Laminar mixing in the stirred tank is widely encountered in chemical and biological industries.Isolated mixing regions(IMRs)usually exist when the fluid medium has high viscosity,which are not conducive to mixing.In t...Laminar mixing in the stirred tank is widely encountered in chemical and biological industries.Isolated mixing regions(IMRs)usually exist when the fluid medium has high viscosity,which are not conducive to mixing.In this work,the researches on IMRs,enhancement of laminar mixing and the phenomenon of particle clustering within IMRs are reviewed.For most studies,the aim is to destroy IMRs and improve the chaotic mixing.To this end,the mechanism of chaotic mixing and the structure of IMRs were well investigated.The methods developed to destroy IMRs include off-centered agitation,dynamic mixing protocol,special designs of impellers,baffles,etc.In addition,the methods to characterize the shape and size of IMRs as well as mixing effect by experiments and simulations are summarized.However,IMRs are not always nuisance,and it may be necessary in some situations.Finally,the present engineering applications are summarized,and the prospect of the future application is predicted.For example,particle clustering will form in the co-existing system of chaotic mixing and IMRs,which can be used for solid–liquid separation and recovery of particles from high viscosity fluid.展开更多
Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting systems.In the present study,a set of tests have been designed and executed to ...Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting systems.In the present study,a set of tests have been designed and executed to assess the air separation performances of these systems for different air inlet temperatures(70°C∼110°C),inlet pressures(0.1∼0.4 MPa),volume flow rates of nitrogen-enriched air(NEA)(30∼120 L/min)and flight altitudes(1.5∼18 km).In particular,the temperature,pressure,volume flow rate,and oxygen concentration of air,NEA and oxygen-enriched air(OEA)have been measured.The experimental results show that the oxygen concentration of NEA,air separation coefficient,and nitrogen utilization coefficient decrease with the rising of air inlet temperature,air inlet pressure,and flight altitude.The effect of air inlet pressure on the above three parameters is significant,while the influence of air inlet temperature and flight altitude is relatively small.展开更多
基金supports from National Key Research and Develop-ment Program(2020YFA0906804)the National Natural Science Foundation of China(21776282,21978296 and 22078229)+4 种基金the NSFC Key Program(21938009)major project(91934301)the National Key R&D Program of China(2019YFC1905805)Chemistry and Chemical Engineering Guangdong Laboratory Shantou(1922006)Innovation Academy for Green Manufacture,Chinese Academy of Sciences(IAGM2020C06)。
文摘Laminar mixing in the stirred tank is widely encountered in chemical and biological industries.Isolated mixing regions(IMRs)usually exist when the fluid medium has high viscosity,which are not conducive to mixing.In this work,the researches on IMRs,enhancement of laminar mixing and the phenomenon of particle clustering within IMRs are reviewed.For most studies,the aim is to destroy IMRs and improve the chaotic mixing.To this end,the mechanism of chaotic mixing and the structure of IMRs were well investigated.The methods developed to destroy IMRs include off-centered agitation,dynamic mixing protocol,special designs of impellers,baffles,etc.In addition,the methods to characterize the shape and size of IMRs as well as mixing effect by experiments and simulations are summarized.However,IMRs are not always nuisance,and it may be necessary in some situations.Finally,the present engineering applications are summarized,and the prospect of the future application is predicted.For example,particle clustering will form in the co-existing system of chaotic mixing and IMRs,which can be used for solid–liquid separation and recovery of particles from high viscosity fluid.
基金This project is supported by the Fund of Natural Science Project of Hunan Province,China,with the Item No.2020JJ5393Education Department of Hunan Province,China,with the Item No.18C0735.
文摘Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting systems.In the present study,a set of tests have been designed and executed to assess the air separation performances of these systems for different air inlet temperatures(70°C∼110°C),inlet pressures(0.1∼0.4 MPa),volume flow rates of nitrogen-enriched air(NEA)(30∼120 L/min)and flight altitudes(1.5∼18 km).In particular,the temperature,pressure,volume flow rate,and oxygen concentration of air,NEA and oxygen-enriched air(OEA)have been measured.The experimental results show that the oxygen concentration of NEA,air separation coefficient,and nitrogen utilization coefficient decrease with the rising of air inlet temperature,air inlet pressure,and flight altitude.The effect of air inlet pressure on the above three parameters is significant,while the influence of air inlet temperature and flight altitude is relatively small.
