Heat and mass transfer in an adjacent internally-cooled membrane-based liquid desiccant dehumidifier (AIMLDD)

Abstract

An adjacent internally-cooled membrane-based liquid desiccant dehumidifier (AIMLDD) is proposed and used for air dehumidification. The AIMLDD is a parallel-plate membrane contactor, which contains cooling channels. The air and the solution streams are separated by selectively permeable membranes, while the solution and the water streams are separated by plastic plate. The air stream flows in a cross-flow arrangement with the solution stream, while the solution stream flows in a co-current flow arrangement with the water stream. Establish a mathematical model in a unit cell, which contains half of an air channel, a piece of membrane, a solution channel, a piece of plastic plate, and half of a cooling channel, to research the conjugate heat and mass transports in the AIMLDD. Use a finite difference method to solve the normalized equations governing momentum, heat and mass transports. The dehumidification amount, the efficiency and outlet parameters are then obtained. A continuous air dehumidification system based on the AIMLDD is set up to validate the numerical results. Compare the efficiency under different condition and different structure of the membrane contactor. It can be found that the dehumidification amount and the efficiency for the AIMLDD are higher than those for an adiabatic one.