Cylinders flow across banks

Forced convection heat transfer is probably the most common mode in the process industries. Forced flows may be internal or external. This subsection briefly introduces correlations for estimating heat-transfer coefficients for flows in tubes and ducts flows across plates, cylinders, and spheres flows through tube banks and packed beds heat transfer to nonevaporating falling films and rotating surfaces. Section 11 introduces several types of heat exchangers, design procedures, overall heat-transfer coefficients, and mean temperature differences. 

The coefficient and exponent vary with the fluid, temperature level, and configuration. For turbulent flow, the exponent on velocity, V, is about 0.52 to 0.61 for flow across a single cylinder, 0.67 for flow across a bank of cylinders, 0.75 for flow parallel to a flat surface, and 0.80 for flow inside a pipe. 

Heat-transfer data for flow normal to cylinders of noncircular cross section are given in the literature. Banks of tubes across which the fluid flows are common in industrial exchangers. Problems of heat flow in tube banks are discussed in Chap. 15. 

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