To confirm that a double-pane window is indeed better than a single-pane window, you ran some tests. A 1.5 mx3 m double-pane window as shown in the figure is used for a comparison of heat loss with an equivalent single-pane window. The window is placed in a test environment where the inside air temperature is 300 K and the outside air temperature is 270 K, as shown in the figure. The thermal conductivity of glass is approximated as 0.93 W/m-K and that of air is approximated as 0.029 W/m-K. Consider the air between the two panes of the double-pane window to be stagnant (not even natural convection is taking place). The convection coefficient on both sides (i.e., inside and outside) of the window is 15 W/m².K. What is the rate of heat transfer through the window? Neglect radiation. 339.8W 2.5 mm Inside 300 K glass 7.5 mm stagnant air glass .5 mm Double-pane Outside 270 K

To confirm that a double-pane window is indeed better than a single-pane window, you ran some tests. A 1.5 mx3 m double-pane window as shown in the figure is used for a comparison of heat loss with an equivalent single-pane window. The window is placed in a test environment where the inside air temperature is 300 K and the outside air temperature is 270 K, as shown in the figure. The thermal conductivity of glass is approximated as 0.93 W/m-K and that of air is approximated as 0.029 W/m-K. Consider the air between the two panes of the double-pane window to be stagnant (not even natural convection is taking place). The convection coefficient on both sides (i.e., inside and outside) of the window is 15 W/m².K. What is the rate of heat transfer through the window? Neglect radiation. 339.8W 2.5 mm Inside 300 K glass 7.5 mm stagnant air glass .5 mm Double-pane Outside 270 K

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.24P

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1.29 A spherical interplanetary probe with a 30-cm diameter contains electronic equipment that dissipates 100 W. If the probe surface has an emissivity of 0.8, what is its surface temperature in outer space? State your assumptions in the calculations.
1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4
1.2 The weight of the insulation in a spacecraft may be more important than the space required. Show analytically that the lightest insulation for a plane wall with a specified thermal resistance is the insulation that has the smallest product of density times thermal conductivity.
Consider a double-paned window consisting of two panes of glass, each with a thickness of 0.500 cm and an area of 0.795 m2 , separated by a layer of air with a thickness of 1.50 cm. The temperature on one side of the window is 0.00 ∘C∘C; the temperature on the other side is 21.0 ∘C∘C. In addition, note that the thermal conductivity of glass is roughly 36 times greater than that of air. Approximate the heat transfer through this window by ignoring the glass. That is, calculate the heat flow per second through 1.50 cmcm of air with a temperature difference of 21.0 ∘C∘C. (The exact result for the complete window is 25.6 J/sJ/s .)
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In a new residential project, you strongly believe thatdouble-paned windows are ‘better’ than single-paned windows.Compare the rate of heat loss between single and double-panedwindows (1.5 m x 1 m) if the thickness of each pane is (th = 0.4 cm)and (k = 0.9 W/m.K). The indoor and outdoor temperatures are 18°C and 2 °C, respectively. Thickness of the air gap between thedouble-paned windows is (th = 1 cm), and (k = 0.022 W/m.K).Image credit: Windowwhirl.
What is the rate of heat transfer, temperature gradient, and the direction of the heat transfer through a piece of Celotex 3 ft by 8 ft by 1 in. in thickness, if the temp of one surface is 80°F and of the other side is 60°F? - thermal conductivity of Celotex in AES = 0.028.
Question Consider heat loss through the two walls of a house on a winter night. The walls are identical, except that one of them has a tightly fit glass window. Through which wall will the house lose more heat? Explain.
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In a new residential project, you strongly believe that double-paned windows are ‘better’ than single-paned windows. Compare the rate of heat loss between single and double-paned windows(1.5 m x 1 m) if the thickness of each pane is (th = 0.4 cm) and (k = 0.9 W/m.K). The indoor and outdoor temperatures are 18 °C and 2 °C, respectively. Thickness of the air gap between the double-paned windows is (th = 1 cm), and (k = 0.022 W/m.K). Image credit: Windowwhirl.
In a new residential project, you strongly believe that double-paned windows are ‘better’ than single-paned windows. Compare the rate of heat loss between single and double-paned windows (1.5 m x 1 m) if the thickness of each pane is (th = 0.4 cm) and (k = 0.9 W/m.K). The indoor and outdoor temperatures are 18 °C and 2 °C, respectively. Thickness of the air gap between the double-paned windows is (th = 1 cm), and (k = 0.022 W/m.K).
The heat conducts through the shape below. The temperature of the right face is 93 °C, while the left face is at 23 °C. If the top and bottom faces are completely insulated, and the thermal conductivity of the material decreases with decreasing temperature. * Assume that the thermal conductivity is 100 at 23, decreased to 10 at 93. A) Sketch the temperature profile inside the plate. B) If both sides of the plate in the above problem is exposed to air: Left side (h = 20 W/m2K, TL = 20 °C) and right side (h = 90 W/m2K). Calculate the temperature of the air on the right side.