Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactors.In this work,the novel curved capillary reactor with different shapes w...Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactors.In this work,the novel curved capillary reactor with different shapes was designed to generate Dean flow,which was used to enhance the liquid-liquid micromixing performance.The Villermaux-Dushman probe reaction was employed to characterize the micromixing performance in different curved capillary microreactors.The effects of experiment parameters such as liquid flow rate,inner diameter,tube length,and curve diameter on micromixing performance were systematically investigated.Under the optimal conditions,the minimum value of the segmentation factor XS was 0.008.It was worth noting that at the low Reynolds number(Re<30),the change of curved shape on the capillary microreactor can significantly improve the micromixing performance with XS reduced by 37.5%.Further,the correlations of segment index XS with dimensionless factor such as Reynolds number or Dean number were developed,which can be used to predict the liquid-liquid micromixing performance in capillary microreactors.展开更多
The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid i...The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.展开更多
将弯道层流流动形成的Dean涡产生的微粒分离原理运用于污水的2级处理,通过研发水动力分离处理装置,采用投加适量絮凝剂后的某河水进行实验,研究在流道中不同体积流量和絮凝剂含量下装置的分离效果。结果表明：当进水粒径在94.55~161.4μ...将弯道层流流动形成的Dean涡产生的微粒分离原理运用于污水的2级处理,通过研发水动力分离处理装置,采用投加适量絮凝剂后的某河水进行实验,研究在流道中不同体积流量和絮凝剂含量下装置的分离效果。结果表明：当进水粒径在94.55~161.4μm时,分离效果最好;当体积流量小于600 m L/min时,体积流量越大则分离效果越高,而体积流量大于600 m L/min后,分离效果基本不变;在体积流量为600 m L/min时对浊度的去除率在90%以上,对TP和SS去除率分别在85%和50%以上,经装置分离后的清水的浊度大致为1 NTU;在体积流量为600 m L/min时,絮凝剂Fe Cl3的适宜投加质量浓度为21 mg/L。展开更多
基金supports of National Natural Science Foundation of China(22308057)Outstanding Talent Introduction Funds from Fuzhou University(0040-511175)Fuzhou University Testing Fund of precious apparatus(2023T003).
文摘Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactors.In this work,the novel curved capillary reactor with different shapes was designed to generate Dean flow,which was used to enhance the liquid-liquid micromixing performance.The Villermaux-Dushman probe reaction was employed to characterize the micromixing performance in different curved capillary microreactors.The effects of experiment parameters such as liquid flow rate,inner diameter,tube length,and curve diameter on micromixing performance were systematically investigated.Under the optimal conditions,the minimum value of the segmentation factor XS was 0.008.It was worth noting that at the low Reynolds number(Re<30),the change of curved shape on the capillary microreactor can significantly improve the micromixing performance with XS reduced by 37.5%.Further,the correlations of segment index XS with dimensionless factor such as Reynolds number or Dean number were developed,which can be used to predict the liquid-liquid micromixing performance in capillary microreactors.
基金The National Natural Science Foundation of China (No.50976022)the National Key Technology R&D Program of China during the 11th Five-Year Plan Period (No.2008BAJ12B02)
文摘The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.
文摘将弯道层流流动形成的Dean涡产生的微粒分离原理运用于污水的2级处理,通过研发水动力分离处理装置,采用投加适量絮凝剂后的某河水进行实验,研究在流道中不同体积流量和絮凝剂含量下装置的分离效果。结果表明：当进水粒径在94.55~161.4μm时,分离效果最好;当体积流量小于600 m L/min时,体积流量越大则分离效果越高,而体积流量大于600 m L/min后,分离效果基本不变;在体积流量为600 m L/min时对浊度的去除率在90%以上,对TP和SS去除率分别在85%和50%以上,经装置分离后的清水的浊度大致为1 NTU;在体积流量为600 m L/min时,絮凝剂Fe Cl3的适宜投加质量浓度为21 mg/L。
