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 1.3P

A concrete wall, which has a surface area of 2 0  m 2 andis 0.30 in thick, separates conditioned room air fromambient air. The temperature of the inner surface of thewall is maintained at 25°C, and the thermal conductivity of the concrete is 1 W/m K .
(a) Determine the heat loss through the wall for outersurface temperatures ranging from 15 ° C to 38°C,which correspond to winter and summer extremes,respectively. Display your results graphically.
(b) On your graph, also plot the heat loss as a function ofthe outer surface temperature for wall materials having thermal conductivities of 0.75 and 1.25 W/m K . Explain the family of curves you have obtained.

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