This project investigates the formation, transport and deposition of iron-containing nanoparticles that can be produced during iron microparticle combustion.

The use of metals as energy carriers of the future offers many advantages, as they are characterised by high energy density, and good transport and storage properties. Iron is a particularly promising candidate because it burns heterogeneously, enabling an energy cycle as investigated in the Clean Circles project (https://www.tu-darmstadt.de/clean-circles/about_cc/index.de.jsp). On the one hand, this involves the reduction of iron oxides using renewable energy, and on the other hand, the oxidation of iron to release energy, i.e. in retrofitted coal power plants. The oxidation of iron has already been simulated in a turbulent shear layer at EBI-TFS (https://vbt.ebi.kit.edu/1074.php) [1,2].

Although the combustion of iron microparticles is heterogeneous, the temperatures reached during the process are high enough to allow for evaporation of iron. The emitted gaseous iron can subsequently condense into nanoparticles, which in turn can agglomerate or deposit on other microparticles. While the removal of nanoparticles in lab-scale exhaust gas streams is possible by the use of HEPA filters, their application at full-scale is not viable. However, removing the nanoparticles in-situ by means of depositing them on iron microparticles provides a sensible option to prevent harmful iron emissions. This requires a thorough understanding of the nanoparticle dynamics in order to optimise the process.

1. Qualitative and quantitative prediction of nanoparticle formation and deposition using boundary layer resolved simulation (BLRS) of single microparticles and small microparticle groups
2. Development of a reduced-order point-particle model for iron microparticle combustion with nanoparticle deposition.

This work is funded by the Friedrich and Elisabeth Boysen foundation (BOY-195).

[1] Luu, T.D. et al. "Carrier-Phase DNS of Ignition and Combustion of Iron Particles in a Turbulent Mixing Layer". Flow Turbulence Combust 112 (2024) 1083-1103.
⇒ https://doi.org/10.1007/s10494-023-00526-y

[2] Luu, T.D. et al. "Carrier-Phase DNS study of Particle Size Distribution Effects on Iron Particle Ignition in a Turbulent Mixing Layer". Proceedings of the Combustion Institute 40 (2024) 105297.
⇒ https://doi.org/10.1016/j.proci.2024.105297

[3] Nguyen, B.-D. et al. "Nanoparticle formation in the boundary layer of burning iron microparticles: modeling and simulation". Chemical Engineering Journal (2025) 160039.
⇒  https://doi.org/https://doi.org/10.1016/j.cej.2025.160039

[4] Hartmann, N. et al. "Modelling nanoparticle deposition rate in iron particle combustion". Fuel (2026) 136268.
⇒ https://doi.org/10.1016/j.fuel.2025.136268

[5] Märker, D. et al. "Modelling nanoparticle formation and deposition in burning iron microparticle arrays". 12th European Combustion Meeting (ECM), Edinburgh, UK, 2025

[6] Märker, D. et al. " Nanoparticle formation and deposition during combustion of iron microparticles using Euler-Lagrange simulations". 32. Deutscher Flammentag, Paderborn, Germany, 2025