The availability of freshwater and the productivity of conventional solar stills are the major factors that restrict the use of solar stills on a large scale. Research on improving the efficiency and effectiveness of solar stills with low-cost enhancement methods is a challenging task. In this paper, the experimental study of single-slope solar stills (SSS) and double-slope solar stills (DSS) is carried out under five different arrangements: (i) conventional solar stills, (ii) solar stills with a bamboo cloth wick, (iii) solar stills with a wick and mild steel energy storage, (iv) solar stills with a wick and cast iron energy storage, and (v) solar stills with a copper metal absorber and a wick. The aim is to find an appropriate solution to increase the productivity, efficiency, and exergy efficiency. The experimental study reveals that the DSS performs better than the SSS for all five arrangements. Among these configurations, Case 5 has the highest level of performance improvement. The DSS in Case 5 has the highest maximum average thermal efficiency of 41.7%, which is 19.1%, 13.2%, 9.8%, 10.7%, and 11.7% higher than the SSS cases. The cumulative freshwater productivity also improves from 3392 mL for the SSS to 3801 mL for the DSS in Case 5. Furthermore, the maximum average exergy efficiency for the DSS is 3.18%, which is higher than 2.7% for the SSS. This study clearly shows that the combination of copper energy storage and wick material provides an effective solution to improve the performance of the solar still.
Rajkumar et al. (Fri,) studied this question.