Fundamentals of Heat and Mass Transfer
7th Edition
ISBN: 9780470501979
Author: Frank P. Incropera, David P. DeWitt, Theodore L. Bergman, Adrienne S. Lavine
Publisher: Wiley, John & Sons, Incorporated
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Textbook Question
Chapter 1, Problem 1.70P
A computer consists of an array of five printed circuit boards (PCBs), each dissipating
(a) If the temperature rise of the airflow.
(h) The component that is most susceptible to thermalfailure dissipates
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Consider a wall that consists of two layers, A and B, with the following values: kA = 0.8 W/m⋅ºC, LA = 8 cm, kB = 0.2 W/m⋅ºC, LB = 5 cm. If the temperature drop across the wall is 18ºC, the rate of heat transfer through the wall per unit area of the wall is
a.
89.6 W/m2
b.
72.0 W/m2
c.
153 W/m2
d.
51.4 W/m2
e.
180 W/m2
Inner radius 15 cm, outer radius 20 cm and k = 15 W / m ∙ Consider a pipe with oC. Heat transfer coefficient of the fluid in the pipe is 40 W / m2 ∙ °C, fluid 500°C average flows with heat. The convection coefficient between the outer surface of the pipe and the surrounding air is 12 W / m2 ∙ revenge and the air temperature is 20 °C. Assume that the heat conduction in the pipe is unidimensional and continuous. by, a) The main differential equation and boundary conditions for heat conduction through the pipe material. Determine. b) By solving this differential equation, the special equation that gives the temperature change in the pipe material. obtain. c) Find the pipe outer surface temperature.
Qi) Consider a large plane wall of thickness L = 0.4 m, thermal conductivity
k= 2.3 W/m · °C, and surface area A= 20 m. The left side of the wall at x= 0 is
subjected of T1
80°C. while the right side losses heated by convection to the
surrounding air at T=15 °C with a heat transfer coefficient of H=24 W/m °C.
Assuming constant thermal conductivity and no heat generation in the wall, (a)
express the differential equation and the boundary conditions for steady one-
MSc. Rasha Nasser
30
Chapter 1 Solutions
Fundamentals of Heat and Mass Transfer
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