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 $,$ while

saturated steam at $2\mathrm{.}455$ 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 pres$-$

sure po of the air? What is the mass rate at which con$-$

densate leaves the annulus