To understand the interactions of coal particles on devolatilization, volatile burning, and char combustion, the combustion characteristics of two interacting equal-sized coal particles placed in the upstream and downstream configuration in a hot laminar flow are numerically investigated. A two-dimensional mathematical model was developed based on the wall surface reaction theory in the commercial software FLUENT. The numerical results show that the particle interaction has different effects on the coal ignition time and combustion characteristics of the upstream and downstream particles. The upstream coal particle undergoes a faster temperature rise, earlier coal devolatilization, and faster char burnout than the downstream one. With increasing the particle separation distance within a certain range, the temperature rise, coal devolatilization, and char combustion processes are further enhanced and weakened for the upstream particle and the downstream particle, respectively. There exists a critical particle separation distance beyond which the combustion processes of the two particles are similar to those of a single particle.
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