Internal forced convective heat transfer in coiled pipes.
Abstract:ESDU 78031 applies to Newtonian single-phase flow of gases or liquids. The method was developed by correlating data from a wide range of sources in the literature. Three Reynolds numbers regimes were identified and for the middle, transition, region no prediction method is available; it is recommended that the most conservative of the predictions for the other two regimes on either side be used. For the low Reynolds number regime three boundary conditions are considered: uniform wall temperature, uniform wall flux, and uniform wall flux axially combined with uniform wall temperature circumferentially. Graphs and equations are given for mean Nusselt number for each of those boundary conditions and for the high Reynolds number regime where no effect of boundary condition was found. A correction factor for cross-sectional variation of fluid properties is also included.In some cases it was found that the curvature effect on heat transfer is negligible; criteria for the applicability of the straight pipe data of ESDU 92003 and ESDU 93018 are given. A flowchart assists in guiding the user through the method and a practical worked example illustrates its use. The method is found to predict experimental results in the literature to within 25 per cent in all cases, although some situations are more closely estimated, for example, the high Reynolds number regime for which the rms error was only 14 per cent.
|Data Item ESDU 78031