Experimental simulation of membrane module performance in direct contact membrane distillation

Abstract The performance of direct contact membrane distillation (DCMD) was measured with a continuous series of mini-modules fabricated by PTFE hollow fibers to simulate a standard length module in the counter-current flow and co-current flow. The behaviors of temperature and pressure difference along the simulated module length were derived from the temperature change of each mini module. The permeated water of each mini module could be considered the permeated water in individual regions of a simulated module. The pressure differences over contact time could be drawn in one curve even if the raw water velocities were different. Instantaneous flux at a certain point of the module could be derived from the product of a mass transfer coefficient and a pressure difference curve. The total flux of a simulated module could be evaluated through the integration of the instantaneous flux from inlet to outlet of the module. The membrane area and number of modules required for processing could be calculated from the flux if a module dimension and an operation condition were determined. These approaches enabled to design the appropriate module for practical use.