Thermal and economical performances analyses of a desiccant wheels-assisted atmospheric water harvesting system used in humid climate regions

Abstract

The thermal and economic performance of an atmospheric water harvesting system that uses four-stage desiccant wheels to pre-humidify processed air was analyzed. A vapor-compression refrigerator was used as the cold source. Two types of heat sources, i.e., heat pump and solar water heater, were considered, and their performance was evaluated. First, thermal performance of the system using different heat sources was analyzed under humid ambient conditions (relative humidity was 40–90 %, dry bulb temperature was 15–35 °C). The results showed that the water harvesting rate was 25.1–94.1 kg/h under these ambient conditions. When a heat pump was used, the water harvesting efficiency with heat recovery was 0.97–2.48 kg/kWh, and 2.41–4.59 kg/kWh when the solar water heater was used. The economic performance of the system was investigated by using diesel generators as the power source. To provide drinking water for 100 people, who consume 3–8 kg/day/person, as compared with bottled water sold in the market, the recovery period of the systems with heat recovery were 0.97–2.58 years and 0.34–0.91 years when the heat pump and solar water heater were used, respectively.