Solve Problem 15.23 if instead of the surface temperatures being known, the air temperatures outside and inside
Question:
Solve Problem 15.23 if instead of the surface temperatures being known, the air temperatures outside and inside are 30 and 75°F, respectively, and the convective heat-transfer coefficients are 7 and 2 Btu/h ft2 °F, respectively.
Data From Problem 15.23
The outside walls of a house are constructed of a 4-in. layer of brick, 1/2 in. of celotex, an air space 35/8 in. thick, and 1/4 in. of wood paneling. If the outside surface of the brick is at 30°F and the inner surface of the paneling at 75°F, what is the heat flux if
a. The air space is assumed to transfer heat by conduction only?
b. The equivalent conductance of the air space is 1.8 Btu/h ft2 °F?
c. The air space is filled with glass wool?
kbrick = 0.38 Btu/h ft °F
kcelotex = 0.028 Btu/h ft °F
kair = 0.015 Btu/h ft °F
kwood = 0.12 Btu/h ft °F
kwool = 0.025 Btu/h ft °F
Step by Step Answer:
Fundamentals Of Momentum Heat And Mass Transfer
ISBN: 9781118947463
6th Edition
Authors: James Welty, Gregory L. Rorrer, David G. Foster