A review of mass transfer measurements using naphthalene sublimation

Publisher Summary This chapter provides an overview of the analytical and experimental hydrodynamics and heat transfer studies of Newtonian and non-Newtonian fluids in laminar and turbulent flow through rectangular tubes. The chapter in particular focuses on the rectangular duct geometry, with emphasis on the friction factor and heat transfer behavior of non-Newtonian fluids. It is recognized that non-Newtonian behavior is generally more complicated than Newtonian flow. In the case of non-Newtonian fluids, the theoretical predictions yield low estimates of the heat transfer under laminar flow conditions. The fact that the available experimental heat transfer measurements lie above the predictions could reflect an inadequacy in the analytical model. For non-Newtonians in turbulent flow through rectangular channels, the situation is even more complicated. Some non-Newtonian fluids act as pseudoplastics, showing some reduction in friction and heat transfer as compared with a Newtonian fluid. Other non-Newtonian fluids experience large reductions in the friction factor and in heat transfer under turbulent flow conditions.

Heat transfer to newtonian and non-newtonian fluids in rectangular ducts

A measurement system consisting of two high- speed two- color pyrometers was used to monitor the flattening degree and cooling rate of zirconia particles on a smooth steel substrate at 75 or 150 °C during plasma spray deposition This instrument provided data on the deformation behavior and freezing of a particle when it impinged on the surface, in connection with its velocity, size, and molten state at impact The results emphasized the influence of temperature and surface conditions on particle spreading and cooling When the substrate temperature was 150 °C, the splats had a perfect lenticular shape, and the thermal interface resistance between the lamella and the substrate ranged from 10− 7 to 10− 8 W/m2 · K The dependence of the flattening degree on the Reynolds number was investigated

Influence of particle parameters at impact on splat formation and solidification in plasma spraying processes

We present a bibliography on moving and free boundary problems for the heatdiffusion equation, particularly regarding the Stefan and related problems. It contains 5869 titles referring to 588 scientific Journals, 122 books, 88 symposia (having at least 3 contributions on the subject), 30 collections, 59 thesis and 247 technical reports. It tries to give a comprehensive account of the western existing mathematicalphysical-engineering literature on this research field. RESUMEN Se presenta una bibliografía sobre problemas de frontera móvil y libre para la ecuación del calor-difusión, en particular sobre el problema de Stefan y problemas relacionados. Contiene 5869 títulos distribuidos en 588 revistas científicas, 122 libros, 88 simposios (teniendo al menos 3 contribuciones en el tema), 30 colecciones, 59 tesis y 247 informes técnicos o prepublicaciones. Se da un informe amplio de la bibliografía matemática, física y de las ingenierías existente en occidente sobre este tema de investigación. Primary Mathematics Subject Classification Number (*): 35R35, 80A22 Secondary Mathematics Subject Classification Number (*): 35B40, 35C05, 35C15, 35Kxx, 35R30, 46N20, 49J20, 65Mxx, 65Nxx, 76R50, 76S05, 76T05, 93C20. (*) Following the 1991 Mathematics Subject Classification compiled by Mathematical Reviews and Zentralblatt fur Mathematik. Primary key words: Enthalpy formulation or method, Filtration, Free boundary problems, Freezing, Melting, Moving boundary problems, Mushy region, Phase-change problem, Solidification, Stefan problem. Secondary key words: Continuous mechanics, Diffusion process, Functional analysis, Heat conduction, Mathematical methods, Numerical methods, Partial differential equations, Variational inequalities, Weak solutions. Palabras claves primarias: Método o formulación en entalpía, Filtración, Problemas de frontera libre, Congelación, Derretimiento, Problemas de frontera móvil, Región pastosa, Problema de cambio de fase, Solidificación, Problema de Stefan. Palabras claves secundarias: Mecánica del continuo, Procesos difusivos, Análisis funcional, Conducción del calor, Métodos matemáticos, Métodos numéricos, Ecuaciones diferenciales a derivadas parciales, Inecuaciones variacionales, Soluciones débiles. El manuscrito fue recibido y aceptado en octubre de 1999. D.A. Tarzia, A bibliography on FBP. The Stefan problem, MAT Serie A, # 2 (2000). 3

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A bibliography on moving-free boundary problems for the heat-diffusion equation. The stefan and related problems

Research in convective heat transfer on internal separated flows has been extensively conducted in the past decades. This review summarizes numerous researches on two topics. The first section focuses on studying the fluid flow and heat transfer behavior of different types of single-phase fluid flows over backward facing step (BFS) at different orientations. The second section concentrates on everything related to nanofluids; its preparation, properties, behavior, applications, and many others. The purpose of this article is to get a clear view and detailed summary of the influence of several parameters such as the geometrical specifications, boundary conditions, type of fluids, and inclination angle on the hydrodynamic and thermal characteristics using (BFS). The reattachment length and maximum Nusselt number are the main target of such research where correlation equations were developed and reported in experimental and numerical studies. The heat transfer enhancement of nanofluids along with the nanofluids preparation technique, types and shapes of nanoparticles, base fluids and additives, transport mechanisms, and stability of the suspension are also discussed.

Convective heat transfer and fluid flow study over a step using nanofluids: A review

An IBM PC was used to obtain finite-difference solutions to a complex heat transfer and fluid flow problem in which the solution domain contained nearly 6000 grid points. The investigated problem was the abrupt, asymmetric enlargement of a parallel-plate channel. The enlargement lakes the form of a backward-facing step, the presence of which causes separation of the flow. Heat transfer occurred at the channel wall which extended downstream from the foot of the step. The present velocity solutions were shown to be at least as accurate as prior numerical solutions and served to extend the range of investigated enlargements. The variation of the local Nusselt number with the Reynolds number took on different forms at various axial distances from the enlargement step. In a region extending downstream from the step, the Nusselt number actually decreased monotonically with increasing Reynolds number. Farther downstream, the Nusselt-Reynolds variation was monotonically increasing, while still farther downstream,...

PC solutions for heat transfer and fluid flow downstream of an abrupt, asymmetric enlargement in a channel

A computationally efficient and highly accurate solution scheme for phase-change problems is described which combines an implicit treatment of the temperature field equations with an explicit treatment of the interface energy balance (s). This scheme avoids the iterative interaction between the field and interface solutions which characterizes a fully implicit treatment. No time-step limitations were encountered in the wide range of numerical solutions that were carried out with the methodology. The accuracy characteristics were established by comparisons with alternative solutions of a number of specific problems involving plane or radial freezing, one or two solid phases, and, in some cases, convective heating at the solid-liquid interface. Depending on the problem, the alternative solutions were analytical, semianalytical, or numerical. The accuracy level of the solid layer thicknesses given by the solution scheme were found to be in the 0.1% range.

An Implicit/Explicit Numerical Solution Scheme for Phase-Change Problems

Turbulent duct flow with streamwise nonuniform heating at the duct wall

Complementary numerical and experimental studies were made of the heat transfer characteristics of a hydrodynamicaUy developed turbulent flow passing through a flat rectangular duct. One, of the principal walls of the duct was maintained at a uniform temperature different from the fluid inlet temperature, while the other walls of the duct were adiabanc. Results were obtained for the local, quasi-local, and average Nusselt numbers in the thermal entrance region and for the fully developed Nusselt number. Both heal and mass transfer versions of the problem were investigated. Excellent agreement prevailed between the experimentally and numerically determined quasi-local Sherwood numbers at a succession of axial stations in the mass transfer entrance region, thereby establishing the analytical model and the numerical solution method. Heat transfer results for airflow were obtained from the numerical solutions for Reynolds numbers between 10,000 and 100,000. It was found that away from the immediate neighborho...

Numerical and experimental turbulent heat transfer results for a one-sided heated rectangular duct

Numerical solutions have been carried out for planar or radial freezing on a cooled wall or cylinder maintained at a uniform temperature lower than the fusion temperature. The solutions were obtained by using an implicit/explicit method developed in the preceding paper in this issue. Results are presented for the frozen layer thick-ness, the instantaneous heat flux at the cooled surface, and the time-integrated heat transfer at the surface, all as a function of time from the beginning of the freezing period. These quantities are normalized in various ways to illuminate their short-time and long-time behaviors and to enable comparisons between planar and radial freezing. Convection at the solid-liquid interface had virtually no effect on the freezing process at short times, but at longer times the convection significantly slowed the freezing and ultimately terminated it. Solid-solid transitions tended to slow the freezing and also to increase the heat transfer at the cooled surface.

W. Chuck

Papers

PC solutions for heat transfer and fluid flow downstream of an abrupt, asymmetric enlargement in a channel

An Implicit/Explicit Numerical Solution Scheme for Phase-Change Problems

Turbulent duct flow with streamwise nonuniform heating at the duct wall

Numerical and experimental turbulent heat transfer results for a one-sided heated rectangular duct

Planar or radial freezing with solid-solid transitions and convective heating atthe solid-liquid interface