Dr Vigneswaran VS, Assistant Professor, Department of Environmental Science and Engineering has worked on improving the performance of the water purification device, solar still with Nano-enhanced Phase Change Material (nPCM). He has published his research as a paper titled “Experimental investigation on diurnal and nocturnal productivity enhancement in solar still using encapsulated metal foam composite nano enhanced phase change material” in the Q1 journal Journal of Energy Storage having an impact factor of 9.8.

This research demonstrates a practical and sustainable way to produce more drinking water using solar energy, especially useful for rural and water-scarce regions.

Abstract

Solar still is considered an ideal sustainable solution to address potable water scarcity. It offers low-cost, simple technology with broader application and adaptability but is characterised by low productivity. This problem can be overcome by employing latent heat storage (LHS) materials. But the inherent low thermal conductivity of LHS materials results in a considerable amount of time being consumed during the charging and discharging cycles. Two modified solar stills were developed and tested to address the issue and enhance the productivity of the solar stills used in this work. One with Multi-Walled Carbon Nano Tubes (MWCNT) enhanced Paraffin wax (nPCM), encapsulated in three sandblasted copper cylinders, and the other with composite nPCM, where the open-cell copper metal foam (Cu metal foam) was embedded in nPCM and encapsulated in three sandblasted copper cylinders. The experiment was conducted simultaneously across all developed stills and the results showed that the freshwater productivity of the still with composite nPCM exceeded that of the conventional still by 52.4% and that of the still with nPCM by 6.5%. The results also showed the incorporation of PCM, MWCNT and Cu metal foam in a copper cylinder thermal energy storage system enhancing the exergy efficiency of the still with composite nPCM by 64.2% and 9.3% compared with a conventional still and still with nPCM respectively. In addition to the above results, the energy savings and carbon credit potential of composite nPCM still obtained were higher than those of nPCM integrated solar still by 6.7% and 6.6% and conventional still by 52.8% and 52.9% respectively.

Future Research Plans

To design and develop a hybrid solar thermal system (HSTS) which desalinates water and removes moisture content from food crops, thereby enhancing its shelf-life without losing the nutrition and market value. Increasing the shelf-life of the food crops in India will facilitate to reduce hunger because on average 10.54% of fruits and 6.24% of vegetables are lost as after harvesting. Reduction in post-harvest losses not only increases the availability of food crops but also abets in reducing the cost. However, the temperature at which a food crop must be dried and the minimum amount of moisture which must be maintained in a food crop is not same with all crops. Hence, it is necessary to control the air temperature, which reaches the drying chamber to ensure the food crops does not losses its nutritional value. Hence, to perform crop drying under controlled temperature, brackish water and PCM will be incorporated in the indirect crop solar dryer used in this study. In addition, the brackish water present in the indirect solar dryer will be evaporated by absorbing the solar radiation reaching the absorber plate of the HSTS, which will be condensed to produce potable water. Thus, the proposed HSTS makes use of solar energy to simultaneously desalinate water and dry food crops at low temperature (< 70 ºC).

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