Packed beds of spherical particles in a cylindrical vessel have a high porosity region next to the vessel wall that allows preferential fluid flow. Consequently, there are radial variations in porosity (ε) and superficial fluid velocity (U) that depend on the vessel-to-particle diameter ratio (D/d_p) and the flow regime of the fluid. This work ascertained if these radial variations affected SuperCritical (SC) CO₂ extraction curves of oil from pre-pressed seeds at 40 °C and 28 MPa, as compared with the commonly adopted plug flow condition. It focused specifically on comparing extraction curves as a function of the controlling mass transfer mechanism (characterized by the dimensionless Biot number, Bi) and D/d_p ratio. A predictive model was adopted to describe the SC-CO₂ extraction of oil from sheared seeds comparing plug flow with radial variations in superficial CO₂ velocity, U(r), from literature correlations. Selected independent variables included the initial oil content of the substrate (132.7 ≤ C_o ≤ 397.2 g/kg), d_p (1 or 2 mm), U (1–4 mm/s), and vessel volume (0.038–495 L). C_o markedly affected the effective diffusivity of the oil (0.780 ≤ D_e ≤ 6.24 × 10⁻¹⁰ m²/s), whereas d_p and U moderately affected the film mass transfer coefficient (2.44 ≤ k_f ≤ 7.40 × 10⁻⁵ m/s). Radial variations in superficial CO₂ velocity decreased extraction rates, with differences between extraction curves when considering plug flow or adopting U(r) diminishing as Bi increased for D/d_p = 20, or as D/d_p increased for Bi = 18. Bi increased by increasing U and k_f, or decreasing C_o and D_e, whereas D/d_p increased by increasing vessel volume. The radial variations in porosity in a packed bed and associated changes in superficial CO₂ velocity may have a more pronounced negative impact in laboratory or pilot plant extraction vessels (small D) than industrial vessels (large D), mainly when extracting small particles and applying large superficial CO₂ velocities. A proxy for the SC-CO₂ extraction of oil from pre-pressed seeds in an industrial extraction vessel (495-L capacity, D/d_p = 270) would be plug flow using the porosity, and superficial CO₂ velocity predicted for the axis of the extraction vessel (ε_o and U_o, respectively). Literature correlations predict a value of ε_o slightly less than ε, and value of U_o slightly less than U. The remainder of the CO₂ bypassing the vessel along a high porosity region near the vessel wall, containing a small fraction of the loaded substrate.

圆柱形容器中球形颗粒的填充床在靠近容器壁的位置具有高孔隙率区域，从而允许优先的流体流动。因此，孔隙率（ε）和表观流体速度（U）存在径向变化，这取决于容器与粒径的比率（D / d _p）和流体的流动状态。这项工作确定了这些径向变化是否影响了超临界（SC）CO ₂与通常采用的塞流条件相比，在40°C和28 MPa下从预压种子中提取油的曲线。它专注于比较提取曲线与控制传质机制（以无量纲的毕奥特数Bi表征）和D / d _p之比的函数。根据文献的相关性，采用预测模型描述了从切碎种子中提取油的SC-CO ₂，比较了塞流和径向CO ₂速度径向变化U（r）。选择的独立变量包括所述基板的初始油含量（132.7≤  Ç _Ò ≤397.2 g / kg），d _p（1或2 mm），U（1-4 mm / s）和容器容积（0.038–495 L）。Ç _Ò显着影响了油状物（0.780≤的有效扩散系数 d _Ë  ≤6.24×10 ^-10 米² /秒），而d _p和ü中度影响薄膜的质量传递系数（2.44≤  ķ _˚F  ≤7.40×10 ^-5 多发性硬化症）。表观CO ₂速度的径向变化会降低萃取率，当考虑塞流或采用U（r时，萃取曲线之间存在差异）减少作为铋增加了对d / d _p  = 20，或作为d / d _p增加了的Bi  = 18的Bi通过增加ù和ķ _˚F，或降低Ç _Ò和d _ë，而d / d _p通过增加容器容积。填充床中孔隙率的径向变化以及表层CO ₂速度的相关变化可能对实验室或中试植物提取容器产生较大的负面影响（较小D）比工业容器（D）大，主要是在提取小颗粒和施加较大的表层CO ₂速度时。在工业提取容器（495-L容量，D / d _p  = 270）中从预压种子中提取油的SC-CO ₂提取的替代品将是利用孔隙度的塞流，并为该油料预测表观CO ₂速度。萃取容器的轴线（ε _ö和ü _ö，分别地）。文献的相关性预测的值ε _ö略小于ε的和值ü _ö稍显不足ü。其余的CO ₂沿容器壁附近的高孔隙率区域绕过容器，其中包含一小部分负载的底物。