Systematic investigations on charging/discharging performances improvement of phase change materials by structured network fins

Abstract

Improving the effectiveness of solar energy utilization and waste heat recovery by ameliorating charging/discharging performances of latent heat thermal energy storage (LHTES) unit, is essential to reduce fossil fuel consumption thus achieve the goal of carbon neutralization. Structured network fins are developed to improve charging/discharging performances of paraffin wax-based LHTES unit. Simulations are conducted by integrating enthalpy-porosity method and Ansys Fluent software package. Influences of horizontal fin number nh and distance d between bottom horizontal fin and bottom wall of enclosure on charging/discharging performances are discussed. Results illustrate that when nh increases from one to six, the maximum enhancement factor for charging approaches to 1.6921 but it decreases to 1.0590 when nh increases from six to ten. The corresponding maximum enhancement factors for discharging are 10.5571 and 1.0382, respectively. An appropriate nh exists. Moreover, an optimum d exists when nh ≤ 3 for charging and when nh ≤ 6 for discharging. Charging/discharging rates are further enhanced by 10.38% and 13.84% respectively through optimizing d. When nh > 3 for charging and nh > 6 for discharging, a smaller d is more profitable. Results suggest nh = 6 and d ≤ 3 mm are appropriate to achieve satisfactory enhancements for charging/discharging performances of paraffin wax-based LHTES simultaneously and introduce minimum extra manufacture complexity.