Repeat Prob. 17€“23, assuming the space between the two glass layers is evacuated.

Data from 17-23

Consider a 1.2-m-high and 2-m-wide doublepane window consisting of two 3-mm-thick layers of glass (k = 0.78 W/m · K) separated by a 12-mm-wide stagnant air space (k = 0.026 W/m · K). Determine the steady rate of heat transfer through this double-pane window and the temperature of its inner surface for a day during which the room is maintained at 24°C while the temperature of the outdoors is 25°C. Take the convection heat transfer coefficients on the inner and outer surfaces of the window to be h₁ = 10 W/m² · K and h₂ = 25 W/m² · K, and disregard any heat transfer by radiation.

Glass 12 3 mm Frame