Evolution mechanism of freezing in porous media at the pore scale: Numerical and experimental study

Abstract

The phase change problem in porous media has attracted extensive attention due to its complexity of both the heat transfer process and pore structure. This study investigates the mechanisms governing the freezing of water at the pore scale in a porous model, employing a combination of experimental and numerical approaches. Mathematical-physical model is used to simulate the phase change process in porous structures. Experiments are conducted on water freezing in porous resin and steel, with a pore distance of 500 μm. The evolutions of the phase interface and temperature field during the freezing process are analyzed. Results demonstrate good agreement between the simulations and experiments. Moreover, when the thermal conductivity of the solid skeleton is lower than that of the fluid (porous resin), the phase interface in the pore evolves from concave to convex, with a non-linear change in relative curvature. The temperature gradient of the fluid and skeleton within the pore channels first decreases and then increases. However, when solid skeletons have higher thermal conductivities than the fluid (porous steel), the evolution of the phase interface and its relative curvature, as well as the temperature gradient in the pore are different from the other case.