加载中…soret effect 索雷特效应
(2012-09-19 22:04:05)
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http://www.ep4.phy.uni-bayreuth.de/ag_koehler/Images/soreteffect_fig1.pngeffect
Compared to other transport properties, reliable experimental data and studies on thermal diffusion in binary liquids are scarce. At the same time, there is no theory available that could predict the amplitude or at least the sign of the Soret coefficient from molecular properties.
Literature
- Thermal Nonequilibrium Phenomena in Fluid Mixtures, edited by W. Köhler and S. Wiegand (Springer, Heidelberg, 2002)
- Thermal Nonequilibrium, edited by S. Wiegand, W. Köhler and J.K.G. Dhont (Research Centre Julich, 2008)
- J. K. Platten, M. M. Bou-Ali, P. Costeseque, J. F. Dutrieux, W. Köhler, C. Leppla, S. Wiegand, and G. Wittko: Benchmark values for the Soret, thermal diffusion, and diffusion coefficients of three binary organic liquid mixtures, Phil. Mag. 83:1965 (2003), doi:10.1080/0141861031000108204
http://www.ep4.phy.uni-bayreuth.de/ag_koehler/en/research_sub/soreteffect.html
Soret Effect
(also thermodiffusion), the diffusion of material in an unevenly heated mixture of gases or a solution caused by the presence of a temperature gradient in the system. The effect is named for the Swiss scientist J. Soret, who was the first to study thermodiffusion (1879).
http://encyclopedia2.thefreedictionary.com/Soret+Effect
Dufour effect is the energy flux due to a mass concentration
gradient occurring as a coupled effect of irreversible
processes.
Thermophoresis, thermodiffusion, or Soret
effect (or Ludwig-Soret effect), is a phenomenon
observed when a mixture of two or more types of motile particles
(particles able to move) are subjected to the force of a temperature
gradient and the different types of particles respond to it
differently. The term "Sorét effect" normally means thermophoresis
in liquids only. The term "thermophoresis" is most often intended
to mean the behavior in aerosols, not liquids,
but the broader meaning is also common. The mechanisms of
thermophoresis in liquid mixtures differ from those in gas
mixtures, and are generally not as well understood.
Dufour effect
The Dufour effect is the energy flux due to a mass concentration gradient occurring as a coupled effect of irreversible processes. It is the reciprocal phenomenen to the Soret effect.[1]
The Dufour effect describes the energy (heat) flux created when a chemical system is under a concentration gradient. This could also be important in CVD problems. This effect is found in the energy equation.
The soret coefficient is the ratio of the thermal diffusion coefficient divided by the ordinary diffusion coefficient.
It is known that both Soret & Dufour effects are negligible, for most applications.
Soret effect- This is a mass flux due to a temperature gradient and appears in the species continuity equation when you have a multicomponent mixture where each species has its own diffusional velocity.
Dufor Effect-This is enthalpy flux due to a concentration gradient and appears in the energy equation for a multicomponent mixture.These effects depend on thermal diffusion which is generally very small but can be sometimes significant when the participating species are of widely differing molecular weights
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