滚筒干燥过程中叶丝状态变化对其热物性的影响

为了分析烟草热湿加工处理中的传热过程,通过自行搭建的滚筒干燥过程中烟丝热物性在线测试平台,利用瞬态平面热源法测定了滚筒干燥过程中烟丝的热物性,考察分析了该过程中烟丝温度、含水率对烟丝导热系数、热扩散系数、体积热容的影响。结果表明:①当含水率相同时,烟丝导热系数、体积热容随着烟丝温度的升高而增大,热扩散系数随温度的升高而降低;②当烟丝温度相同时,烟丝导热系数、体积热容随含水率的降低而减小,热扩散系数随着含水率的降低而增大;③干燥过程中,烟丝含水率逐渐减小,烟丝温度逐渐升高,烟丝导热系数在温度与含水率的共同作用下整体有减小的趋势,表明烟丝含水率对导热系数的影响较温度显著。

Relationship Between State Parameters and Thermal Properties of Cut Tobacco During Drying in Cylinder

In order to analyze the heat transfer process during tobacco heating and moistening,the thermal properties of cut tobacco during drying in a cylinder were measured with transient plane thermal source method by a self-configured online testing platform,and the effects of temperature and moisture content of cut tobacco on its thermal conductivity,thermal diffusivity and volumetric heat capacity were investigated and analyzed.The results showed that:1) At the same moisture content,the thermal conductivity and volumetric heat capacity of cut tobacco increased,while thermal diffusivity decreased with the raise of cut tobacco temperature.2) At the same temperature,the thermal conductivity and volumetric heat capacity of cut tobacco decreased while thermal diffusivity increased with the decrease of moisture content.3) During the process of tobacco drying,along with moisture content decreasing and temperature raising,the thermal conductivity of cut tobacco tended to decrease,which indicated that the moisture content affected thermal conductivity more significantly than did temperature.