Self-thermophoresis and thermal self-diffusion in liquids and gases.

نویسنده

  • Howard Brenner
چکیده

This paper demonstrates the existence of self-thermophoresis, a phenomenon whereby a virtual thermophoretic force arising from a temperature gradient in a quiescent single-component liquid or gas acts upon an individual molecule of that fluid in much the same manner as a "real" thermophoretic force acts upon a macroscopic, non-Brownian body immersed in that same fluid. In turn, self-thermophoresis acting in concert with Brownian self-diffusion gives rise to the phenomenon of thermal self-diffusion in single-component fluids. The latter furnishes quantitative explanations of both thermophoresis in pure fluids and thermal diffusion in binary mixtures (the latter composed of a dilute solution of a physicochemically inert solute whose molecules are large compared with those of the solvent continuum). Explicitly, the self-thermophoretic theory furnishes a simple expression for both the thermophoretic velocity U of a macroscopic body in a single-component fluid subjected to a temperature gradient ∇T , and the intimately related binary thermal diffusion coefficient D{T} for a two-component colloidal or macromolecular mixture. The predicted expressions U=-D{T}∇T≡-βD{S}∇T and D{T}=βD{S} (with β and D{S} the pure solvent's respective thermal expansion and isothermal self-diffusion coefficients) are each noted to accord reasonably well with experimental data for both liquids and gases. The likely source of systematic deviations of the predicted values of D{T} from these data is discussed. This appears to be the first successful thermodiffusion theory applicable to both liquids and gases, a not insignificant achievement considering that the respective thermal diffusivities and thermophoretic velocities of these two classes of fluids differ by as much as six orders of magnitude.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Modeling the Solubility of Acid Gases in Ionic Liquids

In this work, the PC-SAFT equation of state (EoS) has been used to model the solubility of acid gases (CO2 and H2S) in two imidazolium-based ionic liquids (ILs) ([C8-mim][PF6] and [C8-mim][Tf2N]). Parameters of pure ILs were estimated using experimental densities. Two strategies were considered to model densities of pure ILs. In strategy 1, ILs were modeled as nonassociating compounds and in st...

متن کامل

Fluid Flow and Heat Transfer of Nanofluids over a Flat Plate with Conjugate Heat Transfer

The falling and settling of solid particles in gases and liquids is a natural phenomenon happens in many industrial processes. This phenomenon has altered pure forced convection to a combination of heat conduction and heat convection in a flow over a plate. In this paper, the coupling of conduction (inside the plate) and forced convection of a non-homogeneous nanofluid flow (over a flat plate) ...

متن کامل

Thermophoretic depletion follows Boltzmann distribution.

Thermophoresis, also termed thermal diffusion or the Soret effect, moves particles along temperature gradients. For particles in liquids, the effect lacks a theoretical explanation. We present experimental results at moderate thermal gradients: (i) Thermophoretic depletion of 200 nm polystyrene spheres in water follows an exponential distribution over 2 orders of magnitude in concentration; (ii...

متن کامل

سنتز و بررسی رفتار حرارتی مایعات یونی هایپرگول جدید بر پایه کاتیون ایمیدازولیوم و آنیون دی سیانامید

A hypergolic bipropellant s consist of fuels and oxidizers that can ignite rapidly upon mixing without external ignition devices . This self –ignition technology makes the engine ignition more reliable with repeated use. Recently, ionic liquids with the dicyanamide anion which shown good hypergolic properties when contacted with common oxidizer such as concentrated nitric acid, were attracte...

متن کامل

Thermal Diffusion Factor in Gas Mixture-Dufour Effect (I)

The thermal diffusion factor, aT, for a binary gas mixture is calculated on the basis of nonequilibrium thermodynamics. A new formula for aT is derived and this factor is given for several paris of gases according to this formula.

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Physical review. E, Statistical, nonlinear, and soft matter physics

دوره 82 3 Pt 2  شماره 

صفحات  -

تاریخ انتشار 2010