Executive Summary : | Considering the continuously growing population, and industrial developments all around the world, energy consumption has significantly increased. As of now, ~ 80% of the total energy requirements are fulfilled by fossil fuels. However, these non-renewable sources of energy are associated with huge amounts of greenhouse gas emissions where ~ 7% of the global CO₂ emission is contributed by India. On the other hand, the limited availability of fossil fuels and their gradually depleting reserves are the major reason for surging oil and coal prices. Therefore, the governments are now focusing on the efficient utilization of renewables (solar, wind, hydro, etc.) to alleviate the energy crisis. The use of these non-conventional energy resources is often associated with thermal energy storage (TES) systems to address some discrepancies such as the unpredictable and intermittent energy supply. Among all available energy storage technologies (sensible, latent, and chemical), the latent heat-based TES utilizing phase change materials (PCMs) has attracted many researchers as these materials possess high energy density and latent heat capacity, thermal stability, long cycle life, non-toxicity, and small volume variations when changing its phase. PCMs are capable of storing/releasing a significant amount of energy during phase transition, therefore, they find numerous applications such as in building materials, waste heat recovery, HVAC, textiles, electronic and battery cooling, etc. The use of PCMs in large-scale industrial settings is restricted by their high cost, and low thermal conductivity thus various techniques, including the incorporation of nanoparticles, metallic fins, porous metal foam and inserts, etc., have now emerged. Among these, the inclusion of metal foams in PCM appears to be the most advantageous and efficient method due to its high specific area for heat transfer, high thermal conductivity, and rigid structure. Despite voluminous published literature in this domain, only a few studies have dealt with elucidating the effect of variable porosity and pore density of graded metal foams embedded inside PCM. To the best of our knowledge, none of the investigations has explored this effect so far on the triplex-tube heat exchanger system utilizing graded metal foams under the simultaneous charging and discharging (SCD) environment. Owing to the enhanced melting/solidification performance of triplex-tube latent heat energy storage systems and relatively less amount of metal foam usage by geometrically optimized segmental graded/cascaded systems, this project is of great importance. The objective of this research project is to expedite the phase change process in achieving the quickest steady-state melting/solidification conditions. Overall, finite element-based modeling will be carried out to characterize the phase transition phenomena in metal foam-PCM cascaded systems (both 2D and 3D) having varying/anisotropic porosity and pore density. |