加热卷烟复合传热过程的数值模拟

Numerical simulation of combined heat transfer process of heated tobacco products under machine-puffing condition

为了揭示加热卷烟在抽吸过程中的传热机理,建立了基于多孔介质的气体流动模型与气固两相局部热平衡传热模型,模拟烟具和烟支复合情况下加热卷烟在抽吸过程中的温度分布,采用红外热成像法检测烟具表面温度及采用热电偶检测烟支各功能段出口温度来验证传热模型的精确性。结果表明:(1)烟具表面最高温度实测值与模拟值误差小于5℃,说明所建模型准确性较高;(2)烟支各功能段中心位置出口温度实验值和模拟值的总体趋势一致,但数值上存在差异,主要原因是在实际抽吸时烟支加热产生的高热容的气溶胶在流动过程中发生传质现象;(3)加热卷烟温度场和气流场模拟结果显示,烟具温度的分布不均匀,局部区域温度过高,上部靠近烟支处温度最高,抽吸结束后温度达到85℃;抽吸时烟支中空段和气流入口处流速最大,气流流动区域没有贴近烟具外壳会降低进口冷气流对烟具表面的散热效果;(4)加热卷烟散热速率计算结果显示,在整个抽吸过程中,烟具外表面散热速率随时间变化平缓上升,烟支暴露部分外表面散热速率随时间呈“锯齿形”上升,总散热速率最大约为0.95 W。

In order to reveal the heat transfer mechanism of heated tobacco products(HTPs)in the process of smoking,a porous media-based gas flow model and a gas-solid two-phase local heat balance model were established to simulate the temperature distribution of a leading HTP in the process of smoking,and the accuracy of the heat transfer models was verified by measuring the surface temperature of the tobacco stick with infrared thermal imaging method and the exit airflow or aerosol temperature of each functional section of the stick with a thermocouple.The results showed that:1)The error between the measured and simulated values of the maximum stick surface temperature was less than 5℃,indicating that the models were practically accurate.2)The overall trend of the exit airflow temperatures at the center of each functional segment of the stick were consistent with the experimental and simulated values,but there were differences in the absolute values due to the mass transfer occurred in the flow process of the aerosol with high heat capacity generated during puffing.3)The simulation results of the temperature fields and airflow fields of the HTP showed that the temperature distribution of the heating device was not uniform,the local temperature in the upper part of the heating device was higher,especially near the stick where the temperature reached a maximum value of 85℃after puffing.The maximum flow velocity was in the cavity section and at the inlet of the airflow during puffing,the airflow zone was not close to the shell of the heating device,which reduced the heat dissipation effect of the inlet cold airflow on the heating device surface.4)The calculation results of the heat dissipation rate of the HTP showed that during the whole smoking process,the heat dissipation rate of the surface of the heating device increased relatively smoothly with time,and the heat dissipation rate curve of the exposed surface of the stick had a zigzag upward trend with the maximum total heat loss of about 0.95 W.