Experimental and analytical study on productivity augmentation of a novel solar humidification–dehumidification (HDH) system

The aim of this study is to investigate analytically and experimentally the effect of using an induced atmospheric air, water heaters, external reflector and weather condition on the performance augmentation of humidification– dehumidification (HDH) system. This novel HDH system is a modified solar still with air blower and condenser used at humidification chamber inlet and outlet respectively and glass cover is positioned horizontally. Experiments were carried out in April 2014 under the climatological conditions of Madinah (latitude: 24° 33′ N, longitude: 39° 36′ 0″ E), Saudi Arabia. Performance of the HDH system is examined with and without water heaters and reflector. The experimental results showed that the daily productivity of the considered HDH system has improved when using both water heaters and reflector. A remarkable increase in productivity by about 210, 312 and 366% on three test days, namely, April 01, April 15 and April 30 respectively is obtained for still configured with two water heaters at 500 W each and a reflector tilted at 20° compared to that without heaters and reflector. The estimated cost of fresh water produced through the considered HDH system is 0.035 USD/L and the peak efficiency is 0.77. © 2015 Elsevier B.V. All rights reserved.

The present study explained and emphasized the great importance and benefits of using flat external reflector, immersion water heaters and induced atmospheric air that boosts the evaporation rate and consequently augments the performance and fresh water productivity of the HDH system. The following can be concluded from this study: • The daily productivity of fresh water corresponding to three tests, April 01, April 15 and April 30, are 20.2, 26.8 and 30.3 L/m2 respectively in the presence of immersed water heaters and external reflector. • Increases in productivity by about 210%, 312% and 366% were observed on April 01, April 15 and April 30 using the external reflector and immersion water heaters compared to that without external reflector and water heaters. • Analytical model developed for evaporated mass inside the humidification chamber shows a good agreement with the experimental accumulated (daily) evaporated mass with the percentage difference of 12.5%, 16.2% and 0.12% on April 01, April 15 and April 30 respectively. • HDH system efficiency increases remarkably with an increase in solar radiation and shows a peak efficiency of 0.77. • The estimated cost of fresh water produced through the considered experimental setup is 0.035 USD/L. With the usage of PV cells in the future to power the pump, air blower and water heaters, the system running cost will become zero and thus the fresh water productivity costs can be reduced, while at the same time the abovementioned productivities can be obtained.