A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge（DBD） using parallel...A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge（DBD） using parallel-plate reactor in air.The electron energy conservation equation is coupled to the electron continuity equation,the heavy species continuity equation,and Poisson＇s equation for a better description.The reliability of the model is experimentally confirmed.The model can be used to predict the temporal and spatial evolution of species,as well as streamer propagation.The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche.Streamer propagation velocity is about 5.26×104m/s from anode to cathode in the simulated condition.The primary positive ion,negative ion,and excited species are O_2~＋,O_3^-and O_2（1？g） in pulsed DBD in air,respectively.N_2 O has the largest density among nitrogen oxides.e and N_2~＋densities in the streamer head increase gradually to maximum values with the development of the streamer.Meanwhile,the O_2~＋,O,O_3,N_2（A^3Σ） and N_2 O densities reach maximum values in the vicinity of the anode.展开更多
Boiling heat transfer condition has significance for pool-type research reactors cooled by natural circulation.It has important effect on the fuel element safety of reactor.On the basis of heat transfer characteristic...Boiling heat transfer condition has significance for pool-type research reactors cooled by natural circulation.It has important effect on the fuel element safety of reactor.On the basis of heat transfer characteristics of the Xi'an pulsed reactor(XAPR),fuel conduction,single-phase convection and boiling heat transfer,and void fraction models of the core are constructed.To validate the correctness of the physical models presented in the paper,numerical calculation based on a subchannel analysis method of XAPR is carried out,and the temperature fields are measured in some reactor coolant channels.The comparison between the calculated and experimental results verifies the effectiveness of the models.These physical models are used to calculate the thermal-hydraulic parameters of XAPR at the rated power(for XAPR the rated power is 2.0 MW in steady-state operation).The results indicate that subcooled boiling occurs in the XAPR core but it exhibits a subcooling degree which is considerably higher than that of saturation boiling.Subcooled boiling improves the efficiency of heat transfer between the fuel element surface and coolant,as well as effectively protects fuel elements.This research is also a beneficial reference in thermal-hydraulic analysis for other natural circulation reactors.展开更多
An integrated approach combining the development of an innovative catalyst and the research of a set of adequate operating conditions for the propane oxidative dehydrogenation （ODH） is described.The experimental set...An integrated approach combining the development of an innovative catalyst and the research of a set of adequate operating conditions for the propane oxidative dehydrogenation （ODH） is described.The experimental set-up,specially designed for steady-state and transient studies is presented.The preparation method,the characterization and the performances in steady-state and transient regimes of catalysts based on V2W4O194-Lindqvist isopolyanion used as a precursor and supported on alumina are reported.The influence of the preparation method of the catalyst and the role of water in the feed gas are more particularly discussed.展开更多
Efficient and reliable precipitation reactors are of great significance for the recovery of spent nuclear fuel.However,most current spent nuclear fuel precipitation reactors rely on agitation-driven mixing,which suffe...Efficient and reliable precipitation reactors are of great significance for the recovery of spent nuclear fuel.However,most current spent nuclear fuel precipitation reactors rely on agitation-driven mixing,which suffers from low mixing efficiency and high failure rates.In this study,a pulse pressure-driven spent nuclear fuel precipitation reactor was designed and its hydrodynamics performance were investigated using a CFD–DEM–VOF coupled numerical approach.Three key process parameters were systematically examined,including pulse period,pulse pressure,and initial liquid level.The simulation results revealed that pulse period and pulse pressure significantly influenced hydrodynamic behavior and particle suspension performance,whereas the initial liquid level had a subordinate effect.Under optimized pulse conditions,effective mixing and uniform particle suspension could be achieved regardless of the initial liquid height.Furthermore,a quantitative evaluation of mixing and suspension performance was conducted based on average flow velocity,average turbulent kinetic energy,and the relative standard deviation of particle suspension uniformity.The results demonstrated that efficient fluid mixing and homogeneous particle suspension could be realized under appropriate operating conditions.This study provides theoretical guidance for developing high-performance pulse-driven precipitation reactors and optimizing their operational processes in spent nuclear fuel treatment.展开更多
基金supported by National Natural Science Foundation of China(Nos.51366012 and 11105067)Jiangxi Province Young Scientists(Jinggang Star)Cultivation Plan of China(No.20133BCB23008)+1 种基金Natural Science Foundation of Jiangxi,China(No.20151BAB206047)Jiangxi Province Higher School Science and Technology Landing Plan of China(No.KJLD-14015)
文摘A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge（DBD） using parallel-plate reactor in air.The electron energy conservation equation is coupled to the electron continuity equation,the heavy species continuity equation,and Poisson＇s equation for a better description.The reliability of the model is experimentally confirmed.The model can be used to predict the temporal and spatial evolution of species,as well as streamer propagation.The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche.Streamer propagation velocity is about 5.26×104m/s from anode to cathode in the simulated condition.The primary positive ion,negative ion,and excited species are O_2~＋,O_3^-and O_2（1？g） in pulsed DBD in air,respectively.N_2 O has the largest density among nitrogen oxides.e and N_2~＋densities in the streamer head increase gradually to maximum values with the development of the streamer.Meanwhile,the O_2~＋,O,O_3,N_2（A^3Σ） and N_2 O densities reach maximum values in the vicinity of the anode.
文摘Boiling heat transfer condition has significance for pool-type research reactors cooled by natural circulation.It has important effect on the fuel element safety of reactor.On the basis of heat transfer characteristics of the Xi'an pulsed reactor(XAPR),fuel conduction,single-phase convection and boiling heat transfer,and void fraction models of the core are constructed.To validate the correctness of the physical models presented in the paper,numerical calculation based on a subchannel analysis method of XAPR is carried out,and the temperature fields are measured in some reactor coolant channels.The comparison between the calculated and experimental results verifies the effectiveness of the models.These physical models are used to calculate the thermal-hydraulic parameters of XAPR at the rated power(for XAPR the rated power is 2.0 MW in steady-state operation).The results indicate that subcooled boiling occurs in the XAPR core but it exhibits a subcooling degree which is considerably higher than that of saturation boiling.Subcooled boiling improves the efficiency of heat transfer between the fuel element surface and coolant,as well as effectively protects fuel elements.This research is also a beneficial reference in thermal-hydraulic analysis for other natural circulation reactors.
基金supported by CNRS standing for Centre National de la Recherche Scientifique (France),CAPES standing for Coordenao de Aperfeioamento de Pessoal de Nível Superior (Brazil),CNPq standing for Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brazil) and FINEP standing for Financiadora de Estudos e Projetos (Brazil)
文摘An integrated approach combining the development of an innovative catalyst and the research of a set of adequate operating conditions for the propane oxidative dehydrogenation （ODH） is described.The experimental set-up,specially designed for steady-state and transient studies is presented.The preparation method,the characterization and the performances in steady-state and transient regimes of catalysts based on V2W4O194-Lindqvist isopolyanion used as a precursor and supported on alumina are reported.The influence of the preparation method of the catalyst and the role of water in the feed gas are more particularly discussed.
基金supported by the China Nuclear Power Engineering Co.,LTD.
文摘Efficient and reliable precipitation reactors are of great significance for the recovery of spent nuclear fuel.However,most current spent nuclear fuel precipitation reactors rely on agitation-driven mixing,which suffers from low mixing efficiency and high failure rates.In this study,a pulse pressure-driven spent nuclear fuel precipitation reactor was designed and its hydrodynamics performance were investigated using a CFD–DEM–VOF coupled numerical approach.Three key process parameters were systematically examined,including pulse period,pulse pressure,and initial liquid level.The simulation results revealed that pulse period and pulse pressure significantly influenced hydrodynamic behavior and particle suspension performance,whereas the initial liquid level had a subordinate effect.Under optimized pulse conditions,effective mixing and uniform particle suspension could be achieved regardless of the initial liquid height.Furthermore,a quantitative evaluation of mixing and suspension performance was conducted based on average flow velocity,average turbulent kinetic energy,and the relative standard deviation of particle suspension uniformity.The results demonstrated that efficient fluid mixing and homogeneous particle suspension could be realized under appropriate operating conditions.This study provides theoretical guidance for developing high-performance pulse-driven precipitation reactors and optimizing their operational processes in spent nuclear fuel treatment.
