Estimation of Prandtl numbers in binary mixtures of helium and other noble gases

Giacobbe, F. W.

doi:10.1121/1.410615

Cited by 52 publications

(12 citation statements)

References 3 publications

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“…However, the calculation of the predominant boundary layer perturbations when a mixture fills the resonator requires a careful estimate of the thermal conductivity of the mixture. This property was obtained using the methods of kinetic theory reviewed by Giacobbe [14]. Besides the classical absorption caused by the irreversible flows of heat and momentum that are associated with sound propagation in pure gases, extra absorption takes place in a mixture due to mass and thermal diffusion effects, with a contribution to the halfwidths [15]:…”

Section: Analysis and Discussion Of Acoustic Resultsmentioning

confidence: 99%

Shell Perturbations of an Acoustic Thermometer Determined from Speed of Sound in Gas Mixtures

et al. 2010

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With the goal of achieving a better understanding of gas-shell coupling perturbations in the acoustic resonators used at INRiM for the determination of the Boltzmann constant, we measured the variation of their acoustic and microwave resonances induced by changing the composition of a binary He-Ar mixture which filled the cavity at constant temperature and pressure. As a consequence of the progressive dilution of a sample of initially pure He with Ar, the radial acoustic modes of the resonator spanned decreasing frequency intervals, partially overlapping, for several modes. In addition to the expected breathing mode of the shell, the results evidenced the presence of several other shell resonances at lower and higher frequencies, confirming that the elastic response of the assembled resonator significantly differs from that of a simple spherical shell. Experimental results are reported for two resonators which differ in design, dimensions, and constructing material. In spite of their being preliminary and susceptible of significant improvement, these results favor the interpretation of acoustic thermometry measurements with pure gases.

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Section: Analysis and Discussion Of Acoustic Resultsmentioning

confidence: 99%

Shell Perturbations of an Acoustic Thermometer Determined from Speed of Sound in Gas Mixtures

et al. 2010

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“…This is modest but encouraging since the devices can be optimized for higher performance by one to two orders of magnitude. Larger cooling power densities can be achieved by modifying the geometry (such as larger quality factor Q of resonator), raising the gas pressure [4], and using gas mixtures of lower Prandtl number [18]. Heat removal by acoustic radiation from a prime mover provides an approach, which works especially well over short distances from the heat source.…”

Section: Resultsmentioning

confidence: 99%

Design and development of high-frequency thermoacoustic engines for thermal management in microelectronics

Symko

Abdel‐Rahman

Kwon

et al. 2004

Microelectronics Journal

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Thermoacoustic heat engines provide a practical solution to the problem of heat management in microcircuits where they can be used to pump heat or produce spot cooling of specific circuit elements. There are basically two types of thermoacoustic engines, a prime mover where heat is converted to acoustic energy, and a heat pump or cooler where sound can pump heat up a temperature gradient. Such devices are relatively simple, they can be efficient, and they are readily adaptable to microcircuit interfacing. Since this type of engines is usually operated in a resonant mode, the operating frequency determines its size. The devices presented here are pumped at frequencies ranging from 4 to 24 kHz. They have been developed for interfacing with microcircuits as heat pumps or spot coolers. Results of their performance are presented and suggestions for further improvements are discussed. q

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“…The Prandtl number has the ideal gas value of 0.667 for pure helium and pure neon. But according to [5] there is a minimum in the Prandtl number of the mixtures around a neon content of 25%. …”

Section: Choice Of Refrigerantmentioning

confidence: 96%

Nelium, a Refrigerant with High Potential for the Temperature Range between 27 and 70 K

Quack¹,

Haberstroh²,

Seemann³

et al. 2015

Physics Procedia

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In the search for the optimum process for the liquefaction of hydrogen, it was found that mixtures of helium and neon, called "Nelium", allow processes with very high efficiency compared to pure helium or pure neon. This is demonstrated in the design of a 500 kW refrigerator between 40 and 60 K, whereby the composition is varied between pure helium and pure neon. It turns out that helium-rich mixtures have an advantage for the heat exchange, whereas the neon-rich mixtures are easier to compress in turbo compressors. In any case a process efficiency of over 44% is feasible.

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Estimation of Prandtl numbers in binary mixtures of helium and other noble gases

Cited by 52 publications

References 3 publications

Shell Perturbations of an Acoustic Thermometer Determined from Speed of Sound in Gas Mixtures

Shell Perturbations of an Acoustic Thermometer Determined from Speed of Sound in Gas Mixtures

Design and development of high-frequency thermoacoustic engines for thermal management in microelectronics

Nelium, a Refrigerant with High Potential for the Temperature Range between 27 and 70 K

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