Repeatability and Refinement of a Transient Hot-Wire Instrument for Measuring the Thermal Conductivity of High-Temperature Melts

Bilek, J.; Atkinson, J.K.; Wakeham, W. A.

doi:10.1007/s10765-006-0124-4

Cited by 10 publications

(7 citation statements)

References 8 publications

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“…The transient methods for the determination of thermophysical properties, including the hot-wire method, the hot-strip method, the hot-disk method, the hot-plate method, the pulse transient method, the step-wise transient method, the laser-flash method, etc., can be used to perform measurements during the process of heating [11][12][13][14][15][16][17][18][19]. The relatively short duration of the experiments eliminates unwanted physical or chemical changes of the test sample, and hence reduces the measurement errors caused by time; also, the relatively simple experimental setup makes the measurements cost effective.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures

et al. 2012

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Tissue-mimicking phantoms, including bovine serum albumin phantoms and egg white phantoms, have been developed for, and in laboratory use for, realtime visualization of high intensity focused ultrasound-induced thermal coagulative necrosis since 2001. However, until now, very few data are available concerning their thermophysical properties. In this article, a step-wise transient plane source method has been used to determine the values of thermal conductivity, thermal diffusivity, and specific heat capacity of egg white phantoms with elevated egg white concentrations (0 v/v% to 40 v/v%, by 10 v/v% interval) at room temperature (∼20 • C). The measured thermophysical properties were close to previously reported values; the thermal conductivity and thermal diffusivity were linearly proportional to the egg white concentration within the investigation range, while the specific heat capacity decreased as the egg white concentration increased. Taking account of large differences between real experiment and ideal model, data variations within 20 % were accepted.Keywords Egg white phantom · High intensity focused ultrasound (HIFU) ·Step-wise transient plane source (TPS) method · Thermophysical properties ·

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Section: Discussionmentioning

confidence: 99%

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures

et al. 2012

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“…A constant electrical current in the wire results in a nearly constant line source of a heat flux. The theoretical solution of the non-stationary heat transfer problem is known [27][28][29][30][31][32][33]36] for the ideal infinitely long wire. Assuming that the physical properties do not vary during a measurement and heat is generated from a wire of zero radius, the temperature rise T (t) at the extremity of the wire can be represented by…”

Section: Transient Hot-wire Methodsmentioning

confidence: 99%

“…The transient hot-wire method (THW) [27][28][29][30] is used for this purpose in order to avoid the problem related with the influence of the contact resistance on the measurement procedure. This method is well adapted for measurements in liquids [31][32][33][34][35], but the possibility of its application for characterization of porous solid media is an open question. For justification of THW measurements in porous media and estimation of possible errors related with the contact resistance, samples with different thicknesses have been tested.…”

Section: Introductionmentioning

confidence: 99%

Thermal-Conductivity Characterization of Gas Diffusion Layer in Proton Exchange Membrane Fuel Cells and Electrolyzers Under Mechanical Loading

et al. 2011

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Accurate information on the temperature field and associated heat transfer rates is particularly important for proton exchange membrane fuel cells (PEMFC) and PEM electrolyzers. An important parameter in fuel cell and electrolyzer performance analysis is the effective thermal conductivity of the gas diffusion layer (GDL) which is a solid porous medium. Usually, this parameter is introduced in modeling and performance analysis without taking into account the dependence of the GDL thermal conductivity λ (in W · m −1 · K −1 ) on mechanical compression. Nevertheless, mechanical stresses arising in an operating system can change significantly the thermal conductivity and heat exchange. Metrology allowing the characterization of the GDL thermal conductivity as a function of the applied mechanical compression has been developed in this study using the transient hot-wire technique (THW). This method is the best for obtaining standard reference data in fluids, but it is rarely used for thermalconductivity measurements in solids. The experiments provided with Quintech carbon cloth indicate a strong dependence (up to 300 %) of the thermal conductivity λ on the applied mechanical load. The experiments have been provided in the pressure range 0 < p < 8 MPa which corresponds to stresses arising in fuel cells. All obtained experimental results have been fitted by the equation λ = 0.9log(12 p + 17)(1 − 0.4e −50 p ) with 9 % uncertainty. The obtained experimental dependence can be used for correct modeling of coupled thermo/electro-mechanical phenomena in fuel cells and 123 1026 Int J Thermophys (2011) 32:1025-1037 electrolyzers. Special attention has been devoted to justification of the main hypotheses of the THW method and for estimation of the possible influence of the contact resistances. For this purpose, measurements with a different number of carbon cloth layers have been provided. The conducted experiments indicate the independence of the measured thermal conductivity on the number of GDL layers and, thus, justify the robustness of the developed method and apparatus for this type of application.

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“…The sudden changes in time-stepping employed earlier have been removed and the FE model becomes even more accurate. The detailed features of the upgraded FE model, the fundamental mathematical equation as well as the validation of the FE model, have been presented elsewhere [5][6][7][8][9].…”

Section: Modified Transient Hot-wire Techniquementioning

confidence: 99%

“…This new design has been tested in a number of experiments with molten indium, tin, and various solder alloys and the results compared to the values obtained from measurements of the thermal conductivity using the original design [7][8][9]. Both the new and old sensor designs provided similar results with deviations of no more than 2%, which is less than the mutual uncertainty.…”

Section: New Sensor Designmentioning

confidence: 99%

Measurements of the Thermal Conductivity of Molten Lead Using a New Transient Hot-Wire Sensor

2007

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The paper reports new measurements of the thermal conductivity of molten lead at temperatures from 600 to 750 K. The measurements have been carried out with an updated version of a modified transient hot-wire (THW) method, where the hot-wire sensor is embedded within an insulating substrate with a planar geometry. However, unlike previous sensors of the same type, the updated sensor works with the hot-wire divided into three thermally isolated parts. The operation of this sensor has been modeled theoretically using a finite-element (FE) analysis and has subsequently been confirmed by direct observation. The new sensor is demonstrated to have a higher sensitivity and a better signal-to-noise ratio than earlier sensors. Molten lead is used as the test fluid. It has the lowest thermal conductivity of any material we have yet studied. This allows us to probe the limits of our sensor system for the thermal conductivity of high-temperature melts. It is estimated that the uncertainty of the measurements is 3% over the temperature range studied. The results are used to examine the application of the Wiedemann-Franz (W-F) relationship.

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Repeatability and Refinement of a Transient Hot-Wire Instrument for Measuring the Thermal Conductivity of High-Temperature Melts

Cited by 10 publications

References 8 publications

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures

Thermal-Conductivity Characterization of Gas Diffusion Layer in Proton Exchange Membrane Fuel Cells and Electrolyzers Under Mechanical Loading

Measurements of the Thermal Conductivity of Molten Lead Using a New Transient Hot-Wire Sensor

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