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CORESTA Congress, Quebec, 2014, Smoke Science/Product Technology Groups, ST 42

Characterisation of e-cigarette aerosol generation behaviour

VINCENT J.H; COLE A.O.; MASON T.J.P.; TINDALL I.F.
Cerulean, Linford Wood East, Milton Keynes, U.K.

Disposable e-cigarettes generate aerosol by vaporising ‘e-juice’ carried by a wick to a heating element activated by a flow sensor. The onset of aerosol production depends on flow rate (Connor, 2013) and can substantially lag initiation of the puff, sufficient to perturb yield determination in a way that is variable from product to product.

The objective of this work was to characterise aerosol generation in e-cigarettes using simultaneous determination of aerosol temperature rise, pressure drop, air volume flow rate into the e-cigarette and into the puff engine, and opacity of the drawn puff. The aim is to provide a useful tool for product development and to assess consistency of construction and lifetime performance.

Temperature of the drawn puff was measured using a thermocouple mounted close to the product outlet and aerosol opacity was monitored using a photo-diode/receiver. The pressure drop and inlet and drawn volume flow rate through the products were logged on a time base of 0.01 s. Video capture assisted interpretation, in particular to calibrate the optical detector. Flow activated rechargeable and disposable product types were characterised over life under puffing regimes from 35 to 150 ml volume.

It is shown that the pressure drop of e-cigarettes is non-linear with flow rate, which is significant at the high flows associated with e-cigarette vaping and perturbs the (nominally) square puff profiles likely to be recommended for standardisation of e-cigarette vaping. Information from the puff engine is not in itself sufficient to fully characterise the onset trigger flow.

Development of e-cigarettes and monitoring of production consistency will be enhanced by full characterisation of the aerosol generation function during puffing. This must include initial design of the pressure drop vs. flow characteristics and consideration of how this changes over product life.