A heat transfer textbook

https://www.eis.hu.edu.jo/deanshipfiles/pub10311353.pdf

Numerical study of natural convection in partially heated rectangular enclosures filled with nanofluids

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

The autoignition of mixtures of ethane, methane, carbon monoxide and hydrogen in air at atmospheric pressure was studied theoretically using a detailed, free-radical, kinetic model. The elementary reactions for the model were chosen with the help of the sensitivity analysis of Rabitz et al., which utilizes a Green's function transformation. This technique was particularly helpful in identifying those reactions which are important during the induction period prior to ignition. The effects of equivalence ratio, initial temperature and constant rate of heating were investigated for various fuel compositions. Induction times from 10 microns to 11.5 microsec were calculated for adiabatic ignition with initial temperatures from 1300 to 2100 K. Mixtures of pure methane and air were found to have long induction times, but small additions of ethane and even lesser additions of hydrogen, produced dramatic reductions. The flamefront was broadened significantly by large initial concentrations of carbon monoxide, due to its relatively slow rate of oxidation even at high temperature. 11 references.

Computer study of the constant pressure auto-ignition of mixtures of ethane, methane, carbon monoxide and hydrogen in air

The conversion due to first- and second-order, irreversible, equimolar reactions in fully developed isothermal laminar flow in a round tube was computed exactly for perfect, finite, and negligible molecular diffusion of species and energy. The analogous computations for fully developed turbulent flow were based on an essentially exact velocity distribution but an empirical model for the eddy diffusion of species and energy. The effect of a moderate heat of reaction was computed numerically for constant density, constant viscosity, and adiabatic conditions. The identification and implementation of a new dimensionless variable led to the discovery of several near-invariances and, thereby, to very simple but reasonably accurate algebraic representations for the mixed-mean conversion and the mixed-mean temperature for moderately energetic reactions.

Interaction of Reactions and Transport: Homogeneous Reactions in a Round Tube. IV. The First-Order Effects of Flow and Heat of Reaction

Thermally stabilized combustion of premixed ethane and air in a ceramic tube results in a virtual step function in temperature, composition, and velocity at the flame front. Fit the mixture is fuel-rich, the burned gas consists almost wholly of CO, CO{sub 2}, H{sub 2}O, and N{sub 2}. For a tube greater than 30 mm in diameter, the stable range of flow is in the turbulent regime both upstream and downstream from the flame front. In this paper an experimental technique exploiting this environment for study of the devolatilization of coal is described, and illustrative results are presented. As compared with other techniques using heated grids or entrainment, the conditions outside a particle are more uniform and the rate of heating is greater, but the velocity and temperature of the particle must be determined from momentum and energy balances rather than by direct measurement.

Thermally stabilized combustion as a means of studying the devolatilization of coal

Experiments of a premixed flame inside a refractory tube

A transitional regime, as characterized by a point of inflection, links the asymptotic regimes for large and small values of the independent variable in many physical and chemical systems. A new methodology has been devised for representation of the overall behavior including such a transition by a single correlating equation. This development is based on the identification of one exact and one nearly exact solution in closed form for such a transition and on the recognition that these two particular solutions correspond to the same special case of the canonical correlating equation proposed by Churchill and Usagi for multiple regimes. This correspondence previously escaped recognition because it is evident only for one particular arrangement of the closed-form solutions and for one particular reduction and arrangement of the canonical correlating equation. The new generalized formulation appears to be applicable even for behavior for which the internal asymptote representing the transition is not known in advance, which is the usual situation

Stuart W. Churchill

Papers

Computer study of the constant pressure auto-ignition of mixtures of ethane, methane, carbon monoxide and hydrogen in air

Interaction of Reactions and Transport: Homogeneous Reactions in a Round Tube. IV. The First-Order Effects of Flow and Heat of Reaction

Thermally stabilized combustion as a means of studying the devolatilization of coal

Experiments of a premixed flame inside a refractory tube

Correlating Equations for Transitional Behavior