S-ST-1-2 Tubeside Heat Transfer to Liquids and Gases (Pr > 0.5) in Turbulent and Transitional Flow
A confusing number of correlations for the tubeside turbulent heat transfer can be found in the literature. In this report, the major correlational parameters were evaluated against a representative set of data with wide spread of physical properties.
In the developed turbulent range (Re > 10000) the "film" temperature based correlations were found to be of about equal quality to the "bulk" based methods with a viscosity correction factor. In the transitional range, however, the bulk Reynolds number was established as a better correlational parameter. For this reason our recommended equation is based on bulk temperature, combining good correlational properties under a uniform method.
Furthermore, several values of the Prandtl number exponent were investigated and 0.4 was found superior in correlating heating and cooling data. Based on latest data, a new correlation for the tube entry effects as function of L/D and Re is also proposed and designated as a correction factor l.
The tube length correction factor l is defined by eq. 6.4, but can be omitted for (L/D) > 60 and Re > 10000. The term in brackets correlates the transitional region and dies out at higher Reynolds numbers.
Some further preliminary suggestions are offered on the treatment of the lower transitional range 1800 < Re < 3000 to assure a smooth transition to the laminar equation.