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Unformatted text preview: A wall = 0.8 ft 2 and A window = 0.2 ft 2 . Then the rates of heat transfer through the two sections are determined to be Btu/h 0615 . F/Btu . h.ft (13 F) ( ) ft (0.8 wall value, R ) ( 2 2 wall wall wall T T T T A T T A U Q o i o i wall = = = = & Btu/h 160 . F/Btu . h.ft (1.25 F) ( ) ft (0.2 value R ) ( 2 2 window window window window T T T T A T T A U Q o i o i = = = = & Therefore, the rate of heat transfer through a double pane window is much more than the rate of heat transfer through an R13 wall. Discussion The ratio of heat transfer through the wall and through the window is Air R13 Wall Aluminum frames 60 . 2 Btu/h 0.0615 Btu/h 160 . wall window = = Q Q & & Therefore, 2.6 times more heat is lost through the windows than through the walls although the windows occupy only 20% of the wall area. 981...
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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.
 Fall '10
 Dr.DanielArenas
 Thermodynamics, Convection, Mass, Heat

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