Eur. Phys. J. E (2022) 45: 20
https://doi.org/10.1140/epje/s10189-022-00171-9

Regular Article - Flowing Matter

Mass diffusion and Soret coefficient measurements of triethylene glycol/water binary mixtures by dynamic shadowgraphy

¹ E2S UPPA, CNRS, TotalEnergies, LFCR UMR 5150, Universite de Pau et des Pays de l’Adour, Anglet, France
² E2S UPPA, CNRS, TotalEnergies, LFCR UMR 5150, BRGM, F-45060, Orléans, France
³ Department of Structure of Matter, Thermal Physics and Electronics, Faculty of Physics, University Complutense of Madrid, Avda. Complutense s/n, 28040, Madrid, Spain
⁴ CNRS, BRGM, ISTO, Univ. Orléans, UMR 7327, F-45071, Orléans, France

^g henri.bataller@univ-pau.fr

Received: 23 November 2021
Accepted: 8 February 2022
Published online: 7 March 2022

Abstract

The investigation of the transport properties of binary fluid mixtures remains a topic of interest in relation to the more challenging studies of ternary mixtures. In fact, the study of the phase boundary limits of the Gibbs composition triangle can be the initial step for a more complete analysis of ternary mixtures. In this paper, we apply the dynamic shadowgraphy optical technique to study non-equilibrium fluctuations induced by the presence of a gradient of temperature and/or concentration in the triethylene glycol (TEG)/water system. These thermodiffusion and free-diffusion experiments aim at measuring the transport properties of samples of the studied system at different experimental conditions. We scan both the average temperature and the TEG concentration, which allows us investigating both positive and negative thermodiffusive behaviours. The obtained values of mass diffusion coefficient are consistent with data available in the literature in the range of temperature investigated in this study. The mass diffusion coefficient of the sample prepared at 0.7 w/w TEG concentration are characterised by shadowgraphy following the two proposed methods, exhibiting consistent results. An increase of the mass diffusion coefficient as a function of the average temperature is highlighted. On the other hand, the thermodiffusion coefficient appears to be independent of the average temperature of the sample at 0.3 w/w TEG concentration.