Experimental and computational modeling analysis of double slope solar still with a trapezoidal channel for preheating

Abstract

In specific locations in India, water scarcity is an important issue, therefore several efforts are made to produce treated water so that rural and urban areas have access to safe and sustainable drinking water. The solar still method is the most affordable water purification option available in these hot areas. This research aims to enhance the performance of passive double-slope solar stills by analyzing the effects of preheated water on evaporation and yield rates. A new method was adopted to maintain the lowest water depth in the basin of a solar still by using a channel attachment to move the feed water. Additionally, the study investigates the impact of a trapezoidal channel attachment within the solar still, a first-time innovation, on its efficiency and yield rate. Computational fluid dynamics and experimental data collected on February 10, 2024, in Kattankulathur was analyzed to assess temperature variations and yield rates. A three-dimensional full-scale simulation was carried out using Ansys Fluent with a two-phase (evaporation and condensation) model, where the flow in the channels of the rate varied from 0.87 × 10-4 to 5.21 × 10-4 Ls−1 and the highest yield is achieved at flow rate of 1.74 × 10-4 Ls−1. The accuracy of the simulation technique was evaluated by comparing it to experimental data, and found a good match. The results demonstrated that solar still with trapezoidal channels significantly increased the overall yield rate. Optimal performance was achieved under specific environmental conditions, with a cumulative yield of 2.45 Lm−2 at a basin water depth of 10 mm, marking a 37.64 % increase over the conventional solar still. Economic analysis indicated a reduction in the payback period to 299 days, affirming the system’s cost-effectiveness. The trapezoidal channel design is limited to a cross-section of 10 mm2, and positioned at a 17° angle on the middle sidewall to minimize the shadow formation on the basin of still and maintain high yield and evaporation–condensation rates. The novelty of this work is to integrate trapezoidal channels on the double slope solar still and to optimize its design and flow rate to maximize the overall production.