Evaluation of the melting performance in a conical latent heat thermal unit having variable length fins

A conical shell-tube design with non-uniform fins was addressed for phase change latent heat thermal energy storage (LHTES). The shell was filled with nano-enhanced phase change material (NePCM). The cone aspect ratio of the shell and the fins aspect ratio were adopted as the geometrical design parameters. The type and volume fraction of the nanoparticles were other design parameters. The investigated nanoparticles were alumina, graphite oxide, silver, and copper. The finite element method was employed to solve the natural convection flow and phase change thermal energy equations in the LHTES unit. The Taguchi optimization method was utilized to maximize the melting rate in the unit. Two cases of ascending and descending conical shells were investigated. The outcomes showed that the shell-aspect ratio and fin aspect ratio were the most important design parameters, followed by the type and concentration of nanoparticles. Both ascending and descending designs could lead to the same melting rate at their optimum design. The optimum design of LHTES could improve the melting rate by up to 18.5%. The optimum design for ascending (descending) design was a plain tube (a cone aspect ratio of 1.17) filled by 4.5% alumina-Bio-PCM (1.5% copper-Bio-PCM).