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Consider a 300 mm 300 mm window in an aircraft. For a
Chapter , Problem 2.19(choose chapter or problem)
Consider a 300 mm 300 mm window in an aircraft. For a temperature difference of 80 C from the inner to the outer surface of the window, calculate the heat loss through L 10-mm-thick polycarbonate, soda lime glass, and aerogel windows, respectively. The thermal conductivities of the aerogel and polycarbonate are kag 0.014 W/mK and kpc 0.21 W/mK, respectively. Evaluate the thermal conductivity of the soda lime glass at 300 K. If the aircraft has 130 windows and the cost to heat the cabin air is $1/kW h, compare the costs associated with the heat loss through the windows for an 8-hour intercontinental flight
Questions & Answers
QUESTION:
Consider a 300 mm 300 mm window in an aircraft. For a temperature difference of 80 C from the inner to the outer surface of the window, calculate the heat loss through L 10-mm-thick polycarbonate, soda lime glass, and aerogel windows, respectively. The thermal conductivities of the aerogel and polycarbonate are kag 0.014 W/mK and kpc 0.21 W/mK, respectively. Evaluate the thermal conductivity of the soda lime glass at 300 K. If the aircraft has 130 windows and the cost to heat the cabin air is $1/kW h, compare the costs associated with the heat loss through the windows for an 8-hour intercontinental flight
ANSWER:The thermal conductivity of soda lime glass at 300K is 0.84 W/mK.
The heat loss can be calculated by:
Q = U x A x ?T
Where U is the U-value or overall thermal transmittance, A is the area of the window, and ?T is the temperature difference.
For polycarbonate:
Q = (1/kpc x A)/L x ?T