PURPOSE AND SCOPE OF THIS DATA ITEM This Item presents evaluated data relating to forced convective heat transfer in annuli with turbulent flow. The major practical applications for both the presented data@ and other data that can be derived from them using the method of superposition*@ are in the thermal design of double pipe heat exchangers@ aircraft heaters@ and cooling channels in process plant. The general calculation procedures for estimating heat transfer and wall temperatures for an annulus with prescribed thermal boundary conditions are summarised in Section 7. The general applicability of the data in this Item is summarised in Section 3. The definition of the controlling parameters and conditions of heat transfer in an annulus are given in Section 4. The basic correlations used to estimate Stanton or Nusselt numbers for an annulus with particular thermal boundary conditions are described in Section 5. Section 5.1 presents the correlations derived for an annulus with one surface at a constant heat flux and the other surface insulated. Correction factors and methods for dealing with large temperature differences in the radial and in the axial directions are given in Sections 5.1.1 and 5.1.2. For the relatively infrequent case when both surfaces of the annulus are subjected to a heat flux@ Section 5.2 presents additional modifications necessary to the correlations in Section 5.1@ based on the method of superposition*. Section 5.3 presents a method to be used in conjunction with the basic correlations in order to obtain Nusselt numbers for variable axial heat flux distributions on one or both surfaces of the annulus. Guidance is provided in Section 5.4 on how to obtain an approximate Nusselt number for an annulus with one surface held at constant temperature. Section 6 provides some qualitative guidance on the influence of effects such as free-convection@ eccentricity@ developing temperature profile and thermal radiation. Appendix A details the method of superposition and its use in obtaining data for the case when both surfaces of the annulus are heated with a heat flux that can be varying axially for both@ or for only one@ of the surfaces. Appendix B (issued in 1982) provides information concerning the derivation of the data presented. * This method is detailed in Appendix A. The use of the method of superposition is important in extending the applicability of the available experimental data to cover a wider range of thermal boundary conditions.
ESDU 81045 B-1998 history
1998ESDU 81045 B-1998 FORCED CONVECTIVE HEAT TRANSFER IN CONCENTRIC ANNULI WITH TURBULENT FLOW