Thaker Abhijeet H, Ranade Vivek V
Multiphase Reactors and Intensification Group Bernal Institute, University of Limerick, LimerickV94T9PX, Ireland.
Ind Eng Chem Res. 2022 Dec 19;62(45):18837-18851. doi: 10.1021/acs.iecr.2c03714. eCollection 2023 Nov 15.
Liquid-liquid emulsions are used in a variety of industry sectors, including personal care, home care, food, and nutrition. The development of compact and modular systems and devices for creating emulsions with desired droplet size distribution (DSD) is becoming increasingly important. In this work, we have shown use of vortex-based cavitation devices for producing emulsions at nominal flow rate of 1 LPM and 20 LPM. We present new experimental results providing quantitative information on influence of multiple passes through the vortex based hydrodynamic cavitation (HC) device, type of oil and device scale on the breakage process and resulting DSDs. Multiple pass experiments were performed for generating oil-in-water emulsions containing 5 and 15% of oil. Rapeseed oil (RO) and tetrachloroethylene (TCE) were used as oil phases with densities of 915 and 1620 kg/m, respectively. The effect of pressure drop across the HC device in the range of 50-250 kPa on DSD was examined. The HC device was shown to exhibit significant higher efficiency compared to alternative emulsion making devices (i.e., homogenizers, venturi, and orifice-based HC devices), and the Sauter mean drop size was found to reduce from 66 μm to less than 2 μm after about 50 passes in all the device scales. The DSD of the RO-water system showed a bimodal nature, whereas monomodal DSD was found for TCE-water system. Preliminary simulations using the computational fluid dynamics-population balance model (CFD-PBM) models developed in the previous work indicated the inadequacy of developed models to capture the influence of cavitation on DSDs. By carrying out Hinze scale analysis of bimodal DSD, we for the first time showed the existence of two different mechanisms (one based on conventional turbulent shear and the other based on collapsing cavities) of droplet breakage in HC devices. The order of magnitude of turbulence energy dissipation rates generated due to collapsing cavity estimated using Hinze scale analysis showed good agreement with the values reported from cavity dynamics models. The presented experimental results and analysis will be useful for researchers and engineers interested in developing computational models and compact devices for producing emulsions of the desired DSD.
液-液乳液被应用于多个工业领域，包括个人护理、家庭护理、食品和营养领域。开发紧凑且模块化的系统及设备来制备具有所需液滴尺寸分布（DSD）的乳液正变得越来越重要。在这项工作中，我们展示了使用基于涡旋的空化装置在1升/分钟和20升/分钟的标称流速下制备乳液。我们给出了新的实验结果，提供了关于多次通过基于涡旋的流体动力空化（HC）装置、油的类型和装置规模对破碎过程及最终DSD影响的定量信息。进行了多次通过实验以生成含5%和15%油的水包油乳液。菜籽油（RO）和四氯乙烯（TCE）被用作油相，其密度分别为915千克/立方米和1620千克/立方米。研究了HC装置两端50 - 250千帕压力降范围内对DSD的影响。结果表明，与其他乳液制备装置（即均化器、文丘里管和基于孔口的HC装置）相比，HC装置具有显著更高的效率，并且在所有装置规模下，经过约50次通过后，索特平均液滴尺寸从66微米减小到小于2微米。RO - 水体系的DSD呈现双峰性质，而TCE - 水体系的DSD为单峰。使用先前工作中开发的计算流体动力学 - 群体平衡模型（CFD - PBM）进行的初步模拟表明，所开发的模型不足以捕捉空化对DSD的影响。通过对双峰DSD进行欣泽尺度分析，我们首次表明在HC装置中存在两种不同的液滴破碎机制（一种基于传统湍流剪切，另一种基于空化泡溃灭）。使用欣泽尺度分析估计的由于空化泡溃灭产生的湍流能量耗散率的量级与空化动力学模型报告的值显示出良好的一致性。所呈现的实验结果和分析将对有兴趣开发用于制备具有所需DSD乳液的计算模型和紧凑装置的研究人员和工程师有用。
