Heat-not-burn Cigarette Smoke Cooling Structure Design And Flow Field Simulation

Heat-not-burn cigarettes do not burn and smolder,The release of harmful components in heat-not-burn cigarettes has been greatly reduced.However,due to the heating method and product structure,the temperature of the smoke before it reaches the filter is often high,which affects the user experience.At present,most of the popular products on the market use phase change materials to reduce the flue gas temperature,and the phase change materials may release harmful components at the flue gas temperature.Therefore,it is necessary to carry out further research and design for the heat-not-burn cigarette smoke cooling structure.This paper explores the main reasons for the high temperature of HNB tobacco smoke through a combination of experiment and numerical simulation.Based on the common common cellulose acetate filter,the cooling structure is further designed and the flow field simulation is performed,and the smoke is cooled at different temperatures.The flow and heat transfer process under the structure is numerically simulated,so as to obtain an optimized design scheme that comprehensively considers the cooling effect and the sucking resistance.The main research work and conclusions of the thesis are as follows:(1)A smoke extraction experiment device was set up,and the smoke was analyzed by performing simulated smoking experiments of traditional cigarettes under open and circumferential barrier conditions,and heating non-combustion cigarettes under different cooling section filling materials and runners.Factors affecting the outlet temperature.Experiments have found that the circumferential barrier of cigarette paper and the radial density distribution of the filling material in the cooling section have a significant influence on the flue gas outlet temperature,which provides a corresponding structural design idea for the subsequent flow channel design;the cooling effect of the cellulose acetate filling structure is the same as the existing one.IQOS products use phase change materials to cool down the same effect,but their draw resistance is relatively large.(2)Based on the thermal non-equilibrium theory,the flow and heat transfer model of the flue gas in the cellulose acetate cooling structure was established,and the numerical simulation under the Canadian deep suction(HCL)mode was carried out,and the reliability of the simulation results was verified through experiments.Analyzed the flue gas flow field and temperature distribution when the cooling section was uniformly filled with cellulose acetate.It was found that the flue gas entered the porous medium from the hollow flow channel,the velocity decreased from 2.5m/s to 0.57m/s,and the suction resistance reached889Pa;The flow direction gradually decreases,but the outlet flue gas temperature at the central axis is about 10°C higher than the average temperature of the outlet section.(3)In order to improve the situation that the suction resistance is large and the center flue gas temperature is relatively high when the cellulose acetate is uniformly filled,two types of high-porosity porous media structure(scheme 1)and cavity flow channel support structure(scheme 2)are designed.Based on the established numerical model,a simulation analysis of the flow and heat transfer process was carried out for a cooling scheme.The comparison found that the suction resistance of scheme 1 is lower than that of uniform filling and the cooling effect is weakened,and scheme 2 has improved suction resistance and cooling effect.(4)Design optimization of Option 2 by changing the thickness of the support structure and the density of cigarette paper,analyze the flow field and temperature distribution under different structures,and compare the maximum temperature at the outlet of the eight structures,the average flow temperature and the suction resistance,and find Loose cigarette paper-0.4mm cavity flow channel support structure cold air flow into the cavity flow channel more,full use of air cooling,its cooling effect is the best,the average temperature of the flue gas outlet is 35.42 ?,the highest temperature is 38.93 ?,suction The resistance is 420 pa.Although the suction resistance is slightly larger than that of the 1.4mm and 0.9mm cavity channel support structures,the cooling effect is significantly improved and the suction resistance is much smaller than the traditional uniformly filled acetate fiber.