Role of extended fins and graphene nano-platelets in coupled thermal enhancement of latent heat storage system.

Abstract

To bring modernisation in low carbon economy, the latent heat storage (LHS) systems are crucial for sustainable future of smart energy generation and management systems for renewable sources. This article provides in–depth numerical analyses of 3-dimensional computational models incorporating coupled thermal enhancement techniques for identifying optimal solution to guarantee higher charging rate, higher total enthalpy and better thermal distribution of LHS system. Paraffin is selected as phase change material (PCM), graphene nano-platelets (GNP) as nano-additives and longitudinal, circular and wire-wound fins as extended surfaces in vertical shell-and-tube configurations. Based on numerical analyses, the extended surfaces have registered better thermal distributions and charging rates as compared to nano-PCMs. The geometrical orientation of extended surfaces and volume concentration of nano-additives have significant influence on melt front movement, natural convection and heat transfer performance. The peak values of heat fluxes are significantly increased from 2.25 kW/m2 for paraffin without thermal enhancement to 35.86, 47.23 and 88.13 kW/m2 for nano-PCM with 1% GNP in circular, longitudinal and wire-wound fins configurations. Hence, the charging duration for capturing 11.09 MJ is significantly reduced to mere 1.02 h for wire-wound fins configuration as compared to 23.5 h for paraffin without thermal enhancement. Likewise, the charging rate of wire-wound fins configuration is 20.95%, 35.96% and 89.94% higher than circular fins, longitudinal fins and nano-PCMs without extended surfaces, respectively. Moreover, the increase in volume concentration from 1% to 5% has adverse implications on accumulative enthalpy, natural convection and charging rate. Therefore, the novel design of coupled enhancement with wire-wound fins configuration and nano-PCM with 1% GNP are established as optimum solution for potential wide-ranging practical utilisations of LHS system.