Recently, MAAP and MELCOR research teams completed a set of accident simulations to reconstruct the Fukushima-Daiichi accident in order to better understand severe accident progression. One result from this work was t...
详细信息
In this study, the relevant thermal-hydraulic, mechanic-material and burnup effect calculation models were established. On the basis of these mathematic and physic models, a thermal- mechanic-material coupling analysi...
详细信息
ISBN:
(纸本)9781510811843
In this study, the relevant thermal-hydraulic, mechanic-material and burnup effect calculation models were established. On the basis of these mathematic and physic models, a thermal- mechanic-material coupling analysis code for a dispersion-plate-type fuel assembly was independently developed with the consideration of the burnup effects. The coupling program was applied to perform the thermal-mechanical-material behavior analysis of a dispersion-plate-type fuel assembly. Major physical parameters at different burnup stages were well predicted, including flux distribution, temperature profile, Mises stress and mechanic deformations. The result shows that geometric sizes of flow channels are the key parameters determining the coolant flux distribution and the temperature profile of the edge plate presents substantial asymmetry as a result of asymmetric heat transfer caused by the asymmetric geometry. Furthermore, the equivalent stress of base material increased rapidly with burnup because of the thermal expansion and burnup effects, which resulted in substantial plastic deformation and mechanical damage. In addition, the mechanism and process of blistering was investigated for blistering prediction. The result shows that due to the increasing fission gas pressure and the deteriorating yield stress of the cladding, fuel plate blistering may happen when the burnup depth up to a certain value and fuel plate will finally fall into failure as a result of over plastic deformation.
ECC safety injection nozzles are usually placed at the primary circulation pipelines as for the Gen II-plus nuclear reactor. Small Break Loss of Coolant Accident (SBLOCA) may lead to Pressurized Thermal Shock (PTS) on...
详细信息
ISBN:
(纸本)9781510811843
ECC safety injection nozzles are usually placed at the primary circulation pipelines as for the Gen II-plus nuclear reactor. Small Break Loss of Coolant Accident (SBLOCA) may lead to Pressurized Thermal Shock (PTS) on the Reactor Pressure Vessel (RPV) wall. Based on the Emergency Core Cooling (ECC) of a 2nd generation plus PWR, the CFD software CFX was adopted to simulate the thermal mixing phenomenon of the sub-cooled water from safety injection nozzle and high temperature water or steam from the cold leg which later forms into stratified flow. Also the steam-water simulation takes the steam condensation into consideration and steam condensation is characterized by a relatively large interfacial area between the two phases. For simulations of single-phase thermal mixing, the temperature profiles of different points were obtained and agreed well with the experiment. For steam mixing with water, the gas volume profile and the condensation rate of the steam were obtained and compared with the experiment, and the effect of different injection nozzle water velocities were also studied.
The Lattice Boltzmann model of coupling mass transfer（LBM） was used from the micro perspective to simulate the leaching process of ionic type rare earth ore to analysis of the macro regularity. The validity of LBM w...
详细信息
The Lattice Boltzmann model of coupling mass transfer（LBM） was used from the micro perspective to simulate the leaching process of ionic type rare earth ore to analysis of the macro regularity. The validity of LBM was verifed under the selected boundary *** a two-dimensional simulation area and set the simulation parameters, the simulation result of Sherwood number Sh as a function of Reynolds number for the leaching process gret well with the empirical formula. That shows that LBM can effective forecast the solute transfer law of rare earth leaching process. From the simulation of the fluid flow velocity and the solute concentration distribution of filling gaps in rare earth mine changed over time, the best dosage of leaching agent can be determined,which was verified by experiment. The leaching velocity influence on solute transfer was simulated, it showed that the best leaching velocity was 0.25 ~ 0.35 mm/s, which was in agreed with the experimental *** that LBM can effective simulates the leaching process of ionic type rare earth ore.
Graphene is a one-atom-thick sheet of graphite comprising sp2-hybridized carbon atoms arranged in the hexagonal honeycomb *** removing the honeycomb lattices and forming nanopores with specific geometry and size,nanop...
详细信息
Graphene is a one-atom-thick sheet of graphite comprising sp2-hybridized carbon atoms arranged in the hexagonal honeycomb *** removing the honeycomb lattices and forming nanopores with specific geometry and size,nanoporous graphene has been demonstrated as a very high-efScient separation membrane,due to the ultrafast molecular permeation rate for its one atomic *** this presentation,we review the recent advances in nanoporous graphene membrane for the application of gas separation,including the recent theoretical and experimental works,the gas molecular transport mechanisms through the graphene nanopores and the advanced fabrication methods of this stateof-the-art ***,we give a brief introduction on our relevant *** proposed two mechanisms(direct mechanism *** mechanism) for the gas molecular permeation through nanoporous graphene *** quantified the relative contribution of the two mechanisms and showed that the direct flux can be described reasonably accurately using kinetic theory with an appropriate modification assuming steric molecule-pore *** identified an inhibition effect of non-permeable components on the permeation of permeable component,caused by the relatively weakening adsorption on the graphene surface and the blocking effect of non-permeable *** also reported an asymptotically pressure-dependent gas permeation flux owing to the isothermal adsorption *** addition,we demonstrated the potential of nanoporous graphene membranes in natural gas processing to efficiently separate CO2,H2 S,N2,H2 O and others from CH4 with high permeability and selectivity.
Human carotid artery is bifurcated into two arteries in the neck,supplying blood to the brain and facial *** plaque tends to occur and develop in carotid artery sinus,where stenoses and other lesions can cause cerebra...
详细信息
Human carotid artery is bifurcated into two arteries in the neck,supplying blood to the brain and facial *** plaque tends to occur and develop in carotid artery sinus,where stenoses and other lesions can cause cerebral *** is accepted that the chronic exposure of the endothelial cells to lower wall shear stress(WSS)is associated with thickening of the vessel wall and development of atherosclerotic ***,platelet in blood is also accepted to play es-
Solar energy devices/systems are required to have high efficiency at low costs to be competitive with conventional energy *** promising approach is to combine a concentrating photovoltaic cell with a solar thermal col...
详细信息
Solar energy devices/systems are required to have high efficiency at low costs to be competitive with conventional energy *** promising approach is to combine a concentrating photovoltaic cell with a solar thermal collector,referred to as concentrating photovoltaic-thermal hybrid system（PV/T）.The PV/T system provides both electricity and usable heat which can enhance total efficiency of the *** concentrating efficiency,photoelectric and light-thermal conversion efficiency are key factors affecting the performance of concentrating photovoltaic-thermal hybrid *** proposed a new design method of integrated compound parabolic collector（CPC） the uniformity and economy of which become much *** validity of this new design method was verified by testing this prototype of *** to accurate mathematical model,a plate-type PV/T was manufactured by laminating the polycrystaU PV cells connected in series on the flate cooling water channel made of aUuminum *** performance of the system was measured under total solar radiation intensity of 810 W/mwith scattering light proportion of 15%.The results showed a total efficiency of above 62%（50%thermal efficiency plus 12%electrical efficiency）.
Oil spills on the ocean are usually serious marine disasters with tremendous economic loss and environmental *** the spreading of the leaked oil is of great significance to the quick responses and engineering decision...
详细信息
Oil spills on the ocean are usually serious marine disasters with tremendous economic loss and environmental *** the spreading of the leaked oil is of great significance to the quick responses and engineering decisions to deal with such ***,the spread of oil slicks is very difficult to simulate by the
＜正＞Moving Particle Semi-implicit（MPS）method and Smoothed Particle Hydrodynamics（SPH）have been widely applied in modelling free surface ***,application of the meshfree methods was still limited due to the proble...
＜正＞Moving Particle Semi-implicit（MPS）method and Smoothed Particle Hydrodynamics（SPH）have been widely applied in modelling free surface ***,application of the meshfree methods was still limited due to the problem of compressible stress instability,which occurs in the presence of attractive forces when particles are approaching and the low accuracy of the numerical schemes for gradient operator.
暂无评论