Some properties of glass are listed here:
Density: 2300 kg/m^3
Specific heat: 840 J/kg * C, 'C' is degrees Celsius
Coefficient of linear thermal expansion: 8.5 * 10^-6 (C)^-1, 'C' is degrees Celsius.
Thermal conductivity: 0.80 W/(m * C), 'C' is degrees Celsius.
A glass window pane is 2.7-m high, 2.4-m wide, and 2.0-mm thick. The temperature at the inner surface of the glass is 22 degrees Celsius and at the outer surface 4.0 degrees Celsius. How much heat is lost each hour through the window?
How would I go about solving this, what formula, etc? Thanks
Density: 2300 kg/m^3
Specific heat: 840 J/kg * C, 'C' is degrees Celsius
Coefficient of linear thermal expansion: 8.5 * 10^-6 (C)^-1, 'C' is degrees Celsius.
Thermal conductivity: 0.80 W/(m * C), 'C' is degrees Celsius.
A glass window pane is 2.7-m high, 2.4-m wide, and 2.0-mm thick. The temperature at the inner surface of the glass is 22 degrees Celsius and at the outer surface 4.0 degrees Celsius. How much heat is lost each hour through the window?
How would I go about solving this, what formula, etc? Thanks
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The rate of heat conduction (in W = J/s) is given by ..
dH/dt = k A ∆θ/x ..
(k= thermal conductivity, A = Area perp. to heat flow, ∆θ = temperature difference, x = material thickness)
dH/dt = 0.80*(2.70m*2.40m)*(22 - 4)º / 0.002m = 46,656 J/s
For 1hr .. heat loss = 46,656J/s x 3600s .. .. ►H = 1.68^8 J
(this calculation ignores the thin layer of air that normally adheres to glass surfaces (2) which considerably reduces the heat flow .. improving the insulation)
dH/dt = k A ∆θ/x ..
(k= thermal conductivity, A = Area perp. to heat flow, ∆θ = temperature difference, x = material thickness)
dH/dt = 0.80*(2.70m*2.40m)*(22 - 4)º / 0.002m = 46,656 J/s
For 1hr .. heat loss = 46,656J/s x 3600s .. .. ►H = 1.68^8 J
(this calculation ignores the thin layer of air that normally adheres to glass surfaces (2) which considerably reduces the heat flow .. improving the insulation)