Microscopic Measurement of Particle Laden with aHigh Teperature Gas Flow by Using a Fluorescet Method

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The final goal of this study is to obtain better understandings of the temperature of fine particles laden with a high temperature gas fow ( a gas-solid suspension flow), so as to estimate the heat transfer within the suspension fow including radiative heat exchange. In this research project, therefore, a microscopic measurement method for the particle temperature suspended in a gas flow was proposed. The proposed method is based on the "fluorescent method", which utilizes the temperature dependency of intensity and/or lifetime of the fluorescent light. Namely if a fluorescent particle is periodically excited by a blinking light, fluorescent light from the particle is also periodic but the phase of fluorescent light is shifted. The phase difference between the exciting and fluorescent lights is related to the lifetime of fluorescence, and thus temperature of the fluorescent particle can be determined by measuring the phase shift. In the present method, fluorescent particles were periodically excited by making them passed through fringes generated in the measuring volume of a Laser-Doppler Velocimetry (LDV). By using this method, velocity and temperature of individual particles can be simultaneously determined by measuring the frequency of scattered light and the phase shift of fluorescent light, respectively. A prototype measurement system was constructed, and the propriety of the present method was confirmed by measuring the temperature and velocity fields in a simpe gas-slid suspension flow.In addition to this, diffusion of heat within a fluidized partcle layr was experimentaly examined ; the particle layr was reotely heated by using a CO_2 gas laser, and time-dependent temperature distributions were mesured by means of a IR thermograph. The results clearly showed that the effective thermal conductivity of thefluidized particle layr is a value of te order of 5 W/mK, which is smaller than the values reprted in literature.