The impact of the column length (5, 10, and 15 cm) and packing mode (constant pressure and constant flow rate up to 15,000 psi) on the radial and axial heterogeneities of 3.0 mm i.d. research prototype columns packed with the same batch of 2.4 μm BEH-C₁₈ particles was investigated by the flow reversal technique. The data were gathered for a non-retained marker (uracil, acetonitrile/water eluent mixture, 80/20, v/v, flow rate 0.5 mL/min, T = 297 K) and revealed that the radial heterogeneity of the packed bed, characterized by the center-to-wall relative velocity bias (ω_β) and its length scale, is nearly independent on the packing mode: the velocity biases extend over a same length scale estimated at 154 μm while ω_β is in between 4% and 6% for all columns. Secondly, the data revealed that the column length has a slight impact on ω_β: assuming a two-region (wall and center regions) stochastic model of transcolumn eddy dispersion, ω_β increases from 4.6% to 5.1% and to 6.1% for 5, 10, and 15 cm long columns, respectively, when packed at constant flow rate. For columns packed at constant pressure, ω_β increases from 5.0% to 5.2% and to 5.6%, respectively. Finally, it is found that all columns are axially heterogeneous: the bottom half, which is packed first (column inlet), is slightly more uniform than the top half (column outlet) which is packed last. Overall, the results of the flow reversal experiments corroborate recent observations (130 μm thick wall region and ω_β = 5.0%) based on flow simulations in a focused-ion-beam scanning electron microscopy (FIB-SEM) based 3D reconstruction from a 2.1 mm × 50 mm column packed with 2 μm BEH-C₁₈ particles.

色谱柱长度（5、10和15 cm）和填充方式（恒定压力和恒定流速高达15,000 psi）对装有同一批2.4的3.0 mm id研究原型色谱柱的径向和轴向非均质性的影响通过逆流技术研究了μmBEH-C ₁₈颗粒。收集了非保留标记物（尿嘧啶，乙腈/水洗脱液混合物，80/20，v / v，流速0.5 mL / min，T  = 297 K）的数据，并揭示了填充床的径向异质性，其特征在于，所述中心到墙的相对速度偏差（ω _β）和其长度尺度，是几乎独立于包装模式：速度偏差超过估计为154微米，而相同的长度尺度延伸ω _β对于所有列，该值在4％到6％之间。其次，数据显示，该柱长度对有轻微的影响ω _β：假设两区域（壁和中心区）transcolumn涡流分散的随机模型，ω _β增加从4.6％至5.1％和5 6.1％以恒定流速填充时，分别为10厘米，10厘米和15厘米长的色谱柱。对于列的包装，恒压，ω _β分别从5.0％增加到5.2％和5.6％。最后，发现所有列在轴向上都是异质的：首先填充的下半部分（色谱柱入口）比最后填充的上半部分（色谱柱出口）更加均匀。总体而言，流动逆转试验的结果证实了最近的观测（130微米厚的壁区域和ω _β 基于流动模拟中一个= 5.0％）聚焦离子束扫描电子显微镜（FIB-SEM）基于三维重建从2.1装有2μmBEH-C ₁₈颗粒的mm×50 mm色谱柱