Experimental Study of a Solar Driven Water Harvesting System for Fabric Evaporation Roof

Evaporative cooling roof technologies have the benefits of eliminating the urban heat island effect, reducing building cooling loads, and improving the indoor thermal environment. Evaporation roofs are often applied to hot and humid climates due to abundant rainfall resources. However, the cooling efficiency of evaporation roofs was not preferable owing to higher humidity conditions in ambient air. This paper aims to improve the cooling efficiency of wet fiber evaporation roofs and save tap water consumption by experimentally developing a novel water harvesting system for wet fiber roofs. The developed system can harvest water vapor from the humid atmospheric air by silica gel adsorbent. The absorbed water vapor can be further desorbed by solar radiation and then condensed into liquid water by the thermoelectric cooler. It was found that the experimental system was able to acquire liquid water that weighed 130-390 g/kilogram of adsorbent for 24 h. Given the evaporation rate of wet fiber, the efficiency of the water harvesting system was sufficient to meet the evaporation demand for the wet fibre roofs applied to hot and humid climates.