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Zhang, X.; Hendro, W.; Fujii, Minoru; Tomimura, Toshio; Imaishi, Nobuyuki

doi:10.1023/a:1016394104244

Cited by 61 publications

(23 citation statements)

References 13 publications

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“…In either case a long wire is required. About 10 years ago, Fujii et al [9][10][11] proposed an alternative method where the two-dimensional unsteady heat conduction equation was solved simultaneously for the wire and sample fluid, automatically accounting for the finite length of the wire. This method has some important advantages over the conventional technique.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the method is referred to as the "transient short-hot-wire method." The possibility of using a short wire is particularly valuable for reducing the sample size and for measurement of properties of electrically conductive and corrosive fluids where it is necessary to apply a protective coating to the wire [10]. Moreover, the apparatus is simpler than the conventional hot-wire apparatus and all departures from ideal one-dimensional heat conduction are included directly in the numerical model.…”

Section: Introductionmentioning

confidence: 99%

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Determining Thermal Conductivity and Thermal Diffusivity of Low-Density Gases Using the Transient Short-Hot-Wire Method

et al. 2008

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The transient short-hot-wire method for measuring thermal conductivity and thermal diffusivity makes use of only one thermal-conductivity cell, and end effects are taken into account by numerical simulation. A search algorithm based on the Gauss-Newton nonlinear least-squares method is proposed to make the method applicable to high-diffusivity (i.e., low-density) gases. The procedure is tested using computer-generated data for hydrogen at atmospheric pressure and published experimental data for low-density argon gas. Convergence is excellent even for cases where the temperature rise versus the logarithm of time is far from linear. The determined values for thermal conductivity from experimental data are in good agreement with published values for argon, while the thermal diffusivity is about 10 % lower than the reference data. For the computer-generated data, the search algorithm can return both thermal conductivity and thermal diffusivity to within 0.02 % of the exact values. A one-dimensional version of the method may be used for analysis of low-density gas data produced by conventional transient hot-wire instruments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determining Thermal Conductivity and Thermal Diffusivity of Low-Density Gases Using the Transient Short-Hot-Wire Method

et al. 2008

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“…The transient short-hot-wire method for measuring thermal conductivity and thermal diffusivity was developed in the late 1990s by Fujii et al [1][2][3]. It is a variant of the conventional transient hot-wire method with the novelty that only one short conductivity cell is used and end effects are accounted for by numerical simulation of unsteady heat conduction in the cell.…”

Section: Introductionmentioning

confidence: 99%

“…It is a variant of the conventional transient hot-wire method with the novelty that only one short conductivity cell is used and end effects are accounted for by numerical simulation of unsteady heat conduction in the cell. The method is particularly useful for corrosive or electrically conductive fluids, where it is necessary to apply protective coatings to the wire [3]. For such applications, short wire reduces the probability of failure of the insulation.…”

Section: Introductionmentioning

confidence: 99%

A Two-Dimensional Analytical Solution for the Transient Short-Hot-Wire Method

et al. 2008

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Unlike the conventional transient hot-wire method for measuring thermal conductivity, the transient short-hot-wire method uses only one short thermalconductivity cell. Until now, this method has depended on numerical solutions of the two-dimensional unsteady heat conduction equation to account for end effects. In order to provide an alternative and to confirm the validity of the numerical solutions, a twodimensional analytical solution for unsteady-state heat conduction is derived using Laplace and finite Fourier transforms. An isothermal boundary condition is assumed for the end of the cell, where the hot wire connects to the supporting leads. The radial temperature gradient in the wire is neglected. A high-resolution finite-volume numerical solution is found to be in excellent agreement with the present analytical solution.

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“…Mais recentemente, Fujii et al [11] propôs um método chamado de "método do fio quente curto transiente", que pode ser usado para medir de k e α de líquidos simultaneamente. Posteriormente, pôde-se medir estas propriedades de muitos tipos de líquidos, como polímeros derretidos (Zhang et al [12] ), carbonatos fundidos (Zhang et al [13] )…”

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Sonda metálica reduzida para a caracterização térmica de polímeros

2012

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Vários métodos têm sido utilizados na determinação da condutividade e difusividade térmica. Dentre esses, cita-se o Método do Fio Quente, que é muito utilizado por ser um método transiente de troca de calor que determina estas propriedades de forma simultânea e rápida. Neste trabalho o Método do Fio Quente com uma sonda de dimensões reduzidas é usado para obter a condutividade e difusividade térmica do Policloreto de Vinila (PVC) e da Poliamida. Este método se baseia na passagem de uma corrente contínua através de um fio de resistência, gerando calor que aquece uma sonda inserida na amostra. Da dissipação do calor é possível calcular a condutividade térmica. Para determinar a difusividade térmica minimiza-se uma função erro, definida pelo quadrado da diferença entre a temperatura experimental e a numérica. A temperatura numérica é obtida pela solução da equação da difusão unidimensional em coordenadas cilíndricas utilizando o Método de Diferenças Finitas com formulação explícita. O diferencial deste trabalho refere-se às pequenas dimensões da sonda, possibilitando a utilização de amostras menores, além de apresentar um novo dispositivo para fixar corretamente os componentes. Os resultados estimados apresentaram boa concordância com a literatura.

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Cited by 61 publications

References 13 publications

Determining Thermal Conductivity and Thermal Diffusivity of Low-Density Gases Using the Transient Short-Hot-Wire Method

Determining Thermal Conductivity and Thermal Diffusivity of Low-Density Gases Using the Transient Short-Hot-Wire Method

A Two-Dimensional Analytical Solution for the Transient Short-Hot-Wire Method

Sonda metálica reduzida para a caracterização térmica de polímeros

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