Experimental study and prediction model of a liquid desiccant unit for humidification during the heating season

Abstract

Liquid-desiccant-assisted air conditioning systems have attracted considerable interest owing to their potential to save energy and enhance performance through decoupled control of latent and sensible loads. In addition, several studies have suggested using the regenerator of a liquid desiccant system for humidification during the heating season; however, its performance under the winter weather condition has not yet been established. Therefore, the goal of this study is to develop the prediction models of the humidification performance of liquid desiccant systems during the heating season. Experiments were conducted to collect performance data based on the factorial experimental design method. Using the response surface method, two empirical models for the effectiveness of regeneration (R2 = 0.927) and enthalpy exchange (R2 = 0.934) were developed and experimentally validated under the actual conditions during the heating season within 10% error bounds. Significant parameters included the liquid-to-gas ratio and desiccant solution concentration and temperature. Moreover, the prediction model of the Sherwood number was developed which can be used for the numerical simulation. Additionally, the suitable operation settings of the regenerator for humidification were investigated to obtain higher energy and exergy efficiencies based on the developed prediction models. From the results, a higher liquid-to-gas ratio and lower concentration and temperature of the desiccant solution could be recommended considering both energy and energy efficiencies and the practical application of liquid desiccant systems.