In this paper, the nitration characteristic of alcohols with mixed acid for the synthesis of energetic mate-rials in a stainless steel microreactor was investigated experimentally. The nitration of iso-octanol with HN...In this paper, the nitration characteristic of alcohols with mixed acid for the synthesis of energetic mate-rials in a stainless steel microreactor was investigated experimentally. The nitration of iso-octanol with HNO3-H2SO4 mixed acid was chosen as a typical model reaction which involved fast and strong exothermic liquid-liquid heterogeneous reaction process. The influences of mixed acid composition, flow rate, organic/aqueous flow ratio and reaction temperature have been investigated. The results indicated that the reaction could be con-ducted safely and stably in the microreactor at 25-40°C, which are enhanced compared to 15°C or below for safe operating conditions in the conventional reactors. Moreover, the 98.2% conversion of iso-octanol could be obtained and no by-products were detected in all cases.展开更多
Microreaction technology is one of the most innovative and rapid developing fields in chemical engineering, synthesis and process technology. Many expectations toward enhanced product selectivity, yield and purity, im...Microreaction technology is one of the most innovative and rapid developing fields in chemical engineering, synthesis and process technology. Many expectations toward enhanced product selectivity, yield and purity, improved safety, and access to new products and processes are directed to the microreaction technology. Microfluidic mixer is the most important component in microfluidic devices. Based on various principles, active and passive micromixers have been designed and investigated. This review is focused on the recent developments in microfluidic mixers. An overview of the flow phenomena and mixing characteristics in active and passive micromixers is presented, including the types of physical phenomena and their utilization in micromixers. Due to the simple fabrication technology and the easy implementation in a complex microfluidic system, T-micromixer is highlighted as an example to illustrate the effect of design and operating parameters on mixing efficiency and fuid flow inside microfluidic mixers.展开更多
In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter...In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance,particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and compared.The results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.展开更多
Chaotic mixing in eight different types of micro T-mixer flow has been studied experimentally and numerically. The present experimental study was performed to visualize two-liquid flows in a micro T-mixer with baffles...Chaotic mixing in eight different types of micro T-mixer flow has been studied experimentally and numerically. The present experimental study was performed to visualize two-liquid flows in a micro T-mixer with baffles. The Reynolds number, baffle height and setting angle were varied to investigate their effect on the mixing performance. Three micro T-mixer models were produced, which are several centimeters long and have a rectangular cross-section of few millimeters a side. The mixing of two-liquid was measured using the laser induced fluorescence (LIF) technique. Moreover, three-dimensional numerical simulations were conducted with the open-source CFD solver, OpenFOAM, for the same configuration as used in the experiments to investigate the detailed mechanism of the chaotic mixing. As a result, it was found that the mixing of two-liquid is greatly improved in the micro T-mixer with baffle. The baffle height and setting angle show a significant influence on the mixing performance.展开更多
Calcium dibutyryladenosine cyclophosphate is a widely used cardiovascular drug.The traditional batch synthesis process suffers from long reaction times,tedious operations,and unstable yields.Herein,a sequential contin...Calcium dibutyryladenosine cyclophosphate is a widely used cardiovascular drug.The traditional batch synthesis process suffers from long reaction times,tedious operations,and unstable yields.Herein,a sequential continuous flow synthesis combined with a multistage in-line purification process of calcium dibutyryladenosine cyclophosphate was developed.The acylation reaction was completed in a continuous coil reactor at 160℃ in 20 min.And the high toxic solvent pyridine was replaced by acetonitrile.Furthermore,the multistage in-line purification process was integrated into the homemade 3D circular cyclone-type micromixer chip.Combining with the membrane phase separators,the residence time of the purification step was 30 s.The isolated yield of this sequential continuous process was 92%with 99%purity.展开更多
Using gas-liquid segmented micromixers to prepare nanoparticles that have a homogeneous particle size, controllable shape, and monodispersity advantages. Although nanoparticle aggregation within a microfluid has been ...Using gas-liquid segmented micromixers to prepare nanoparticles that have a homogeneous particle size, controllable shape, and monodispersity advantages. Although nanoparticle aggregation within a microfluid has been shown to be affected by the shear effect, the shear effect triggering conditions in gasliquid two-phase flow is unclear and the aggregation behavior of nanoparticles under the shear effect is difficult to predict, resulting in uncontrollable physical and chemical properties of nanoparticle aggregates. In this study, a numerical simulation of nanoparticle aggregation in gas-liquid two-phase flow under the shear effect is performed using the CFD-DEM method. Then, the effects of total flow rate,gas-liquid two-phase flow ratio, and particle volume fraction on particle aggregation were analyzed to achieve control of particle aggregation shape and size. Meanwhile, the triggering mechanism of the shear effect and the mechanism of the shear effect on the aggregation of nanoparticles were clarified. The results show that increasing the total flow rate or decreasing the gas-liquid two-phase flow rate ratio can induce the shear effect, which reduces the particle aggregation size and makes the morphology tend to be spherical. Moreover, increasing the particle volume fraction, and total flow rate or decreasing the gas-liquid two-phase flow rate ratio also increases the number of particle collisions and induce interparticle adhesion. Hence, particle adhesion and the shear effect compete with each other and together affect particle aggregation.展开更多
In this work, we present a three dimensional micromixer which consists of two layers of spiral channels overlapped together in the vertical direction. This micromixer is designed by using a smooth channel twisted into...In this work, we present a three dimensional micromixer which consists of two layers of spiral channels overlapped together in the vertical direction. This micromixer is designed by using a smooth channel twisted into double-layer spiral geometry with simple topological structure. Based on the principle of Dean effects, this kind of structure is beneficial to produce, enhance and sustain the Dean vortices, which can perturb the laminar fluid effectively. In order to improve the mixing performance, the detailed parameters have been optimized by using the computational fluid dynamics software. The results indicate that the erect channel which is connected with the two layers of spiral channels plays a critical role for well mixing. Meanwhile, the effect of mixing has been identified in a fabricated glass-micromixer. The mixing efficiency of 90% has been achieved by optimizing the flow rate and the structure of the erect channel. Thus, this micromixer has manifested high mixing efficiency and presents good practicability in the versatile microfluidic systems.展开更多
基金Supported by the National Natural Science Foundation of China (20490208)the National High Technology Research and Development Program of China (2007AA030206)the Open Fund of State Key Laboratory of Explosion Science and Technology,BIT (KFJJ06-1)
文摘In this paper, the nitration characteristic of alcohols with mixed acid for the synthesis of energetic mate-rials in a stainless steel microreactor was investigated experimentally. The nitration of iso-octanol with HNO3-H2SO4 mixed acid was chosen as a typical model reaction which involved fast and strong exothermic liquid-liquid heterogeneous reaction process. The influences of mixed acid composition, flow rate, organic/aqueous flow ratio and reaction temperature have been investigated. The results indicated that the reaction could be con-ducted safely and stably in the microreactor at 25-40°C, which are enhanced compared to 15°C or below for safe operating conditions in the conventional reactors. Moreover, the 98.2% conversion of iso-octanol could be obtained and no by-products were detected in all cases.
基金the National High Technology Research and Development Program of China(2006AA030202,2006AA05Z316)
文摘Microreaction technology is one of the most innovative and rapid developing fields in chemical engineering, synthesis and process technology. Many expectations toward enhanced product selectivity, yield and purity, improved safety, and access to new products and processes are directed to the microreaction technology. Microfluidic mixer is the most important component in microfluidic devices. Based on various principles, active and passive micromixers have been designed and investigated. This review is focused on the recent developments in microfluidic mixers. An overview of the flow phenomena and mixing characteristics in active and passive micromixers is presented, including the types of physical phenomena and their utilization in micromixers. Due to the simple fabrication technology and the easy implementation in a complex microfluidic system, T-micromixer is highlighted as an example to illustrate the effect of design and operating parameters on mixing efficiency and fuid flow inside microfluidic mixers.
文摘In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance,particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and compared.The results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.
文摘Chaotic mixing in eight different types of micro T-mixer flow has been studied experimentally and numerically. The present experimental study was performed to visualize two-liquid flows in a micro T-mixer with baffles. The Reynolds number, baffle height and setting angle were varied to investigate their effect on the mixing performance. Three micro T-mixer models were produced, which are several centimeters long and have a rectangular cross-section of few millimeters a side. The mixing of two-liquid was measured using the laser induced fluorescence (LIF) technique. Moreover, three-dimensional numerical simulations were conducted with the open-source CFD solver, OpenFOAM, for the same configuration as used in the experiments to investigate the detailed mechanism of the chaotic mixing. As a result, it was found that the mixing of two-liquid is greatly improved in the micro T-mixer with baffle. The baffle height and setting angle show a significant influence on the mixing performance.
基金supported by the National Natural Science Foundation of China(No.22278087)。
文摘Calcium dibutyryladenosine cyclophosphate is a widely used cardiovascular drug.The traditional batch synthesis process suffers from long reaction times,tedious operations,and unstable yields.Herein,a sequential continuous flow synthesis combined with a multistage in-line purification process of calcium dibutyryladenosine cyclophosphate was developed.The acylation reaction was completed in a continuous coil reactor at 160℃ in 20 min.And the high toxic solvent pyridine was replaced by acetonitrile.Furthermore,the multistage in-line purification process was integrated into the homemade 3D circular cyclone-type micromixer chip.Combining with the membrane phase separators,the residence time of the purification step was 30 s.The isolated yield of this sequential continuous process was 92%with 99%purity.
基金supported by the Shanghai Beyond Limits Manufacturing Projectthe National Natural Science Foundation of China(Nos.11502044, U1906233)+2 种基金the Fundamental Research Funds for the Central Universities (No.DUT22JC08)Dalian city supports innovation and entrepreneurship projects for high-level talents (No.2021RD16)Liaoning Province’s Xing Liao Talents Program (No.XLYC2002108)。
文摘Using gas-liquid segmented micromixers to prepare nanoparticles that have a homogeneous particle size, controllable shape, and monodispersity advantages. Although nanoparticle aggregation within a microfluid has been shown to be affected by the shear effect, the shear effect triggering conditions in gasliquid two-phase flow is unclear and the aggregation behavior of nanoparticles under the shear effect is difficult to predict, resulting in uncontrollable physical and chemical properties of nanoparticle aggregates. In this study, a numerical simulation of nanoparticle aggregation in gas-liquid two-phase flow under the shear effect is performed using the CFD-DEM method. Then, the effects of total flow rate,gas-liquid two-phase flow ratio, and particle volume fraction on particle aggregation were analyzed to achieve control of particle aggregation shape and size. Meanwhile, the triggering mechanism of the shear effect and the mechanism of the shear effect on the aggregation of nanoparticles were clarified. The results show that increasing the total flow rate or decreasing the gas-liquid two-phase flow rate ratio can induce the shear effect, which reduces the particle aggregation size and makes the morphology tend to be spherical. Moreover, increasing the particle volume fraction, and total flow rate or decreasing the gas-liquid two-phase flow rate ratio also increases the number of particle collisions and induce interparticle adhesion. Hence, particle adhesion and the shear effect compete with each other and together affect particle aggregation.
基金We gratefully acknowledge the financial support from Ministry of Science and Technology of China，the National Natural Science Foundation of China，Chinese Academy of Sciences
文摘In this work, we present a three dimensional micromixer which consists of two layers of spiral channels overlapped together in the vertical direction. This micromixer is designed by using a smooth channel twisted into double-layer spiral geometry with simple topological structure. Based on the principle of Dean effects, this kind of structure is beneficial to produce, enhance and sustain the Dean vortices, which can perturb the laminar fluid effectively. In order to improve the mixing performance, the detailed parameters have been optimized by using the computational fluid dynamics software. The results indicate that the erect channel which is connected with the two layers of spiral channels plays a critical role for well mixing. Meanwhile, the effect of mixing has been identified in a fabricated glass-micromixer. The mixing efficiency of 90% has been achieved by optimizing the flow rate and the structure of the erect channel. Thus, this micromixer has manifested high mixing efficiency and presents good practicability in the versatile microfluidic systems.
