Effect of voidage on the smoldering of the mixed dust layer of wood dust and shavings on a hot plate

In the wood processing industry, wood dust commonly mixes with other processing by-products to form piles, which generally have large voidage due to differences in component sizes. It is essential to understand the effect of voidage on the true ignition and smoldering behavior of wood dust layer on hot plates. In this study, wood dust and shavings were selected as experimental materials. The effects of voidage on the minimum ignition temperature of the dust layer (MITL), ignition delay time, and smoldering behaviors were investigated by means of a hot plate test. The results showed that the addition of large-sized shaving particles significantly enhanced the overall voidage of the dust layer. With the increased deposit voidage, the ignition delay time decreased, and smoldering propagation accelerated. When the shavings content was less than 50%, the MITL decreased; however, further addition of shavings significantly increased the MITL. The analysis shows that voidage affects the ignition and smoldering behavior of the dust layer mainly by influencing oxygen transport and heat transfer processes. These findings offer a new insight for the prevention and control of dust fires under real working conditions.