Prediction of Interfacial Heat Transfer Coefficients by Using a Modified Lump Capacitance Method for Aluminum Casting in a Green Sand Mold

Abstract

This paper analyzes the heat flux and heat transfer coefficient at the mold/metal interface in the green sand mold casting of a cylindrical aluminum component. In the present casting experiment, thermocouples are used to measure the temperature at various points in the molten metal and the sand mold. Using the acquired temperature data, the heat flux and heat transfer coefficient at the sand-mold/metal interface are computed using a modified lump capacitance method, in which the latent heat term is calculated by considering the time-dependent variation of the solid/liquid interface location. For comparison purposes, the heat flux and heat transfer coefficient are also computed using Beck's inverse scheme. The results obtained from the two computational methods are found to be similar. The casting process is simulated by entering the values of the interfacial heat transfer coefficients computed by the two schemes into a commercial finite element analysis program (FIDAP). The cooling curve computed using the interfacial heat transfer coefficient determined by the modified lump capacitance method is found to be in good agreement with the experimental results. The predicted solidification time differs from that observed experimentally by just 2.8%. Furthermore, it is found that the Biot number is very small for the present aluminum casting. Therefore, the present results verify the feasibility of using the modified lump capacitance method to compute the interfacial heat flux and heat transfer coefficient in the green sand mold casting of small-sized components.