Abstract: In order to explore the effect of particle size on dust explosion and related characteristics of medium density fiberboard, 20 L explosion ball, minimum ignition temperature device of dust cloud, cone calorimeter and Hartman tube device were used to study the lower explosion limit concentration, maximum explosion pressure, minimum ignition temperature, heat release rate and flame propagation law of dust with different particle sizes. The results show that with the decrease of dust particle size, the lower explosion limit concentration and minimum ignition temperature decrease, and the maximum explosion pressure increases gradually; The dust combustion process is divided into five stages: temperature rise, ignition, transition, intensification and extinction, and there are two peaks. The change time and heat absorption time of heat release rate increase with the decrease of particle size, and the peak value of heat release rate increases; With the decrease of particle size, the propagation of flame in the pipe first increases and then decreases, the shape of "fireball" outside the pipe is larger, the number of sparks decreases after the flame dissipates, and the tail end of the flame is more slender.

Key words: medium density fiberboard, dust explosion, heat release rate, flame propagation