73 x 105

G 103

éDo + ÉDt where B is the atmospheric pressure (in. Hg), T is temperature (°R), and G is the mass velocity (lbm/ft2 hr).

Pressure Drop in Ducts. In practical applications, the essential need is to predict pressure drops in piping and duct networks. The friction factor approach is adequate for straight runs of constant area ducts. But valves nozzles, elbows, and many other types of fittings are necessarily included in a network. This can be accounted for by defining an equivalent length Le for the fitting. Table I.10 shows Le/D values for many different fittings.

Pressure Drop across Tube Banks. Another commonly encountered application of fluid dynamics is the pressure drop caused by transverse flow across arrays of heat-transfer tubes. One technique to calculate this effect is to find the velocity head loss through the tube bank:

Bernoulli's Equation. There are some cases where the equation

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