There is a growing interest in a fluidized bed particle receiver that directly irradiates sunlight to particles in the fluidized bed as a solar thermal collector for heating. Thermal performance of directly-irradiated fluidized bed gas heater is strongly affected by the physical properties of the particles. The effect of SiC particle size on heat transfer characteristics in the solar fluidized bed gas heater (50 mm-ID × 100 mm high) has been determined. The outlet gas temperatures showed a maximum value with increasing gas velocity due to the particles motion by bubble behavior in the bed, and the maximum values were found at 3.6 times of U_mf for fine SiC and less than 2.0 times of U_mf for coarse SiC. Heat absorption from the receiver increased with increasing gas velocity, showing with maximum 18 W for the fine SiC and 23 W for the coarse SiC at 4.5 times of U_mf. The thermal efficiency of the receiver increased with increasing gas velocity, but was affected by the content of finer particles. The maximum thermal efficiency of the receiver was 14% for fine SiC and 20% for coarse SiC within the experimental range, but showing higher for the fine SiC at the same gas velocity. A design consideration was proposed to improve the thermal efficiency of the system.

中文翻译：

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床粒度对直接辐射流化床气体加热器热性能的影响

人们对流化床颗粒接收器的兴趣日益增长，该接收器将太阳光直接辐射到流化床中的颗粒上作为太阳能集热器进行加热。直接辐射的流化床气体加热器的热性能受到颗粒物理性质的强烈影响。已经确定了SiC粒度对太阳能流化床气体加热器（内径50 mm×高100 mm）中传热特性的影响。出口气体温度由于床中气泡行为引起的颗粒运动而随着气体速度的增加而显示出最大值，发现最大值是细SiC的U _mf的3.6倍，小于U _mf的2.0倍。用于粗碳化硅。从接收器吸收的热量随着气体速度的增加而增加，在U _mf的4.5倍下，细SiC的最大值为18 W，粗SiC的最大值为_23W。接收器的热效率随着气体速度的增加而增加，但受细颗粒含量的影响。在实验范围内，接收器的最大热效率是细SiC为14％，粗SiC为20％，但在相同的气体速度下，细SiC的接收效率最高。提出了设计考虑以提高系统的热效率。