Performance assessment of a flat-sheet membrane-based dehumidifier with serpentine flow channels: An experimental study

Abstract

Membrane-based dehumidification system is an emerging technology which drives based on the renewable low-grade energy sources. Water vapor selective membrane is able to separate water vapor from the air which can be used to condition air in buildings, more efficiently than conventional air-conditioning equipment. Flow channel designs (especially serpentine-type) and their impacts on the thermal–hydraulic performance of membrane-based dehumidifiers are essential and not well-studied. In the present work, a novel flat-sheet membrane dehumidifier with serpentine flow channels is designed and evaluated experimentally. The serpentine flow channel offers a long flow path that the air in the wet and dry sides of the channel interacts with each other through the membrane, thereby improving the heat and water vapor transfer. The effect of inlet air flow rate, relative humidity, and temperature of both wet and dry sides on the dehumidification rate, approach temperature, pressure drop, and coefficient of performance of the dehumidifier is examined. Results show that passing the humid air with higher flow rate, humidity, and temperature through the wet side channel leads to the higher dehumidification rate, approach temperature, and pressure drop. Increase of wet side air temperature and flow rate enhances the coefficient of performance, and the effect of inlet air relative humidity on the coefficient of performance is observed negligible at high air flow rates. Parametric study of dry side air condition reveals that the air with lower humidity improves the dehumidification rate and coefficient of performance, while its effect on the approach temperature and pressure drop is observed negligible. Elevated air temperature of dry side has positive and negative impact on the approach temperature and coefficient of performance of the dehumidifier, respectively.