Experimentally validated model for atmospheric water generation using a solar assisted desiccant dehumidification system

Abstract

This paper examines an alternative solution for emergency situations where freshwater and utilities are often interrupted. Generating freshwater from the atmosphere using a small-scale air-cooled desiccant wheel dehumidifier was experimented. Condensed water was collected and systematically recorded against local meteorological data. A synthetic model simulating the actual lay-out of the experiment was built in TRNSYS. The model validated the experimental results and generated approximately 52 litres in 9 days. The validated model is then run for three different climates; Sydney, Abu Dhabi and London to estimate annual water production. Abu Dhabi showed the best results compared with Sydney and London by generating 18.5 kL of water per year. The model is further developed to evaluate thermodynamic benefits of using dehumidified processed air as a feed stream for a proposed small-scale air-conditioning system. The energy required for the wheel regeneration process is met by thermal gain of modified solar PVT panels where the stagnant heat at the back is used to heat up the regeneration air stream. It was found that the dehumidification process can significantly decrease the latent load of the air-conditioner and easily bring indoor humidity level to the human comfort zone. However, dehumidified process air is also increasing the sensible load because of the higher temperature associated with dehumidification process. Rooftop solar PV panels can easily meet the power demand of appropriate lighting, a computer and mini refrigerator for extended hours if an appropriate set of batteries are fitted, but unable to exclusively meet the air-conditioner power demand to maintain indoor temperature within human comfort zone.