A model for predicting air permeation between temperature-fluctuated refrigerated room and ambience through magnetic seal

The air permeation caused by the pressure difference at both sides of the magnetic seal accounts for a significant part of energy loss in a refrigerated room. The purpose of this study is to model the air permeation rate. Based on momentum equations of air flow along the permeation paths, the air permeation rate is deduced as a function of the average height of permeation paths and the flow factor. The average height is obtained by a resultant force of magnetic attraction and pressure difference under the assumption of parabolic asperity profile in the permeation paths; and the flow factor is calculated by semi-empirical correlations based on the average height of the permeation paths. An experiment is designed to validate the model, and the results show that the predicted air permeation rate can describe 98% of the experimental data within a deviation of ± 15% and the mean deviation is 5.6%.