Thermodynamics HW Solutions 331

Thermodynamics HW Solutions 331 - Chapter 4 Transient Heat...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 4 Transient Heat Conduction 4-54 The center temperature of potatoes is to be lowered to 6 ° C during cooling. The cooling time and if any part of the potatoes will suffer chilling injury during this cooling process are to be determined. Assumptions 1 The potatoes are spherical in shape with a radius of r 0 = 3 cm. 2 Heat conduction in the potato is one-dimensional in the radial direction because of the symmetry about the midpoint. 3 The thermal properties of the potato are constant. 4 The heat transfer coefficient is constant and uniform over the entire surface. 5 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 conductivity and thermal diffusivity of potatoes are given to be k = 0.50 W/m ⋅° C and α = 0.13 × 10 -6 m 2 /s. Analysis First we find the Biot number: Bi W/m . C) m 0.5 W / m C 2 == ° ° = hr k 0 19 0 03 114 (( . ) .
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

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.

Ask a homework question - tutors are online