Development of paraffin wax & used cooking oil based composite thermal energy storage for efficient potable water generation in a solar distillation unit

Abstract

The purpose of this study is to develop a novel composite thermal energy storage system (CTESS) using blends of used cooking oil (UCO) and paraffin wax (PW) and experimentally investigate its effect on the performance of solar still for effective seawater desalination. The CTESS was developed by mixing UCO with PW in various volume ratios and the volume ratio of UCO and PW was optimized at 1:1. The objective was to examine the performance of the solar still with used cooking oil and paraffin wax (SSUCO) and compare it with a conventional solar still (CSS) without any energy storage. The investigation was carried out experimentally, and the results show that the SSUCO significantly enhanced freshwater production compared to CSS. On the first day, the overall freshwater production from SSUCO and CSS was found to be approximately 2870 ml/m2 and 1830 ml/m2, respectively, whereas, on the second day, it was about 2680 ml/m2 and 1750 ml/m2. The productivity of SSUCO increased by 56.83 % and 53.14 % on day 1 and day 2, respectively. The thermal efficiency of SSUCO on day 1 and day 2 was found to be 45.52 % and 41.67 %, respectively, whereas, for CSS, it was 29.03 % and 27.21 %. Economic analysis showed that the cost per litre of yield and payback period for SSUCO was reduced by 40.54 % compared to CSS. Moreover, the environmental analysis revealed that the carbon credit gained by SSUCO was 64.2 % higher than that of CSS. The results indicate that CTESS is a highly promising technique for seawater desalination in solar stills. It provides notable advantages such as increased productivity, enhanced thermal efficiency, and significant economic and environmental benefits.