Thermodynamics HW Solutions 39

# Thermodynamics HW Solutions 39 - Properties The thermal...

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Chapter 1 Basics of Heat Transfer 1-81E The inner and outer glasses of a double pane window with a 0.5-in air space are at specified temperatures. The rate of heat transfer through the window is to be determined Assumptions 1 Steady operating conditions exist since the surface temperatures of the glass remain constant at the specified values. 2 Heat transfer through the window is one-dimensional. 3 Thermal properties of the air are constant.
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Unformatted text preview: Properties The thermal conductivity of air at the average temperature of (60+42)/2 = 51 ° F is k = 0.01411 Btu/h.ft. ° F (Table A-15). Analysis The area of the window and the rate of heat loss through it are 2 m 36 ft) 6 ( ft) 6 ( = × = A Btu/h 439 = ° − ° = − = ft 12 / 25 . F ) 42 60 ( ) ft F)(36 Btu/h.ft. 01411 . ( 2 2 1 L T T kA Q & Air Glass 60 ° F 42 ° F Q & 1-39...
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