Calorimetric investigation of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate as salt mixture encapsulated materials for thermal energy storage

Abstract

The use of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate salt composite as an encapsulated phase change material in solar water heater storage unit for thermal energy storage was experimentally tested and investigated in this research study. A differential scanning calorimetry is performed to determine the properties such as melting temperature, specific heat capacity, and latent heat of the selected mixtures for the proportion 70:30 and 80:20 by weight. For the experimentation, these two samples are stored separately in the aluminum canisters and filled in storage tank to avoid the heat loss directly. The thermal performance of the solar water heater at different zones on collector with and without using encapsulated phase change material in storage tank was tested experimentally. Maximum temperature achieved in solar water collector was 50°C at midpoint and 46°C at outlet of the tank. It is found that even after late evenings 18.00 IST, the average storage tank temperature with phase change material was found to be nearly 2.6 to 3.2 times greater than conventional solar water heater and the average temperature of phase change material is 42°C. The test results shows that sample B 80:20 will produces higher amount of hot water and stores the maximum heat compared to sample A 70:30. The results demonstrate that this encapsulated phase change material cylinder stores higher latent heat of fusion and, it can also be used for indirect solar cooking and other low temperature application even at late evenings.