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  • 1
    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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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 19 (1998), S. 305-315 
    ISSN: 1572-9567
    Schlagwort(e): calorimetry ; emissivity ; heat capacity ; high temperature ; radiant exchange
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Radiant power exchange for thermal radiation calorimetry was investigated both theoretically and experimentally. The geometrical relation in which a disk-shaped copper specimen and a graphite plate are facing each other was used as the model configuration. Surfaces of the specimen and the plate were blackened with colloidal graphite to achieve a high surface emissivity. The radiant power density absorbed by the specimen was calculated by taking into account the geometrical configuration factors and the total emissivity of the blackened surfaces obtained form spectral reflectivity. A value of 0.56±0.01 was obtained for the radiant power exchange coefficient from the theoretical results in the temperature range from 220 to 430°C. The coefficient obtained experimentally by use of a heat capacity measurement was constant with temperature, with a value of 0.54±0.01 within experimental error. No hysteresis in the coefficient was observed for either heating or cooling processes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 20 (1999), S. 709-719 
    ISSN: 1572-9567
    Schlagwort(e): calorimetry ; emissivity ; high temperature specific heat capacity ; thermal radiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Specific heat capacity measurements of disk-shaped specimens have been performed with an apparatus based on thermal radiation calorimetry. The specimen surfaces were irradiated by two fiat heaters in a vacuum chamber so that homogeneous temperature distribution within an insulating specimen was achieved. Homogeneity was confirmed by computer simulation based on the control-volume method. The values of specific heat capacity were obtained by measurement of the specimen temperature, the time rate change of the specimen temperature, and the radiant power from the heater for heating and cooling modes. The specific heat capacities of Ni metal, A12O3 ceramic, MgO ceramic, and A1N ceramic were measured in the temperature range from 220 to 500°C to confirm the validity of this calorimeter. The relative error involved in the measured values was estimated to be ±3%.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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