In order to explore heat transfer characteristics in the micro reactor of biothermal sensor, effects of micro-particle diameters (I.e. 1 mm, 0.75 mm and 0.45 mm) and very low fluid velocities (5 mL·min-1, 3 mL·min-1 and 1 mL·min-1) on the temperature distributions in micro-packed beds were investigated experimentally under the constant wall temperature condition (I.e. 60℃). Effective radial thermal conductivities and wall heat transfer coefficients of the micro reactor were also derived based on the two-dimensional heat transfer model. The results show that the temperature distribution of entrance section is very non-uniform even if the flow rate is very low (e.g. 1 mL·min-1), which means that the entrance effect is still significant, but this non-uniformity decreases quickly with increasing axial distance. The smaller the particle diameter, the lower the effective thermal conductivity and the wall heat transfer coefficient because of the poor thermal conductivity of micro-particle materials which leads to a larger thermal resistance and hydraulic resistance, those are not favorable for detecting the micro thermal signal from biothermal sensor reactor. At the same particle Reynolds number Rep, the effective radial thermal conductivities obtained by this work are obviously less than that published in literatures, but the effective wall heat transfer coefficients obtained are close to those published in literatures.%为探索微小型热生物传感器中反应器内部的传热特性,研究了恒壁温(60℃)条件下,低流量(5,3和1 mL·min-1)和微细颗粒直径(平均直径分别为1,0.75和0.45 mm)对固定床内部温度分布的影响,并结合二维均相传热理论模型,获得了有效径向导热系数和有效壁面传热系数等重要参数.研究结果表明,即使在流量非常小(如1 mL·min-1)的情况下,固定床入口段温度分布也很不均匀,存在明显的“入口段效应”,但随着床层的增高,这种效应快速减弱；实验所采用树脂颗粒的导热系数很低,颗粒直径越小,接触热阻和流动阻力也越大,导致其有效传热参数越小,不利于热生物传感器中微量反应热信号的检测；在相同Rep时,本研究的有效径向导热系数明显小于文献值,而有效壁面传热参数与多数文献值比较接近.
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