Enhancement of Solar Water Desalination Using Nanoparticle

Mechanical Engineering

Energy, particularly renewable energy, is central to sustainable development. This thesis explores solar still technology enhanced with nanofluids to improve water desalination efficiency. Solar stills, simple devices that use solar energy to purify saline or brackish water, are a sustainable technology especially suited for water-scarce regions with abundant sunlight. The primary objective of this research is to enhance the thermal performance of a conventional single-slope solar still (SBSS) by incorporating aluminum oxide (Al₂O₃) nanoparticles into the basin water to improve heat transfer, evaporation rates, and overall productivity. A single-basin solar still (SBSS) design is used for experimentation, due to its simplicity and widespread use. Solar stills traditionally suffer from low productivity due to limitations in heat retention and slow evaporation rates. The experimental work undertaken in this study addresses these limitations by leveraging the higher thermal conductivity of Al₂O₃ nanoparticles, which are suspended in the basin water. The nanoparticles improve the thermal conductivity of the water, leading to more efficient absorption of solar energy and faster heating. The experimental setup involved a comparative analysis of two solar stills: one operating without nanoparticles and one enhanced with Al₂O₃ nanoparticles. Both stills were evaluated under identical environmental conditions at the Radharaman Institute of Technology and Science, Bhopal (23.26°N, 77.41°E). The experiments, conducted over three days, measured solar radiation, relative humidity, wind speed, basin temperature and accumulated productivity. The experimental data and results show that using nanoparticles leads to higher basin temperatures, facilitating faster water evaporation and condensation. The relative humidity inside the solar stills decreased as the basin temperature increased, leading to better water vapor saturation. The greater reduction in humidity enhances evaporation rates, as the air can hold more water vapor. The addition of Al₂O₃ nanoparticles increased the basin water temperature by 9% compared to the still without nanoparticles. The experiment showed a maximum basin temperature of 64.8°C for the nanoparticle enhanced still, compared to 57.6°C for the traditional still. This temperature enhancement is due to the higher thermal conductivity of Al₂O₃ (37 W/m•K) compared to that of water (0.6 W/m•K). The accumulated productivity of distilled water over the experiment also increased by 13-22% due to the higher thermal conductivity of the Al₂O₃ nanoparticles. The productivity of the solar still with nanoparticles was consistently 13% to 22% higher than that of the conventional still, with the most significant gains observed during periods of high solar radiation.

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