22 Janvier – Thesis defense - Sébastien Soulet
10 h Amphi La Rochefoucauld-Liancourt / I2M (ENSAM - Talence)
Thermodynamics contribution to the understanding of the electronic cigarette functioning.
The e-cigarette is a nicotine delivery tool that vaporizes an e-liquid. At present, the literature focuses on the study of risks to the consumer and in particular on the chemical analysis of the aerosol and not on the processes leading to its generation. The main objective of this thesis is to provide an understanding of these processes through thermodynamics and then to propose a modeling of them. The experimental study examined the influence of vaping parameters on the amount of liquid vaporized relative to the power applied. Three vaporization regimes are observed: a pre-heating regime that does not generate aerosol, an optimal regime limited by a minimum and maximum power and a overheating regime that are related to the triggering and critical flows of nucleated boiling. The notion of critical flow proves to be a limit of operation from which the risk for the consumer increases significantly. Then, the developed model is built on a three-step diagram: 1) boiling of the e-liquid; 2) adiabatic mixture of the steam generated with fresh air; 3) transport of the resulting mixture. The simulation results have a qualitative agreement with the experimental measurements. They also show that the size and composition distribution of the aerosol generated is highly dependent on each of these steps.