Thermal Conductivity of Ultrapure NaF Using Two-Fluid Anharmonic Phonon Theory

1983 ◽  
pp. 437-445
Author(s):  
Baxter H. Armstrong
Keyword(s):  
Thermal Conductivity ◽  
Two Fluid ◽  
Phonon Theory

Thermal Stability of Two Fluid Layers Separated by a Solid Interlayer of Finite Thickness and Thermal Conductivity

1984 ◽  
Vol 106 (3) ◽  
pp. 605-612 ◽  
Author(s):  
I. Catton ◽  
J. H. Lienhard
Keyword(s):  
Thermal Conductivity ◽  
Fluid Layer ◽  
Heated Surface ◽  
Finite Thickness ◽  
Fluid Layers ◽  
The Stability ◽  
Stability Limits ◽  
Range Of Values ◽  
Two Fluid ◽  
Thermal Stability Of

Stability limits of two horizontal fluid layers separated by an interlayer of finite thermal conductivity are determined. The upper cooled surface and the lower heated surface are taken to be perfectly conducting. The stability limits are found to depend on the ratio of fluid layer thicknesses, the ratio of interlayer thickness to total fluid layer thickness, and the ratio of fluid thermal conductivity to interlayer thermal conductivity. Results are given for a range of values of each of the governing parameters.

An explanation of the Al2O3 nanofluid thermal conductivity based on the phonon theory of liquid

Energy ◽  
2016 ◽  
Vol 116 ◽  
pp. 786-794 ◽  
Author(s):  
Fabrizio Iacobazzi ◽  
Marco Milanese ◽  
Gianpiero Colangelo ◽  
Mauro Lomascolo ◽  
Arturo de Risi
Keyword(s):  
Thermal Conductivity ◽  
Phonon Theory ◽  
Al2o3 Nanofluid

The thermal conductivity of tin at low temperatures

1955 ◽  
Vol 229 (1179) ◽  
pp. 473-492 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperatures ◽  
Fluid Model ◽  
Accurate Method ◽  
Resistance Thermometers ◽  
Lattice Waves ◽  
Normal States ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Good Agreement

An account is given of an accurate method of measuring the thermal conductivity of metals between 0·2 and 4°K using carbon aquadag resistance thermometers. Experimental curves are shown for tin specimens of different crystal structure and of varying impurity contents in both superconducting and normal states, and they are analyzed on the basis of the two-fluid model of superconductivity. It appears that at low temperatures the conductivity is mainly due to the lattice, since the observed temperature variation for all specimens is consistent with a T 3 law at sufficiently low temperatures. Good agreement is obtained between the effective mean free paths of the lattice waves and the values expected from the rod dimensions and crystal sizes. The electronic contribution to the thermal conduction in the superconducting state falls very rapidly below T c , and, to a first approximation, the ratio of this contribution to that in the normal state is a function of temperature and not of impurity. The effects of magnetic fields on measurements of thermal conductivity are also briefly discussed and it is shown that the results may be complicated by frozen-in flux.

Fluctuation Hydrodynamics, Thermophoresis of Nanoparticles and Heat Transfer in Nanofluids

2012 ◽  
Author(s):  
Alexandr S. Dmitriev
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Brownian Motion ◽  
Temperature Gradient ◽  
Long Wavelength ◽  
Long Wave ◽  
New Type ◽  
The One ◽  
Fluid Hydrodynamics ◽  
Two Fluid

In this paper we studied in the framework of two-fluid hydrodynamics with fluctuations the behavior of nanoparticles in the liquid with temperature gradient [1, 2]. It is shown that the acoustic long-wave fluctuations are not damped in liquids (long-wavelength phonons) and leads to an additional force acting on the nanoparticles, as well as lead to the emergence of a new force of thermophoresis [3], which is proportional to the temperature in three second degree. It is also shown that such a thermophoresis force arising under the two-fluid hydrodynamics, can lead to instability of an ensemble of nanoparticles in the presence of a temperature gradient. The last effect leads to the possible merger of the nanoparticles in the form of elongated clusters. The appearance of such clusters on the one hand, leads to an increase in effective thermal conductivity of nanofluids, and secondly, appearing elongated clusters contribute to the propagation of long-wavelength phonons along of such clusters. In fact, this new type of heat transfer in nanofluids, which must be considered in addition to the Brownian motion of nanoparticles.

scholarly journals Thermal conductivity difference between nanofluids and micro-fluids: Experimental data and theoretical analysis using mass difference scattering

2019 ◽  
Vol 23 (6 Part B) ◽  
pp. 3797-3807
Author(s):  
Fabrizio Iacobazzi ◽  
Gianpiero Colangelo ◽  
Marco Milanese ◽  
Risi de
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Theoretical Analysis ◽  
Metal Oxides ◽  
Mass Difference ◽  
Deionized Water ◽  
Experimental Results ◽  
Experimental Campaign ◽  
Nanometric Particles ◽  
Phonon Theory

In this work, an experimental campaign on different nanofluids and micro-fluids, obtained by the dispersion of three different metal oxides (CuO, ZnO, and TiO2) with diathermic oil or deionized water has been carried out, in order to extend phonon theory to liquids, as already done in a previous work on Al2O3. Thermal conductivity of stable samples was evaluated by time. The experimental results on thermal conductivity of stable micrometric and nanometric particles suspensions in oil and water showed a further proof of mass difference scattering phenomenon.

scholarly journals Two-Fluid Theory of Interplanetary Shock Waves

1980 ◽  
Vol 91 ◽  
pp. 327-331
Author(s):  
P. Rosenau
Keyword(s):  
Thermal Conductivity ◽  
Solar Wind ◽  
Fluid Flow ◽  
Interplanetary Shock ◽  
Blast Waves ◽  
Time Dependent ◽  
Post Shock ◽  
Fluid Theory ◽  
Thermally Conducting ◽  
Two Fluid

A 2-fluid time-dependent analytical model of the perturbed solar wind is presented. The expansion of newly emitted material, caused, for instance, by the outburst of a solar flare, is simulated by a spherical piston. For a given thermal conductivity in the limit of strong coupling, one fluid flow in a thermally conducting medium is recovered. A pattern of flow which resembles one-fluid flow in adiabatic medium may be recovered if heat is removed from the perturbed plasma into the propelling plasma. The perturbed flow consists of a thermal precursor which is followed by a shock across which electrons are isothermal while protons are compressed and heated. Finally, we show that the post-shock rise and fall of density cannot be used to distinguish piston-driven waves from blast waves.

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