Proposed Correlations and Flow Regime Map for Laminar, Transition, and Turbulent Heat Transfer in Plain Tubes with Different Inlet Configurations

Abstract

Using the experimental data presented in Chap. 3, this chapter presents the developed accurate heat transfer correlations for the laminar, transitional, and turbulent dimensionless heat transfer coefficients (Nusselt number) in the entrance and fully developed regions of plain tubes under uniform wall heat flux boundary condition and different inlet configurations (square-edged and re-entrant). The proposed correlations were used to develop a flow regime map. The flow regime map provided in this study can be used to assist the heat exchanger designer in determining the influence of buoyancy in a horizontal circular tube with uniform wall heat flux boundary condition for a specified inlet configuration for all flow regimes. For the identified pure or mixed convection heat transfer regimes, heat transfer calculations can be made based on the recommended correlations. In addition, an illustrative example is presented to demonstrate the use of the proposed correlations.KeywordsSingle-phase flowPlain tubesHeat transfer correlationsLaminar flowTransitional flowTurbulent flowEntrance regionFully developed regionUniform wall heat flux boundary conditionSquare-edged inletRe-entrant inletMixed convectionBuoyancyFlow regime mapIllustrative example