Example 4: Hot air at atmospheric pressure and 80°C enters an 8–m-long uninsulated square duct of cross section 0.2 m x 0.2 m that passes through the attic of a house at a rate of 0.15 m³/s (Figure). The duct is observed to be nearly isothermal at 60°C. Determine the exit temperature of the air and the rate of heat loss from the duct to the attic space. p = 0.9994 kg/m³ k = 0.02953 W/m · °C v = 2.097 × 10-5 m²/s = 1008 J/kg · °C T;=60°C 0.2 m Pr = 0.7154 Air I atm 80°C 0.2 m 8 m

Example 4: Hot air at atmospheric pressure and 80°C enters an 8–m-long uninsulated square duct of cross section 0.2 m x 0.2 m that passes through the attic of a house at a rate of 0.15 m³/s (Figure). The duct is observed to be nearly isothermal at 60°C. Determine the exit temperature of the air and the rate of heat loss from the duct to the attic space. p = 0.9994 kg/m³ k = 0.02953 W/m · °C v = 2.097 × 10-5 m²/s = 1008 J/kg · °C T;=60°C 0.2 m Pr = 0.7154 Air I atm 80°C 0.2 m 8 m

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.34P

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