Thermal Conductivity of Loose-Fill Materials by a Radial-Heat-Flow Method

Flynn, D R

doi:10.1007/978-1-4615-3286-6_2

Cited by 9 publications

(7 citation statements)

References 2 publications

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“…The effective thermal conductivity of a ZnO + C powder mixture was experimentally determined by the radial heat flow method. 26 The apparatus is depicted in Figure 11. It features two concentric cylinders of radii r 1 and r 2 , the inner one containing the central electric heater of length L H , and the powder placed between the two cylinders.…”

Section: Appendix: Effective Thermal Conductivitymentioning

confidence: 99%

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Solar Carbothermal Reduction of ZnO: Shrinking Packed-Bed Reactor Modeling and Experimental Validation

Osinga

Olalde

Steinfeld

2004

Ind. Eng. Chem. Res.

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The thermodynamics and kinetics of the carbothermic reduction of ZnO are examined over the temperature range 400−1600 K. Above 1340 K, the equilibrium composition of the stoichiometric chemical system consists of an equimolar gas mixture of Zn (vapor) and CO. Assuming a first-order rate constant for the surface reaction kinetics between ZnO(s) and CO and further applying a shrinking spherical particle model with an unreacted core, the apparent activation energy obtained by linear regression of the thermogravimetric data is E A = 201.5 kJ/mol. A numerical model is formulated for a solar chemical reactor that uses concentrated solar radiation as the energy source of process heat. The model involves solving, by the finite-volume technique, a 1D unsteady-state energy equation that couples heat transfer to the chemical kinetics for a shrinking packed bed exposed to thermal radiation. Validation is accomplished by comparison with experimentally measured temperature profiles and Zn production rates as a function of time, obtained for a 5-kW solar reactor tested in a high-flux solar furnace. Application of the model for a scaled-up reactor predicts a large temperature gradient at the top layer, which is typical of ablation processes where heat transfer through the bed becomes the rate-controlling mechanism. Once the temperature of the top layer exceeds 1200 K, the bed shrinks at an approximately constant speed of 2.8 × 10-5 m/s as the reaction proceeds under a constant radiative flux input.

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Section: Appendix: Effective Thermal Conductivitymentioning

confidence: 99%

“…The effective thermal conductivity of a ZnO + C powder mixture was experimentally determined by the radial heat flow method . The apparatus is depicted in Figure .…”

mentioning

confidence: 99%

Solar Carbothermal Reduction of ZnO: Shrinking Packed-Bed Reactor Modeling and Experimental Validation

Osinga

Olalde

Steinfeld

2004

Ind. Eng. Chem. Res.

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“…Even if the measurement principle is the same, the first group uses Cartesian geometry (see Figure 1) [3,4], while the second uses cylindrical geometry [5]. For the first, the sample has the form of a slab, and a sandwich is assembled, consisting of the heater, the sample, and a hot sink (e.g., a water circulation circuit).…”

Section: Guarded Hot Ring and Guarded Hot Platementioning

confidence: 99%

“…Regarding the thermal diffusivity measurements, the laser flash method is handled in Sections 4.1 and 4.2, the dual-probe method in Section 4.3, photothermal methods in Section 4.4, and the thermal waving source method in Section 4. 5.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Measuring Thermodynamic and Transport Thermophysical Properties: A Review

et al. 2022

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The present review describes the up-to-date state of the evaluation of thermophysical properties (TP) of materials with three different procedures: modeling (also including inverse problems), measurements and analytical methods (e.g., through computing from other properties). Methods to measure specific heat and thermal conductivity are described in detail. Thermal diffusivity and thermal effusivity are a combination of the previously cited properties, but also for these properties, specific measurement and calculation methods are reported. Experiments can be carried out in steady-state, transient, and pulse regimes. For modeling, special focus is given to the inverse methods and parameter estimation procedures, because through them it is possible to evaluate the thermophysical property, assuring the best practices and supplying the measurement uncertainty. It is also cited when the most common data processing algorithms are used, e.g., the Gauss–Newton and Levenberg–Marquardt least squares minimization algorithms, and how it is possible to retrieve values of TP from other data. Optimization criteria for designing the experiments are also mentioned.

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“…6,7 The steady state methods measure thermal properties by establishing a temperature gradient that does not change over time. Absolute technique, 8 radial heat flow method, 9 and parallel thermal conductance technique 10 are common examples of steady-state methods. However, very often these methods require a relatively large sample (centimeter scale), a standard circular or rectangular shape, and usually a long measurement time, even up to a few hours per measurement point.…”

Section: Introductionmentioning

confidence: 99%

Combination of thermal and electric properties’ measurement techniques in a single setup suitable for radioactive materials in controlled environments and based on the 3ω approach

Shrestha

Gofryk

2018

Review of Scientific Instruments

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We have designed and developed a new experimental setup, based on the 3ω method, to measure thermal conductivity, heat capacity, and electrical resistivity of a variety of samples in a broad temperature range (2-550 K) and under magnetic fields up to 9 T. The validity of this method is tested by measuring various types of metallic (copper, platinum, and constantan) and insulating (SiO) materials, which have a wide range of thermal conductivity values (1-400 W m K). We have successfully employed this technique for measuring the thermal conductivity of two actinide single crystals: uranium dioxide and uranium nitride. This new experimental approach for studying nuclear materials will help us to advance reactor fuel development and understanding. We have also shown that this experimental setup can be adapted to the Physical Property Measurement System (Quantum Design) environment and/or other cryocooler systems.

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Thermal Conductivity of Loose-Fill Materials by a Radial-Heat-Flow Method

Cited by 9 publications

References 2 publications

Solar Carbothermal Reduction of ZnO: Shrinking Packed-Bed Reactor Modeling and Experimental Validation

Solar Carbothermal Reduction of ZnO: Shrinking Packed-Bed Reactor Modeling and Experimental Validation

Modeling and Measuring Thermodynamic and Transport Thermophysical Properties: A Review

Combination of thermal and electric properties’ measurement techniques in a single setup suitable for radioactive materials in controlled environments and based on the 3ω approach

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