Synergizing theory and experiment: Enhancing solar distillation performance with external reflector in a passive 4-stage model

Abstract

Passive multi-stage solar distillers are pivotal in sustainable water purification, effectively utilizing solar energy. This study addresses the underexplored impact of reflective characteristics by integrating an aluminum reflector with radiation-trapping properties into a passive 4-stage solar distiller leveraging both experimental and theoretical methodologies. The influence of reflector height and angle on solar input, water production rate, and the Gain Output Ratio (GOR) was examined. Findings revealed a water production rate of 5.98 kg∙m−2hr−1and a GOR enhancement to 156 % at an optimal reflector setup of 40 mm height and 120° angle. Theoretical analysis assessed heat distribution and thermal efficiency across various air gaps and solar radiation levels. Evaporation emerged as the dominant heat mechanism, achieving 91 % thermal efficiency in the first stage with a 6.5 mm air gap and 1.50 kW∙m−2 of reflected solar radiation. Conversely, a 16 mm gap significantly lowered efficiency to 72 % in the last stage due to increased lateral heat loss. Transient analysis of the newly defined dissipation percent showed that narrower air gaps boosted heat retention in the distiller for evaporation and greater heat dissipation through the last stage, optimizing heat recycling for thermal applications. Increasing the solar input leads to sustained dissipation capacity.