Exhaust gases from a manufacturing plant are being discharged through a 10-m-tall exhaust stack with outer diameter of 1 m. The exhaust gases are discharged at a rate of 1.2 kg/s, while temperature drop between inlet and exit of the exhaust stack is 30°C, and the constant pressure specific heat of the exhaust gasses is 1600 J/kg · K. On a particular day, wind at 27°C is blowing across the exhaust stack with a velocity of 10 m/s, while the outer surface of the exhaust stack experiences radiation with the surrounding at 27°C. Solar radiation is incident on the exhaust stack outer surface at a rate of 1400 W/m², and both the emissivity and solar absorptivity of the outer surface are 0.9. Determine the exhaust stack outer surface temperature. Evaluate the air properties at 80°C.

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Exhaust gases T L = 10 m Exhaust stack α=&=0.9 MA Tin-Tout=30°C Manufacturing plant Wind, 27°C