Modelling Direct Contact Membrane Distillation Heat and Mass Transfer in Hollow Fibre Modules

Membrane distillation (MD) is one of the membrane-based separation processes. Among the four types of MD configurations, direct contact membrane distillation (DCMD) is the first configuration that was developed and is the simplest as it does not require an external condenser or complex module design. As the membrane is the only barrier between both solutions, DCMD can produce higher fluxes than other configurations and is therefore best suited for concentration of aqueous solutions. but DCMD is a complex process due to the simultaneous heat and mass transfers that occur. It is therefore essential to optimize the process in order to minimize the required energy, while maintaining an adequate flux throughout the operation. Such a goal can only be achieved by modelling, and computer-aided simulation. This paper presents a new procedure for modelling the simultaneous heat and mass transfer in direct contact membrane distillation (DCMD) in a hollow fibre configuration. Five types of hollow fibers were used in this paper. The DCMD mathematical model was formulated in MATLAB code. A sequential technique was successfully employed to determine membrane quality parameters, K۱ and the membrane’s pore tortuosity, τ. Heat and mass transfer analysis showed that among the studied membranes, Halar fibres possessed the combinational qualities such as low thermal conductivity and high vapour permeability, which are much needed for an efficient DCMD application. In contrast, PVDF fibres were considered to be inefficient in low temperature DCMD, and therefore not desirable

Keywords:

Direct Contact Membrane Distillation (DCMD) , Hollow Fibre , Modeling , Heat and Mass Transfer.