Thermodynamics HW Solutions 258

Thermodynamics HW Solutions 258 - Chapter 3 Steady Heat...

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Chapter 3 Steady Heat Conduction Analysis Using the available R -values from Tables 3-6, the total R- value of the wall is determined in the table below. R- value, Construction m 2 . ° C/W 1. Outside surface, 24 km/h 0.030 2. Face brick, 100 mm 0.075 3. Common brick, 100 mm 0.12 4. Urethane foam insulation, 25-mm 0.98 5. Gypsum wallboard, 13 mm 0.079 6. Inside surface, still air 0.12 5 1 2 3 4 6 Total unit thermal resistance of each section, R 1.404 m 2 . ° C/W The U -factor of each section, U = 1/ R 0.712 W/m 2 . ° C Therefore, the overall unit thermal resistance of the wall is R = 1.404 m 2 . ° C/W and the overall U-factor is U = 0.712 W/m 2 . ° C. 3-146 The U -value of a wall under winter design conditions is given. The U -value of the wall under summer design conditions is to be determined. Assumptions 1 Steady operating conditions exist. 2 Heat transfer through the wall is one-dimensional.
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This note was uploaded on 01/19/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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