The effects of compaction pressures at 50, 130, and 210 kPa on airflow resistance on different classes of paddy rice (long thin, long, and short) were evaluated. The pressure drop was analysed by fitting the Shedd, Ergun, and Hukill & Ives models to the experimental data. The results indicated that differences in the mass compaction percentages were due to the compaction pressure rather than the distinct characteristics of the different rice classes, and compaction increased predominantly when higher pressure was applied. The applied compaction pressures produced mass compaction percentages of the paddy rice ranging from 2 to 3% for 50 kPa, 7 to 8% for 130 kPa, and 10 to 12% for 210 kPa. The three models applied to analyse the compacted grain mass showed good fit to the experimental data, with high coefficients of determination (R2) for the three compaction pressures and rice classes studied. Based on the average relative errors and the high coefficients of determination, the Ergun model is most suitable for modelling the pressure drop in rice grains. Another advantage of the Ergun model is that it consistently predicted slightly higher pressure drop values than the experimental data. Thus, there is an added safety factor if this model is used to design aeration systems since the actual pressure drop experienced in the system will be less than the design value.

中文翻译：

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压实对稻谷气流阻力的影响

评估了 50、130 和 210 kPa 的压实压力对不同类别水稻（长、细、长和短）的气流阻力的影响。通过将 Shedd、Ergun 和 Hukill & Ives 模型拟合到实验数据来分析压降。结果表明，质量压实百分比的差异是由于压实压力而不是不同水稻类别的不同特征，当施加更高的压力时，压实度主要增加。施加的压实压力使水稻的质量压实百分比在 50 kPa 时为 2% 至 3%，130 kPa 时为 7% 至 8%，210 kPa 时为 10% 至 12%。用于分析压实颗粒质量的三个模型显示出与实验数据的良好拟合，对所研究的三种压实压力和大米等级具有高决定系数 (R2)。基于平均相对误差和较高的决定系数，额尔古纳模型最适合模拟稻谷压降。Ergun 模型的另一个优点是它始终如一地预测比实验数据略高的压降值。因此，如果将此模型用于设计曝气系统，则会增加安全系数，因为系统中经历的实际压降将小于设计值。Ergun 模型的另一个优点是它始终如一地预测比实验数据略高的压降值。因此，如果将此模型用于设计曝气系统，则会增加安全系数，因为系统中经历的实际压降将小于设计值。Ergun 模型的另一个优点是它始终如一地预测比实验数据略高的压降值。因此，如果将此模型用于设计曝气系统，则会增加安全系数，因为系统中经历的实际压降将小于设计值。