Missions

Liquid hydrogen is characterized by several important limitations and challenges that restrict its current use. One of them is the cryogenic boiling losses associated with storing, transporting and handling of liquid hydrogen and which can consume up to 40% of its available combustion energy. Molecular hydrogen exists in two allotropic (spin isomers) forms, ortho-hydrogen and para-hydrogen, differentiated by the nuclear spin state of the protons in each hydrogen atom. For a given temperature, the equilibrium ratio of ortho- to para-hydrogen concentrations: [𝑯𝟐, 𝒑𝒂𝒓𝒂]𝒆𝒒 and [𝑯𝟐, 𝒐𝒓𝒕𝒉𝒐]𝒆𝒒 can be calculated [1], but the kinetics of the exothermic conversion can take weeks when the temperature is rapidly dropped. Therefore, reliable in situ measurement's method of this concentration is important for the hydrogen industrial sector.

One way to measure these concentrations consists in using the thermal properties of hydrogen, such as the enthalpy difference [2] or the difference of thermal conductivity [3] between ortho and para hydrogen. Transport of heat in a fluid is usually assumed to be determined together by advection and diffusion phenomena. In some specific cases, transport of heat relies upon complex processes at molecular scale that can potentially deviate from conventional transport by heat diffusion. In these conditions, the thermal conductivity is no longer a constant parameter but varies in time and space, leading either to faster or slower heat transport. Fluids close to super-critical conditions like dihydrogen in cryogenic conditions exhibit for instance a super diffusivity of heat with a transport much faster than expected by normal diffusion [4]. A solid understanding of the anomalous transport properties of heat in unconventional conditions [5] opens the way for more robust and faster concentration estimates based on thermal conductivity measurements.


[1] L. Barrón-Palos, R. Alarcon, S. Balascuta et. al., Determination of the parahydrogen fraction in a liquid hydrogen target using energy-dependent slow neutron transmission, Nuclear Instruments and Methods in Physics Research, 2011, 659, 579-586.
[2] J. Essler, C. Haberstroh, Performance of an ortho-para concentration measurement cryostat for hydrogen, AIP Conf. Proc., 2012, 1434 (1), 1865–1872.
[3] D. Zhou, G.G. Ihas and N.S. Sullivan, Determination of the Ortho-Para Ratio in Gaseous Hydrogen Mixtures, Journal of Low Temperature Physics, 2004, 134, 401–406.
[4] B. Zappoli, D. Bailly, Y. Garrabos et al., Anomalous heat transport by the piston effect in supercritical fluids under zero gravity, Phys. Rev. A, 1990, 41(4), 2264.
[5] A. Lemarchand, B. Nowakowski, G. Dumazer, and C. Antoine, Microscopic simulations of supersonic and subsonic exothermic chemical wave fronts and transition to detonation, Journal of Chemical Physics, 2011, 134, 034121.

Activités

The postdoctoral applicant will be asked to help design a cryostat with engineers of Institut Néel prior to perform the development and fabrication of an innovative sensor for assessment of chemical composition of a gaseous mixture based on a heat transfer at various temperatures at LGF in Mines Saint-Etienne. A knowledge modeling of the sensor, based on physical first principles, as well as a behavior modeling based on the experimental sensor's responses to various excitations is also planned to validate measurements in laboratory conditions.

- Design a cryostat at the Institut Néel
- Development and fabrication of an innovative sensor for chemical composition of a gaseous mixture based on a heat transfer at various temperatures at Mines Saint-Etienne. Determination of measurement uncertainties.
- Adaptation of an existing gas bench with associated instrumentation for the generation of gas mixtures.
- Modeling of the sensor, based on physical first principles, as well as a behavior modeling based on the experimental sensor's responses to various excitations to validate measurements in laboratory conditions.
- Validation of the measurement system and gas mixture composition prediction models on control gases (N2/O2/CO2) under laboratory conditions and at different temperatures.

Compétences

• PhD in Physics of transport processes, Thermodynamics, Condensed-Matter Physics or a closely relat-ed discipline.
• The project's subject includes different disciplines (fluid mechanics, transfers, engineer-ing, automatics) and involves also digital and experimental development.
• Therefore, strong versatility is expected from the candidate. Excellent written and oral communication skills.

Contexte de travail

The project is a collaboration between Institut Néel (https://neel.cnrs.fr/) and Laboratory George Friedel (LGF – UMR 5307 – Mines Saint-Etienne https://www.mines-stetienne.fr/lgf/) within the PARACHUTE project, funded by the ANR.
Supervisors: Dr. Patricia de Rango (CNRS Researcher - Néel), Guillaume Donnier-Valentin (CNRS IR - Néel), Philippe Camus (CNRS Researcher - Néel), Riadh Lakhmi (EC-LGF), Mathilde Rieu (EC-LGF) and Guillaume Dumazer (EC-LGF), Gaetan Becker (Fives CRYO).

The Institut Néel is a CNRS laboratory (related to CNRS Physique) with around 300 permanent staff and 150 PhD students and post-doc. As a fundamental research laboratory in condensed matter physics, the Néel Institute also forges interdisciplinary links with chemistry, engineering and the life sciences. The main areas of research are magnetism and spin electronics, photonics and non-linear optics, quantum, molecular and wide band gap electronics, correlated systems, quantum fluids and superconductivity, as well as materials for energy. The post-doc recruited will join the Matériaux Rayonnements Structure (MRS) team, whose expertise ranges from elaboration methods to structural and functional characterization, supported by theoretical developments. This team has been working for many years on metal hydrides for hydrogen storage, and has several hydrogen test benches at its disposal. Researchers at the Institut Néel benefit from the support of a dozen technology clusters, and in particular the Cryogenics cluster, which focuses on the design, production and development of original cryogenic devices.

Mines Saint-Etienne 'Responsible engineering school, driving innovation with a societal impact' reflects the commitment of our teaching and research staff and our administrative and technical staff to meeting the challenges of the major transitions of the 21st century. With over 200 years of history and the excellence of our staff and students, we are committed to education, research, innovation, transfer to industry and scientific, technical and industrial culture. With 2,500 students, 500 staff and a budget of €50m, we have 3 campuses dedicated to the industry of the future, health and well-being and digital sovereignty and microelectronics, located in 3 major cities: Saint-Etienne, Lyon and Aix-Marseille-Provence. Ranked in the national Top 10 by the magazine l'Etudiant and in the international rankings, Mines Saint-Etienne is a member of the T.I.M.E. network of the world's best technological universities and, through its membership of the Institut Mines-Telecom, a member of the European University EULIST. The SPIN centre (Science of Industrial and Natural Processes), which will be heavily involved in the post-doc, is developing its expertise within Mines Saint-Etienne in the field of Process Engineering applied to dispersed systems: grains, particles, drops, bubbles and porous media. He also has skills in the development of sensors and instrumentation.

The position will be based at Institut Néel in Grenoble and at Mines Saint-Etienne.
Post-doc start date: Between 1st September 2025 and 1st October 2025.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

Risks inherent in handling cryogenic fluides.