- Author
- Muramatsu, M.
- Title
- Studies on the Transport Phenomena in Naturally Smoldering Cigarettes.
- Report
- Report 123, 1981, 78 p.
- Keywords
- cigarettes | smoldering | thermal conductivity | thermal analysis | oxygen consumption | temperature | tobacco | density effects
- Abstract
- [ABSTRACT IN ENGLISH] The principal objects of this study are to elucidate the smoldering mechanism of cigarette and to obtain the fundamental knowledges for controlling the smoldering process. Two major reaction zones exist in the smoldering cigarette: [1] the evaporation-pyrolysis zone (100-450 deg C), and [2] the high-temperature burning zone (above 450 deg C). Many factors, such as reaction rate and mass and heat transfer, govern the processes occurring in the two smoldering zones. Prior to theoretical investigations, these factors and smoldering characteristics were experimentally evaluated as summarized below. [1] Effective thermal conductivity in cigarette columns and specific heat of tobacco were evaluated by a transient hot-wire method and by a DSC method, respectively. [2] Thermal analyses (TG, DTG, DSC) of tobacco and its carbonaceous residue were carried out in a helium atmosphere and in a nitrogen atmosphere containing a certain amount of oxygen respectively. Applying n-th order Arrhenius kinetics, apparent kinetic parameters for the pyrolysis reaction of tobacco and the oxidation reaction of the carbonaceous residue were determined. [3] The amounts of oxygen consumed and carbon oxides formed during the natural smolder of cigarette were measured in a closed chamber. The amount of heat evoluved was estimated from the heat of formation of carbon oxides and water produced in the burning zone. [4] The behavior of the natural smolder were characterized by smoldering rate, and temperature and density profiles. On the basis of the experimental results and the postulated mechanism of natural smolder, theoretical models for both the evaporation-pyrolysis and the burning processes were developed, in which mass and heat transfer phenomena were expressed by a set of simultaneous differential equations. The smoldering rate, temperature-, density-, and oxygen profiles and so on of smoldering cigarette predicted from the numerical solutions of the equations approximated well to the experimental results, including the validity of the postulated mechanism of the smolder. Based on the model, the influences of many physical parameters on the smoldering rate and temperature were confirmed to obtain the systematic knowledges for controlling the somoldering process of the cigarette.