Why does this project matter?

Biomass pyrolysis converts lignocellulosic residues into syngas, bio-oil, and chemical building blocks, playing a key role in the circular bioeconomy. However, lignocellulosic biomass (LCB) feedstocks are profoundly heterogeneous: particle size, moisture content, intraparticle pore structure, and chemical composition all vary between sources, and all influence the coupled chemistry and transport phenomena from pore to reactor scale. Existing models oversimplify biomass properties, leading to poor predictive accuracy and slow scale-up. Electrification via microwave heating adds further complexity: the interaction between the electromagnetic field, particle properties, and fluid flow creates a strongly coupled dynamic system that current models cannot capture. P6 develops the first multiscale, multiphysics framework that explicitly accounts for biomass heterogeneity and electrified heating for tolerant pyrolysis process design.

What are we aiming to achieve?

P6 aims to design a reactor and develop operational strategies for a tolerant and efficient biomass pyrolysis process under dynamic electromagnetic heating. Objectives are: (1) characterize LCB morphological and chemical heterogeneity and incorporate key properties into a pore-informed particle model; (2) develop and validate a reactor-scale CFD model in OpenFOAM; (3) extend the model to include microwave heating; and (4) use the validated multiphysics model to identify reactor configurations and operating strategies for tolerant performance under variable feedstock composition and energy supply.

What will you work on as a PhD researcher?

As a doctoral researcher in P6, you will develop multiscale modelling strategies that couple sub-particle, particle, and reactor scales within an integrated CFD framework implemented in OpenFOAM. Your research will focus on identifying, modelling, and integrating the governing physical, chemical, and morphological phenomena involved in the high-temperature thermochemical conversion of biomass, which will serve as the reference reactive system throughout the project.

You will begin by extending an existing particle-scale model to incorporate biomass heterogeneity, including variations in morphological, chemical, and physical properties relevant to thermochemical conversion processes. The model will be validated against experimental data obtained from an existing particle-scale reactor facility. Advanced characterization techniques, including X-ray micro-computed tomography and in-situ optical diagnostics, will be employed to quantify both intra-particle and external morphological evolution during reaction. Reactive conversion processes will be characterized using thermogravimetric analysis (TGA), micro-gas chromatography coupled with thermal conductivity detection (µ-GC-TCD), and Fourier-transform infrared spectroscopy (FTIR). In addition, in-situ optical diagnostics will provide temporally and spatially resolved measurements of temperature fields and species concentrations.

The validated particle-scale model will subsequently be used to generate a systematic simulation database exploring the influence of feedstock type, particle size, moisture content, and structural heterogeneity on pyrolysis performance. The resulting dataset will support the identification of the biomass properties and coupled physicochemical mechanisms that most strongly govern conversion behaviour, while also enabling the development of stochastic representations of biomass variability for integration into reactor-scale CFD models.

In the second phase of the doctorate, you will develop a reactor-scale CFD model in OpenFOAM and devise robust methodologies for incorporating particle-scale physics into the coarser reactor-scale description while maintaining predictive accuracy. This will include the integration of deterministic transport and reaction models with stochastic representations of unresolved heterogeneity and uncertainty. As part of the development of a comprehensive multiphysics framework, the model will also be designed to enable the future integration of electromagnetic field effects associated with microwave-assisted heating.

Skills and methods you will develop during your doctorate:

• Multiscale integration methods for CFD reactive multiphase modelling

• Hybrid deterministic–stochastic modelling techniques for heterogeneity and uncertainty representation

• Network analysis and data-driven interpretation of reactive systems

• High-performance computing: running and post-processing large-scale OpenFOAM simulations

• Scientific programming: Python for data analysis, visualization, and model post-processing

• Thermochemical reaction kinetics: e.g., pyrolysis kinetics of lignocellulosic components

• Operation of particle-scale reactor and application of advanced spectroscopic and optical diagnostic techniques

• Introduction into the development of multiphysics modelling frameworks integrating transport, reaction, and electromagnetic phenomena

Who will you work with and where?

The Diéguez Alonso group is internationally recognized for multiscale experimental and numerical investigation of thermochemical biomass conversion, with unique expertise combining laser-based in-situ diagnostics (laser-induced fluorescence), X-ray micro-computed tomography (µ-CT) for intraparticle structural characterization, and advanced CFD modelling in OpenFOAM. The laboratory is equipped with particle-scale and reactor-scale pyrolysis reactor setups, micro-GC, FTIR, and TGA for product and mass loss characterization, and laser diagnostic systems. Access to TU Dortmund's high-performance computing (HPC) infrastructure enables large-scale multiphysics simulations. Embedded in RTG TALENT, you gain access to a structured qualification program that combines advanced scientific training with transferable skills development, active exchange with academic and industrial collaboration partners, and tailored career support including the opportunity for a three-month placement in research, industry, or a start-up aligned with your career goals.