EXPERIMENTAL INVESTIGATION OF A LATENT HEAT STORAGE SYSTEM

Abstract

Solar energy storage devices are one of the key technologies for energy conservation. This energy storage is best suited for heating and cooling applications. Thermal energy storage is an essential requirement for utilization of solar energy as it is a variable with time and season. A continuous supply of energy at low to medium temperature is necessary for many applications. Thermal energy storage in the phase change material is one of viable options Experimentally the heat transfer characteristics involved in such devices is studied. The capsule type of storage was found to have better characteristics. Hence in the present work the heated air from a solar air heater was used to supply energy to a PCM in capsules of spherical shape. Studies have been done on solar energy storage using various phase change material such like CaC12. 6H20, paraffin wax, capric, lauric acid `and MgC12. 6H20. Besides this a great emphasis is also done on various phase change material holding devices like spherical capsule, rectangular, cylindrical containers. The use of PCM in spherical capsule has been found to be a best method. The objective of the present study was to investigate the thermal characteristics of Zinc Nitrate in the melting process. The parameters were the Reynolds number and inlet temperature for a. PCM in thermal storage system. It is seen that as the mass flow rate kJ- 62M& (a d Q +', c e' 1(rL J~ • increases the Reynolds number also increases a the phase change period is reduced substantially indicating to get faster storage of energy in the PCM, the mass flow, rate iii should be high. It is also found that the average heat transfer coefficient increases with Reynolds number and for a range of Reynolds number from 1200-3000 approximately the variation is linear.For the higher Reynolds number (Re. > 3000), heat transfer coefficient increases sharply. iv