The spherical shell method of determining the thermal conductivity of a thermal insulator

Green, S E

doi:10.1088/0959-5309/44/3/307

Cited by 8 publications

(2 citation statements)

References 6 publications

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“…This polymerization range includes a dramatic increase in the heat capacity, 79 and the thermal conductivity monotonically increases until the sulfur reaches a depolymerization 80 point, where the thermal conductivity plateaus and is a nearly constant ∼0.17 W m −1 K −1 up to the vaporization temperature. It is nice to note that our measurements closely follow those from the literature for orthorhombic, [81][82][83][84][85] monoclinic, 84 and molten sulfur. 84,86 The most important aspect of this measurement, however, is that it shows that the measurement procedure (sensor design and data analysis) can function through solid and liquid phase transformation and is even sensitive enough to pick up changes in thermal properties due to solid-solid phase transformations in a reactive/corrosive material.…”

Section: Measurementssupporting

confidence: 81%

“…Experimental measurements are shown in comparison to literature values. 81,82,84,86 sulfur undergoes polymerization, 75 where the sulfur rings begin to break apart and form long chains. This polymerization range includes a dramatic increase in the heat capacity, 79 and the thermal conductivity monotonically increases until the sulfur reaches a depolymerization 80 point, where the thermal conductivity plateaus and is a nearly constant ∼0.17 W m −1 K −1 up to the vaporization temperature.…”

Section: Measurementsmentioning

confidence: 99%

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Frequency-domain hot-wire sensor and 3D model for thermal conductivity measurements of reactive and corrosive materials at high temperatures

Wingert

Zhao

Kodera

et al. 2020

Review of Scientific Instruments

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High temperature solids and liquids are becoming increasingly important in next-generation energy and manufacturing systems that seek higher efficiencies and lower emissions. Accurate measurements of thermal conductivity at high temperatures are required for the modeling and design of these systems, but commonly employed time-domain measurements can have errors from convection, corrosion, and ambient temperature fluctuations. Here, we describe the development of a frequency-domain hot-wire technique capable of accurately measuring the thermal conductivity of solid and molten compounds from room temperature up to 800 ○ C. By operating in the frequency-domain, we can lock into the harmonic thermal response of the material and reject the influence of ambient temperature fluctuations, and we can keep the probed volume below 1 μl to minimize convection. The design of the microfabricated hot-wire sensor, electrical systems, and insulating wire coating to protect against corrosion is covered in detail. Furthermore, we discuss the development of a full three-dimensional multilayer thermal model that accounts for both radial conduction into the sample and axial conduction along the wire and the effect of wire coatings. The 3D, multilayer model facilitates the measurement of small sample volumes important for material development. A sensitivity analysis and an error propagation calculation of the frequency-domain thermal model are performed to demonstrate what factors are most important for thermal conductivity measurements. Finally, we show thermal conductivity measurements including model data fitting on gas (argon), solid (sulfur), and molten substances over a range of temperatures.

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