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High rates of environmental pollution by boilers and thermal power plants burning coal of different grades are the main reason for active research in the world aimed at the development of alternative fuels. The solution to the formulated problem acceptable in terms of environmental, technical and economic criteria is the creation of composite slurry fuels with the use of fine coal or coal processing and enrichment waste, water of different quality, and oil sludge additive. This study considers modern technologies of burning slurry fuels as well as perspective research methods of the corresponding processes. A model combustion chamber is developed for the adequate study of ignition processes. The calculation of the basic geometric dimensions is presented. The necessity of manufacturing the combustion chamber in the form of an object of complex geometry is substantiated. With its use, several typical modes of slurry fuel ignition are determined. Principal differences of ignition conditions of a single droplet and group of fuel droplets are shown. Typical vortex structures at the fuel spray injection are shown. A comparison with the trajectories of fuel aerosol droplets in real combustion chambers used for the combustion of slurry fuels is undertaken.

Industrialized regions of the world are actively polluting the environment. In this research, we consider one of the developed industrial regions, Siberia (Russia), as an example. The paper presents typical volumes of annually stored waste, in particular, waste of oil production and a refinery (76 800 tons), liquid and watered waste of the municipal sector (167 875 tons), and food waste (5906 tons). The parameters of ignition and combustion of such wastes are studied in the compositions of coal–water slurry fuels with petrochemicals. The experimental results demonstrate that most of the wastes in the industrial region under study have high potential (according to environmental, economic, and energy criteria) as additives to fuels. In particular, a comprehensive comparative analysis shows that the ignition delay time for fuel slurries with waste can be reduced by 10–60%; the minimum ignition temperature, by 10–45 °C; and concentrations of NO x and SO2 emissions, by 5–50%. The combustion heat of composite fuels can be increased by 5–20% when using admixtures from industrial waste.

We investigated the conditions, characteristics, and outcomes of liquid droplet interaction in the gas medium using video frame processing. The frequency of different droplet collision outcomes and their characteristics were determined. Four interaction regimes were identified: bounce, separation, coalescence, and disruption. Collision regime maps were drawn up using the Weber, Reynolds, Ohnesorge, Laplace, and capillary numbers, as well as dimensionless linear and angular parameters of interaction. Significant differences were established between interaction maps under ideal conditions (two droplets colliding without a possible impact of the neighboring ones) and collision of droplets as aerosol elements. It was shown that the Weber number could not be the only criterion for changing the collision mode, and sizes and concentration of droplets in aerosols influence collision modes. It was established that collisions of droplets in a gaseous medium could lead to an increase in the liquid surface area by 1.5–5 times. Such a large-scale change in the surface area of the liquid significantly intensifies heat transfer and phase transformations in energy systems.

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In this paper, we describe the results of experimental research into secondary droplet atomization for several heterogeneous, water-oily liquid compositions including some highly heterogeneous emulsions and slurries. The group of schemes is studied, in addition to relevant experiments reported in the literature: droplets colliding with each other, with a heated or not heated walls, and with an air flow, as well as exposed to conductive or convective heating followed by micro-explosive breakup. After the analysis of experimental data, we calculate the size and number distributions of the liquid fragments generated using each of the approaches. We determine the duration of initial droplets' fragmentation as a function of the We numbers and the density of the supplied heat flux. The comparative analysis gave us optimal conditions for several aerosol generation techniques providing minimal fragment size with relatively low electric power consumption. It is shown that each of used atomization techniques provides a comparable number of liquid fragments on average, considering the amount of power required. Several techniques for combined atomization are proposed, based on the investigated approaches.