Impact of Operating Conditions on the Performance of a Flat Membrane Humidifier with Two-Way Serpentine Channels in Building Applications

In common flat membrane humidifiers, the flow channels have a simple parallel arrangement on two dry and wet sides. The implementation of serpentine flow improves the residence time of gases within the channels, creates vortices in the bends of the channels and reduces the contact surface of the channel shoulders with the membrane. The aim of this study is 3D numerically model a membrane humidifier with two-way serpentine channels for building applications. In these simulations, the functioning of the membrane humidifier is examined in Isfahan, Iran, in summer and winter. A humidifier with serpentine channels is fabricated and tested, and the numerical findings are confirmed with empirical data. The results indicate that during summer, the relative humidity of the dry-side outlet air decreases as the dry-side flow rate increases. Furthermore, for a fixed dry-side flow rate, the outlet relative humidity rises with an increase in the wet-side relative humidity. During winter, the relative humidity of the dry-side outlet air increases with the dry-side flow rate. Additionally, at a constant dry-side flow rate, the outlet relative humidity rises as the wet-side temperature increases. In a situation where the humidity is considered 60%, a humidifier can be used for the flow rates of 1 to 1.6 m3/h on the dry side. In a situation where the humidity on the wet side changes from 70 to 80%, the humidifier can convert the outside air is converted into usable air in the building for flow rates of 3.4-1.6 and 4 m3/h in dry channels, respectively. The flow rate of the dry section should be about 3.6-4 m3/h for an efficient humidifier when the air temperature of the wet side is 35 ºC.