Design of apparatus for optimum water collection from humidity based on Abu Dhabi's climate

Abstract

The UAE has an arid climate with rapid economic development and a fast-growing population, which will lead to future water demand that outstrips the limited fresh water supplies. One of the methods of supplying water to satisfy the future demands in the UAE could be water harvesting from humidity. This report addresses the design of an apparatus based on the temperature-responsive polymer Poly-(Nisopropylacrylamide) which changes from hydrophilic-to-hydrophobic in aqueous solution across a lower critical solution temperature (LCST) of 32 °C. Below this temperature the PNIPAM adsorbs water and swells, and above 32 °C it expels the water and shrinks The apparatus is designed to take advantage of this unique behavior of the polymer to collect water from the humid atmosphere at night when the temperature is low, and release the water during the day with the aid of solar power. Nevertheless, the need to enhance apparatus performance beyond materials limit is one of the objective of this study. Hence, two techniques are being employed to achieve better adsorption and desorption. Sky radiation cooling is used to reduce the temperature of the polymer below its critical temperature during the adsorption process at night, and solar heating is used to increase the temperature of the polymer during the day to ease the desorption process. The results obtained showed that the sky radiator set up in the apparatus could achieve temperatures 10 times lower than the ambient. On the other hand, the solar collector outcomes, indicated that the system might experience overheating, above the required temperature of 70 °C specially during the summer. Therefore, further considerations were followed to avoid the overheating including a high tilt angle for the solar absorber, and a lower transparency material for the apparatus body.

Date of Award	2015
Original language	American English
Supervisor	Saeed Al Hassan (Supervisor)