Fins-nanoparticle combination for phase change material enhancement in a triplex tube heat exchanger: A numerical approach to thermal sustainability

Abstract

Many phase change materials exhibit low thermal conductivity, leading to incomplete melting and solidification processes. To address this issue, researchers have numerically explored the integration of alumina nanoparticles (Al2O3) with paraffin (RT82), a phase change material with a solidification temperature of 65 °C, in a triplex-tube heat exchanger. The phase change material model with internal longitudinal fins employed the both-sides freezing technique and was conducted using Ansys Fluent software, employing the enthalpy-porosity method within a finite-volume framework to model the phase change material behavior during both melting and solidification phases. This methodology aims to significantly improve the thermal performance of thermal energy storage systems by enhancing heat transfer efficiency within the phase change material (PCM), thereby ensuring more effective utilization of stored thermal energy. The numerical findings show that the pure PCM completely solidified in 780 min. By dispersing 1 %, 4 %, 7 %, and 10 % of Al2O3 in the PCM, thermal conductivity improved by 3 %, 12.5 %, 22.5 %, and 32.5 %, respectively. Additionally, the inclusion of nano-PCM reduced the solidification time. This research also compares the overall energy release in two different situations: PCM with and without nanoparticles. The computer-generated simulation results closely correlated with the practical experimentation results.