Technology, energy, agriculture transport AIC

Tetyana BORETSKA– Head of the Scientific and Organizational Department of the Scientific and Research Part of the Vinnytsia National Agrarian University (3 Sonyachna St., Vinnytsia, Ukraine, 21008, e-mail: ipserhiy@gmail.com, https://orcid.org/0000-0002-7966-228X).
Mykola ZHARSKY– postgraduate student of Vinnytsia National Agrarian University (3 Sonyachna St., Vinnytsia, Ukraine, 21008, e-mail: ipserhiy@gmail.com, https://orcid.org/0009-0005-8184-4583).

The article is dedicated to the analysis and mathematical modeling of the combustion process of three-fuel mixtures consisting of conventional diesel fuel, biodiesel (for example, based on rapeseed oil or waste), and bioethanol in diesel internal combustion engines. In the context of global environmental challenges, such as reducing harmful emissions and depleting fossil fuel resources, the authors examine the potential of these mixtures to improve engine efficiency and reduce dependence on imported oil. In particular, optimal component proportions are discussed, for example, 70% diesel fuel, 20-25% biodiesel, and 5-10% bioethanol, which allow achieving a balance between performance, economy, and environmental friendliness. Studies show that such mixtures can reduce soot emissions by 15-20%, nitrogen oxides by 25-30%, and carbon dioxide by 10-15%, depending on engine operating modes and specific physical properties of the fuel.
The work provides an overview of key experimental and theoretical studies conducted from 2008 to 2024. In particular, data from Romanian scientists at the Transilvania University of Cluj-Napoca are analyzed, who studied the physical characteristics of mixtures, such as density (0.841-0.852 kg/dm³), viscosity (2.756 mm²/s for the B25M70E5 mixture), and surface tension (up to 0.03465 N/m), as well as their impact on fuel atomization in injectors. Experiments using high-speed cameras confirmed that biodiesel additives increase the spray angle (up to 0.055 rad), while bioethanol accelerates evaporation due to its lower boiling point. In addition, the article references models from the journal Processes (2022), where a combined kinetic mechanism with 430 reactions was developed for simulating oxidation and emission formation, demonstrating a decrease in cylinder pressure by 4.31% and temperature by 1.23% with increasing ethanol content.
The mathematical apparatus of modeling is based on conservation equations for mass, momentum, energy, and species, taking into account turbulence (k-ε and k-ζ-f models), atomization (KIVA 3V), evaporation, and chemical reactions. Adapted thermodynamic models are described, such as the Wiebe function for the heat release curve (x = 1 - exp(C φ^{m+1})), with division into ignition and diffusion combustion phases, as well as gas dynamics equations for predicting parameters such as BSFC (with an error of about 1.12%). Simulations in AVL-Fire software and CFD tools confirm an increase in heat release rate due to prolonged ignition delay, but also highlight risks, such as deteriorated mixing at low loads.
The modeling results demonstrate practical value: for BE10-BE20 mixtures, BSFC increases by 18.64%, but BTE by 2.09%, with significant reductions in NOx emissions (by 29.32%), CO (by 39.57%), and soot (by 15.95%). The authors emphasize that three-fuel mixtures are suitable for implementation in agricultural machinery and transport without significant engine modifications, but recommend additional tests for material durability due to the possible impact of bioethanol on elastomers. Overall, the article contributes to the development of sustainable energy technologies, offering tools for optimizing fuel systems and reducing environmental impact.

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