A double-glazed window consists of two panes of glass, each of thickness t = 6 mm. The

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A double-glazed window consists of two panes of glass, each of thickness t = 6 mm. The inside room temperature is Ti = 20°C with h= 7.7 W/m· K, while the outside temperature is T= –10°C with h= 25 W/m· K. The gap between the glass sheets is of thickness L = 5 mm and is filled with a gas. The glass surfaces may be treated with a low-emissivity coating to reduce their emissivity from ε = 0.95 to ε = 0.95. Determine the heat flux through the window for case 1: ε= ε= 0.95, case 2: ε= ε= 0.05, and case 3: ε1 = 0.05, ε= 0.95. Consider either air or argon of thermal conductivity kAr = 17.7 X 10–3 W/m· K to be within the gap. Radiation heat transfer occurring at the external surfaces of the two glass sheets is negligible, as is free convection between the glass sheets.

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Fundamentals Of Heat And Mass Transfer

ISBN: 9780470501979

7th Edition

Authors: Theodore L. Bergman, Adrienne S. Lavine, Frank P. Incropera, David P. DeWitt

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