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Solved: A type-302 stainless steel tube of inner and outer
Chapter , Problem 11.2(choose chapter or problem)
A type-302 stainless steel tube of inner and outer diameters Di 22 mm and Do 27 mm, respectively, is used in a cross-flow heat exchanger. The fouling factors, R , for the inner and outer surfaces are estimated to be 0.0004 and 0.0002 m2 K/W, respectively. (a) Determine the overall heat transfer coefficient based on the outside area of the tube, Uo. Compare the thermal resistances due to convection, tube wall conduction, and fouling. (b) Instead of air flowing over the tube, consider a situation for which the cross-flow fluid is water at 15C with a velocity of Vo 1 m/s. Determine the overall heat transfer coefficient based on the outside area of the tube, Uo. Compare the thermal resistances due to convection, tube wall conduction, and fouling. (c) For the waterair conditions of part (a) and mean velocities, um,i , of 0.2, 0.5, and 1.0 m/s, plot the overall heat transfer coefficient as a function of the cross-flow velocity for 5 Vo 30 m/s. (d) For the waterwater conditions of part (b) and cross-flow velocities, Vo, of 1, 3, and 8 m/s, plot the overall heat transfer coefficient as a function of the mean velocity for 0.5 um,i 2.5 m/s.
Questions & Answers
QUESTION:
A type-302 stainless steel tube of inner and outer diameters Di 22 mm and Do 27 mm, respectively, is used in a cross-flow heat exchanger. The fouling factors, R , for the inner and outer surfaces are estimated to be 0.0004 and 0.0002 m2 K/W, respectively. (a) Determine the overall heat transfer coefficient based on the outside area of the tube, Uo. Compare the thermal resistances due to convection, tube wall conduction, and fouling. (b) Instead of air flowing over the tube, consider a situation for which the cross-flow fluid is water at 15C with a velocity of Vo 1 m/s. Determine the overall heat transfer coefficient based on the outside area of the tube, Uo. Compare the thermal resistances due to convection, tube wall conduction, and fouling. (c) For the waterair conditions of part (a) and mean velocities, um,i , of 0.2, 0.5, and 1.0 m/s, plot the overall heat transfer coefficient as a function of the cross-flow velocity for 5 Vo 30 m/s. (d) For the waterwater conditions of part (b) and cross-flow velocities, Vo, of 1, 3, and 8 m/s, plot the overall heat transfer coefficient as a function of the mean velocity for 0.5 um,i 2.5 m/s.
ANSWER:Step 1 of 18
Calculate overall coefficient based on outside area of the tube for the stainless steel tube;
Here, the overall heat transfer coefficient of tube is represented by 
