Experimental study on dehumidification performance enhancement by TiO2 superhydrophilic coating for liquid desiccant plate dehumidifiers

Abstract

Liquid desiccant air dehumidification is a promising dehumidification technology with lower energy consumption, less pollution and more flexible humidity control. However, the incomplete wetting conditions of liquid desiccant deteriorates the dehumidification performance and limits the development. Therefore, how to enhance the surface wettability is critical to improving the dehumidification performance as well as reducing the building energy consumption. In this paper, a novel TiO2 superhydrophilic coating was applied in a plate dehumidifier to enhance the surface wettability and improve the dehumidification performance. Firstly, the characterization of the coating was conducted. The test results showed the surface wettability was effectively improved with the contact angle dramatically decreasing from 84.6° to 8.8°. Then two single-channel internally-cooled liquid desiccant dehumidifiers were fabricated to investigate the effect of TiO2 coating on dehumidification performance. The experimental results indicated that the dehumidification performance was significantly enhanced with the mean enhancing ratios of 1.60 and 1.63 for moisture removal rate and dehumidification efficiency, respectively. Besides, the influencing factors on dehumidification performance were analysed comprehensively. Based on the analysis, the new empirical correlations of mass transfer coefficients were developed with different contact angles. Lastly, the energy consumption of liquid desiccant air-conditioning system with coated dehumidifiers for a commercial building in Hong Kong was simulated and around 80MW⋅h of the electricity consumption could be saved. This study is helpful to researchers and engineers who are interested in enhancing the dehumidification performance and reducing the building energy consumption.