Quantitative evaluation of CO yields for the typical flue-cured tobacco under the heat-not-burn conditions using SSTF

• CO yields of flue-cured tobacco under the low-temperature heating conditions were quantitatively evaluated using SSTF.
• The effects of temperature, air velocity and elemental compositions on CO yields were studied, respectively.
• Temperature slightly influenced CO yield of heated tobacco at a fixed air velocity.
• CO yield, with reducing air velocity, first increased fast and then tended to remain unchanged at a fixed temperature.
• K/S is a very important factor influencing CO yields of heated tobacco.

In this paper, the quantitative evaluation of CO yields of flue-cured tobacco under the low-temperature heating conditions was investigated using a steady state tube furnace (SSTF) on the basis of controlled equivalence ratio method. Then the effect of temperature, ventilation condition and elemental compositions on the CO yields was studied, respectively. There was a strikingly low CO yield of heated tobacco under a fixed ventilation condition in comparison with flaming or even smouldering tobacco, and the temperature just slightly influenced the CO yield of flue-cured tobacco under the low-temperature heating states. At a fixed temperature of 450 °C, the CO yield, with reducing air velocity, first increased fast and then tended to remain unchanged. The correlation study indicates that there were no significant relationships between CO yields and the individual element except for the content of carbon and hydrogen, while the significant negative correlations of CO yields with the ratio of potassium to sulphur (K/S) at the 0.01 level appeared. Further random-Forest analysis revealed that K/S is another important factor influencing CO yields of fuel-cured tobacco under the externally heated pyrolysis conditions after hydrogen content.