Laminar flow and heat transfer in plate membrane channels: Effects of the deformation heights

•Plate membrane channels are used for air humidification/dehumidification.•Effects of the deformation heights (Δh) on the laminar flow and heat transfer are studied.•Mean friction factor and Nusselt number in the channels are obtained.•The results are useful for performance evaluations of the channels.

Membrane channels have been extensively used for air humidity control and energy recovery. The membranes are commonly parallel-plate type. However they probably are deformed because of their weak mechanical strengths and fluid pressure. Effects of the deformation heights (Δh) on the laminar flow and heat transfer in the plate membrane channels are studied based on two unit cells. Each one of them includes two neighboring membranes and a channel sandwiched by the membranes. The equations governing the momentum and heat transports are established together with a uniform wall temperature boundary condition and numerically solved by a finite volume approach. The mean (fRe) and Nusselt number (Num) are obtained. The influences of the deformation heights (Δh), aspect ratios (b/a), and Reynolds numbers (Re) on the (fRe)m and Num are calculated. It can be found that when the b/a is less than or equal to 25, the Num rises with the Δh increasing for the air channel. However the Num firstly rises, and then decreases with the Δh increasing when the b/a ranging from 30 to 40. For the water/LiCl solution channels, the Num for the LiCl solution is about 40%–56% larger than that for the water stream.