For spacecraft working in vacuum environment, sublimator is an effective heat rejection approach to reject system's peak heat load, and supplement spacecraft radiation heat rejection. For a spacecraft active fluid...For spacecraft working in vacuum environment, sublimator is an effective heat rejection approach to reject system's peak heat load, and supplement spacecraft radiation heat rejection. For a spacecraft active fluid loop thermal control system combined with sublimator, waste heat generated from multi-point distributed heat sources could be collected by the fluid loop efficiently. However, the heat and mass transfer performances of the sublimator combined with fluid loop have not been adequately studied in previous research, especially for the influences of the heat load. Since work fluid mass flow rate is the main factor affecting heat load of the fluid loop, this context experimentally studied influences of the fluid loop mass flow rate on sublimator start-up transient characteristics, including heat transfer performances, response time, and work stability. Results indicated that the fluid loop mass flow rate affected the sublimator heat and mass transfer performances obviously, but the heat rejection ability is not always increase with the increasing of the fluid loop mass flow rate. In addition, we obtained the condition to judge whether there is a positive correlation between heat rejection ability and fluid loop mass flow rate.展开更多
Phosphogypsum(PG)is a solid waste produced in the wet process of producing phosphoric acid.Lignite is a kind of promising chemical raw material.However,the high sulfur of lignite limits the utilization of lignite as a...Phosphogypsum(PG)is a solid waste produced in the wet process of producing phosphoric acid.Lignite is a kind of promising chemical raw material.However,the high sulfur of lignite limits the utilization of lignite as a resource.Based on fluidized bed experiments,the optimal reaction conditions for the production syngas by lignite chemical looping gasification(CLG)with PG as oxygen carrier were studied.The study found that the optimal reaction temperature should not exceed 1123 K;the mole ratio of water vapor to lignite should be about 0.2;the mole ratio of PG oxygen carrier to lignite should be about 0.6.Meanwhile,commercial software Comsol was used to establish a fuel reaction kinetics model.Through computational fluid dynamics(CFD)numerical simulation,the process of reaction in fluidized bed were well captured.The model was based on a two-fluid model and coupled mass transfer,heat transfer and chemical reactions.This study showed that the fluidized bed presents a flow structure in which gas and solid coexist.There was a high temperature zone in the middle and lower parts of the fluidized bed.It could be seen from the results of the flow field simulated that the fluidized bed was beneficial to the progress of the gasification reaction.展开更多
The Solar Close Observations and Proximity Experiments(SCOPE)mission,which has been proposed by the Yunnan Observatories,Chinese Academy of Sciences,aiming to operate at a distance of 5 to 10 solar radii from the Sun,...The Solar Close Observations and Proximity Experiments(SCOPE)mission,which has been proposed by the Yunnan Observatories,Chinese Academy of Sciences,aiming to operate at a distance of 5 to 10 solar radii from the Sun,plans to complete the in situ detection of the solar eruption process and observation of the magnetic field structure response.The solar flux received by the satellite ranges from 10^(3) to 10^(6) Wm^(-2),which poses challenges for thermal management of the solar arrays.In this work,the solar array cooling system of the Parker Solar Probe is discussed,the developments of the fluid loop technique are reviewed,and a research plan for a next-generation solar array cooling system is proposed.This paper provides a valuable reference for novel thermal control systems in spacecraft for solar observation.展开更多
In this paper, the characteristics of fluid mixing time in a novel extra-loop fluidized bed were studied. The results showed that the mixing time was shortened with the increase of fluid velocity. All the discrete num...In this paper, the characteristics of fluid mixing time in a novel extra-loop fluidized bed were studied. The results showed that the mixing time was shortened with the increase of fluid velocity. All the discrete numbers of the reactor were above 0.2. The serial number n was 2.5 -3.0. It was judged accordingly that the reactor fluid state was continous stirred tank reactor （CSTR） mainly. When the inspiratory capacity increased the mixing time of the reactor was shortened. Thus the air input was beneficial for the fluid mixing. During the three phases mixing process, the mixing time of the reactor could be decreased by the n increase of carrier and air loading together, but the change was not significant. The parameters affecting the reactor fluid state were fluid velocity, inspiratory capacity and carrier. KLa could be increased with the air loading increase, and at the same gas/liquid ratio when the pressure drop was high, KL~ value was increased. The amount of carrier complex influence on KLa. As the carrier loading continued to increase, its value had been dropped but the changes was not significant, and optimization condition was found at above 800 1 000 g carrier loading （pouzzolane） or 600 g PVC. Under gas/liquid ratio of 0.8% -5.2%, KLa was （0.62-1.37）×10^-2· s^-1.展开更多
Hydrodynamics of airlift loop reactors was studied in detail experimentally andtheoretically.An internal airlift loop reactor was designed and set up for this study.An instru-mentation system based on the electrochemi...Hydrodynamics of airlift loop reactors was studied in detail experimentally andtheoretically.An internal airlift loop reactor was designed and set up for this study.An instru-mentation system based on the electrochemical method was adapted to measure local gas holdup andliquid velocity.A two-dimensional two-fluid model based on the first principles was established andimplemented to model the flow in airlift loop reactors.A corrected turbulent model was incorporatedin the simulation.The shear rate,shear stress and energy dissipation are evaluated from the flowfield.The numerically predicted results and experimental data obtained from this work as well as thesereported in literature are analyzed and compared.展开更多
Understanding of hydrodynamics in liquid jet loop reactors is a prerequisite step for the fur-ther study of multi-phase flow in loop reactors.A hydrodynamic simulation for liquid jet loop reac-tors is developed from t...Understanding of hydrodynamics in liquid jet loop reactors is a prerequisite step for the fur-ther study of multi-phase flow in loop reactors.A hydrodynamic simulation for liquid jet loop reac-tors is developed from the first principles of transport phenomena in this paper.The turbulence istaken into account by using the standard k-ε model.This approach is used to study the influence ofconfiguration and viscosity on the hydrodynamics.The results are in very reasonable coincidence to ex-perimental data in literature.展开更多
Slurry reactors are popular in many industrial processes,involved with numerous chemical and biological mixtures,solid particles with different concentrations and properties,and a wide range of operating conditions.Th...Slurry reactors are popular in many industrial processes,involved with numerous chemical and biological mixtures,solid particles with different concentrations and properties,and a wide range of operating conditions.These factors can significantly affect the hydrodynamic in the slurry reactors,having remarkable effects on the design,scale-up,and operation of the slurry reactors.This article reviews the influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry reactors.Firstly,the influence of fluid properties,including the density and viscosity of the individual liquid and gas phases and the interfacial tension,has been reviewed.Secondly,the solid particle properties(i.e.,concentration,density,size,wettability,and shape)on the hydrodynamics have been discussed in detail,and some vital but often ignored features,especially the influences of particle wettability and shape,as well as the variation of surface tension because of solid concentration alteration,are highlighted in this work.Thirdly,the variations of physical properties of fluids,hydrodynamics,and bubble behavior resulted from the temperature and pressure variations are also summarized,and the indirect influences of pressure on viscosity and surface tension are addressed systematically.Finally,conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.展开更多
The external loop airlift reactor(ELALR)is widely used for gasliquid reactions.It’s advantage of good heat and mass transfer rates compared to conventional bubble column reactors.In the case of fermentation applicati...The external loop airlift reactor(ELALR)is widely used for gasliquid reactions.It’s advantage of good heat and mass transfer rates compared to conventional bubble column reactors.In the case of fermentation application where a medium is highly viscous and coalescing in nature,internal in riser helps in the improvement of the interfacial area as well as in the reduction of liquidphase back mixing.The computational fluid dynamic(CFD)as a tool is used to design and scaleup of sectionalized external loop airlift reactor.The present work deals with computational fluid dynamics(CFD)techniques and experimental measurement of a gas holdup,liquid circulation velocity,liquid axial velocity,Sauter mean bubble diameter over a broad range of superficial gas velocity 0.0024≤UG≤0.0168 m s 1.The correlation has been made for bubble size distribution with specific power consumption for different plate configurations.The effects of an internal on different mass transfer models have been completed to assess their suitability.The predicted local mass transfer coefficient has been found higher in the sectionalized external loop airlift reactor than the conventional ELALR.展开更多
Techno-economic development of chemical looping combustion （CLC） process has been one of the most pursued research areas of the present decade due to its ability to reduce carbon foot print during utilization of coa...Techno-economic development of chemical looping combustion （CLC） process has been one of the most pursued research areas of the present decade due to its ability to reduce carbon foot print during utilization of coal to generate energy. Based on a 2D computational fluid dynamics model, the present work provides a computational approach to study the effect of operating pressure--a key parameter in designing of CLC reactors, on optimum operating conditions. The effects of operating pressure have been examined in terms of reactors temperature, percentage of fuel conversion and purity of carbon dioxide in fuel reactor exhaust. The simulated results show qualitative agreement with the trends obtained by other investigators during experimental studies.展开更多
基金supports of the National Natural Science Foundation of China(No.11472040)the National Science Technology Major Project of China
文摘For spacecraft working in vacuum environment, sublimator is an effective heat rejection approach to reject system's peak heat load, and supplement spacecraft radiation heat rejection. For a spacecraft active fluid loop thermal control system combined with sublimator, waste heat generated from multi-point distributed heat sources could be collected by the fluid loop efficiently. However, the heat and mass transfer performances of the sublimator combined with fluid loop have not been adequately studied in previous research, especially for the influences of the heat load. Since work fluid mass flow rate is the main factor affecting heat load of the fluid loop, this context experimentally studied influences of the fluid loop mass flow rate on sublimator start-up transient characteristics, including heat transfer performances, response time, and work stability. Results indicated that the fluid loop mass flow rate affected the sublimator heat and mass transfer performances obviously, but the heat rejection ability is not always increase with the increasing of the fluid loop mass flow rate. In addition, we obtained the condition to judge whether there is a positive correlation between heat rejection ability and fluid loop mass flow rate.
基金Financial support for this project were provided by National Natural Science Foundation of China(No.21666016)National Key Research and Development Program of China(2018YFC1900200)State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2021-K39)。
文摘Phosphogypsum(PG)is a solid waste produced in the wet process of producing phosphoric acid.Lignite is a kind of promising chemical raw material.However,the high sulfur of lignite limits the utilization of lignite as a resource.Based on fluidized bed experiments,the optimal reaction conditions for the production syngas by lignite chemical looping gasification(CLG)with PG as oxygen carrier were studied.The study found that the optimal reaction temperature should not exceed 1123 K;the mole ratio of water vapor to lignite should be about 0.2;the mole ratio of PG oxygen carrier to lignite should be about 0.6.Meanwhile,commercial software Comsol was used to establish a fuel reaction kinetics model.Through computational fluid dynamics(CFD)numerical simulation,the process of reaction in fluidized bed were well captured.The model was based on a two-fluid model and coupled mass transfer,heat transfer and chemical reactions.This study showed that the fluidized bed presents a flow structure in which gas and solid coexist.There was a high temperature zone in the middle and lower parts of the fluidized bed.It could be seen from the results of the flow field simulated that the fluidized bed was beneficial to the progress of the gasification reaction.
基金This work has been supported by National Key R&D Program of China No.2022YFF0503804.
文摘The Solar Close Observations and Proximity Experiments(SCOPE)mission,which has been proposed by the Yunnan Observatories,Chinese Academy of Sciences,aiming to operate at a distance of 5 to 10 solar radii from the Sun,plans to complete the in situ detection of the solar eruption process and observation of the magnetic field structure response.The solar flux received by the satellite ranges from 10^(3) to 10^(6) Wm^(-2),which poses challenges for thermal management of the solar arrays.In this work,the solar array cooling system of the Parker Solar Probe is discussed,the developments of the fluid loop technique are reviewed,and a research plan for a next-generation solar array cooling system is proposed.This paper provides a valuable reference for novel thermal control systems in spacecraft for solar observation.
基金Project supported by the Foundation Social European,Republoque Francaise
文摘In this paper, the characteristics of fluid mixing time in a novel extra-loop fluidized bed were studied. The results showed that the mixing time was shortened with the increase of fluid velocity. All the discrete numbers of the reactor were above 0.2. The serial number n was 2.5 -3.0. It was judged accordingly that the reactor fluid state was continous stirred tank reactor （CSTR） mainly. When the inspiratory capacity increased the mixing time of the reactor was shortened. Thus the air input was beneficial for the fluid mixing. During the three phases mixing process, the mixing time of the reactor could be decreased by the n increase of carrier and air loading together, but the change was not significant. The parameters affecting the reactor fluid state were fluid velocity, inspiratory capacity and carrier. KLa could be increased with the air loading increase, and at the same gas/liquid ratio when the pressure drop was high, KL~ value was increased. The amount of carrier complex influence on KLa. As the carrier loading continued to increase, its value had been dropped but the changes was not significant, and optimization condition was found at above 800 1 000 g carrier loading （pouzzolane） or 600 g PVC. Under gas/liquid ratio of 0.8% -5.2%, KLa was （0.62-1.37）×10^-2· s^-1.
基金Supported by the National Natural Science Foundation of China.
文摘Hydrodynamics of airlift loop reactors was studied in detail experimentally andtheoretically.An internal airlift loop reactor was designed and set up for this study.An instru-mentation system based on the electrochemical method was adapted to measure local gas holdup andliquid velocity.A two-dimensional two-fluid model based on the first principles was established andimplemented to model the flow in airlift loop reactors.A corrected turbulent model was incorporatedin the simulation.The shear rate,shear stress and energy dissipation are evaluated from the flowfield.The numerically predicted results and experimental data obtained from this work as well as thesereported in literature are analyzed and compared.
基金Supported by the National Natural Science Foundation of China.
文摘Understanding of hydrodynamics in liquid jet loop reactors is a prerequisite step for the fur-ther study of multi-phase flow in loop reactors.A hydrodynamic simulation for liquid jet loop reac-tors is developed from the first principles of transport phenomena in this paper.The turbulence istaken into account by using the standard k-ε model.This approach is used to study the influence ofconfiguration and viscosity on the hydrodynamics.The results are in very reasonable coincidence to ex-perimental data in literature.
基金supported by the National Natural Science Foundation of China(2187831821808234)+5 种基金the Dalian National Laboratory for Clean Energy Cooperation Fund,CAS(DNL201902)“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(XDA21060400)Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT)and Dalian National Laboratory for Clean Energy(DNL)of CAS(QIBEBT ZZBS201803QIBEBT I201907)Director Innovation Fund of Synthetic Biology Technology Innovation Center of Shandong Province(sdsynbio-2020-ZH02)Project of CNPC-DICP Joint Research Center。
文摘Slurry reactors are popular in many industrial processes,involved with numerous chemical and biological mixtures,solid particles with different concentrations and properties,and a wide range of operating conditions.These factors can significantly affect the hydrodynamic in the slurry reactors,having remarkable effects on the design,scale-up,and operation of the slurry reactors.This article reviews the influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry reactors.Firstly,the influence of fluid properties,including the density and viscosity of the individual liquid and gas phases and the interfacial tension,has been reviewed.Secondly,the solid particle properties(i.e.,concentration,density,size,wettability,and shape)on the hydrodynamics have been discussed in detail,and some vital but often ignored features,especially the influences of particle wettability and shape,as well as the variation of surface tension because of solid concentration alteration,are highlighted in this work.Thirdly,the variations of physical properties of fluids,hydrodynamics,and bubble behavior resulted from the temperature and pressure variations are also summarized,and the indirect influences of pressure on viscosity and surface tension are addressed systematically.Finally,conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.
文摘The external loop airlift reactor(ELALR)is widely used for gasliquid reactions.It’s advantage of good heat and mass transfer rates compared to conventional bubble column reactors.In the case of fermentation application where a medium is highly viscous and coalescing in nature,internal in riser helps in the improvement of the interfacial area as well as in the reduction of liquidphase back mixing.The computational fluid dynamic(CFD)as a tool is used to design and scaleup of sectionalized external loop airlift reactor.The present work deals with computational fluid dynamics(CFD)techniques and experimental measurement of a gas holdup,liquid circulation velocity,liquid axial velocity,Sauter mean bubble diameter over a broad range of superficial gas velocity 0.0024≤UG≤0.0168 m s 1.The correlation has been made for bubble size distribution with specific power consumption for different plate configurations.The effects of an internal on different mass transfer models have been completed to assess their suitability.The predicted local mass transfer coefficient has been found higher in the sectionalized external loop airlift reactor than the conventional ELALR.
文摘Techno-economic development of chemical looping combustion （CLC） process has been one of the most pursued research areas of the present decade due to its ability to reduce carbon foot print during utilization of coal to generate energy. Based on a 2D computational fluid dynamics model, the present work provides a computational approach to study the effect of operating pressure--a key parameter in designing of CLC reactors, on optimum operating conditions. The effects of operating pressure have been examined in terms of reactors temperature, percentage of fuel conversion and purity of carbon dioxide in fuel reactor exhaust. The simulated results show qualitative agreement with the trends obtained by other investigators during experimental studies.
