Quantitative kinetics and enthalpy measurements of biphasic underflow chemical reactions using infrared thermography

• Set-up of a novel non-contact thermal characterization technique for multiphase flows.
• Thermo-physical properties estimation by infrared thermography.
• Monitoring of the kinetics by the heat released of the reaction.

The aim of this paper is to present an experimental infrared thermography study of a well-known chemical reaction in a biphasic millifluidic droplet flow. Through a simple thermal evaluation, it is possible to characterize the kinetics and enthalpy of exothermic chemical reactions. The originality of this work lies in the combination of two versatile techniques and a thermal evaluation based on a homogenized thin body approximation to perform calorimetric estimations. This novel calorimeter requires thermal calibration to estimate the heat losses. A correlation method was therefore applied for the simultaneous estimation of the heat source (ϕ) and the characteristic coefficient due to convective heat transfer effects (H). This methodology was applied to an acid-base chemical reaction performed at different flow rate ratios. The reaction enthalpy was estimated with an error smaller than 2% compared with the literature value. In addition, the procedure for the estimation of the mixing kinetics of the reaction is revealed by the time-integrated heat flux. Finally, a non-contact thermal calorimeter based on millifluidic and IR thermography was developed. The proposed methodology is demonstrated to be a convenient and powerful tool for the characterization of chemical reactions performed in a droplet flow.