hw3-solution - 1. The heat transfer coefficient for air...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
1. 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 66ºC before it is inserted into an airstream having a temperature of 27ºC. A thermocouple on the outer surface of the sphere indicates 55ºC, 69 seconds 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. ASSUMPTIONS: (1) Temperature of sphere is spatially uniform, (2) Negligible radiation exchange, (3) Constant properties. PROPERTIES: Table A-1 , for pure copper (333K): ρ = 8933 kg/m 3 , c p = 389 J/kg K, k = 398 W/m K. ANALYSIS: Assuming the uniform temperature over the sphere, we use the Lumped Capacitance Method. t cL ρ h t cV ρ hA T T T T c i exp exp where 002117 . 0 6
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/05/2011 for the course ME me352 taught by Professor Koraykadirsafak during the Spring '11 term at Yeditepe Üniversitesi.

Page1 / 4

hw3-solution - 1. The heat transfer coefficient for air...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online