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A large plane wall, 40 cm thick and 8 m2 area, is heated from one side and temperature distribution at a certain time instant is approximately prescribed by the relation T = 80 – 60 x +12 x2 + 25 x3 – 20 x4 Where temperature t is in degree Celsius and the distance x in meters. Make calculations for heat energy stored in the wall in unit time. For wall material: Thermal conductivity = 6 W/m K and thermal diffusivity = 0.02 m2/hr.

A large plane wall, 40 cm thick and 8 m2 area, is heated from one side and temperature distribution at a certain time instant is approximately prescribed by the relation T = 80 – 60 x +12 x2 + 25 x3 – 20 x4 Where temperature t is in degree Celsius and the distance x in meters. Make calculations for heat energy stored in the wall in unit time. For wall material: Thermal conductivity = 6 W/m K and thermal diffusivity = 0.02 m2/hr. Correct Answer 791.04 W

Q IN = – k A (d t/d x)X = 0 = 2880 W and Q OUT = – k A (d t/d x)X = 0.4 = 2088.96 W.

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