Metal porous media which enables the gas and liquid separation is adopted to enhance heat transfer. Due to the different mechanical behavior between gas and liquid in the porous wall

the gas-liquid two-phase can be separated along the porous media insert

where gas cannot enter the porous wall and the liquid is free to flow in the center. Thus

the gas can flow along the tube wall and the liquid flow in the center of the tube

leading to a high heat transfer performance. Capillary force of the porous media has an important influence on the enhancement performance. In this paper

a novel capillary force testing method is used to test the capillary force of the metal porous media inserts. It is found that the capillary force of the porous media is associated with the powder material

particle size and the filling of the porosity. The particle shape is the most important factor affecting the capillary force and then the particle size

while the porosity is the weakest one.