Comparative study on the melting rate of PCM for circular and semi-circular LHTES system
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Date
2021-02
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Latent heat thermal energy storage (LHTES) technique using different types of phase change materials (PCM) has become popular in the last few decades. It helps to reduce the problems related to discrepancy between supply and demand of energy. In the present study, the melting characteristics of a lauric acid in a semi-circular and circular latent heat storage unit has been studied. The low melting rate of PCM in the lower half of a circular heat storage unit can be enhanced by confining the PCM in the upper region by configuring the outer shell of semi-circular cross-section. The recent literature shows that no work has been carried out on the effect of the melting performance of PCM in a semi-circular LHTES unit. So, it has been decided to investigate the melting performance of PCM experimentally and numerically for semi-circular LHTES system. The investigation of the melting performance of PCM in a semi-circular heat storage unit has been done through by developing a numerical 2D model which has been analysed through ANSYS FLUENT. The results obtained from numerical simulation are validated through experimental results. The enhancement in the melting rate at three different inner tube position values (e = 0.20, 0.23 and 0.25) for inner tube from the bottom surface of outer semi-circular shell is investigated and it is found that the enhancement is maximum when the inner tube is nearest to the bottom surface of the outer shell i.e., for e = 0.20. The melting performance of PCM is also studied for different values of inlet temperature of heat transfer fluid for tube position e = 0.20 and it is observed that the increase in Stefan number, enhances the melting rate of PCM in semi-circular LHTES system. The semi-circular heat storage unit is also compared with circular heat storage unit by considering the equal quantity of PCM in both the cases. The semi-circular LHTES system shows enhancement in melting performance of PCM as compared to circular LHTES system. The semi-circular LHTES system melts the PCM completely in almost half time as compared to circular LHTES system. It is found that the thermal energy stored in PCM for semi-circular LHTES system is 416.4 KJ which is 12.04 % more as compared to TES of PCM for circular LHTES for the same time duration of 4800 sec and the thermal energy storage efficiency of semi-circular LHTES unit is 11 % more as compared to the circular LHTES unit.