The condenser of a steam power plant consists of AISI 302 stainless steel tubes (k s = 15 W/m ∙ K) each of outer and inner diameters Do = 30 mm and Di = 26 mm, respectively. Saturated steam at 0.135 bar condenses on the outer surface of a tube, while water at a mean temperature of Tm = 290 K is in fully developed flow through the tube.

(a) For a water flow rate of m = 0.25 kg/s, what is the outer surface temperature Ts.o of the tube and the rates of heat transfer and steam condensation per unit tube length? As a first estimate, you may evaluate the properties of the liquid film at the saturation temperature. If one wishes to increase the transfer rates, what is the limiting factor that should be addressed?

(b) Explore the effect of the water flow rate on Ts.o and the rate of heat transfer per unit length.