Numerical investigation of an amalgamation of two phase change materials thermal energy storage system

Abstract

In the last three decades, many researchers have published their findings on the storage of thermal energy using various phase transition materials (both organic and non-organic). One of their goals was to have a higher heat storage capacity with a shorter heat charging cycle for thermal energy storage. This study looked into a floating capsule thermal energy storage system (TESS). A number of spherical capsules filled with beeswax were placed in a paraffin-filled cylindrical shell. With heat transfer fluid flowing through three hexagonal tubes arranged at 120° inside the TESS core, the two phase change materials (beeswax with a thermal conductivity of 0.25 W/mK and paraffin with a thermal conductivity of 0.23 W/mK) were charged and discharged. For the proposed TESS, a mathematical model was created and utilised to forecast thermal energy storage capacity and charging/discharge times for various configurations. In TESS, a 70–30% mixture of the two PCMs results in a 21.5 percent increase in heat storage capacity when beeswax alone is used, and an 8.4 percent decrease in storage capacity when paraffin alone is used. For a heat storage capacity of 7300 kJ, the model estimates charging and discharging times of around 2.6 and 3.2 hours, respectively.