Probabilistic Study of a Refrigerator Steel Heat Loop Tube Joint

A probabilistic study was performed on a refrigerator heat loop joint to determine the relative significance of design changes and geometry process variation on the stress/strain at the tube joint. The heat loop is an extension of the condenser that is routed behind the front flange of a refrigerator cabinet to prevent condensate from forming on the flange. During assembly of the refrigerator, the heat loop is brazed to the condenser tube. Currently, the heat loop is copper for North American Products. Changing the material from copper to steel is potentially a large material cost savings. Unfortunately, brazing the two steel tubes together sometimes results in a crack in the heat loop tube due to Liquid Metal Embattlement (LME). In order to understand what is causing the cracks, the process variation had to be modeled using probabilistic methods. The probabilistic study indicated that both the design and the process variables are significant to the cracking of the joint. This understanding will aid the implementation of the design change while maximizing the material savings, which has a potential in excess of $800,000/year.

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