Hot air flows with a mass flow rate m = 0.09 kg/s through an uninsulate of diameter D = 0.15 m, which is in the crawlspace of a house. The hot air enters at 110°C and, after a distance of L 5 m, cools to 80°C. The heat transfer coefficient between the duct surface and the ambient air at To 0°C is known to be h, = 9 W/m²K. (a) Calculate the heat loss from the duct over the length L. (b) Determine the heat flux and the surface temperature at x = L. (c) Determine the heat flux and the surface temperature at x = 0. neet %3D Assume, for air at Tm 368 K: Cp = 1011 J/kg.K; for air at Tm,L = 353 K: k = 0.030 W/m.K, u 209x10 N.s/m2, Pr= 0.70; for air at Tm,0 =383 K: k = 0.033 W/m.K, u 223x10 N.s/m2, Pr = 0.69. Show all calculations.

Hot air flows with a mass flow rate m = 0.09 kg/s through an uninsulate of diameter D = 0.15 m, which is in the crawlspace of a house. The hot air enters at 110°C and, after a distance of L 5 m, cools to 80°C. The heat transfer coefficient between the duct surface and the ambient air at To 0°C is known to be h, = 9 W/m²K. (a) Calculate the heat loss from the duct over the length L. (b) Determine the heat flux and the surface temperature at x = L. (c) Determine the heat flux and the surface temperature at x = 0. neet %3D Assume, for air at Tm 368 K: Cp = 1011 J/kg.K; for air at Tm,L = 353 K: k = 0.030 W/m.K, u 209x10 N.s/m2, Pr= 0.70; for air at Tm,0 =383 K: k = 0.033 W/m.K, u 223x10 N.s/m2, Pr = 0.69. Show all calculations.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Question

Hot air flows with a mass flow rate m = 0.09 kg/s through an uninsulated sheet metal duct
of diameter D = 0.15 m, which is in the crawlspace of a house. The hot air enters at 110°C
and, after a distance of L 5 m, cools to 80°C. The heat transfer coefficient between the
duct surface and the ambient air at To 0°C is known to be h, = 9 W / m²K.
(a) Calculate the heat loss from the duct over the length L.
(b) Determine the heat flux and the surface temperature at x = L.
(c) Determine the heat flux and the surface temperature at x = 0.
Assume, for air at Tm 368 K: c, 1011 J/kg.K;
for air at Tm.L = 353 K: k= 0.030 W/m.K, u = 209x10' N.s/m2, Pr = 0.70%;
for air at Tm,0 = 383 K: k = 0.033 W/m.K, u=223x10" N.s/m2, Pr = 0.69.
Show all calculations.
Cold Air
Hot air
in
-L-

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