The performance of spirally enhanced tubes is discussed in this paper in terms of heat transfer enhancement, friction factor enhancement, and enhancement efficiency as a function of a single nondimensional geometric parameter, the severity. Heat transfer and friction factor data from more than 60 different tubes are shown to collapse to a single curve with minimal scatter when plotted as a function of the severity. It is shown that in turbulent flow the increase in friction factor is usually much larger than the corresponding increase in heat transfer. In addition, values of severity between 0.001 and 0.01 are shown to yield optimum enhancement for turbulent flow.

Units: Dual