat transfer and increases the flux of the membrane. However, the most effective way to increase the membrane flux is to increase the temperature of the feed liquid. In view of the characteristics of tangential inflow in the hot chamber of membrane distillation, this paper considers that the empirical formula of convective swept plate is more suitable, and the empirical formula of convection heat transfer in hot chamber is fitted according to the experimental results. The calculated results are in good agreement with the experimental results it is good. Air gap thickness greater than 3mm, due to the natural air convection heat transfer, the air gap transfer heat increases, and the higher the inlet temperature, the natural convection heat transfer greater impact on the total heat flux. According to the experimental results, the formula of surface heat transfer coefficient of water vapor condensation on the surface of cold wall is given.