TY - GEN A1 - Ngũgĩ, John Mbũrũ A1 - Richter, Sandra A1 - Braun-Unkhoff, Marina A1 - Naumann, Clemens A1 - Riedel, Uwe T1 - A study on fundamental combustion properties of trimethyl orthoformate: experiments and modeling T2 - Volume 2: Coal, Biomass, Hydrogen, and Alternative Fuels; Controls, Diagnostics, and Instrumentation; Steam Turbine N2 - Trimethyl orthoformate (TMOF: HC(OCH3)3) has recently been examined as a viable biofuel. TMOF is a branched isomer of oxymethylene ether-2 (OME2) that, due to its high oxygen content and lack of direct carbon-carbon bonds, considerably reduces the formation of soot particles. To meet the challenges of a more flexible and sustainable power generation, a detailed understanding of its combustion properties is essential for its safe and efficient utilization, neat or in blends. In this work, two fundamental combustion properties of TMOF were studied: (i) Auto-ignition of TMOF / synthetic air mixtures (φ = 1.0; diluted 1:5 with N2) using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) Laminar burning velocities of TMOF / air mixtures using the cone angle method at ambient and elevated pressures of 3 and 6 bar. Furthermore, the impact of TMOF addition to a gasoline surrogate (PRF90) on ignition delay times was studied using the shock tube method at φ = 1.0, 1:5 dilution with N2, T = 900–2 Y1 - 2022 SN - 978-0-7918-8598-7 U6 - https://doi.org/10.1115/GT2022-83029 PB - American Society of Mechanical Engineers ER - TY - GEN A1 - Fradet, Quentin A1 - Ali, Mohammed Liaket A1 - Riedel, Uwe T1 - Development of a porous solid model for the direct reduction of iron ore pellets T2 - steel research international Y1 - 2022 U6 - https://doi.org/10.1002/srin.202200042 SN - 1869-344X SN - 1611-3683 VL - 93 IS - 12 ER - TY - GEN A1 - Fradet, Quentin A1 - Kuhn, Carola A1 - Deutschmann, Olaf A1 - Riedel, Uwe T1 - Towards carbon-free energy carriers: kinetics of the thermochemical reduction/oxidation of iron oxide/iron T2 - 18th International Conference on Numerical Combustion N2 - ron and its oxides are at the center of an innovative carbon-free chemical energy cycle within the Clean Circles research association. Energy can be stored within iron particles through the thermochemical reduction of iron oxide using green hydrogen; the stored energy is then released through the dust-firing of iron. Accurate kinetics models of both thermochemical processes are of prime importance for the design and operation of industrial systems. While the high-temperature oxidation of iron is a novel topic of research, many kinetic studies were already conducted on reducing iron oxide or iron ore. However, the discrepancies between studies are manifest, that it is in terms of reaction models, kinetic parameters, or even in terms of species involved. One of the issues is the simplicity of the mathematical models employed, based on linearization techniques of a limited number of thermogravimetric analysis (TGA) curves. The present work will tackle the kinetics of the thermochemical reduction/oxidation of iron oxide/iron utilizing the leastsquare method, allowing for a direct comparison between experiments and modeling. The experiments supporting the modeling will originate both from the literature and from our own measurements and will be of various types: isothermal TGA, TGA with linear heating rates, temperature-programmed reduction and X-ray diffractions. The influence of parameters, such as the particle size distribution or porosity, on the kinetics will be discussed. Y1 - 2022 UR - https://elib.dlr.de/204587/ ER - TY - GEN A1 - Ali, Mohammed Liaket A1 - Fradet, Quentin A1 - Riedel, Uwe T1 - Kinetic mechanism development for the direct reduction of single hematite pellets in H2/CO atmospheres T2 - steel research international N2 - Increasing interest in the direct reduction process of iron ore has revived investigations on gaseous and heterogeneous iron oxides’ kinetics. Despite extensive studies on the reduction of iron oxides with pure hydrogen or syngas, the development of a generic reduction mechanism for iron oxides is still lacking. The conventional shrinking core model hardly distinguishes between transport and reaction processes, leading to biases or even errors in the kinetic models. In the present study, a porous solid model, which solves mass balances of the individual gas‐phase species and solid ones assuming spherical symmetry, is used for developing a heterogeneous kinetic mechanism accounting for different iron oxidation stages (Fe2O3, Fe3O4, FeO). It also accounts for carbon accumulation and cementite formation to model the carburization phenomena when using carbon‐containing reducing agents like syngas. The proposed generic mechanism successfully reproduces 49 experimental data sets from the literature for single iron Y1 - 2022 U6 - https://doi.org/10.1002/srin.202200043 SN - 1611-3683 VL - 93 IS - 12 PB - Wiley ER -