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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 20 (1999), S. 733-742 
    ISSN: 1572-9567
    Schlagwort(e): calorimetry ; diffusivity ; emissivity, heat capacity ; radiant exchange ; simultaneous measurement ; thermal conductivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Thermal radiation calorimetry has been applied to measure the thermal diffusivity of a solid specimen, along with simultaneous measurements of specific heat capacity and thermal conductivity. In this calorimeter, a disk-shaped solid specimen whose surfaces are blackened is heated and cooled slowly on one face by irradiation in a vacuum chamber. A quasi-steady-state approximation in which a linear temperature gradient within the specimen was assumed is considered in the analysis. The validity of this approximation was confirmed by the results of computer simulation based on the control-volume method. Measurements of Pyroceram 9606 and Pyrex 7740 by use of thermocouples in the temperature range between 250 and 400°C gave values consistent with those obtained by previous authors, within experimental error, for all three thermophysical properties.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 21 (2000), S. 927-940 
    ISSN: 1572-9567
    Schlagwort(e): calorimetry ; emittance ; fused silica ; hemispherical total emissivity ; refractive index ; spectral emissivity ; thermal conductivity ; virtual mode ; Vycor glass
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract An attempt to derive the hemispherical total emissivity from the normal emission spectrum is proposed for Vycor and fused silica glasses. The normal emission spectrum from a clear surface has been measured at steady state in the temperature range from 400 to 750 K. The sample is heated on one metal-backed face by thermal radiation from a heater. Temperatures inside the sample were monitored by thermocouples at two points near the surfaces. Evaluation of the hemispherical total emissivity from the normal emission spectrum is determined by means of Kramers–Krönig analysis and virtual mode equations. Assuming a linear temperature distribution within the sample, the thermal conductivities of silicate glasses were obtained at elevated temperatures. The results are comparable with those obtained by previous investigators. The effect of radiation heat transfer in a sample is also discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 19 (1998), S. 291-304 
    ISSN: 1572-9567
    Schlagwort(e): calorimetry ; emissivity ; high temperature ; specific heat capacity ; thermal conductivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Thermal radiation calorimetry has been applied to measure the thermal conductivity and the specific heat capacity of an isolated solid specimen simultaneously. The system, in which a disk-shaped specimen and a flat heater are mounted in a vacuum chamber with the specimen heated on one face by irradiation, is presented. A theoretical formulation of the simultaneous measurement at quasi-steady state is described in detail. Noncontact temperature measurement of both specimen surfaces has been performed using pyrometers and a thermocouple set in the gap between the heater and the specimen. Pyroceram 9609 specimens, whose surfaces were blackened with colloidal graphite, were used in the measurement. The largest error involved in the noncontact temperature measurement is ±2°C in the range from 450 to 650°C. The resultant values of the specific heat capacity and the thermal conductivity deviate by about 10% from the recommended values for the Pyroceram specimen.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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