Steam at 1 atm and 100C is flowing across a 5-cm-OD tube at a velocity of 6 m/s. Estimatethe Nusselt number, the heat transfer coefficient, and the rateof heat transfer per meterlength of pipe if the pipe is at 200C.

, ,

Explanation:

Let assume that steam has a fully developed and turbulent flow and that tube is smooth and thin-walled. The steam is heated while flowing through the tube. The Nusselt number is given by the Dittus-Boelter equation:

Properties of steam at given pressure and temperature are:

The Reynolds and Prandtl numbers are, respectively:

(which demonstrates the reasonability of the supposition of turbulent flow)

The Nusselt number is:

The Nusselt number has the following definition:

The heat transfer coefficient is:

The convection is the dominant heat transfer mechanism, then:

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