烟草形态对烟草热物性的影响

Influences of tobacco's shape on its thermophysical properties

为了研究烟草形态(片状、丝状、粉状)对烟草热物性参数的影响,采用瞬态平面热源法测量了不同形态烟草堆积体的导热系数、热扩散系数和质量热容,分析了烟草形态对测量重复性、导热系数、质量热容以及热物性对温度敏感程度的影响。结果表明:(1)热物性参数测量重复性为导热系数>热扩散系数>质量热容;对于同一个热物性参数,烟草尺寸越小,测量重复性越好,即烟粉>烟丝>烟片。(2)随着堆积密度增大,烟草样品的导热系数逐渐增大,质量热容呈稍微减小的趋势。(3)烟草的特征尺寸越小,导热系数越小;烟片的导热系数对温度的敏感程度大于烟丝的导热系数对温度的敏感程度。

In order to investigate the influences of tobacco＇s shape（lamina,cut tobacco,powder） on its thermophysical properties,the thermal conductivity,thermal diffusivity and mass heat capacity of bulk tobacco were measured by the transient plane thermal source method,and the influences of tobacco＇s shape on measurement repeatability,thermal conductivity,mass heat capacity,and the temperature sensitivity of the said properties were analyzed.The results showed that： 1） The parameters of thermophysical properties in the descending order of measurement repeatability were thermal conductivity,thermal diffusivity,mass heat capacity.For an individual parameter,smaller tobacco particles presented higher measurement repeatability,in the order of tobacco powder 〉cut tobacco 〉tobacco lamina.2） With the increase of bulk density,thermal conductivity increased gradually,while mass heat capacity reduced slightly.3） Thermal conductivity reduced with the decrease of characteristic size of tobacco particles,and the thermal conductivity of lamina was more sensitive to temperature variation than that of cut tobacco.