1991 Volume 17 Issue 6 Pages 1168-1174
Heat and mass balance of direct-contact membrane distillation using PTFE porous membrane were studied using 1.0 wt % NaCl solution as feed liquid. Parameters such as temperatures and flow rates of feed and cooling water were varied and heat and mass transfer characteristics were studied by measuring the permeate rate and the heat transfer rate. It was found that in the membrane distillation system the permeate rate was proportional to the vapor pressure difference between feed and cooling water, but was influenced by membrane thickness, porosity and other variables. The heat loss by sensible heat transfer was reduced by operating at a high temperature level and a low temperature difference between feed and cooling water. The permeate rate and heat transfer rate were simulated by using a theoretical equation and experimental results of heat conductivity and membrane tortuosity.
