Thermodynamics HW Solutions 353

# Thermodynamics HW Solutions 353 - Chapter 4 Transient Heat...

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Chapter 4 Transient Heat Conduction 4-77E A hot dog is dropped into boiling water. The center temperature of the hot dog is do be determined by treating hot dog as a finite cylinder and an infinitely long cylinder. Assumptions 1 When treating hot dog as a finite cylinder, heat conduction in the hot dog is two- dimensional, and thus the temperature varies in both the axial x - and the radial r - directions. When treating hot dog as an infinitely long cylinder, heat conduction is one-dimensional in the radial r - direction. 2 The thermal properties of the hot dog 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 the hot dog are given to be k = 0.44 Btu/h.ft. ° F, ρ = 61.2 lbm/ft 3 C p = 0.93 Btu/lbm. ° F, and α = 0.0077 ft 2 /h.
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