Regulatory mechanism and applicability of pulsed gas on drying uniformity of non-spherical wet grains in a fluidized-bed

Abstract

Pulsed gas can regulate the uniform fluidization of particles, thereby enhancing the product quality of wet grains after drying. However, due to the diversity of grain shapes, the regulatory mechanism and applicability of pulsed gas on the drying uniformity of grains remain unclear. This study used an improved CFD-DEM drying model for wet grains to investigate how particle shape and pulsed frequency affect flow, heat transfer, and mass transfer. The results showed that increasing pulsed frequency can change the particle mixing mechanism from convective to diffusive, and reduce the particle residence time in high-temperature regions. The formation frequency of horizontal channel-like bubbles influences the mesoscale structure evolution and interphase heat transfer uniformity. However, higher pulsed frequency decreases contact time between particles and bubbles, requiring a balance between mixing intensity and bubble contact. Finally, the intercriteria correlation method quantified the applicability of pulsed frequency for drying particles with different shapes.