Numerical study on heat and mass transfer performance of the planar membrane-based humidifier for PEMFC

Abstract

In this work, a numerical study is developed to examine the performance in a planar membrane-based humidifier (PMH) to optimize the operation with respect to a detailed parametric analysis. Firstly, a 3-dimensional simulation is built up to explore the heat and mass transfer in PMHs. Then, humidification performances including dew point approach temperature (DPAT), water recovery ratio (WRR), pressure drop (ΔP), and coefficient of performance (COP) are studied with focus on the effects of the duct cross-section aspect ratio (AR), defined as width/height, and the length of ducts. Among AR = 0.5, 1 and 2 with the duct length of 200, 300 and 400 mm, the maximum WRR and the best COP occur at the duct with AR = 2 for all cases of different duct lengths. Finally, influences of governing parameters named mass flow rate, inlet temperature of dry duct, and inlet relative humidity (RH) of wet duct on PMH performances are further investigated. An increase in mass flow rates both enhances DPAT and ΔP, but degrades WRR and COP of the PMH. Enhancing the inlet temperature of dry air reduces the WRR and DPAT, but increases the ΔP leading to a descending trend of the COP. Increasing the inlet RH of wet duct has a small effect on ΔP and an enhancement in the WRR and COP.