Consider a double-paned window consisting of two panes of glass, each with a thi

Question

Consider a double-paned window consisting of two panes of glass, each with a thickness of 0.500 cm and an area of 0.725msqrd, separated by a layer of air with a thickness of 1.75 cm. The temperature on one side of the window is 0.00 °C; the temperature on the other side is 20.0 °C. In addition, note that the thermal conductivity of glass is roughly 36 times greater than that of air. (a) Approximate the heat transfer through this window by ignoring the glass. That is, calculate the heat flow per second through 1.75 cm of air with a temperature difference of 20.0 C°. (The exact result for the complete window is 19.1 J/s.) (b) Use the approximate heat flow found in part (a) to find an approximate temperature difference across each pane of glass. (The exact result is 0.157 C°.) (Thermal conductivity of glass is 0.84 W/(m*K) and of air is 0.0234 W/(m*K))

Explanation / Answer

(a)           Q /t   = k A [ T /L ]                    = 0.0234 * 0.725 [ 20oC / 0.00175]                    = 193.88 J /s (b)       T = ( Q / t) ( L / kA )              =193.88 * ( 0.005 / 0.84 * 0.725 )             = 0.8366o C Hope this helps u! (a)           Q /t   = k A [ T /L ]                    = 0.0234 * 0.725 [ 20oC / 0.00175]                    = 193.88 J /s (b)       T = ( Q / t) ( L / kA )              =193.88 * ( 0.005 / 0.84 * 0.725 )             = 0.8366o C Hope this helps u!

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