Thermal Performance Analysis of an Integrated Solar Still and Solar Thermal Collector System

Abstract

Solar still desalination is a simple and low-energy technology for producing freshwater from saline water, however, its practical application is still limited by low evaporation rate and distillate productivity. This study analytically evaluates the thermal performance of a double-slope solar still integrated with a flat-plate solar thermal collector. The objective is focused on assessing the effect of collector integration on useful heat gain, thermal efficiency, and water productivity. The system was modelled using a thermal resistance network under quasi-steady hourly conditions from 06:00 to 18:00 WIB. The analytical model accounts for conduction, convection, and radiation heat transfer, along with the evaporation and condensation processes. The results show that adding the solar thermal collector significantly improves the thermal performance of the solar still. The daily average thermal efficiency increased from 30% to 55% during the dry season and from 25% to 45% during the rainy season. Daily productivity also increased from 0.86 to 1.10 L/m²/day in the dry season and from 0.51 to 0.96 L/m²/day in the rainy season. Therefore, integrating a solar thermal collector enhances solar still performance by increasing thermal energy supply to the evaporation chamber.