Authors

Abstract

To address the challenges of millet threshing mixtures, namely their light mass, small volume, minimal differences in component suspension speeds, and susceptibility to interference from impurities during sorting, which lead to high loss and impurity rates, this study applies the Brazil Nut Effect (BNE) to optimize the operating parameters of an air-sieve-type grain sorting device. The discrete element method (DEM) was used to numerically simulate the sieving and segregation processes of the millet threshing mixture, to clarify the grain population structure most conducive to effective sieving, and to identify the main factors influencing segregation and stratification as well as the appropriate parameter ranges. A bench-scale multifactor performance test was conducted to establish regression equations describing the effects of amplitude, stepped jitter plate length, crank rotational speed, and fan shaft rotational speed on loss rate and impurity rate. Using a multi-objective optimization method, the optimal parameter combination was determined as follows: amplitude of 26 mm, stepped jitter plate length of 450 mm, crank rotational speed of 580 rpm, and fan shaft rotational speed of 645 rpm. Under these conditions, the loss rate was 2.68% (with coiling loss below 0.5%) and the impurity rate was 3.95%. The results of this study provide a reference for optimizing the operating parameters of millet cleaning devices.

Abstract in Chinese

针对谷子籽粒质量轻、体积小、脱出物各成分悬浮速度差异小，清选时籽粒易受杂余裹挟，造成损失与含杂率高等问题，本研究基于巴西果效应对风筛式谷子清选装置作业参数进行优化。采用离散元方法对谷子脱出物透筛、离析过程进行数值模拟，明确最有利于籽粒透筛的粒群结构，得到影响离析分层的主要因素和参数选择范围。进行了台架多因素性能试验，建立振幅、抖动板长度、曲柄转速、风机轴转速对损失率、含杂率建立回归方程，并利用多目标优化方法获取最优参数组合为：振幅26mm、抖动板长度450mm、曲柄转速580r/min、风机轴转速645r/min，在此参数组合下，损失率为2.68%，其中裹挟损失小于0.5%，含杂率为3.95%。研究结果为谷子清选装置参数优化提供了参考。