You recently moved to a new high-rise apartment building and you want to calculate the total energy gain or loss through your floor-to-ceiling bedroom window during a cold, sunny day. Your window is the third one on the series of windows, as shaded in the Figure, with each window being 3.3 meters wide and 2.9 meter high. Air blows past the windows at -15°C and 27 m/s. You also know that: • The outside surface of the glass is at 3°C. • The window exchanges radiation with the sky at -35°c. • The emissivity of the window is 0.7 and its absorptivity is 0.6. • The sun heats the room at a rate of 200 W per square meter of window. Calculate the net rate of heat gain or loss through the window. Clearly indicate whether the calculated amount is energy gain or loss.

You recently moved to a new high-rise apartment building and you want to calculate the total energy gain or loss through your floor-to-ceiling bedroom window during a cold, sunny day. Your window is the third one on the series of windows, as shaded in the Figure, with each window being 3.3 meters wide and 2.9 meter high. Air blows past the windows at -15°C and 27 m/s. You also know that: • The outside surface of the glass is at 3°C. • The window exchanges radiation with the sky at -35°c. • The emissivity of the window is 0.7 and its absorptivity is 0.6. • The sun heats the room at a rate of 200 W per square meter of window. Calculate the net rate of heat gain or loss through the window. Clearly indicate whether the calculated amount is energy gain or loss.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.57P

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