Pressure and Gas Flow Distribution Inside the Filter of a Non-Filter Ventilated Lit Cigarette During Puffing

Abstract

SUMMARYEstablishing a realistic gas flow velocity distribution inside a cigarette filter during smoking is important to understand filtration mechanisms of different mainstream smoke species and the overall effect of filter designs on mainstream smoke composition. In this paper, an experimental method is described which directly measures the gas pressure field inside a cellulose acetate filter during cigarette smoking. This was demonstrated by using 3R4F research reference cigarettes smoked under a 35 mL puff of 6 s duration. In addition, filter temperature measurements were also carried out at multiple locations within the filter. Both the temperature and pressure sensing locations were selected to match the radial and longitudinal directions of the cigarette filter. The temperature and pressure measurements were then used to calculate the velocity according to Darcy's Law along the mainstream flow direction in the cigarette filter at each puff. The spatially resolved maps of temperature, pressure and flow velocity on a puff-by-puff basis provide useful insights into the dynamic filtration of smoke aerosol under the influence of the approaching burning coal and progressive accumulation of smoke particulate matter. [Beitr. Tabakforsch. Int. 27 (2017) 113-124]

Integration of Time and Spatially Resolved In-Situ Temperature and Pressure Measurements With Soft Ionisation Mass Spectrometry Inside Burning Superslim and King-Size Cigarettes

“…A series of temperature and gas-flow velocity maps were produced that characterized the dynamic combustion system in the cigarette in response to an externally applied air flow (12). Our approach builds on recent work by LI et al in which a semi-automatic sampling stage was used to obtain two-dimensional measurements of temperature and pressure inside a burning cigarette, yielding gradient maps of temperature and pressure as a function of time during smouldering and puffing (21)(22)(23)(24). The temperature and pressure sensor arrays were combined with a microprobe for simultaneous sampling of the gas flow for chemical analysis by single-photon soft ionisation time-of-flight mass spectrometry (SPI-TOF-MS) (12), an analytical technique that allows both real-time measurements of volatile organic compounds, and on-line puff-bypuff monitoring of tobacco smoke constituents ranges (26,1,2,27).…”

“…It was attempted to minimize the disturbance of the overall processes by the probes but this could not be completely be excluded. The thermocouple array, measuring the gas-phase temperature, had multiple K-type thermocouples (23,24). Temperature and pressure data collected at each location were directly processed by MATLAB to produce the respective temperature gradient and axial air flow velocity (23,24), and interpolated data from multiple locations enabled distribution maps to be generated as a function of time.…”

“…The thermocouple array, measuring the gas-phase temperature, had multiple K-type thermocouples (23,24). Temperature and pressure data collected at each location were directly processed by MATLAB to produce the respective temperature gradient and axial air flow velocity (23,24), and interpolated data from multiple locations enabled distribution maps to be generated as a function of time. Chemical mapping of a cigarette was done as described previously by ADAM et al (2,3), HERTZ et al (17), HERTZ-SCHÜNEMANN et al (18), and CUI et al (12).…”

Aerosol Formation and Transfer in Open- and Closed-Ended Heated Tobacco Products

“…LI et al used fine thermocouples to measure the gas-phase temperature and its distribution inside the burning cone during puffing (9)(10)(11), which mimicked one of the most important studies for characterizing the combustion behavior of a cigarette conducted by BAKER and others (1-3). In addition to show that the gas-phase temperature and its distribution within a burning cone is a key parameter reflecting the heat and mass transfer processes (12)(13)(14)(15), these researchers also extended this approach to include fine pressure probes to measure in-situ pressure variations during the puffing (16)(17). Their reconstructed 2D gas flow maps in and around the burning cone showed an increase in the draw resistance towards the front of the burning cone, accompanied by the changed airflow pathway and air flow velocity during a 2-s bell-shaped puff.…”

“…Mainstream smoke is normally thought to be swept out of the rod by the puffing air flowed (16). The fact is quite different from a stable and homogeneous airflow field that delivers through the gas flow (17). Heated tobacco products (HTPs) are on the increase in some markets (18)(19)(20)(21)(22)(23)(24); commercial examples such as IQOS (25) and glo (26) use different heating technologies designed to eliminate combustion and reduce pyrolysis of tobacco.…”