Experimental Analysis of Storage of Solar Energy in Phase Change Materials Encapsulated in Copper Cylinders

Abstract

The Demand and increase in the cost of fossil fuels have made the entire world to turn towards the renewable energy resources. There are various renewable energy out of which solar energy is the efficient energy and available in abundant. The main disadvantage of solar energy is that it is not continuous and it is available only in the day time and so the storage of solar thermal energy is considered as an important one. In this study, thermal energy is transmitted through the therminol-55 oil which is the Heat Transfer Fluid (HTF). D-Mannitol-a white, crystalline solid with the chemical formula C6H8(OH)6 is taken as the Phase Change Material (PCM) and stored inside the copper cylindrical encapsulations. The D-mannitol PCM was stored in the copper cylinder encapsulations with and without fins. These encapsulations were immersed in a cylindrical mild steel tank containing HTF. The therminol-55 oil was allowed to flow through the solar parabolic trough collector to transfer heat. Along with this, an additional heater was provided for heating HTF up to the temperature 300oC. This hot oil was allowed to flow in to the PCM tank where the PCM copper cylinders were immersed. The experiments were conducted in two stages one with finned encapsulations and another without finned encapsulations. Here the experiments were done in two modes one is charging mode and another one is discharging mode. In charging mode the temperature of the HTF was raised to 300oC and was allowed to cool during its discharging mode to 120 oC. The time taken for the charging and discharging of heat was measured to analyse the heat transfer study of thermal storage system.