Study of the numerical model and humidification strategy of wet-membrane humidifier

Abstract

Despite the fact that wet-membrane humidifiers are commonly used, their designs and forecasts of humid air are generally based on very simple experimental data, which has resulted in certain design errors. Though some numerical models have been developed in the literature, these models make some idealized assumptions about the fluid flow inside the wet-membrane medium in order to solve the momentum conservation equation. Besides, these models had not been validated using accurate experimental data. Thus, based on a thorough examination of the physical procedure of wet-membrane humidification, a new numerical model for the wet-membrane humidification process is developed that can precisely predict the outlet air temperature and Relative Humidity (RH) under a variety of conditions. To verify the model's correctness, the authors built a wet-membrane humidification test-bed and carried out orthogonal experiments with various inlet factors. The numerical model was validated using the experimental data, and it was then utilized to compare various humidifier design strategies. It is found that the ability of the wet-membrane humidifier to humidify the air under the same heat gain increases when the inlet water is heated rather than the inlet air. While using this method, the inlet water parameters and wet-membrane size must be properly set in order to prevent humid air supersaturation.