Effects of air vents on the flow of reacting polyurethane foam in a refrigerator cavity

The transport equations for momentum, enthalpy, and chemical species are solved to simulate the reactive flow of polyurethane foam in a refrigerator cavity. The chemical reactions are described by a mechanism with four reactions and eight species. The numerical findings are also supported by dimensional arguments, which lead to important design attributes. Results prove that the model can be used not only to predict the flow features during the expansion of a multi-component foam, but also to determine the locations and the size of the air vents to avoid air bubbles trapped during the solidification process. It appears that the distribution of the vent holes must be evenly balanced around the cabinet cavity, where the larger holes must be located at positions far from the injector. To prevent the formation of large air voids, which cannot reach the vent holes by the action of gravity, there must be additional holes located on the lower surfaces of the cavity to purge the air trapped.