Influence of organic coal-water fuel composition on the characteristics of sustainable droplet ignition

• High-speed video recording, PIV, and Stereo PIV methods were used for studies.
• Waste from coal and oil processing is typical components of organic coal-water fuel.
• Ignition conditions were established for several different fuel compositions.
• Mass fraction variation (15%) of components influences on ignition delay time (40%).
• The greatest effect on ignition have oxidizer temperature and droplet size.

This paper presents an experimental study of the ignition conditions and characteristics of the single droplets of organic coal-water fuels. The study examines suspension compositions based on low-grade coals, typical (with various characteristics of combustion) coal processing wastes (filter cakes obtained after the filtration of crushed coal), waste oils, water–oil emulsions. In the experiments, the mass fraction of the main components of organic coal-water fuel varies within the following ranges: 40–60% coal dust or filter cakes, 0–20% flammable liquid, 40–60% water. For recording the main parameters of ignition, we use high-speed video cameras, cross-correlation complexes, and a quartz cylindrical channel. To process the experimental results, specialized software systems Tema Automotive and Actual Flow are applied. We find the times of the ignition delay and complete combustion of organic coal-water fuel droplets with the sizes (radius) of 0.5–1.5 mm. The temperature and rate of air flow vary between 500 and 900 K and 0.5–5 m/s (to enable the use of research results in different fuel technologies). Further, we identify the boundary conditions of the sustainable ignition of organic coal-water fuel droplets with various compositions (by component concentrations). Also, the study establishes the scale of the effect of organic coal-water fuel component composition on these conditions.

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