Investigations on nano enhanced phase change materials for heat transfer applications

Abstract

Scientists across the globe have been working on alternative solutions to handle the newlinepersisting energy crisis and to use technologies powered by renewable energy sources. newlineThe major limitation of renewable energy sources is the difficulty associated with energy newlinestorage. Research is being conducted to bring out new methods of energy storage. newlineThermal energy storage is a highly explored area that stores energy in the form of newlinesensible heat, latent heat, or thermo-chemical heat. Latent heat storage materials like newlinephase change materials (PCMs) are characterized by their very high value of heat storage newlinecapacity. The major factor that limits the use of PCMs in practical applications is their newlinelow thermal conductivity, which can affect the charging/discharging and heat transfer newlinerates in thermal systems. PCMs dispersed with nanoparticles that were proved to be newlinegreat thermal conductivity enhancers (TCEs) have gained popularity in the last decade, newlinegiving rise to a new segment of PCMs, known as nano-enhanced phase change materials newlineor NEPCMs. Even though thermal conductivity enhancement is observed in NEPCMs, newlinenegative impacts have been observed on other parameters such as dispersion stability newlineand latent heat due to the high loading of nanoparticles in the system. Thus, the newlineperformance of a NEPCM depends on a compromise between different thermophysical newlineparameters. The present thesis focuses on enhancing the thermal conductivity of PCMs newlineusing low loading levels of graphene nano platelets (GNP) and GNP-Ag hybrid newlinenanoparticles and analyzing their effect on heat transfer rates. The hybrid nanoparticles newlinewere synthesized using in-situ methods and characterized using different techniques. newlineIn this work, the T-history method was used for the thermophysical characterization of newlineorganic and inorganic PCMs dispersed with nanoparticles. newline