Repeat Problem 7.17 for air flowing over the same two surfaces in the Reynolds number range between 40,000 and 200,000. Neglect radiation. From Problem 7.17: Develop an expression for the ratio of the rate of heat transfer to air at 40°C from a thin flat strip of width πD/2 and length L at zero angle of attack and a tube of the same length and diameter D in cross-flow with its axis normal to the flow. Assume both surfaces are at 90°C.

GIVEN

• Air flowing over a thin flat strip at zero angle of attack or a tube in crossflow
• Air temperature (T_∞) = 40°C
• Tube diameter = D
• Strip width = πD/2
• Tube and strip length = L
• Reynolds number : 40,000 < Re < 200,000

ASSUMPTIONS

• Radiative heat transfer is negligible
• Steady state for both cases
• The tube and strip temperatures (T_s) are 90°C