Receiving heat from a PCM tank by using natural convection of water and NEPCM: A simulation for LHTES application

Latent heat thermal energy storage (LHTES) systems are widely used due to their ability to store a lot of heat energy as latent, and few studies have directly or indirectly investigated on the heat exchange methods with LHTES systems. In the present study, the free convection of a mixture of water and Nano-encapsulated phase change material (NEPCM) with a porous medium was used to exchange heat energy between a cold-water stream and a hot tank filled phase change material (PCM). NEPCM are nanostructures consisted of a solid shell and a PCM core, and the addition of these nanostructures to water has remarkable effects on the heat transfer parameters. In this research, a number of cases were simulated using computational fluid dynamic (CFD) to observe the impacts of injecting NEPCM to water, the porosity of the porous media and the location of the phase change zone on the average heat flux of the PCM tank. The results showed that increment of porosity number from 0.85 to 0.95 decreased the average heat flux of the PCM tank by 13.8%. Moreover, adding 3% NEPCM to water enhanced the average heat flux of the PCM tank by 22.2% and 18.4% when porosity numbers were 0.85 and 0.95, respectively.