Heat Exchanger 11.2 A type-302 stainless steel tube of inner and outer diam- eters D₁ = 22 mm and D. = 27 mm, respectively, is used in a cross-flow heat exchanger. The fouling fac- tors, R, for the inner and outer surfaces are estimated to be 0.0004 and 0.0002 m² K/W, respectively. Fouling R factors R Tube, SS302 Water m=75°C "=0.5 m/s johno ad unt We Still tod Air excl D D V-20 m/s by age T= 15°C (a) Determine the overall heat transfer coefficient based on the outside area of the tube, U. Compare the thermal resistances due to convection, tube wall conduction, and fouling. (b) Instead of air flowing over the tube, consider a situ- ation for which the cross-flow fluid is water at 15°C with a velocity of V = 1 m/s. Determine the overall heat transfer coefficient based on the outside area of the tube, U. Compare the thermal resistances due to convection, tube wall conduction, and fouling.