Thermodynamics HW Solutions 892

Thermodynamics HW Solutions 892 - A low-e coating on the...

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Chapter 11 Fundamentals of Thermal Radiation 11-68C A device that blocks solar radiation and thus reduces the solar heat gain is called a shading device. External shading devices are more effective in reducing the solar heat gain since they intercept sun’s rays before they reach the glazing. The solar heat gain through a window can be reduced by as much as 80 percent by exterior shading. Light colored shading devices maximize the back reflection and thus minimize the solar gain. Dark colored shades, on the other hand, minimize the back refection and thus maximize the solar heat gain. 11-69C
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Unformatted text preview: A low-e coating on the inner surface of a window glass reduces both the ( a ) heat loss in winter and ( b ) heat gain in summer. This is because the radiation heat transfer to or from the window is proportional to the emissivity of the inner surface of the window. In winter, the window is colder and thus radiation heat loss from the room to the window is low. In summer, the window is hotter and the radiation transfer from the window to the room is low. 11-70C Glasses coated with reflective films on the outer surface of a window glass reduces solar heat both in summer and in winter. 11-30...
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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