INVESTIGATION ON COMBINED SENSIBLE-LATENT HEAT THERMAL ENERGY STORAGE SYSTEM

Abstract

The global energy demand is increased by 60% since 1990 and it likely to be increase by 28% till 2040 as per the report published by United States based Energy Information Administration. The major part of the global energy demand is accomplished through the use of fossil fuels. According to International Energy Agency, global concentration of CO2 has increased by 66% since 1960. Solar energy being major source of renewable energy can play a keen role in maintaining supply of energy as per its demand. Due to the intermittent nature and variable supply of solar energy, there is a need to integrate the efficient storage systems with solar thermal energy systems. Thermal energy storage (TES) is a system that stores thermal energy by heating the storage material, which can be used for later use in power generation, heating, cooling applications. In TES systems, sensible and latent heat storage technologies were prominently used which have their both advantages and limitations. Keeping the context in view, it is the need of an hour to develop a novel combined Sensible-Latent thermal energy storages which overcomes the shortcomings of previous counterparts increasing the overall thermal performance and efficiency of the TES system. Under this present dissertation study, detailed investigation on combined Sensible-latent thermal energy system is carried out. Experimental setup is developed under renewable energy R&D lab and experimental trials were performed on combined TES with 20% volume fraction of PCM by varying the position of PCM. It was deducted that, keeping the flow rate at 0.025 kg/s and shifting the PCM to top from middle of the tank resulted in an increase of 6% of total energy storage. Operating and system parameters were identified and a numerical modelling analysis has been performed to access the impact of those parameters on combined TES system. After experimental runs, it was found out that by increasing the flow rate from 0.025 to 0.032 kg/s charging time was decreased by 10 %. Validation of numerical and experimental results was carried out and results obtained are in good agreement.