CIESC Journal ›› 2024, Vol. 75 ›› Issue (11): 4205-4216.DOI: 10.11949/0438-1157.20240560

• Fluid dynamics and transport phenomena • Previous Articles     Next Articles

Influence of buoyancy direction on droplet coaxiality in a coaxial microchannel

Jingjing HOU(), Da RUAN, Ziyi BO, Xuehu MA()   

  1. Liaoning Key Laboratory Clean Utilization of Chemical Resources, Dalian University of Technology, Dalian 116024, Liaoning, China
  • Received:2024-05-26 Revised:2024-07-22 Online:2024-12-26 Published:2024-11-25
  • Contact: Xuehu MA

浮力方向对同轴微通道内液滴同轴度的影响规律

侯静静(), 阮达, 薄紫一, 马学虎()   

  1. 大连理工大学,辽宁省化工资源清洁利用重点实验室,辽宁 大连 116024
  • 通讯作者: 马学虎
  • 作者简介:侯静静(1995—),女,博士研究生,Houjj0420@mail.dlut.edu.cn
  • 基金资助:
    国家自然科学基金项目(22478050)

Abstract:

In the process of preparing quantum dots in droplet-based microreactors, the perfluoropolyether oil as the continuous phase and the dispersed phase will change the motion behavior of droplets and affect the heat and mass transfer of the reaction due to the large density difference. The effects of the relative direction of buoyancy and flow and the two-phase flow on the dynamic behavior of the droplet were studied by using coaxial microchannels. The results show that the axial symmetry of the flow field in the horizontal droplet is affected by the buoyancy force, and the coaxiality of the droplet decreases to 0% in the early stage of shedding. By adjusting the relative direction of flow and buoyancy, droplet coaxiality stabilized to 100% at a low continuous phase flow rate (Qc=1.514 ml/min), but at a high Qc (3.666 ml/min) the droplet coaxiality (96.8%) decreased by only 3.2%. By adjusting the two-phase flow rate, the droplet size can be controlled within 537—980 μm. Based on the mechanism of promoting and inhibiting the horizontal/upward and downward droplet by buoyancy, the droplet size prediction model is established with the deviation less than ±10%. The experiment elucidates the effect of buoyancy on droplet behavior in microchannel and provides guidance for the design of droplet based microreactor.

Key words: microchannel, droplet, buoyancy, two-phase flow, coaxiality

摘要:

液滴基微反应器制备量子点过程中,作为连续相的全氟聚醚油与分散相由于密度差较大,会改变液滴运动行为并影响反应的热质传递。实验利用同轴微通道研究了浮力与流动的相对方向及两相流量对液滴动态行为的影响。结果表明,浮力影响水平液滴内部流场的轴对称性使其在脱落前期同轴度降至0%。通过调控流动与浮力的相对方向,实现液滴在较低的连续相流量(Qc=1.514 ml/min)下同轴度稳定至100%,但在较高Qc(3.666 ml/min)向下液滴的同轴度(96.8%)仅降低了3.2%。调控两相流量,液滴尺寸可控制在537~980 μm,基于浮力分别对水平/向上和向下液滴的促进和抑制作用机制,建立液滴尺寸预测模型,偏差约为±10%。实验阐明了微通道内浮力对液滴行为的影响,为液滴基微反应器设计提供指导。

关键词: 微通道, 液滴, 浮力, 两相流, 同轴度

CLC Number: