A cooling tower, shown schematically, has outside surface temperature of 70ºC when quiescent air is 10ºC. If the nominal diameter of the tower is 20 m, estimate a) the vertical distance up from the base where turbulent flow begins and b) total heat transfer due to natural convection.
What will be an ideal response?
The tower has a large enough diameter that it can be treated as a vertical wall. For this situation turbulent flow due to natural convection occurs at about a Rayleigh number of 1 x 109. Here the temperature difference is 60ºC, air has a Prandtl number of about 0.7, and the film temperature is the average temperature, 40ºC. Then turbulent flow begins at about L predicted from
You might also like to view...
An EM wave with a wavelength of 500 nm will be visible
Indicate whether the statement is true or false
Which feature of Neptune's atmosphere has disappeared since the Voyager 2 fly-by?
a. white methane clouds b. Great Dark Spot c. belt-zone circulation d. Great Red Spot e. its bluish hue
A helicopter is traveling at 54 m/s at a constant altitude of 100 m over a level field. If a wheel falls off the helicopter, with what speed will it hit the ground? Note: g = 9.8 m/s2 and air resistance is negligible
a. 40 m/s c. 60 m/s b. 50 m/s d. 70 m/s
Gamma rays are photons with very high energy. How many visible-light photons with a wavelength of 500 nm would you need to match the energy of a gamma-ray photon with energy 4.1 × 10-13 J? (h = 6.626 × 10-34 J ? s, c = 3.00 × 108 m/s)
A) 1.0 × 106 B) 1.4 × 108 C) 6.2 × 109 D) 3.9 × 103