Micromixing in the submerged circulative impinging stream reactor (SCISR) developed by the authors is investigated with the Bourne's reaction scheme. The values measured for the impinging velocity, u0, under the ...Micromixing in the submerged circulative impinging stream reactor (SCISR) developed by the authors is investigated with the Bourne's reaction scheme. The values measured for the impinging velocity, u0, under the conditions of SCISR normal operation, only is of the order of 0.1m·s^-1, are much slower than that inferred,suggesting low power requirement for operation. The values of the characteristic time constant for micromixing,tM, determined in the impinging velocity range of 0.184m·s^-1 < u0 < 0.326m·s^-1 are ranged from 192ms to 87 ms, showing that impinging streams promotes micromixing very efficiently. The data follow approximately the relationship of tM∝ u0^-1.5. A comparative study shows that the micromixing performance of SCISR is much better than that of the traditional stirred tank reactor. The tM values predicted with the existing theoretical model are systematically longer than those measured by about 2--3 times, implying that the regularity of impinging streams promoting micromixing is unclear yet.展开更多
Micromixing efficiency of viscous media in Y-type micro-channel reactor was studied by using iodide-iodate test reaction as working system.Experiments were carried out in water-glycerin mixtures with 7 different visco...Micromixing efficiency of viscous media in Y-type micro-channel reactor was studied by using iodide-iodate test reaction as working system.Experiments were carried out in water-glycerin mixtures with 7 different viscosities.The experimental results showed that segregation index of the micro-channel reactor increases with the decrease of volumetric flow rate and the increase of solution viscosity.Based on the incorporation model,the micromixing time tm of the micro-channel reactor was estimated in the range of 10-4-10-3s at different viscosities,which indicated that the micro-channel reactor possesses a much better micromixing performance compared to the stirred tank(tm=0.02-0.2s).展开更多
Microchannel reactors are widely used in different fields due to their intensive micromixing and, thus, high masstransfer efficiency. In this work, a single countercurrent-flow microchannel reactor(S-CFMCR) at the siz...Microchannel reactors are widely used in different fields due to their intensive micromixing and, thus, high masstransfer efficiency. In this work, a single countercurrent-flow microchannel reactor(S-CFMCR) at the size of ~1 mm was developed by steel micro-capillary and laser drilling technology. Utilizing the Villermaux/Dushman parallel competing reaction, numerical and experimental studies were carried out to investigate the micromixing performance(expressed as the segregation index XS) of liquids inside S-CFMCR at the low flow velocity regime.The effects of various operating conditions and design parameters of S-CFMCR, e.g., inlet Reynolds number(Re),volumetric flow ratio(R), inlet diameter(d) and outlet length(L), on the quality of micromixing were studied qualitatively. It was found that the micromixing efficiency was enhanced with increasing Re, but weakened with the increase of R. Moreover, d and L also have a significant influence on micromixing. CFD results were in good agreement with experimental data. In addition, the visualization of velocity magnitude, turbulent kinetic energy and concentration distributions of various ions inside S-CFMCR was illustrated as well. Based on the incorporation model, the estimated minimum micromixing time tmof S-CFMCR is ~2 × 10-4s.展开更多
Confined impinging jet reactor(CIJR)offers advantages for chemical rapid processes and has become an important new reactor used in the chemical industry.The micromixing efficiency in a T-shaped CIJR for two tubes of i...Confined impinging jet reactor(CIJR)offers advantages for chemical rapid processes and has become an important new reactor used in the chemical industry.The micromixing efficiency in a T-shaped CIJR for two tubes of inner diameter of 3 mm was studied by using a parallel competing iodide–iodate reaction as the working system.In this work,the effects of different operating conditions,such as impinging velocity and acid concentration,on segregation index were investigated.In addition,the effects of the inner nozzles diameter and the distance L between the jet axis and the top wall of the mixing chamber on the micromixing efficiency were also considered.It is concluded that the best range of L in this CIJR is 6.5–12.5 mm.Based on the incorporation model,the estimated minimum micromixing time tmof CIJR approximately equals to 2×10-4s.These experimental results indicate clearly that CIJR possesses a much better micromixing performance compared with the conventional stirred tank(micromixing time of 2×10-3to 2×10-2s).Hence,it can be envisioned that CIJR has more promising applications in various industrial processes.展开更多
作者根据前文〔10〕的拍摄结果与有关湍流理论,分析了微观混和过程,从而导出了新的单参数微观混和模型。模型对在搅拌反应釜中进行的α—萘酚与对氨基苯磺酸重氮盐的偶合反应的选择性进行了模拟,模拟结果与实验结果符合程度相当令人满意...作者根据前文〔10〕的拍摄结果与有关湍流理论,分析了微观混和过程,从而导出了新的单参数微观混和模型。模型对在搅拌反应釜中进行的α—萘酚与对氨基苯磺酸重氮盐的偶合反应的选择性进行了模拟,模拟结果与实验结果符合程度相当令人满意,同时得到了实验条件下模型参数的关联式。实验结果证实,本文提出的模型能成功地描述微观混和过程及其对化学反应的影响,与其他模型相比,具有结构合理、计算简单、便于应用等优点。本文还分析讨论了体积比α、混和模数 M 以及 Sc 数对微观混和过程状况的影响。所有这些研究结果,为进一步的研究以及新型反应器的设计开发提供了一定的理论基础,具有一定的工业意义。展开更多
The mixing-precipitation process for producing phenylpyruvic acid sodium salt(PPNa) by neutralization of phenylpyruic acid(PPA) with aqueous sodium hydroxide in a semi-batch stirred tank was studied.The effects of mix...The mixing-precipitation process for producing phenylpyruvic acid sodium salt(PPNa) by neutralization of phenylpyruic acid(PPA) with aqueous sodium hydroxide in a semi-batch stirred tank was studied.The effects of mixing characteristics and chemical characteristics on the precipitation process were investigated experimentally.It was found that the crystals growth rate and morphology obviously changed due to ripening.Crystal redissolution agglomeration and solvent inclusion also changed the purity of PPNa product considerably.展开更多
Glucose oxidization was catalyzed by glucose peroxidase, reactive products peroxides could have Chemiluminescence reaction with luminol. These were applied to detect glucose quantitatively in-situ or on-line by the mi...Glucose oxidization was catalyzed by glucose peroxidase, reactive products peroxides could have Chemiluminescence reaction with luminol. These were applied to detect glucose quantitatively in-situ or on-line by the microreactor with micromixer and FIA system. In this paper, the effects of many factors, such as the characters of microchip, modification of microchip glass surface, pH values of the detecting system, CL intensifying agent and so on, were studied in detail on the glucose detection. A new reliable and portable easily automatable system was set up for the glucose detection.展开更多
基金Supported by the National Natural Science Foundation of China (No. 29276260, No. 20176043).
文摘Micromixing in the submerged circulative impinging stream reactor (SCISR) developed by the authors is investigated with the Bourne's reaction scheme. The values measured for the impinging velocity, u0, under the conditions of SCISR normal operation, only is of the order of 0.1m·s^-1, are much slower than that inferred,suggesting low power requirement for operation. The values of the characteristic time constant for micromixing,tM, determined in the impinging velocity range of 0.184m·s^-1 < u0 < 0.326m·s^-1 are ranged from 192ms to 87 ms, showing that impinging streams promotes micromixing very efficiently. The data follow approximately the relationship of tM∝ u0^-1.5. A comparative study shows that the micromixing performance of SCISR is much better than that of the traditional stirred tank reactor. The tM values predicted with the existing theoretical model are systematically longer than those measured by about 2--3 times, implying that the regularity of impinging streams promoting micromixing is unclear yet.
基金Supported by the National-Natural Science Foundation of China （20821004, 20806004） and the National High Technology Research and Development Program of China （2007AA030207, 2006AA030202, 2006AA030203）.
文摘Micromixing efficiency of viscous media in Y-type micro-channel reactor was studied by using iodide-iodate test reaction as working system.Experiments were carried out in water-glycerin mixtures with 7 different viscosities.The experimental results showed that segregation index of the micro-channel reactor increases with the decrease of volumetric flow rate and the increase of solution viscosity.Based on the incorporation model,the micromixing time tm of the micro-channel reactor was estimated in the range of 10-4-10-3s at different viscosities,which indicated that the micro-channel reactor possesses a much better micromixing performance compared to the stirred tank(tm=0.02-0.2s).
基金Supported by the National Natural Science Foundation of China(21576012)the National Key Research and Development Program of China(2017YFB0307202)
文摘Microchannel reactors are widely used in different fields due to their intensive micromixing and, thus, high masstransfer efficiency. In this work, a single countercurrent-flow microchannel reactor(S-CFMCR) at the size of ~1 mm was developed by steel micro-capillary and laser drilling technology. Utilizing the Villermaux/Dushman parallel competing reaction, numerical and experimental studies were carried out to investigate the micromixing performance(expressed as the segregation index XS) of liquids inside S-CFMCR at the low flow velocity regime.The effects of various operating conditions and design parameters of S-CFMCR, e.g., inlet Reynolds number(Re),volumetric flow ratio(R), inlet diameter(d) and outlet length(L), on the quality of micromixing were studied qualitatively. It was found that the micromixing efficiency was enhanced with increasing Re, but weakened with the increase of R. Moreover, d and L also have a significant influence on micromixing. CFD results were in good agreement with experimental data. In addition, the visualization of velocity magnitude, turbulent kinetic energy and concentration distributions of various ions inside S-CFMCR was illustrated as well. Based on the incorporation model, the estimated minimum micromixing time tmof S-CFMCR is ~2 × 10-4s.
基金Supported by the National Natural Science Foundation of China(21206002,21121064,20990224)the State Key Laboratory of Chemical Engineering(SKL-Ch E-13A03)
文摘Confined impinging jet reactor(CIJR)offers advantages for chemical rapid processes and has become an important new reactor used in the chemical industry.The micromixing efficiency in a T-shaped CIJR for two tubes of inner diameter of 3 mm was studied by using a parallel competing iodide–iodate reaction as the working system.In this work,the effects of different operating conditions,such as impinging velocity and acid concentration,on segregation index were investigated.In addition,the effects of the inner nozzles diameter and the distance L between the jet axis and the top wall of the mixing chamber on the micromixing efficiency were also considered.It is concluded that the best range of L in this CIJR is 6.5–12.5 mm.Based on the incorporation model,the estimated minimum micromixing time tmof CIJR approximately equals to 2×10-4s.These experimental results indicate clearly that CIJR possesses a much better micromixing performance compared with the conventional stirred tank(micromixing time of 2×10-3to 2×10-2s).Hence,it can be envisioned that CIJR has more promising applications in various industrial processes.
文摘作者根据前文〔10〕的拍摄结果与有关湍流理论,分析了微观混和过程,从而导出了新的单参数微观混和模型。模型对在搅拌反应釜中进行的α—萘酚与对氨基苯磺酸重氮盐的偶合反应的选择性进行了模拟,模拟结果与实验结果符合程度相当令人满意,同时得到了实验条件下模型参数的关联式。实验结果证实,本文提出的模型能成功地描述微观混和过程及其对化学反应的影响,与其他模型相比,具有结构合理、计算简单、便于应用等优点。本文还分析讨论了体积比α、混和模数 M 以及 Sc 数对微观混和过程状况的影响。所有这些研究结果,为进一步的研究以及新型反应器的设计开发提供了一定的理论基础,具有一定的工业意义。
文摘The mixing-precipitation process for producing phenylpyruvic acid sodium salt(PPNa) by neutralization of phenylpyruic acid(PPA) with aqueous sodium hydroxide in a semi-batch stirred tank was studied.The effects of mixing characteristics and chemical characteristics on the precipitation process were investigated experimentally.It was found that the crystals growth rate and morphology obviously changed due to ripening.Crystal redissolution agglomeration and solvent inclusion also changed the purity of PPNa product considerably.
文摘Glucose oxidization was catalyzed by glucose peroxidase, reactive products peroxides could have Chemiluminescence reaction with luminol. These were applied to detect glucose quantitatively in-situ or on-line by the microreactor with micromixer and FIA system. In this paper, the effects of many factors, such as the characters of microchip, modification of microchip glass surface, pH values of the detecting system, CL intensifying agent and so on, were studied in detail on the glucose detection. A new reliable and portable easily automatable system was set up for the glucose detection.
