Modeling of nicotine and harmful gas yields in carbon-heated tobacco products: Effect of hole arrangement

Carbon-heated tobacco products (CHTPs) recently emerged as a type of safer nicotine product. To prevent the discharge of harmful substances, the heating and pyrolysis of tobacco should be precisely controlled. Herein, we investigate the heat transfer mechanism and pyrolysis characteristics of tobacco using computational fluid dynamics (CFD) modeling of a CHTP. In addition, we analyze the yields of volatile species, the thermal stability of the CHTP during pyrolysis, and the optimal combination of holes. We also fabricated a prototype heat source and used the temperature distribution thereof in the CFD modeling. Using one particular hole location, puffing exhibited a significant effect on the temperature distribution of the tobacco plug and the yields of volatile species. Furthermore, in terms of nicotine yield distribution, the air flow rate through this hole was a significant factor. However, an extremely high air flow rate increased the yields of harmful substances by leveling the temperature of the tobacco plug. In the cases investigated, the maximum overall nicotine yield was 81.1%, while nicotine, tar, CO, and other gases were obtained in respective yields of 76%, 75%, 26%, and 63% under the condition minimizing the ratio between the combined yield of harmful substances and the yield of nicotine. To the best of our knowledge, this is the first published CFD study regarding CHTPs and yields valuable insight into their manufacturing parameters.