Thermodynamics HW Solutions 898

# Thermodynamics HW Solutions 898 - 2 (Table 11-5). Analysis...

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Chapter 11 Fundamentals of Thermal Radiation 11-76 A house has double door type windows that are double pane with 6.4 mm of air space and aluminum frames and spacers. It is to be determined if the house is losing more or less heat than it is gaining from the sun through a South window in a typical day in January. Assumptions 1 The calculations are performed for an “average” day in January. 2 Solar data at 40 ° latitude can also be used for a location at 39 ° latitude. Properties The shading coefficient of a double pane window with 3-mm thick clear glass is SC = 0.88 (Table 11-5). The overall heat transfer coefficient for double door type windows that are double pane with 6.4 mm of air space and aluminum frames and spacers is 4.55 W/m 2 . ° C (Table 9-6). The total solar radiation incident at a South-facing surface in January during a typical day is 5897 Wh/m
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Unformatted text preview: 2 (Table 11-5). Analysis The solar heat gain coefficient (SHGC) of the windows is determined from Eq.11-57 to be Double-pane window Sun Solar heat gain Heat loss 22°C 10°C SHGC = 0.87 × SC = 0.87 × 0.88 = 0.7656 Then the solar heat gain through the window per unit area becomes kWh 4.515 Wh 4515 = = = × × = ) Wh/m )(5897 m 1 ( 7656 . 2 2 l daily tota solar, glazing gain solar q A SHGC Q The heat loss through a unit area of the window during a 24-h period is kWh 1.31 Wh 1310 = = ° − ° ⋅ = − = Δ = h) C(24 ) 10 )(22 m 1 ( C) W/m 55 . 4 ( ) day 1 )( ( 2 2 ave , window window window loss, window loss, T T A U t Q Q i & Therefore, the house is gaining much more heat than it is loosing through the South windows during a typical day in January. 11-36...
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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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