Abstract The present study focuses on the intensification of flow and mixing in coiled flow inverter (CFI) geometries in order to achieve higher mixing efficiency with a lower base footprint. For this, two designs of “compact coiled flow inverter (CCFI)”, namely, symmetrical compact coiled flow inverter and asymmetrical compact coiled flow inverter, are proposed within the same floor area as covered by a standard design of a conventional CFI. The design of the symmetrical CCFI is based on incorporating as many as possible 90° bends, whereas the asymmetrical CCFI is based on incorporating as much as possible mixing volume. In order to quantify the improvements caused by proposed designs, all three geometries (two CCFIs and one standard CFI) are compared (experimentally and numerically) with each other in terms of dimensionless dispersion number (D/UL) and mixing efficiency (that measures induced radial mixing by incorporating pressure drop penalty), over laminar flow regime ( 10 ⩽ N R e ⩽ 145 ). After validation of the numerical model (CFD) with experimental data, the RTD at different cross-sectional planes along the length of coiled tube is investigated. Such a study provides the relative contribution of helical turns and 90° bends in reducing axial dispersion, and also provides an insight of the required length of coiled tube that is sufficient to achieve a desired reduction in the axial dispersion. The present study reveals that the symmetrical compact coiled flow inverter has the highest mixing efficiency per unit occupied floor area, and requires the least length of coiled tube in order to reduce the axial dispersion at same extent. Thus, the symmetrical CCFI has potential to save significant material and operational energy cost in the Industry.

中文翻译：

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用于过程强化的紧凑型连续流逆变器

摘要 本研究侧重于盘管流逆变器 (CFI) 几何结构中流动和混合的强化，以实现更高的混合效率和更低的基础占地面积。为此，在与传统 CFI 的标准设计相同的占地面积内，提出了两种“紧凑型盘管逆变器 (CCFI)”设计，即对称紧凑型盘管逆变器和非对称紧凑型盘管逆变器。对称 CCFI 的设计基于包含尽可能多的 90° 弯曲，而非对称 CCFI 的设计基于包含尽可能多的混合体积。为了量化由提议的设计引起的改进，所有三种几何形状（两个 CCFI 和一个标准 CFI）在无量纲色散数 (D/UL) 和混合效率（通过结合压降惩罚来测量诱导的径向混合）方面（通过实验和数字）在层流上相互比较流态（ 10 ⩽ NR e ⩽ 145 ）。在用实验数据验证数值模型 (CFD) 后，研究了沿盘管长度的不同横截面处的 RTD。这样的研究提供了螺旋匝和 90° 弯曲在减少轴向色散方面的相对贡献，并且还提供了对足以实现所需的轴向色散减少的盘管所需长度的洞察。目前的研究表明，对称紧凑型盘流逆变器的单位占地面积混合效率最高，并且需要最少的盘管长度，以同样程度地减少轴向扩散。因此，对称 CCFI 具有在行业中节省大量材料和运营能源成本的潜力。