Thermo-fluidic characteristics of contact melting mechanism for water-phase change material mixture: A numerical optimization

Abstract

The paper introduces a novel composite heat transfer structure integrating sensible heat and latent heat utilizing water and phase change material, facilitated by a high thermal conductivity contact melting process. A numerical model is developed and validated. Optimization of the trapezoidal structure for the refractory zone during PCM melting ensures the volume proportion of water and PCM remains unchanged. The study compares and analyzes the melting properties of different structures (melting time, heat charging rate, energy storage rate of different media, dimensionless temperature response, etc.), and explores the impact of heat source temperature and initial temperature conditions. The findings indicate that adding water enhances the thermal conductivity and convective effect of upper PCM, however, at the end of melting, the square structure exhibits a refractory zone. It is worth noting that compared with the square initial structure Case 0, the positive trapezoid structure (Case 3) reduces the heat storage time of PCM by 6.14 % and increases the average heat storage rate of PCM and water by 5.81 % and 4.62 %, respectively, while the inverted trapezoid structure weakens the heat transfer process. Additionally, an increase in heat source temperature from 340.15 K to 354.15 K leads to a 67.10 % rise in the mean heat transfer rate of PCM and 101.75 % for water. Conversely, augmenting the initial temperature negatively affects the heat transfer rate and total heat storage of water, while reducing the melting time. This study holds significance for the development of new contact melting methods and enhancing heat transfer mechanisms.