Study on High Performance Process of Radiant Heat Drying Utilizing Spectral Selectivity and Composition

采用考虑光谱发射率和吸收率的半透明湿颗粒层内辐射热流模型，对半透明湿颗粒层的辐射热干燥进行了理论分析。通过对不同条件下非稳态传热传质方程的数值计算，得到了各层温度、含水率和干燥速率随时间的变化规律。将计算结果与在红外灯和远红外加热器照射下湿玻璃颗粒层干燥的实验结果进行了比较。计算结果与实验结果吻合较好，表明理论分析在本实验条件下是有效的。结果表明，基于光谱选择性和成分利用的辐射源发射和干层吸收之间的光谱组合对内加热效果和干燥过程的性能有很大影响。

Radiant heat drying of a semitransparent and wetted particle layer was analyzed theoretically by using radiant heat flux model in the layer with consideration of spectral emissivity and absorptivity. By numerical calculation of unsteady state heat and mass transfer equations under the various conditions, the time-changes of temperature and moisture content in the layers and the drying rate were obtained. The calculation results were compared with the experimental results for drying of the wetted glass particle layers under the irradiation of an infrared lamp and a far infrared heater. The calculation results agreed fairly with the experimental results, and it was found that the theoretical analysis is valid within the range of present experimental conditions. It was shown that the spectral combination between the radiant source emission and the dried layer absorption, which is based on utilization of spectral selectivity and composition, has a great influence on the effects of internal heating and the performance of drying process.