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1

Nanofluid and ferrofluid slip flow in rectangular and circular microchannels and miniehanneis

Avsec J., Vitrič P., Naterer G.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 3

5-8

EN

This paper has developed a formulation of fluid motion and entropy production in microchannels. We have developed the formulations for pressure driven flow, flow under electric forces and flow under ferromagnetic forces. Friction, thermal and electromagnetic irreversibilities have significance in energy efficiency of microfluid systems. The results indicate that entropy and the Second Law have practical significance in electrokinetic liquid transport through microchannels.

PL

W artykule pokazano rozwój sformułowania ruchu płynu i entropii produkowanej w mikrokanalikach. Rozwinięte zostały sformułowania dla przepływów poddanych ciśnieniu, przepływów w polu elektrycznym i przepływów poddanych siłom ferromagnetycznym. Ciśnienie, cieplna i elektromagnetyczna nieodwracalność mają istotne znaczenie dla efektywności energetycznej systemów mikroprzepływowych. Wyniki wskazują, że entropia i drugie prawo termodynamiki mają praktyczbe znaczenie w transporcie płynów elektrokinetycznych przez mikrokanaliki.

2

Analysis of coreless stator axial flux permanent magnet synchronous generator characteristics by using equiva lent circuit

Vitrič P., Avsec J.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 3

208-211

EN

This paper presents calculation procedure to predict the characteristics in coreless stator axial flux permanent magnet synchronous generators with surface mounted permanent magnets and double extemal rotor by using equivalent circuit. The input data for the calculation procedure are obtained from the measurements. The characteristics obtained by using measurements and equivalent circuit are in good agreement with analytically calculated results.

PL

Artykuł przedstawia procedurę obliczeń przy użyciu schematu zastępczego do predykcji charakterystyki w bezrdzeniowych stojanach silników synchronicznych z magnesem trwałym o strumieniu osiowym z powierzchniowo zamontowanym magnesem i podwójnym wirnikiem zewnętrznym. Dane wejściowe do procedury obliczeniowej otrzymane są z pomiarów. Charakterystyki otrzymane z pomiarów i i z obliczeń pozostają w dobrej zgodności.

3

Non-equilibrium statistical mechanics formulation of thermal transport properties for binary and ternary gas mixtures

Avsec J., Naterer G., Marcic M.

Archives of Thermodynamics

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2008

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Vol. 29, no. 2

21-46

EN

The paper develops a new statistical formulation to calculate the thermal diffusivity, binary diffusion coefficient, thermal diffusion factor, viscosity and thermal conductivity of gas mixtures with non-equilibrium statistical mechanics. For the analytical calculation of transport properties, the models of Kihara and Chapman-Cowling (up to the third order) have been used. Thermal transport properties for mixtures involving carbon monoxide, helium, argon, xenon and krypton have been computed with the new formulation in this paper. New mixing rules for the calculation of transport properties for mixtures are developed. Close agreement is obtained between the analytical results (based on statistical mechanics) and experimental data. The results exhibit comparable or better accuracy than previous methods, while providing new insight regarding the detailed statistical mechanisms of intermolecular interactions, as they contribute to the transport property variations with temperature.

4

Calculation of equilibrium and nonequilibrium thermophysical properties by means of statistical mechanics

Avsec J.

Journal of Technical Physics

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2003

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Vol. 44, no 2

163-179

EN

The paper features the mathematical model of computing equilibrium and nonequilibrium ther-mophysical properties of state in the liquid and gas domain for pure refrigerants and mixtures with the help of classical thermodynamics and statistical thermodynamics. The paper features all important contributions (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). To calculate the thermodynamic properties of real fluid, the models on the basis of Lennard-Jones intermolecular potential were applied. To calculate the thermodynamic properties of real fluid by means of classical thermodynamics, we used the Tillner-Roth-Watanabe-Wagner (TRWW) equation on the base of Helmholtz type. We have developed a mathematical model for the calculation of all equilibrium and nonequilibrium thermodynamic functions of state for pure refrigerants. The analytical results obtained by statistical thermodynamics are compared with the TRWW model and show a relatively good agreement.

5

Calculation of transport coefficients of R-32 and R-125 with the methods of statistical thermodynamics and kinetic theories of gas

Avsec J.

Archives of Thermodynamics

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2003

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Vol. 24, no 3

69-82

EN

The paper features theoretical model of computing (based on methods of statistical thermodynamics and kinetic theories of gas) viscosity and thermal conductivity in the liquid and gas domain for pure components. To calculate the viscosity of real fluid, the models developed on the basis of Lennard-Jones intermolecular potential are applied. Heat capacities are calculated by use of statistical thermodynamics. The paper features all important contributions (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). The analytical results obtained by statistical thermodynamics are compared with the REFPROP model and show relatively good agreement.

6

Comparison of thermodynamic functions calculated by means of various methods

Avsec J., Marcic M.

Journal of Technical Physics

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2002

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Vol. 43, no 3

309-321

EN

The paper deals with the Lennard-Jones fluid and presents the mathematical model of computating thermodynamic functions of state in the liquid and gas domain by means of statistical thermodynamics. To calculate the thermodynamic properties of a real fluid, we used the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin equation of state, the Chunxi-Yigui-Jiufang equation of state based on the simple perturbation theory, and the complex Tang-Tong-Lu model based on the solution of the Ornstein-Zernike equation obtained by means of the perturbation theory. The analytical results are compared with the thermodynamical data, and with the results obtained from classical thermodynamics.

7

Calculation of thermophysical properties for solids with application of statistical thermodynamics

Avsec J., Marcic M.

Journal of Technical Physics

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2001

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Vol. 42, no 3

327-336

EN

The paper deals with a mathematical model for calculation of the thermodynamic properties of solids. The mathematical model, based upon statistical thermodynamics, is designed to assess the impact of atom vibration, electron excitation and the effect of intermolecular energy between atoms in a crystal. To calculate the configuration integral, the perturbation theory was used with the Van der Waals model as perturbation. The temperature-variable coefficients were introduced into the model presented in this paper. Finally, the model was compared with the experimental data proving a good matching.

8

Calculation of thermodynamical properties in liquid-gas region

Avsec J., Marcic M.

Journal of Technical Physics

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2000

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Vol. 41, no 3

241-252

EN

The paper presents the mathematical model used for the computation of thermodynamic functions of state in the liquid and gas domain, with the aid of statistical thermodynamics of Lennard-Jones fluid. To calculate the thermodynamic properties of a real fluid, we used the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin equation of state, the Chunxi-Yigui-Jiufang equation of state based on the simple perturbation theory, and the complex Tang-Tong-Lu model based on the solution of the Ornstein-Zernike equation obtained by means of the perturbation theory. The analytical results are compared with the thermodynamical data, and with the results obtained from classical thermodynamics. \\@ng\

9

Application of statistical thermodynamics in refrigeration

Avsec J., Marcic M.

Journal of Technical Physics

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1999

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Vol. 40, no 2

247-258

EN

The paper presents the mathematical model for computing the thermodynamical properties in the liquid, gas and two-phase domain by means of statistical thermodynamics. The paper features all important components (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). To calculate the thermodynamic properties of real gases, we have developed the cluster theory, which yields better results than the virial equation. In case of real liquids, the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin (BWR) equation was applied. The Lennard-Jones intermolecular potential was used. The analytical results are compared with the thermodynamical data and models obtained from classical thermodynamics, and they show relatively good agreement.