Chapter 5 Numerical Methods in Heat Conduction 5-120 Frozen steaks at -18°C are to be defrosted by placing them on a 1-cm thick black-anodized circular copper defrosting plate. Using the explicit finite difference method, the time it takes to defrost the steaks is to be determined. Assumptions 1Heat transfer in both the steaks and the defrosting plate is one-dimensional since heat transfer from the lateral surfaces is negligible. 2 Thermal properties, heat transfer coefficients, and the surrounding air and surface temperatures remain constant during defrosting. 3 Heat transfer through the bottom surface of the plate is negligible. 4 The thermal contact resistance between the steaks and the plate is negligible. 5 Evaporation from the steaks and thus evaporative cooling is negligible. 6 The heat storage capacity of the plate is small relative to the amount of total heat transferred to the steak, and thus the heat transferred to the plate can be assumed to be transferred to the steak.
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