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Internal-Flow Forced Convection Correlations

UPDATED: 03/07/2018

This workbook computes the Nusselt number for forced convection in a circular pipe as a function of the Reynolds (based on diameter) and Prandtl numbers (and, where appropriate, one or two other parameters). It includes subroutines for laminar, transition and turbulent flows, and for liquid metals (Pr<<1). Results for a range of Reynolds and Prandtl numbers are show in this plot. This spreadsheet was developed to aid in verifying our internal flow module.

 

Nusselt number for forced convection in pipes as a function of Reynolds number and Prandtl number. Note that these results are counterintuitive. The Nusselt number is higher for oils (Pr>>1) than for liquid metals (Pr<<1). But when in dimensional form (h, the convective heat transfer coefficient) is much higher for liquid metals than for oils.
Nusselt number for forced convection in pipes as a function of Reynolds number and Prandtl number, computed from the usual recommended correlations. This plot is misleading.  For the heat transfer practitioner, the bottom line is “h,” the convection coefficient, not Nusselt number. With h = Nu * k/D, convection heat transfer coefficients are generally much higher for liquid metals than for oils.

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