直接接触式与气隙式膜蒸馏的比较研究

Comparative study on direct contact and air gap membrane distillation

采用模拟计算和实验的方法对直接接触式膜蒸馏 (DCMD)和气隙式膜蒸馏 (AGMD)过程进行了比较研究。模拟计算及实验结果表明 ,AGMD中的气隙构成了过程的主要阻力 ,使得跨膜温差远小于膜两侧流体主体温差 ,这是两种膜蒸馏方式行为差别的主要原因所在。与AGMD相比 ,DCMD不仅膜通量水平高 ,而且膜通量对操作条件反应灵敏 ,易于实施过程的强化。而DCMD的热效率与AGMD相比差距并不太大。

The difference between direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD) is compared,both by the prediction of the mathematical models of these two processes and by membrane distillation experiments.Results indicate that the limit step in AGMD process is the transport in air gap,and this makes the temperature difference between two sides of the membrane much lower than that of two fluids on the two side of the membrane.Compared with AGMD,DCMD process exhibits higher level of water flux,and its water flux is much more sensitive to operating conditions,and this makes it easier to optimize the process.And DCMD can acquire an acceptable thermal efficiency,although its value is some lower than that of AGMD.