Improving solar still performance with heat pipe/pulsating heat pipe evacuated tube solar collectors and PCM: An experimental and environmental analysis

Abstract

This study comparatively assesses the efficiency of various single-slope solar stills employing thermosyphon and pulsating heat pipe evacuated solar collectors, integrated with phase change material. The evaporator of the thermosyphon/pulsating heat pipe system is affixed to the evacuated tube, while the condenser is immersed in water to assist the transfer the solar irradiation heat energy. Paraffin wax is utilized as the PCM, positioned at two filling ratios within the thermosyphon/pulsating heat pipe evacuated tube at two filling ratios of 50 % and 100 %, to investigate its impact on water production during periods of low solar irradiation. The thermal energy of the solar radiation stored in the PCM and remove it to the thermosyphon/pulsating heat pipe system. The findings demonstrate that the highest daily freshwater production was 2248 ml/m2, showcasing a notable 40.7 % increase in productivity compared to conventional solar stills (CSSs). Moreover, the system employing pulsating heat pipe and full PCM showcased significant reductions in CO2, SO2, and NO emissions, approximating 19.53 tons, 117.1 tons, and 449.2 tons, respectively. Additionally, solar stills utilizing heat pipes (SSTHP) and solar stills employing pulsating heat pipes (SSPHP) exhibited energy efficiencies of 19.4 % and 20.3 %, respectively. Furthermore, the exergy-economic factors for CSS, SSTHP, and SSPHP were approximately 1.27 kWh/$, 1.56 kWh/$, and 1.62 kWh/$, respectively.