Consumption of Oxygen and Heat Evolved during Natural Smolder of a Cigarette

Abstract

As a part of studies on the mechanism of the process of natural smolder of a cigarette, the amounts of O₂ consumed and smoke components formed during natural smolder have been measured in a closed combustion chamber, in which O₂ with adjusted concentration has been circulated gently. The amount of heat evolved has been estimated from the heat of formation of CO, CO and H₂O produced in the combustion zone of a cigarette. In addition, the influences of concentration of atmospheric O₂ on the consumption of O₂, yields of gaseous components, amount of heat evolved, smoldering rate, and smoldering temperature have been experimentally examined.
The amount of consumed O₂ and that of heat evolved per gram of a cigarette, under atmospheric conditions of approximatelly 21% of O₂, corresponding to an ordinary air composition, were found to be 14-19 x 10^-3 mole and 1.2-1.6 kcal, respectively.
The amount of heat evolved per unit mass of a cigarette decreased with increasing O₂ amount in an atmosphere; however the amount of heat evolved per unit mole of O₂ consumed was independent of both amount of O₂ and tobacco types, showing a constant value of about 84 kcal/mol. The amount of CO formed, the smoldering rate, and the smoldering temperature increased with increasing amount of ambient O₂, whereas the amounts of O₂ consumed and CO₂ formed decreased. The above mutual relationship was presumed to be due to the shift occurred in the equilibrium of the reaction, CO₂+ C 2CO, at the combustion zone.