Thermodynamics HW Solutions 395

Thermodynamics HW Solutions 395 - Chapter 4 Transient Heat...

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Chapter 4 Transient Heat Conduction 4-126 The engine block of a car is allowed to cool in atmospheric air. The temperatures at the center of the top surface and at the corner after a specified period of cooling are to be determined. Assumptions 1 Heat conduction in the block is three-dimensional, and thus the temperature varies in all three directions. 2 The thermal properties of the block are constant. 3 The heat transfer coefficient is constant and uniform over the entire surface. 4 The Fourier number is τ > 0.2 so that the one-term approximate solutions (or the transient temperature charts) are applicable (this assumption will be verified). Properties The thermal properties of cast iron are given to be k = 52 W/m. ° C and α = 1.7 × 10 -5 m 2 /s. Analysis This rectangular block can physically be formed by by the intersection of two infinite plane walls of thickness 2 L = 40 cm (call planes A and B) and an infinite plane wall of thickness 2 L = 80 cm (call plane C). We measure x from the center of the block.
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This note was uploaded on 01/19/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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