Research on the mechanical behavior of the biomass densification process based on a thick-walled cylinder

Abstract

The mechanical behavior of the biomass densification process has noticeable influences on energy consumption and pellet quality. In the authors’ previous work, a method was proposed to determine the inner pressure by testing the circumferential strain of the outer die wall. Based on this method, a device was developed with strain gauges in the form of a single pellet unit. With this device, experiments were conducted with wood shavings, rice straw, and wheat straw under different levels of particle size, compression rate, and moisture content. The effects of these factors on the inner pressure were analyzed. The relationships among the inner pressure, pellet density, and specific energy consumption were obtained. Results showed that the pressure ratio increased linearly and then decreased and became constant during the relaxation period. The pressure change during the relaxation period was isotropic. The results could provide mechanical explanations for the phenomena in biomass densification processes.