Correlating equations for laminar and turbulent free convection from a vertical plate

Correlating equations for laminar and turbulent free convection from a horizontal cylinder

A single comprehensive equation is developed for the rate of heat and mass transfer from a circular cylinder in crossflow, covering a complete range of Pr (or Sc) and the entire range of Re for which data are available. This expression is a lower bound (except possibly for RePr < 0.2); free-stream turbulence, end effects, channel blockage, free convection, etc., may increase the rate. In the complete absence of free convection, the theoretical expression of Nakai and Okazaki may be more accurate for RePr < 0.2. The correlating equation is based on theoretical results for the effect of Pr in the laminar boundary layer, and on both theoretical and experimental results for the effect of Re. The process of correlation reveals the need for theoretical results for the effect of Pr in the region of the wake. Additional experimental data for the effect of Pr at small Pe and for the effect of Re during the transition in the point of separation are also needed.

A Correlating Equation for Forced Convection From Gases and Liquids to a Circular Cylinder in Crossflow

Heat transfer model for evaporation in microchannels. Part I: presentation of the model

Reference LTCM-ARTICLE-2005-021View record in Web of Science Record created on 2005-07-06, modified on 2017-05-10

Heat Transfer Model for Evaporation in Microchannels, Part I: Presentation of the Model

The expression Y = (1 + Zn)1/n where Y and Z are expressed in terms of the solutions for asymptotically large and small values of the independent variable is shown to be remarkably successful in correlating rates of transfer for processes which vary uniformly between these limiting cases. The arbitrary exponent n can be evaluated simply from plots of Y versus Z and Y/Z versus 1/Z. The expression is quite insensitive to the choice of n and the closest integral value can be chosen for simplicity. The process of correlation can be repeated for additional variables in series. Illustrative applications are presented only for flow, conduction, forced convection, and free convection, but the expression and procedure are applicable to any phenomenon which varies uniformly between known, limiting solutions.

R. Usagi

Papers

A general expression for the correlation of rates of transfer and other phenomena

A Standardized Procedure for the Production of Correlations in the Form of a Common Empirical Equation