Effect of heating tube arrangement on nano-enhanced thermal energy storage

Improvement of thermal performance of energy storage leads to energy savings and reduction of carbon emissions. In this study, the effect of tube arrangement on the performance of thermal energy storage is examined during the melting process of a phase change material (RT50). The heat transfer and phase change modeling are based on conservation equations and lattice Boltzmann method. The combined effect of the tube's vertical position and nanoparticles are studied for various nanoparticle concentrations and Rayleigh numbers. Natural convection, melt fraction, heat storage, and storage time are examined and discussed. The results indicate that tubes placed at the horizontal centerline of the cavity is the best arrangement for reducing the charging time at low heating rates (Ra = 104), while downward displacement of one heating tube is more effective at high heating rates (Ra ≥ 105), the loading time can be reduced by up to 28%. The results of this study can guide design of efficient thermal energy storage systems.