In recent years, natural cooling techniques become very important from the viewpoint of high reliability and noise control. In this study, to precisely predict the air temperature rise in the enclosure, we proposed two simple equations about the heat transfer on the outside wall and the inside wall. By using these equations, in which the effect of convection is separated from radiation, we considered the average convective heat transfer coefficient without the effect of radiation. We calculated the average heat transfer coefficient from the results of the experiment and the CFD analysis. As a result, the average heat transfer coefficient of outside wall obtained from proposed equation with experimental results showed good agreement with that from CFD analysis. However, the average heat transfer coefficient of inside wall with experimental results and that from CFD analysis showed different values. This difference seems to be caused by inappropriate model of radiation in our proposed equation about inside wall.
