Seasonal Performance of Solar still

The present research is based on the hypothesis that integration of nanofluid-based solar thermal enhancement techniques with conventional solar desalination systems can significantly improve heat transfer characteristics, evaporation rate, freshwater productivity, and overall thermal performance. The study proposes that nanofluids, due to their enhanced thermal conductivity and volumetric solar absorption capability, can absorb higher solar energy, increase basin water temperature, reduce thermal losses, and improve the efficiency of solar desalination systems. The experimental investigation was conducted on a modified single-basin solar still integrated with a nanofluid-based solar collector (NBSC) and compared with a conventional solar still under similar climatic conditions. The objective was to evaluate the influence of nanofluid concentration, basin water depth, solar radiation intensity, and operating parameters on the thermal behaviour and freshwater production of the system. The experimental setup consisted of a solar still coupled with a nanofluid circulation system. Experiments were performed by varying the nanofluid concentration (1.25 ml/L and 2.5 ml/L) and basin water depth (30 mm, 40 mm, and 50 mm). The nanofluid was circulated at a flow rate of 3 L/min using a 12 V DC pump with 19 W power input. Paraffin oil was incorporated as a thermal energy storage medium to improve heat retention and maintain evaporation during periods of reduced solar intensity. The experiments were carried out under actual outdoor climatic conditions, and data were collected at regular intervals. The measured parameters included solar radiation intensity, ambient temperature, wind velocity, basin water temperature, absorber temperature, glass cover temperature, collector outlet temperature, and hourly distillate production. Solar radiation was measured using a calibrated pyranometer, while temperature variations were recorded through thermocouples connected to a data acquisition system. The collected data were analysed to determine the effect of nanofluid integration on thermal performance, productivity enhancement, and system efficiency. The optimized nanofluid-based volumetric absorption solar collector (NBVASC) integrated solar still achieved a distillate productivity of approximately 4.78 L/m²/day with an efficiency improvement of around 39.10% compared with the conventional solar still. These findings confirm that nanofluid-assisted solar desalination can effectively overcome the limitations of conventional systems by improving energy conversion and freshwater production.