Performance optimization of the dehumidifier with parallel-plate membrane modules

Abstract

A numerical model of a dehumidifier with parallel-plate membranes is established and validated, and the orthogonal optimization method is adopted to investigate the dehumidifier performance. The impact order of the main operating parameters, including dimensionless factors (mass flow rate ratio m∗ and number of heat transfer units NTU), air conditions (inlet air temperature and relative humidity) and solution conditions (inlet solution temperature and concentration), on the system effectiveness (i.e. sensible and latent effectiveness) is identified. The NTU is the most important parameter affecting the system effectiveness, followed by mass flow rate ratio m∗. Although the sensible and latent effectiveness increase with the NTU and m∗, no significant improvement can be achieved when their values are higher than 2 and 4 respectively. Increasing inlet solution concentration can enhance latent effectiveness without reducing sensible effectiveness. Inlet air temperature and relative humidity have weak influences on the system performance, but increasing the temperature difference between the inlet solution and air can make the outlet air achieve heat transfer balance within a shorter distance inside the dehumidifier.