An air heater for an industrial application consists of an insulated, concentric tube annulus, for which air flows through a thin-walled inner tube. Saturated steam flows through the outer annulus, and condensation of the steam maintains a uniform temperature Ts on the tube surface.

Consider conditions for which air enters a 50-mm-diameter tube at a pressure of 5 atm, a temperature of Tm,i; = 17°C, and a flow rate of m = 0.03 kg/s, while saturated steam at 2.455 bars condenses on the outer surface of the tube. If the length of the annulus is L = 5 m, what are the outlet temperature Tm,o and pressure Po of the air? What is the mass rate at which condensate leaves the annulus?

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Insulation- Di- T, Air m, Tmi Pi Saturated steam, Pst