The environmental, economic, and energy problems of the modern world motivate the development of alternative fuel technologies. Multifuel technology can help reduce the carbon footprint and waste from the raw materials sector as well as slow down the depletion of energy resources. However, there are limitations to the active use of multifuel mixtures in real power plants and engines because they are difficult to spray in combustion chambers and require secondary atomization. Droplet micro-explosion seems the most promising secondary atomization technology in terms of its integral characteristics. This review paper outlines the most interesting approaches to modeling micro-explosions using in-house computer codes and commercial software packages. A physical model of a droplet micro-explosion based on experimental data was analyzed to highlight the schemes and mathematical expressions describing the critical conditions of parent droplet atomization. Approaches are presented that can predict the number, sizes, velocities, and trajectories of emerging child droplets. We also list the empirical data necessary for developing advanced fragmentation models. Finally, we outline the main growth areas for micro-explosion models catering for the needs of spray technology.

The article is devoted to estimating the intensifying efficiency of methane-air ignition by adding a small amount of hydrogen and/or ethylene. It presents features of the experimental determination of the ignition delay period for fuel-air mixtures using shock installation and methods of processing empirical data. The testing of the known ignition kinetic models for methane, hydrogen, and ethylene with air was carried out. The results of test calculations were compared with those previously published, as well as original experiments. The kinetic model was chosen to provide the minimum discrepancy between the calculated and experimental data. The regularities of the effect of hydrogen and ethylene additives on the ignition dynamics of the methane-air mixture for the range of initial pressures from 1 to 8 bar at temperatures from 900 to 1100 K were obtained with the use of non-stationary numerical modeling. Methane-air mixtures with the mass fraction of additives not exceeding 10% were studied. The quantitative indicators of possible reduction in the ignition delay period of methane-air mixtures were detected.

A novel meso-scale 3-channel 5-turn Swiss-roll type combustor was designed and tested. The non-catalytic combustion of lean ethanol–air mixtures was experimentally investigated in relation to the oxygen excess ratio (α), which varied from 1.5 to 7. Depending on the control parameters used, two distinct regimes of combustion were experimentally observed: one with a combustion zone within the central chamber and another with a combustion zone in the inflow channel. The combustion temperature was virtually independent of stoichiometry. For richer mixtures and lower flow rates, the combustion zone is established in the inflow channel, thus limiting the combustion temperature. A qualitative model was proposed for the process and solved analytically; it described how the combustion regime self-adjusted, with the reaction zone moving into the inflow channel from the central chamber. This study confirmed the possibility of the sustainable combustion of ultra-lean fuel mixtures in a Swiss-roll combustor.

An experimental investigation into the conversion of ethanol to syngas by partial oxidation in a non-premixed counterflow moving bed filtration combustion reactor was carried out. Regimes of conversion depending on the mass flow rates of fuel and air (separate feeding), as well as a granular solid heat carrier, were studied. Depending on the mass flow rate of the heat carrier, two combustion modes were realized—reaction trailing and intermediate—with different temperature patterns in the gas preheating, combustion, and cooling zones along the reactor. The product gas composition is far from the predictions of the equilibrium model; it contains substation fractions of methane and ethylene. Combustion temperature and conversion are limited by the relatively high level of heat loss from the laboratory-scale reactor. The effect of the heat loss can be reduced by enhancing the absolute flow rate of the reactants.

The growing interest in hydrogen as an alternative fuel for advanced aviation engines highlights the need for simplified combustion mechanisms suitable for modeling complex hydrodynamic, flame propagation, and detonation processes. A thermodynamic analysis method, accounting for both thermodynamic and kinetic factors, was applied to identify the most significant reactions in the detailed hydrogen combustion scheme (68 reactions). This analysis highlighted eight key reactions, for which rate constants were refined by matching the calculated combustion kinetics of a stoichiometric H₂ + O₂ mixture to experimental data. The resulting reduced mechanism M-I (12 reversible reactions) shows only minor deviation from the experimental ignition limits. Further exclusion of the two least contributing reactions (mechanism M-II) leads to significant errors in the upper ignition limit at pressures above 10 mmHg. The proposed thermodynamic approach enables effective reduction of the hydrogen combustion mechanism while maintaining sufficient accuracy for applied modeling tasks.

This paper considers theoretical and empirical approaches to the formation of a mathematical model of heating and evaporation of polydisperse water droplets with diameters of 5…100 μm in an air flow with an initial temperature of up to 600 K and a velocity of up to 100 m/s at Weber numbers not exceeding critical values. The developed mathematical model takes into account the change in gas temperature when its initial enthalpy is spent on heating and evaporation of dispersed liquid as well as a decrease in the level of interphase convective heat exchange at the onset of liquid evaporation and the formation of a vapor layer near the droplets. Based on the analysis of the previously obtained experimental database, the values of empirical coefficients for the developed mathematical model were established. In order to validate the mathematical model, a detailed comparison of the calculated data with previously published experiments of the authors' team as well as other researchers was carried out. The presented equations and regularities can be adapted for various modes of heat and mass transfer between dispersed liquids and gases used in power engineering.