Modelling of heat and mass transfer in DCMD: Study of membrane parameters

Membrane distillation (MD), A thermally-driven membrane separation process has been widely studied in recent years and the membrane properties are known to have significant effect on the performance of the MD process. In the present study, heat and mass transfer in direct contact membrane distillation (DCMD) has been analysed by a hydrophobic PTFE single layer flat sheet membrane. This model has been solved numerically using MATLAB software. The influence of some membrane parameters such as thickness, thermal conductivity, porosity and pore size on DCMD performance has been considered. The results indicated that the membrane parameters play important roles in determining the performance of a DCMD. Mass flux and higher energy efficiency increased over membranes with incresing pore size, porousity and decreasing thermal conductivity. Two competitive effects were observed for mass flux and energy efficiency with membarane thickness. increasing thickness from ۴۵ μm to ۹۰ μm, leading to flux as low as ۶.۹۴ kg/m۲hr and temperature polarization coefficient increased from o.۲۸ to ۰.۴۴. consequently, with inceasing temperature polarization coefficient, energy efficiency also increases. Therefore, it is suggested that an optimal thickness must exist, balancing between mass flux and energy efficiency.

کلیدواژه ها:

Membrane distillation ، Heat transfer ، Mass transfer ، Membrane parameters ،