Gas-phase pressure and flow velocity fields inside a burning cigarette during a puff

Heat and mass transfer inside a burning cigarette directly influence the level and chemical composition of its mainstream and sidestream emissions. During a 2-s 35 mL model puffing regime, different thermophysical processes occur inside the burning coal as a result of forced air flow, including rapid temperature rise up to 900 °C and a series of pyrolytic or oxidative reactions leading to the formation of smoke aerosol. Accurate measurements of transient thermophysical parameters such as temperature, pressure and gas velocity are thus an essential step towards understanding the smoke formation. In this study, we have developed micro-sensors that can be accurately inserted at specific locations into a 3R4F research reference cigarette, and used to follow these sensitive and highly dynamic responses as a result of the puffing burn. Both temperature and pressure responses were systematically measured, and in combination with a computational method based on Darcy's Law, we obtained the gas flow velocity of the burning cigarette puffed under a standard machine-smoking protocol. These quantitative data provide unparalleled insights into the complex thermochemical processes responsible for smoke formation inside a burning cigarette.