Two Fundamental Problems of Refrigerator Thermal Insulation Design

This article presents the solutions to two fundamental problems in the design of the insulation for a refrigerator. The first problem is how to incorporate the new generation of non-CFC materials in a composite layer that also contains polyurethane foam. The article shows how to select the thickness of each sublayer in the composite so that the total cost is minimized over the lifetime of the refrigerator. The second problem addresses the distribution of a given amount of insulation material around the refrigerator, for example, over the freezer and cooler sections. The article reports the optimal insulation thicknesses for the freezer and cooler sections so that the overall heat leak into the cold space is minimum. Notes Address correspondence to Prof. Adrian Bejan, Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708-0300.