Air pressure inside a refrigerator changes periodically when the temperature of the refrigerator fluctuates around the set value. Mass transfer occurs through the suction surface of refrigerator seals between air inside and outside the refrigerator. Water vapor can permeate through the contact surface

leading to frosting and an increase in thermal load in the refrigerator. To reduce the permeation of water vapor

the calculation method of water vapor permeation through refrigerator seals is developed in this paper. The permeable passage scale of the contact surface is determined to be the magnitude of um with the observation of the seal surface feature

which is much larger than that of the mean free path of the water molecules

determines that a viscous flow occurs when water vapor permeates through the surface. A formula of water vapor permeation is established based on Darcy’s law of viscous flow. The permeation coefficient is fitted with the experiment results of water vapor permeation of the contact surface. The water vapor permeation values calculated through the formula are compared with the experimental data

and the results show that the deviation of water vapor permeation predicted by the established formula is less than 15%

which indicates that the formula can be used to calculate the water vapor permeation through the contact surfaces of refrigerator seals.