Nicotine is a dependence-producing component in electronic cigarettes. The nicotine release characteristics of electronic cigarettes are closely connected with human exposure and respiratory health. In this paper, a theoretical model was established to study the effects of the compositions of e-liquids and the heating powers of device on the emission and gas/particle partitioning characteristics of nicotine in aerosols at equilibrium. The simulation results of nicotine emissions were compared with the experimental data. The errors between them were within a reasonable range. At a larger heating power level, a higher nicotine yield and a larger vaporization amount of e-liquids could be observed. Under the same heating power condition, a higher vegetable glycerin content in e-liquids could result in a lower nicotine emission. When the heating powers supplied by the device increased, a larger mass fraction of particle-phase nicotine in aerosols at equilibrium would appear. As more propylene glycol was added into e-liquids, a lower mass fraction of gas-phase nicotine would exist in aerosols at equilibrium. The results may provide more information for the industry to set technical standards for electronic cigarettes and for the government department to make regulatory policies.

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The thermodynamic behaviors of electronic atomizer during the multi-puffing process have an important influence on the product performances. Exploring the thermodynamic mechanisms behind the vaporization phenomena is helpful for engineers and consumers to understand electronic atomizer. The theoretical modelling and simulation of the multi-puffing process for the electronic atomizer were carried out in this study. During 1∼10 puffing number, the mass fraction of propylene glycol in the residual e-liquid reduced when the puffing number increased. Meanwhile, the mass fraction of vegetable glycerin in the residual e-liquid increased gradually. The total particulate matter of aerosol generated from the electronic atomizer decreased with the puffing number increasing. The maximum vaporization temperatures of the residual e-liquid rose gradually in the multi-puffing process.

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