Performance investigation of active double slope solar stills incorporating internal sidewall reflector, hollow circular fins, and nanoparticle-mixed phase change material

Abstract

Productivity and efficiency augmentation of solar stills have been receiving significant importance owing to their cost and energy-effectiveness in addition to cleaner operation in producing potable water. The present work aims on improving the performance of active modified double slope solar distiller units by the integrated impact of internal sidewall reflector, hollow circular fins, and nanoparticle-mixed phase change material (nano-PCM). The experimentation includes a total of five individual stills, one conventional, and four others modified with the mentioned attachments. The results indicate the achievement of a maximum productivity output of 1853 mL/day by the solar still modified with reflector, fins, and nano-PCM. The use of paraffin wax-Al2O3 nanoparticle (nano-PCM) mixture in the system is found to be the most effective modification providing almost twice as much accumulated productivity compared to the pure PCM (only paraffin) case. The distillate accumulation is found to surpass the conventional case by 61.36 % and 92 %, respectively in the pure PCM and nano-PCM cases. Moreover, the maximum energy efficiency of 21.56 % is achieved with the combined influence of circular fin, reflector, and nano-PCM. The economic analyses of the solar still cases have estimated the cost of water remaining within the ranges of 0.0199–0.022 $/L. Also, it is found that the projected payback period of 284 days for the conventional case can be reduced to as less as 258 days through the proposed modifications, with the best outcome attained by the nano-PCM case.