Work

Progress in multicomponent thermodiffusion studies in connection with the DCMIX space experiments

Year: 2024

Type: article

Abstract: The understanding of thermodiffusion in ternary mixtures has made significantprogress during the course of the DCMIX microgravity experiments onboardthe International Space Station (ISS). Here, we give a short overviewof the four DCMIX campaigns that were successfully launched between 2012and 2018. Essential for the success was a detailed understanding of the impactof residual vibrations on the thermodiffusion experiments. A systematicanalysis was performed during the IVIDIL campaign and accelerations weremonitored during the DCMIX experiments. Two-color optical techniques, asemployed in the SODI experiment on the ISS, are frequently used to separatethe two independent concentrations in a ternary mixture. We describe theessential ideas and methods for data processing. In any case, a frequentlyill-conditioned contrast factor matrix needs to be inverted, which leads toa strong error amplification along a certain direction in the ternary compositionspace. Exemplarily we discuss major outcomes of the DCMIX campaignand related laboratory experiments. A benchmark for ternary mixtureswas established by a detailed comparison of DCMIX1 microgravity data andground bases measurements. Other than in binary mixtures, cross diffusioncan provide a significant contribution to the separation in the Soret equilibrium.A newly developed approach introduces Soret vectors to describe thelocal composition variation over the entire Gibbs triangle. For the DCMIX3system, the existence of a singlular point could be demonstrated, where allthree Soret coefficients vanish simultaneously. The difficult inversion of thecontrast factor matrix can be avoided in situations where additional a prioriassumptions can be made, e.g., polymers or colloids in mixed solvents.

Source: Chemical Physics Reviews

DOI: 10.1063/5.0218425

Authors: V. Shevtsova, W. Köhler, M. M. Bou-Ali, A. Mialdun

Institutions: Ikerbasque, Mondragon Unibertsitatea, University of Bayreuth, Université Libre de Bruxelles

Language: English

Topic: Field-Flow Fractionation Techniques

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: diamond

Funders: Deutsches Zentrum für Luft- und Raumfahrt, Eusko Jaurlaritza, Biobanco Vasco, Agencia Estatal de Investigación