# Ch3Pr - 2 = 125 mm The end temperatures are T 1 = 600 K and...

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ChEn 323 – Chapter 3 Problems - Slide 1 Problem 3.14 Consider the composite wall of Problem 3.13 under conditions for which the inside air is still characterized by T ¥ ,i = 20°C and hi = 30 W/m2K. However, use a more realistic conditions for which the outside air is characterized by a diurnal varying temperature of the form With ho = 60 W/m2K. Assuming quasisteady conditions for which changes in energy storage within the wall may be neglected, estimate the daily heat loss through the wall if its total surface area is 200 m2. h t t K T h t t K T o o 24 12 , 24 2 sin 11 273 ) ( 12 0 , 24 2 sin 5 273 ) ( , , + = + = p p

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ChEn 323 – Chapter 3 Problems - Slide 2 Problem 3.14 (continued)
ChEn 323 – Chapter 3 Problems - Slide 3 Problem 3.29 A conical section is fabricated from pure aluminum. It is of circular cross section having diameter D = a x 1/2 , where a = 0.5 m 1/2 . The small end is located at x 1 = 25 mm and the large end at x

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Unformatted text preview: 2 = 125 mm. The end temperatures are T 1 = 600 K and T 2 = 400 K, while the lateral surface is well insulated. 1.Derive an expression for the temperature distribution T(x) in symbolic form, assuming one-dimensional conditions. Sketch the temperature distribution. 2.Calculate the heat rate q x . ChEn 323 – Chapter 3 Problems - Slide 4 Problem 3.29 (continued) ChEn 323 – Chapter 3 Problems - Slide 5 Problem 3.141 Determine the percentage increase in heat transfer associated with attaching aluminum fins of rectangular profile to a plane wall. The fins are 50 mm long, 0.5 mm thick, and are equally spaced at a distance of 4 mm (250 fins/m). The convection coefficient associated with the bare wall is 40 W/m 2 K, while that resulting from attachment of the fins is 30 W/m 2 K. ChEn 323 – Chapter 3 Problems - Slide 6 Problem 3.141 (continued)...
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## This homework help was uploaded on 03/26/2008 for the course CHEN 323 taught by Professor Johnbaldwin during the Fall '03 term at Texas A&M.

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Ch3Pr - 2 = 125 mm The end temperatures are T 1 = 600 K and...

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