Acquisition of Thermophysical Data for the Optimization of a Hydrothermal Gasification process

The material and energy recovery of industrial and household waste has become a major challenge in addressing the environmental and energy issues facing our society. Converting waste into valuable resources is fully aligned with the principles of the circular economy. Numerous processes have been developed to treat and valorize waste, including combustion, pyrolysis, pyrogasification and microbial degradation. Although highly effective, these technologies are not always suitable for highly aqueous feedstocks such as sewage sludge, manure, industrial sludges, or certain waste solvents.
Hydrothermal gasification is an innovative technology particularly well suited to this type of feedstock. It involves processing organic matter in an aqueous medium under high-pressure and high-temperature conditions, above the critical point of water (221 bar, 374°C). In this process, the mineral fraction of the waste (salts, ash, and minerals) can be separated, while the dissolved organic matter is converted into a gas mixture rich in methane, hydrogen, and carbon dioxide. This process therefore offers strong potential for the production of renewable gases while reducing the volume of waste requiring disposal.
The optimization of hydrothermal gasification and its scale-up to industrial applications require detailed knowledge of the thermophysical properties of the fluids involved. Among the most important properties are density, viscosity, heat capacity, absorption coefficient and thermal conductivity, which govern heat and mass transfer, the energy consumption of the process, and the overall performance of the reactor.
The feedstocks considered are complex multicomponent mixtures. In this context, the correlations available in the literature are not sufficiently accurate to predict their thermophysical properties. In addition, the extreme operating conditions make experimental measurements difficult, costly, and time-consuming. These limitations highlight the value of numerical modeling approaches, which nevertheless require reliable experimental data for their development and validation.
The main objective of this PhD project is therefore to design and develop a miniaturized experimental device based on millifluidic technology. This setup will enable the measurement of thermophysical properties under high-pressure and high-temperature conditions with precise control of operating parameters.
In an initial phase, the experimental setup will be designed, instrumented, and validated using simple single-component, single-phase model systems. In a second phase, mixtures of increasing complexity will be investigated in order to progressively reproduce the characteristics of real feedstocks. The data obtained will allow analyzing the influence of composition, temperature, and pressure on the measured properties.
Ultimately, these results will be used to develop new equations of state and predictive correlations adapted to the complex media encountered in hydrothermal gasification. These correlations will be integrated into numerical simulation tools to improve process design, energy optimization, and performance assessment.
This work, at the interface of chemical engineering, experimental thermodynamics, and data science, will provide significant advances for the development of innovative waste valorization processes.

The “Institut de Chimie de la Matière Condensée de Bordeaux” (UMR5026) is a Joint Research Unit of the CNRS, of the University of Bordeaux and Bordeaux INP.
The ICMCB has strong expertise in solid state chemistry, materials science and chemical processing. It uses this know-how for the development of new materials and new concepts for materials synthesis, shaping and recycling, covering the application fields energy, environment, health, electronics and photonics. Recently, the ICMCB has also become active in machine learning and artificial intelligence.

About ENGIE
As a long-established energy provider in France, ENGIE is a key player in the country’s energy transition. The Group offers electricity and natural gas supply services to households, local authorities, businesses and industrial customers, as well as innovative and high-performance energy services, drawing on its unique expertise in green electricity, gas infrastructure and energy efficiency. The Group’s decarbonization strategy is ambitious, with the aim of achieving carbon neutrality by 2045. To achieve this goal, ENGIE can rely on its corporate R&D center: ENGIE Lab CRIGEN.
ENGIE Lab CRIGEN is a R&D center dedicated to low-carbon gases (hydrogen, biogas and liquefied gases), new uses of energy in cities / buildings and industry, and cross-functional support expertise (sustainability, monitoring and inspection, and testing facilities). ENGIE Lab CRIGEN carries out operational R&D projects, develops pilot schemes, and implements innovative solutions to stimulate and accelerate the energy transition. ENGIE Lab CRIGEN brings together key expertise and testing facilities unique in Europe at its premises to develop the energy solutions of tomorrow. It also helps to accelerate and strengthen collaboration between French and international R&D ecosystems.
Among the 8 research Labs that make up CRIGEN, the BBW Lab (Biogas, Biomass & Waste) investigates technologies for producing low-carbon gas from biomass and waste. The BBW Lab studies all the value chain of biological (anaerobic digestion, biological methanation) and thermochemical (pyro-gasification, hydrothermal gasification) pathways. The Lab naturally collaborates with CRIGEN’s other research groups, in particular the Computational Fluid Dynamics (CFD) simulation team, to accelerate the development of comprehensive solutions, evaluate them, and scale them up to industrial level.

University Master degree in physical chemistry, physics, chemical engineering

English level B2 minimum (CEFR), Willingness to learn French

Rigorous scientific attitude and collaborative spirit