Exhaust gases from a wire processing oven are discharged into a tall stack, and the gas and stack surface temperatures at the outlet of the stack must be estimated. Knowledge of the outlet gas temperature Ts.o is useful for predicting the dispersion of effluents in the thermal plume, while knowledge of the outlet stack surface temperature Ts.o indicates whether condensation of the gas products will occur. The thin-walled, cylindrical stack is 0.5 m in diameter and 6.0 m high. The exhaust gas flow rate is 0.5 kg/s, and the inlet temperature is 600°C.

(a) Consider conditions for which the ambient air temperature and wind velocity are 4°C and 5 m/s, respectively. Approximating the thermo physical properties of the gas as those of atmospheric air, estimate the outlet gas and stack surface temperatures for the given conditions.

(b) The gas outlet temperature is sensitive to variations in the ambient air temperature and wind velocity. For T∞ = – 25°C, 5°C, and 35°C, compute and plot the gas outlet temperature as a function of wind velocity for 2

Thermal plume Outlet - iameter, 0.5 m Stack Height, 6 m Building Stack base Oven Inlet Oven exhaust gases