Description du sujet de thèse

Although currently underutilized, Concentrated Solar Technologies (CST) represent a promising solution for decarbonizing the energy mix and certain industrial processes. CST systems produce heat by concentrating solar radiation onto a receiver using a field of mirrors. This heat, removed by a Heat Transfer Fluid (HTF), can either be used directly in an industrial process or converted into electricity through a thermodynamic cycle. In the latter case, the system is referred to as a Concentrated Solar
Power (CSP) plant. The only operational CSP plant in France is located in Llo, in the Cerdagne region. It uses linear Fresnel collectors. Solar radiation is concentrated onto a horizontally positioned tube with an internal diameter of approximately 50, mm, located a few meters above the mirrors. The Heat Transfer Fluid (HTF) is subcooled water. Under solar irradiation, the receiver tube wall heats up, and the water removes the heat by convection. Once the saturation point is reached, a boiling flow
develops. Various flow regimes emerge depending on the control parameters. In Llo, the generated steam is used in a turbine to produce electricity [5, 4]. However, an alternative and promising pathway focuses on industrial decarbonization by directly using the generated steam in industrial processes that require it [3]—such as in the food industry, papermaking, or oil extraction. It is essential to be able to predict the flow regimes inside the receiver for two main reasons. First, steam production directly
depends on the prevailing flow regime. Second, the thermomechanical stresses exerted on the receiver tube—which have a direct impact on its lifespan—also vary with the flow regime. In particular, when part of the receiver tube dries out, hot spots may develop due to the poor heat removal capability of the vapor.

Objectives and Methodological Approach
The PhD project is based on a combined approach, integrating experimental investigations using the ConBo facility and numerical modeling of the system using an Euler-Euler framework (by coupling the NEPTUNE_CFD and Syrthes codes [1], developed by key players in the French nuclear sector).
The work plan includes:
. A detailed literature review on boiling flow regimes and their modeling.
. The enhancement of the ConBo experimental setup with the integration of a Wire Mesh Sensor (W) to measure the void fraction at the outlet of the test section, and strain gauges on the heated section.
. The physical analysis of heat and mass transfer mechanisms occurring in these flows, based on the collected experimental database.
. The assessment of closure models within the Euler-Euler approach – particularly the wall heat flux partitioning model [2, 6] – through comparison with the experimental data.


References:
[1] I. Aguilera-Cortes, A. Toutant, and S. Mer – 2025 – Solar Energy , 287
[2] L. Favre, C. Colin, S. Pujet, and S. Mimouni – 2023 – International Journal of Heat and Mass Transfer , 211
[3] Kyotherm. Vapeur Solaire pour la brasserie Heineken de Valence (Espagne) - W. 2024.
[4] E. Montanet, S. Rodat, Q. Falcoz, and F. Roget – 2023 – Energy , 274
[5] M. Ploquin, S. Mer, A. Toutant, and F. Roget – 2022 – Solar Energy , 245
[6] C. Reiss, A. Gerschenfeld, and C. Colin – 2024 – International Journal of Multiphase Flow , 181

Contexte de travail

Profile: We are looking for Master's-level candidates with a background in fluid mechanics or thermal engineering. Given the scope of the research project, a strong interest in both experimental work and numerical modeling is essential. Familiarity with Linux and a programming language (C/C++ or Python) is a plus but not mandatory.
Location: PROMES CNRS Laboratory – Perpignan site
Starting date: April 1st , 2026 at the latest
Salary: Minimum gross monthly salary of € 2,200
Application: Applications must be submitted through the CNRS job portal ( W CNRS) and should include: a CV, a motivation letter, transcripts from both Bachelor's and Master's degrees, and contact details (email and phone) for two references.

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.