Study of solar irradiation distribution in narrow channel of desiccant rotor

Abstract

The objective of this paper is to present experimental results on distribution characteristics of solar irradiation absorbed by the narrow channel wall of desiccant rotor. Experiments are performed with the channel made by the silica gel and the poly propylene (PP). Energy absorption rate is measured in conditions of different channel lengths, incident irradiation angles, air temperatures, and humidity. The result of the present measurement for silica gel is equal to that of the previous study [J. Li, Y. Hamamoto, and H. Mori, Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers 32(2), 149–154 (2015)], which is conducted using laser light as a source. It is confirmed the previous prediction model of laser light is suitable for this solar light system. Moreover, the previous model is improved, because the rate of laser for PP is larger than that of solar. These models are applicable to predict desorption rate of the water vapor in a desiccant rotor heated directly by the concentrated solar irradiation. The results show that the absorption rates of solar irradiation and red laser are equal to each other in the silica gel channel. The absorption rates of the laser irradiation are larger than that of the solar irradiation for PP materials. It is clear that the solar irradiation absorption rate cannot be influenced by the ambient humidity and temperature. The prediction model of the absorption efficiency based on the laser for silica gel channel can reproduce well the absorption efficiency of experiment based on solar irradiation. In the case of PP, the difference between the prediction and the measurement is observed.