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...
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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...
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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.
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...
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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-
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...
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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.
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...
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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）.
＜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.
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...
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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
A series of experiments were carried out in a batch reactor at the temperature range of 313-343 K to study the synthesis of tert -amyl ethyl ether from ethanol (EtOH) and 2-methyl-1-butene (2M1B) catalyzed by t...
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A series of experiments were carried out in a batch reactor at the temperature range of 313-343 K to study the synthesis of tert -amyl ethyl ether from ethanol (EtOH) and 2-methyl-1-butene (2M1B) catalyzed by the NKC-9 ion-exchange resin. The suitable reaction pressure was obtained by using the method of the Gibbs free energy minimization. The activity coefficients of each component were accurately calculated using the Wilson method, then, the equilibrium constants was obtained. The effect of catalyst size, stirring rate, temperature and EtOH/2M1B molar ratio was investigated at the chosen pressure, respectively. A kinetic model which considered the variation of each component volume was established. The method of nonlinear least square combined with genetic algorithm (NLS-GA) was proposed to estimate the kinetic constant in the forward direction. Results indicated that simulated kinetics results were agreed well with the experimental data.
The design of layer assignment and arrangement still remains an obstacle for optimizing the performance of the multi-stream plate-fin heat exchangers. A novel layer assignment and arrangement modelling and optimizatio...
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ISBN:
(纸本)9782362150128
The design of layer assignment and arrangement still remains an obstacle for optimizing the performance of the multi-stream plate-fin heat exchangers. A novel layer assignment and arrangement modelling and optimization method are proposed in this paper. It is a combination method of the equipartition of entropy production and the balance of local heat load, by means of which the pressure drop rise and heat transfer performance drop caused by inappropriate layer assignment and arrangement could be reduced to a large extent. The specific entropy generation rates of heat transfer and fluid friction are adopted as the dual objective functions and simultaneously minimized. This model exhibits a good robustness and high efficiency when used to design main heat exchanger in air separation plants, and simultaneity optimizes the plate fin configurations and layer arrangement.
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