Thermodynamics HW Solutions 754

Thermodynamics HW - Chapter 9 Natural Convection 9-87 The U-factor for the center-of-glass section of a double pane window is to be determined

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Chapter 9 Natural Convection 9-87 The U-factor for the center-of-glass section of a double pane window is to be determined. Assumptions 1 Steady operating conditions exist. 2 Heat transfer through the window is one-dimensional. 3 The thermal resistance of glass sheets is negligible. Properties The emissivity of clear glass is given to be 0.84. The values of h i and h o for winter design conditions are h i = 8.29 W/m 2 . ° C and h o = 34.0 W/m 2 . ° C (from the text). Analysis Disregarding the thermal resistance of glass sheets, which are small, Air space i h 1 space 1 h o h 1 ε = 0.84 Glass 13 mm the U-factor for the center region of a double pane window is determined from 11 1 Uh h io center space ≅+ + 1 h where h i , h space , and h o are the heat transfer coefficients at the inner surface
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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