The influence of pore size distribution on thermal conductivity, permeability, and phase change behavior of hierarchical porous materials

Porous foams have been widely employed to improve heat storage rate and prevent leakage of phase change materials (PCMs). Actual porous foams have non-uniform or hierarchical pore size distribution, which is usually neglected in most researches. Here, we establish hierarchical porous models considering different pore size distributions by using Voronoi tessellations. Effects of pore size distribution on thermal conductivity, permeability, and phase change behavior of hierarchical porous foams/PCMs composites are investigated. Uneven pore size distributions are found to decrease the thermal conductivity of porous foams to some extent. On the other hand, the permeability can be reduced by 27.6%, and the heat storage rate can be improved by 7.7% by introducing moderate hierarchy without changing the total porosity. This work opens a new route to enhance heat storage performance of PCMs via leveraging hierarchy of pore size distribution of porous foams.