Netsu Bussei
Online ISSN : 1881-414X
Print ISSN : 0913-946X
ISSN-L : 0913-946X
Volume 16 , Issue 4
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  • Eisyun Takegoshi, Shin-ichiro Kakuno, Yoshio Hirasawa, Takao Nagamoto
    2002 Volume 16 Issue 4 Pages 146-151
    Published: October 31, 2002
    Released: January 19, 2009
    JOURNALS FREE ACCESS
    ln this study, the insulation performance of mixed powders was investigated by measuring the effective thermal conductivity. Silica (Si02) which was semi-transparent for thermal radiation was used as a main powder and opaque powders for the thermal radiation, namely, titanium oxide (Ti02), carbon black, fly ash, and iron oxide (Fe203) were mixed in the main powder. The effective thermal conductivity was measured by the dual cylindrical method with a steady heat flow as shown in Fig.1 in the range of room temperature to 600°C. Experimental results were analyzed by the theoretical equation of Wang and Tien(1) for heat transfer in a semi-transparent medium. The heat transfer in the mixed powders was divided by two contributions of pure conduction and thermal radiation and the ratios of those were calculated qualitatively for the mixed powders.
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  • Etsuro Yamada, Eiichi Serita, Kaneko Takahashi
    2002 Volume 16 Issue 4 Pages 152-159
    Published: October 31, 2002
    Released: January 19, 2009
    JOURNALS FREE ACCESS
    The effective thermal diffusivity of dispersed materials has been studied by numerical simulation on the random model that has macroscopic homogeneity and isotropy. The two kinds of thermal diffusivity are obtained by pulse heated method (direct value) and by eq. (1) used thermal conductivity calculated from steady state comparison method (indirect one). These values are compared each other and we estimate critical condition for macroscopic homogeneity. We propose also clear graphical expression that is shown by the nondimensional thermal diffusivity vs. the ratio of specific heat capacity of particle to matrix.
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