Jean Toutain

Processing of temperature field in chemical microreactors with infrared thermography

This work is devoted to the first analysis of temperature fields related to chemical microfluidic reactors. The heat transport around and inside a microchannel is both convective and diffusive with spatial distribution of source terms and strong conductive effects in the channel surrounding. With simplified assumptions, it is shown that Infrared thermography and processing methods of the temperature frames allow to estimate important fields for the chemical engineers, such as the heating source distribution of the chemical reaction along the channel. A validation experiment of a temperature field processing method is proposed with Joule effect as calibrated source term and non reactive fluids. From such previous experiment, a Peclet field is estimated and used in a further step in order to study an acid-base flow configuration

Quantitative thermal analysis of heat transfer in liquid–liquid biphasic millifluidic droplet flows

In this paper, infrared thermography is used to propose a simple quantitative approach toward understanding the thermal behaviour of a liquid–liquid biphasic millifluidic droplet flow under isoperibolic conditions. It is shown that due to the isoperibolic boundary condition, the thermal behaviour at the established periodic state can be managed according to different orders, i.e. either a continuous or fluctuating contribution. A complete analytical solution is proposed for the complex problem model, then a simplified model is proposed. Finally, a simple homogeneous equivalent thin body model approximation with a characteristic coefficient function of a biphasic flow mixing law is sufficient for describing the thermal behaviour of the media under isoperibolic conditions. From this theoretical validation, the experimental results concerning the behaviour of a biphasic oil and droplet flow are presented. An analytical representation law is proposed to quantitatively estimate and predict the thermal behaviour of the flow. Moreover, it is demonstrated that with this new method, the thermophysical properties of the phase can be estimated with a deviation less than 5% from that reported by the suppliers.

Influence of Coil Power Ranges on the E-Liquid Consumption in Vaping Devices

As electronic cigarettes (e-cigarettes) represent a new constantly evolving product category, the systematic analysis of the developed devices and the e-liquid vaporization is challenging. Indeed, understanding how e-cigarettes work and the role of key parameters in the process are major issues. This work focuses on an experimental study of how the power supplied by the battery to the atomizer coil influences e-liquid consumption. The reproducibility and the repeatability of e-liquid consumption were investigated over 20 series of 20 puffs for one of the tested atomizers. Then, the reproducibility and the repeatability of the e-liquid consumption was investigated over five series of 20 puffs for each tested atomizer. The wire behavior according to the supplied power could be separated into three regimes: under-heating (insufficient power to generate an aerosol), optimal vaporization characterized by a linear trend (vaporization of the e-liquid proportional to the supplied energy) and over-heating (dry-burn occurs). Using a controllable and repeatable energy supply, the reproducibility of the quantity of vaporized e-liquid was verified for each of the five series of 20 puffs programed for all the atomizers except one. Finally, the influence of the supplied power on the vaporization and the consumption of the e-liquid as well as the optimal power ranges were investigated and discussed. The results showed that atomizers with resistance ranging from 1 Ω to 1.8 Ω are efficient using all the energy supplied by the battery to vaporize the e-liquid and reducing the energy lost in the cotton or in the metal part of atomizer coil.