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Air at atmospheric pressure and 200 C flows with 6 m/s velocity through main trunk duct of air conditioning system. The duct is rectangular in cross-section and measures 40 cm × 80 cm. Determine heat loss per meter length of duct corresponding to unit temperature difference. The relevant thermo physical properties of air are: $ν = 15 × 10{-6} m^2/s , \alpha = 7.7 × 10{-2} m^2/hr , k = 0.026 W/m-deg K. Use Nu = 0.023 (Re)^{0.8}× (Pr)^{0.4}$.