Effect of nano-enhanced phase change materials on performance of cool thermal energy storage system: A review

Abstract

The cooling demand is anticipated to rise threefold between 2010 and 2050. The comfort temperature in the building is important, and the demand for cooling is rising vastly worldwide. In order to address the issues arising from electrical load fluctuations and the associated high kVA charges, it is imperative to eliminate the mismatch between energy supply and demand. The Cool Thermal Energy Storage (CTES) system proves to be a viable solution for energy storage by utilizing Phase Change Materials (PCM) during off-peak times. This stored energy can then be effectively utilized to meet peak demand requirements. Deionized (DI) water is a commonly used phase change material (PCM) in CTES systems due to its high energy storage density, high latent heat, non-corrosive nature towards encapsulating materials, and excellent thermal-stability. The addition of carbon-based nanomaterials like graphene nanoplatelets (GNP) and multiwalled carbon nanotubes (MWCNT) enhances the thermal conductivity of the PCM (compared to the metal and metal oxide nanoparticles). To create a CTES system with increased energy storage density, the use of surfactants must be drastically reduced or eliminated. Few researchers have started functionalizing nanomaterials to produce greater dispersion and a quicker nucleation rate as a result of current advancements in nanotechnology. In order to avoid the nanoparticles from aggregating and to increase the stability of the nano-enhanced phase change material (NEPCM) through stable dispersion without significantly altering the specific heat and latent heat, the covalent technique of functionalization is used. There is a need to apply the CTES concept in residential air-conditioning, small-scale process cooling, and vaccine applications. To meet the above demands, the CTES system needs to be designed with low capacity (≤0.5TRhr) with a controlled discharging rate.