The following thermal-resistance data were obtained on a 50,000-ft2 condenser constructed with 1-in.-OD brass tubes, 23 3/4 ft long, 0.049 in. wall thickness, at various water velocities inside the tubes [Trans. ASME, vol. 58, p. 672, 1936].

Assuming that the heat transfer coefficient on the steam side is 2000 Btu/(h ft2 ?F) and the mean bulk water temperature is 50?C, determine the scale resistance.GIVENWater flowing inside a brass tube condenserTotal transfer are (At) = 50,000 ft2Tube outside diameter (D) = 1 inTube length (L) = 23.75 ftTube wall thickness (t) = 0.049 inHeat transfer coefficient on the steam side (hcs) = 2000 Btu/(h ft2 ?F)Mean bulk water temperature = 50?CThermal resistance data shown aboveASSUMPTIONSData were taken at steady stateThe tube temperature can be considered uniform and constantCondenser surface area is based on the tube outsidediameter

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1/U, x 10 ((h ft F/Btu) Water Velocity Water Velocity 1E,x 10' (th ftD/Btu) (fps) (fps) 2.060 3.076 2.743 2.95 6.91 6.35 5.68 4.90 2.93 4.12 2.113 2.212 2.374 6.76 2.86 2.498 3.356 2.209 6.27 3.001 2.081 7.01