Heat transfer, and Energy, Exergy, Economic, Exergoeconomic, Exergoenvironment, Enviroeconomic (6E) analysis of a modified pyramidal solar still with pulsating heat pipe, PCM and fins: An experimental investigation

Abstract

The rising global demand for freshwater, driven by population growth and water scarcity, necessitates efficient desalination solutions. This study presents a comprehensive heat transfer analysis and a 6E assessment (Energy, Exergy, Economic, Exergoeconomic, Exergoenvironmental, and Enviroeconomic) of novel solar still (SS) design integrating a Pulsating Heat Pipe (PHP), Phase Change Material (PCM), and fins. Three configurations of pyramidal solar stills (PSS) were assessed through experimental investigations: Case 1 is a Conventional Pyramidal Solar Still (CPSS), Case 2 integrates Phase Change Material (PCM) and fins (MPSS1), and Case 3 incorporates Pulsating Heat Pipe (PHP), PCM, and fins (MPSS2). The yield in Case 3 was 5.42 L/m²/day, which was 35.40 % and 94.96 % higher than the yields of Case 2 and Case 1, respectively. Case 3 also demonstrated an average energy efficiency of 44.10 %, surpassing Case 2 and Case 1 by 23.58 % and 31.51 %, respectively. Additionally, the exergy efficiency of Case 3 was 28.72 % higher than Case 2 and 19.30 % greater than Case 1. The average total heat transfer coefficient for Cases 1, 2, and 3 were 24.54 W/m²-K, 25.23 W/m²-K, and 30.29 W/m²-K, respectively. Economic analysis indicated Cost per Liter (CPL) values of $0.014 for Case 3, which exhibited cost reductions of 14.28 % and 41.33 % compared to Case 2 and Case 1, respectively. Energy production factors for Cases 1, 2, and 3 were 0.89, 0.69, and 0.73 yr⁻¹, respectively. Case 3 achieved the highest savings ($217.5), surpassing Case 2 by 35.07 % and Case 1 by 83.54 %. Its advanced design with PHP, PCM, and fins resulted in the highest energy-economic parameter (22.178 kWh/$). The treated water met potable standards with a pH of 6.98, salinity removal, and reduced TDS (72 mg/L). This study emphasizes that incorporating fins, PCM, and PHP into CPSS enhances water yield, energy efficiency, and economic feasibility while promoting sustainability.