A feedwater heater that supplies a boiler consists of a shell-and-tube heat exchanger with one shell pass and two tube passes. One hundred thin-walled tubes each have a diameter of 20 mm and a length (per pass) of 2 m. Under normal operating conditions water enters the tubes at 10 kg/s and 290 K and is heated by condensing saturated steam at 1 atm on the outer surface of the tubes. The condensed flow exits at saturated state. The convection coefficient of the saturated steam is 10,000 W/m^2.K. Required:
Using the effectiveness-NTU method, determine the water outlet temperature.