quiz4_F09 - Quiz #4 ECH 3223, Fall 2009 Monday, October 12...

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Unformatted text preview: Quiz #4 ECH 3223, Fall 2009 Monday, October 12 Directions: • Forty-five minutes. • Open book, though not required. • No notes. • Calculator not needed. • Maximize your score by showing all work. • Good luck to you!! Internally heated, isothermal object Generate a model of the time rate of change of the temperature of a spatially isothermal object having internal energy generation. The object is initially at a temperature of Ti when a constant and uniform generation of ˙ energy, Eg (W), is turned on. The object has a volume V and surface area A. The thermal conductivity is k , the heat transfer coefficient is h, density ρ, and heat capacity c; all these quantities are known and constant. a) b) What is the steady temperature, Ts , of the object? A quick, macroscopic balance should provide a good route to the solution. By performing a macroscopic balance and integrating, determine the function f (t) governing the temperature change of the object in time, Θ(t) = f (t), Θi where Θ(t) = T (t) − Ts and Θi = Ti − Ts . ...
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This note was uploaded on 01/08/2010 for the course ECH 3223 taught by Professor Asthigiri during the Spring '08 term at University of Florida.

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