Effect of a Heat Exchanger on the Performance of an Inverted Trickle Solar Still

An available inverted trickle solar still was rebuilt, and its performance was tested at different conditions of solar radiation, feedwater flow rate, and natural convection existence. The still was designed to desalinate water of high salinity by flowing it on the back side of an absorber plate with the help of a layer of jute attached to that side of the plate. The still produces three types of water: saline, intermediate, and condensate. Enhancements were made on the current still to improve its performance. The main improvement made was increasing the size of the heat exchanger to its possible maximum to study its effect on the still’s performance. Also, other improvements were made to the still, such as increasing the contact between the absorber plate and the jute under it and increasing the sealing tightness to prevent internal and external leakage of water. The study was carried out for 5 days from 9:00 a.m. to 5:00 p.m. Data were measured for solar radiation, temperatures on several parts of the still, and flow rates of inlet and outlet water. Tap water was tested for 4 days on different flow rates and natural convection conditions, and brackish water was tested in the fifth day. It was found that the still’s productivity increased by 15%, reaching $2.55\mathrm{L}/\text{day}{\mathrm{m}}^2$ of fresh water, with an average salinity of 60 ppm. The main advantage of the still is that it provides another product from the so-called intermediate header, which is approximately twice the productivity of the condensate header. It is a product of reduced salinity such that if brackish water has a 12,000-ppm salinity, for example, the intermediate product would be approximately 9,000 ppm at a productivity of approximately $5.53\mathrm{L}/\text{day}{\mathrm{m}}^2$. In addition, the still’s daily efficiency increased by 8.6% relative to that of previous work to reach 23.7%.