Analysis of Heat Transfer Coefficients in Direct Contact Membrane Distillation Modules Using CFD Simulation

Abstract

Membrane distillation (MD) isan emerging separation technology for desalination, solution concentration and waste water treatment. As a thermal driven device, heat transfer coefficients are critical to theMDperformance. In this study, the transmembrane heat and mass transfers are rigorously accounted for in the computational fluid dynamics (CFD) simulation. Flat plate direct contact membrane distillation (DCMD) modules with smooth-surface and rough-surface channels as well as in co-flow and counter-flow configurations are analyzed for the desalination application. For different rough-surface channels, flow configurations and operation conditions, the simulated permeation fluxes are fairly close to the experimental results. The local distributions of heat transfer coefficients show very high values at fluid inlets. For the simulated flat plate modules, the local heat transfer coefficients fall between conventional correlations of heat exchangers with circular channels and parallel plates and the module average heat transfer coefficients are much higher than the conventional correlations. This study reveals the values and distribution characteristics of the heat transfer coefficients in DCMD modules, which is important for the design of DCMD modules.