Solidification characteristics of biomass-activated aloe vera PCM in a spherical enclosure for efficient cool thermal energy storage
A. Sathishkumar, P. Sundaram, K.S. Vignesh, M. Cheralathan, A. Kalaisselvane, Rajendran Prabakaran, Sung Chul Kim
Abstract
The present work aims to examine the potential of aloe vera liquid (AVL) and activated carbon (AC) as a phase-change material (PCM) for energy efficient cool thermal energy storage (CTES) applications. The low-viscosity and supercooling behavior of deionized water (DIW) limits its usage in the CTES system. Three variants of NEPCMs containing activated-carbon (AC) at concentrations of 1.5 wt%, 1.0 wt%, and 0.5 wt% were analyzed (AVL, DIW, and AVL + DIW). Zeta-potential distribution analysis shows that all the AVL-NEPCMs (−44 mV) are stable, with the particles exhibiting strong mutual repulsion. A maximum thermal-conductivity (TC) enhancement of 24 % and 34 % was noted for the AVL-NEPCMs in the liquid and solid phases, respectively. The AVL has a latent heat of 332 J/g during melting and 305 J/g during freezing, which is nearly equal to that of DIW. In addition, a slight reduction in latent-heat of 8 %, was observed owing to the non-active participation of AC. The freezing characteristics of NEPCMs were studied with spherical enclosure by maintaining a chiller temperature of −8 °C. A 22 % reduction in total solidification time was observed for the AVL-based NEPCM with 1.5 wt% AC, due to the faster nucleation and the elimination of the supercooling process.