Performance enhancement of solar-assisted liquid desiccant dehumidifiers using super-hydrophilic surface

Abstract

Solar-assisted liquid desiccant dehumidification technology is attracting much attention due to lower energy consumption and less pollution. This study aims at adopting surface-modification technology to improve the dehumidification efficiency and analysing the energy saving of solar-assisted liquid desiccant air-conditioning system. Firstly a novel super-hydrophilic coating was successfully fabricated using nanoscale anatase TiO2 particles with high dispersion. The characterization of the coating was conducted using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) test. After surface treatment, the surface free energy was significantly increased from 15.71 to 90.15 mJ/m2 and the contact angle was rapidly reduced from 90° to 10° Then, an experimental system with two single-channel plate-type liquid desiccant dehumidifiers was designed. The experimental results indicated that the falling film shrinkage of desiccant solution was effectively prevented and the contact area was rapidly increased by the novel coating. The maximum wetting ratio was increased from 75% to almost 100%. The influence of operating parameters on heat and mass transfer performance was comprehensively analysed. To better evaluate the benefits of the surface-modification technology, a dynamic model of solar-assisted liquid desiccant air-conditioning system was developed. The simulation results indicated that 9% (94MW · h) of electricity could be saved. This finding is very useful in other falling film applications, such as heat exchangers and cooling towers to improve the efficiency and reduce the energy consumption.