O H.W.: The heat transfer coefficient for air flowing over a sphere is to be determined by observing the temperature-time history of a sphere fabricated from pure copper. The sphere, which is 12.7 mm in diameter, is at 66°C before it is inserted into an airstream having a temperature of 27°C. A thermocouple on the outer surface of the sphere indicates 55°C 69 s after the sphere is inserted in the airstream. Assume, and then justify, that the sphere behaves as a spacewise isothermal object and calculate the heat transfer coefficient. 3 p= 8933 kg/m, Cp 389 J/kg-K, k 398 %3D Too =27°C T(0) = 66°C T(69s) =55°C -D=12.7mm 21 Warith Alanbiyaa (Dr. ALI M) Heat Transfer

O H.W.: The heat transfer coefficient for air flowing over a sphere is to be determined by observing the temperature-time history of a sphere fabricated from pure copper. The sphere, which is 12.7 mm in diameter, is at 66°C before it is inserted into an airstream having a temperature of 27°C. A thermocouple on the outer surface of the sphere indicates 55°C 69 s after the sphere is inserted in the airstream. Assume, and then justify, that the sphere behaves as a spacewise isothermal object and calculate the heat transfer coefficient. 3 p= 8933 kg/m, Cp 389 J/kg-K, k 398 %3D Too =27°C T(0) = 66°C T(69s) =55°C -D=12.7mm 21 Warith Alanbiyaa (Dr. ALI M) Heat Transfer

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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= 2562 J/kg.k, Pr 51.3, µ = 5.22E-3 Pa.s, k 0.260 W/m.K" flows at 0.9 kg/min inside a 3-mm diameter, thin- walled tube. The tube is coiled and Hot fluid %3D %3D %3D 00 submerged in a water bath maintained at 23°C. The fluid experiences a temperature drop of 65°C and leaves the tube at 35°C. What is the required length of the tube "m"? Neglect heat transfer · enhancement associated with the coiling. Assume fully developed flow, if turbulent flow use Dittus, Boelter equation: Nu = 0.023 Re 71 Pr. Select one: A. 18.40 B. 20.07 C. 21.98 D. 23.90 O E. 25.33 S PAGE NEXT PAGE nation