In order to analyze the forming quality and energy consumption of salix twigs pellet fuel under three kinds of compression methods: uniform velocity, uniform deceleration and superposition vibration, a discrete element model of salix particles uniaxial compression was established by using the discrete element analysis software, selecting the Hertz-Mindlin (no-slip) contact model, pre-setting the initial conditions of particles and the contact parameters, and fixing the acceleration of gravity as 9.81 m/s2. The particle factory generated 2 400 particles by using the dynamic way. The load face moved downwardly after all particles had been generated. The simulated results showed that the compression method had no significant influence on the maximum pressure. By analyzing the contact force of the pellet fuel in the axial direction, the quality of the molding fuel under vibration compression method was better than those of the other two methods. The molding quality was the worst when the uniform compression method was ap-plied. The measured results of the pellet fuel density and voidage after the dense molding also agreed with this conclu-sion. The work of uniform velocity, uniform deceleration and superposition vibration were 37.52 J, 36.15 J and 40.41 J, respectively, by using numerical integration through the compressive force-displacement data, which showed that the vibration compression method consumed the most energy, followed by the uniform compression method and the uniform deceleration compression method. The total energy of particles in different compression methods can also indi-cate the accuracy of this conclusion. By analyzing the molding density and energy consumption at different initial speeds and accelerations, it can be found that the appropriate compression displacement and mold holding time should be selected in order to make the molding quality better. The simulated results can provide a theoretical basis for the se-lection of compression methods in the process of biomass solidification. The discrete element method can provide an effective analytical method for biomass dense molding process.%为分析匀速、匀减速和叠加振动3种压缩方式下沙柳细枝颗粒燃料的成型质量和能耗,建立沙柳颗粒单向受压的离散元模型,设置初始条件和参数,且在颗粒生成完毕后使加载面向下运动.模拟结果表明:压缩方式对最大压力无明显影响.分析颗粒燃料沿轴向的接触力,得到叠动振动压缩方式下成型燃料品质优于其他2种方式,匀速压缩方式下的成型质量最差.成型后颗粒燃料的密度和空隙率结果也与这一结论相吻合.通过分析压缩力-位移数据,利用数值积分计算出匀速、匀减速和叠加振动3种压缩方式的做功分别为37.52,36.15和40.41 J,得出叠加振动方式消耗的能量最多,匀速方式次之,匀减速方式最小.分析不同压缩方式下颗粒的总能量也表明这一结论的准确性.模拟结果可以为生物质固化成型过程中压缩方式的选取提供理论依据.
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