Temperature distribution inside a burning cigarette

Abstract

THE study reported here has been undertaken to resolve the large discrepancies between reports of the temperature distribution in the combustion coal of a cigarette. Studies using bare thermocouples (refs 1–4 and R. G. Hook, paper presented at Twentieth Tobacco Chemists' Conference, Winston-Salem, North Carolina, November 1966) indicate that the highest temperatures occur on the central axis of the coal (the actual reported values vary considerably but are usually in the range 800–900° C during a puff, 700–800° C during the natural smoulder between puffs, and 800–850° C under steady state continuous draw conditions). Under all smoking regimes, the thermocouple-measured temperature decreases by up to 300° C along a radius from the maximum central temperature to the periphery of the coal, although one thermocouple study² has reported the occurrence of occasional peripheral hot spots, with temperatures higher than the centre of the coal. (Ref. 2 contains a comprehensive compilation of more than forty studies of temperature measurements inside burning cigarettes prior to 1968.) In contrast, temperature measurements by X-ray observations of the melting of small metal particles placed within the cigarette⁵ indicate that the highest temperatures (900° C) occur at the periphery of the coal. Furthermore, measurements of the coal's surface temperature by radiation methods (ref. 5 and A. T. Lendvay, F. M. Watson III, and T. S. Laszlo, paper presented at the CORESTA/Tobacco Chemists' Joint Conference, Williamsburg, Virginia, October 1972) have recorded temperatures of about 850–920° C during a puff, 700° C (below the surface ash) during smoulder, and short-lived hot spots on the coal's surface as high as 1200° C (ref. 5).