Inorganic materials can solve transportable and on-site hydrolytic hydrogen generation issues.CaH_(2)/(Al/Si)composites are preferable due to their notable chemical properties.However,these composites require pretreat...Inorganic materials can solve transportable and on-site hydrolytic hydrogen generation issues.CaH_(2)/(Al/Si)composites are preferable due to their notable chemical properties.However,these composites require pretreatments,an inert environment,and long hours of physical ball milling for high homogeneity and synergistic effects.CaH_(2)also inhibits the hydrolysis reaction by forming its products on the Al/Si surface,which hinders the direct utilization of composites.This work represents the first investigation of NaH-CaH_(2)(Al/Si)fuel composites,which greatly overcome these limitations and can be directly used for on-site hydrogen generation and proton exchange membrane(PEM)fuel cells.The NaH-CaH_(2)(Al/Si)fuel composites were prepared by using a straightforward mixing method with variable composition ratios,showing high H_(2)yield and fuel cell(FC)performance.NaH addition provides the bridge effect,which opens up a new way to enable efficient hydrolysis and greatly enhances the hydrolysis activity of CaH_(2)/(Al/Si)composites.The novel fuel composites(NaH-CaH_(2)/Al)have extraordinary FC performance and a 0.42 W/cm2 peak power density greater than commercial hydrogen generators.It provides high H_(2)yield 84.4%for NaH-CaH_(2)/Al and 82%for NaH-CaH_(2)/Si compared to NaOH-CaH_(2)(Al/Si),NaCl-CaH_(2)(Al/Si),and KCl-CaH_(2)(Al/Si)composites.The NaH bridge effect hinders the direct water contact and stops the formation of Ca(OH)2 around Al/Si,which provides adequate pathways for the CaH_(2)(Al/Si)hydrolysis.The impressive capabilities of novel fuel composites are anticipated to offer practical uses in fuel cells,automobile applications,and portable/on-board H_(2)generation.展开更多
A wide range of wastes can potentially be used to generate thermal and electrical energy.The co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their reco...A wide range of wastes can potentially be used to generate thermal and electrical energy.The co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their recovery.In this research,we use thermogravimetric analysis and differential scanning calorimetry to study the thermal behavior and kinetics of coal slime,biomass,waste oils,and blends on their basis.We also analyze the concentrations of gaseous emissions.The results show that biomass,oils,and coal slime significantly affect each other in the course of their co-combustion when added to slurry fuels.The preparation of coal-water slurry based on slime and water reduced the ignition and burnout temperature by up to 16%.Adding biomass and waste oils additionally stimulated the slurry ignition and burnout,which occurred at lower temperatures.Relative to dry coal slime,threshold ignition temperatures and burnout temperatures decreased by 6%–9%and 17%–25%,respectively.Also,the use of biomass and waste oils as part of slurries inhibited NOхand SO_(2)emission by 2.75 times.According to the kinetic analysis,added biomass and waste turbine oil provide a 28%–51%reduction in the activation energy as compared to a coal-water slurry without additives.展开更多
To study the combustion performance of aluminum-based micro-cell composite fuel aluminum@ammonium perchlorate(Al@AP),in hydroxyl-terminated polybutadiene(HTPB)solid propellant,the Al@AP was added to HTPB solid propell...To study the combustion performance of aluminum-based micro-cell composite fuel aluminum@ammonium perchlorate(Al@AP),in hydroxyl-terminated polybutadiene(HTPB)solid propellant,the Al@AP was added to HTPB solid propellant instead of Al powder and part of AP.Firstly,the ignition and energy performance of Al@AP were investigated and the effects of Al@AP on the combustion,process and mechanical properties of HTPB solid propellant were studied by means of sphere explosion test system,adiabatic oxygen bomb calorimeter test,standard test engine test,residual active Al test,viscosity test,and tensile test.In addition,the combustion mechanism of Al@AP in HTPB solid propellant was analyzed.The results indicate that Al@AP composites offer faster ignition response than simple physical blends,and the heat of HTPB solid propellant increases from 7385 J·g^(-1) to 7834 J·g^(-1) when 21.3%Al@AP was used instead of aluminium powder.The amount of residue decreases from 3.88%to 2.10%in mass fraction,the content of active Al in residue decrease from 6.14%to 2.57%,and the particle size d_(50) of residue decrease from 298μm to 62μm.The combustion efficiency of HTPB solid propellant improves from 94.0%to 94.6%.The mechanical and process properties of HTPB propellant containing Al@AP can satisfy the application.展开更多
One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the...One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.展开更多
The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transp...The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities,and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.展开更多
Aluminum(Al)powder is widely used in solid propellants.In particular,nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al.However,the exist...Aluminum(Al)powder is widely used in solid propellants.In particular,nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al.However,the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder,which greatly limits its application.Hence,this paper used iron,a component of solid propellant,to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder.SEM,TEM,EDS,XRD,XPS,and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes.The results show that Fe was uniformly coated on the surface of Al powder.There was no reaction between Fe and Al,and Fe/Al composite fuels had a larger specific surface area than pure Al,which could better improve the reactivity of pure Al.Besides,the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored.The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder.Especially,the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder.Hence,Fe/Al composite fuels are expected to be widely used in solid propellants.展开更多
A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale cr...A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.展开更多
New powdered sorbent Lignosorb based on the hydrophobized hydrolysis lignin has been developed at the Belarusian State University. Hydrolysis lignin is a commercial waste product of biomass processing in the hydrolysi...New powdered sorbent Lignosorb based on the hydrophobized hydrolysis lignin has been developed at the Belarusian State University. Hydrolysis lignin is a commercial waste product of biomass processing in the hydrolysis production of ethanol. In spite of the various proposals for hydrolysis lignin usage, the wide application has not found yet. Special area of hydrophobized hydrolysis lignin usage as a sorbent for oil spills removal and oil products waste recovery is discussed. Lignosorb, thanks to the rather high bulk density, can be applied manually or mechanically by conventional sprayers. It does not sink after oil adsorption and transforms liquid oil film on the water surface into the solid mass. The solid product is a complete mass and is easily collected from the surface of water. Lignosorb when blended with oil products waste in the volume forms the granular free-running product. The rheological properties of the Lignosorb suspensions in oil products at different sorbent to oil product ratio have been estimated. Saturated by different oil products Lignosorb one can granulate or pellet and utilize as a composite solid fuel including the co-firing regime of combustion. It has the higher heating value of 32.1 - 38.8 MJ/kg while the coal has 20.9 - 30.1 MJ/kg. It has been shown that composite fuel burning has less longstanding inflammation stage, more long stable burning stage and less longstanding phase of smoldering in the comparison to wood and Lignosorb burning.展开更多
The coating layers of Tri-structural Isotropic Particles(TRISO)serve to protect the kernel and act as barriers to fission products.Sintering aids in the silicon carbide matrix variably react with TRISO coating layers,...The coating layers of Tri-structural Isotropic Particles(TRISO)serve to protect the kernel and act as barriers to fission products.Sintering aids in the silicon carbide matrix variably react with TRISO coating layers,leading to the destruction of the coating layers.Investigating how carbon content affects element diffusion in silicon carbide-based TRISO composite fuel is of great significance for predicting reactor safety.In this study,silicon carbide-based TRISO composite fuels with different carbon contents were prepared by adding varying amounts of phenolic resin to the silicon carbide matrix.X-ray Diffraction(XRD)and Scanning Electron Microscopy(SEM)were employed to characterize the phase composition,morphology,and microstructure of the composite fuels.The elemental content in each coating layer of TRISO was quantified using Energy-Dispersive X-ray Spectroscopy(EDS).The results demonstrated that the addition of phenolic resin promoted the uniform distribution of sintering aids in the silicon carbide matrix.The atomic percentage(at.%)of aluminum(Al)in the pyrolytic carbon layer of the TRISO particles reached its lowest value of 0.55%when the phenolic resin addition was 1%.This is because the addition of phenolic resin caused the Al and silicon(Si)in the matrix to preferentially react with the carbon in the phenolic resin to form a metastable liquid phase,rather than preferentially consuming the pyrolytic carbon in the outer coating layer of the TRISO particles.The findings suggest that carbon addition through phenolic resin incorporation can effectively mitigate the deleterious reactions between the TRISO coating layers and sintering aids,thereby enhancing the durability and safety of silicon carbide-based TRISO composite fuels.展开更多
An enhanced thermal conductivity UO2-BeO composite nuclear fuel was studied. A methodology to generate ANSYS （an engineering simulation software） FEM （finite element method） thermal models of enhanced thermal cond...An enhanced thermal conductivity UO2-BeO composite nuclear fuel was studied. A methodology to generate ANSYS （an engineering simulation software） FEM （finite element method） thermal models of enhanced thermal conductivity oxide nuclear fuels was developed. The results showed significant increase in the fuel thermal conductivities and have good agreement with the measured ones. Thus BeO is one of the promising candidates for fabricating two-phase high thermal conductivity ceramic nuclear fuels with UO2. The reactor performance analysis showed that the decrease in centerline temperature was 250-350 K depending on different fabrication methods for the UO2-BeO composite fuel, and thus we can improve nuclear reactors＇ performance and safety, and high-level radioactive waste generation for the existing and next generation nuclear reactors.展开更多
The temperature-dependent effective thermal conductivity of UN-X-UO_(2)(X=Mo,W)nuclear fuel composite was estimated.Following the experimental design,the thermal conductivity was calculated using Finite Element Modeli...The temperature-dependent effective thermal conductivity of UN-X-UO_(2)(X=Mo,W)nuclear fuel composite was estimated.Following the experimental design,the thermal conductivity was calculated using Finite Element Modeling(FEM),and compared with analytical models for 10%,30%,50%,and 70%(in mass)uncoated/coated UN microspheres in a UO_(2) matrix.The FEM results show an increase in the fuel thermal conductivity as the mass fraction of the UN microspheres increases from 1.2 to 4.6 times the UO_(2) reference at 2,000 K.The results from analytical models agree with the thermal conductivity estimated by FEM.The results also show that Mo and W coatings have similar thermal behaviors,and the coating thickness influences the thermal conductivity of the composite.At higher weight fractions,the thermal conductivity of the fuel composite at room temperature is substantially influenced by the high thermal conductivity coatings approaching that of UN.Thereafter,the thermal conductivity from FEM was used in the fuel thermal performance evaluation during LWR normal operation to calculate the maximum centerline temperature.The results show a significant decrease in the fuel maximum centerline temperature ranging from−94 K for 10% UN to−414 K for 70%(in mass)UN compared to UO_(2) under the same operating conditions.展开更多
Proton irradiation with a primary ion energy of 2 MeV was used to simulate radiation damage in UN and(U,Zr)N fuel pellets.The pellets,nominally at room temperature,were irradiated to peak levels of 0.1,1,10 dpa and 10...Proton irradiation with a primary ion energy of 2 MeV was used to simulate radiation damage in UN and(U,Zr)N fuel pellets.The pellets,nominally at room temperature,were irradiated to peak levels of 0.1,1,10 dpa and 100.0 dpa resulting in a peak hydrogen concentration of at most 90 at.%.Microstructure and mechanical properties of the samples were investigated and compared before and after irradiation.The irradiation induced an increase in hardness,whereas a decrease in Young’s modulus was observed for both samples.Microstructural characterization revealed irradiation-induced cracking,initiated in the bulk of the material,where the peak damage was deposited,propagating towards the surface.Additionally,transmission electron microscopy was used to study irradiation defects.Dislocation loops and fringes were identified and observed to increase in density with increasing dose levels.The high density of irradiation defects and hydrogen implanted are proposed as the main cause of swelling and consequent sample cracking,leading simultaneously to increased hardening and a decrease in Young's modulus.展开更多
基金financial support granted by the National Natural Science Foundation of China (No. 22402225)the Gusu Innovation and Entrepreneurship Leading Talent Plan(No. ZXL2023193)+2 种基金the Sinano Talents Plan (No. 2022000175)the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515111133)the ANSO Scholarship for Young Talents
文摘Inorganic materials can solve transportable and on-site hydrolytic hydrogen generation issues.CaH_(2)/(Al/Si)composites are preferable due to their notable chemical properties.However,these composites require pretreatments,an inert environment,and long hours of physical ball milling for high homogeneity and synergistic effects.CaH_(2)also inhibits the hydrolysis reaction by forming its products on the Al/Si surface,which hinders the direct utilization of composites.This work represents the first investigation of NaH-CaH_(2)(Al/Si)fuel composites,which greatly overcome these limitations and can be directly used for on-site hydrogen generation and proton exchange membrane(PEM)fuel cells.The NaH-CaH_(2)(Al/Si)fuel composites were prepared by using a straightforward mixing method with variable composition ratios,showing high H_(2)yield and fuel cell(FC)performance.NaH addition provides the bridge effect,which opens up a new way to enable efficient hydrolysis and greatly enhances the hydrolysis activity of CaH_(2)/(Al/Si)composites.The novel fuel composites(NaH-CaH_(2)/Al)have extraordinary FC performance and a 0.42 W/cm2 peak power density greater than commercial hydrogen generators.It provides high H_(2)yield 84.4%for NaH-CaH_(2)/Al and 82%for NaH-CaH_(2)/Si compared to NaOH-CaH_(2)(Al/Si),NaCl-CaH_(2)(Al/Si),and KCl-CaH_(2)(Al/Si)composites.The NaH bridge effect hinders the direct water contact and stops the formation of Ca(OH)2 around Al/Si,which provides adequate pathways for the CaH_(2)(Al/Si)hydrolysis.The impressive capabilities of novel fuel composites are anticipated to offer practical uses in fuel cells,automobile applications,and portable/on-board H_(2)generation.
基金supported by a grant from the Ministry of Science and Higher Education of Russia,Agreement No 075-152020-806 (Contract No 13.1902.21.0014)。
文摘A wide range of wastes can potentially be used to generate thermal and electrical energy.The co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their recovery.In this research,we use thermogravimetric analysis and differential scanning calorimetry to study the thermal behavior and kinetics of coal slime,biomass,waste oils,and blends on their basis.We also analyze the concentrations of gaseous emissions.The results show that biomass,oils,and coal slime significantly affect each other in the course of their co-combustion when added to slurry fuels.The preparation of coal-water slurry based on slime and water reduced the ignition and burnout temperature by up to 16%.Adding biomass and waste oils additionally stimulated the slurry ignition and burnout,which occurred at lower temperatures.Relative to dry coal slime,threshold ignition temperatures and burnout temperatures decreased by 6%–9%and 17%–25%,respectively.Also,the use of biomass and waste oils as part of slurries inhibited NOхand SO_(2)emission by 2.75 times.According to the kinetic analysis,added biomass and waste turbine oil provide a 28%–51%reduction in the activation energy as compared to a coal-water slurry without additives.
文摘To study the combustion performance of aluminum-based micro-cell composite fuel aluminum@ammonium perchlorate(Al@AP),in hydroxyl-terminated polybutadiene(HTPB)solid propellant,the Al@AP was added to HTPB solid propellant instead of Al powder and part of AP.Firstly,the ignition and energy performance of Al@AP were investigated and the effects of Al@AP on the combustion,process and mechanical properties of HTPB solid propellant were studied by means of sphere explosion test system,adiabatic oxygen bomb calorimeter test,standard test engine test,residual active Al test,viscosity test,and tensile test.In addition,the combustion mechanism of Al@AP in HTPB solid propellant was analyzed.The results indicate that Al@AP composites offer faster ignition response than simple physical blends,and the heat of HTPB solid propellant increases from 7385 J·g^(-1) to 7834 J·g^(-1) when 21.3%Al@AP was used instead of aluminium powder.The amount of residue decreases from 3.88%to 2.10%in mass fraction,the content of active Al in residue decrease from 6.14%to 2.57%,and the particle size d_(50) of residue decrease from 298μm to 62μm.The combustion efficiency of HTPB solid propellant improves from 94.0%to 94.6%.The mechanical and process properties of HTPB propellant containing Al@AP can satisfy the application.
文摘One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.
文摘The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities,and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.
文摘Aluminum(Al)powder is widely used in solid propellants.In particular,nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al.However,the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder,which greatly limits its application.Hence,this paper used iron,a component of solid propellant,to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder.SEM,TEM,EDS,XRD,XPS,and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes.The results show that Fe was uniformly coated on the surface of Al powder.There was no reaction between Fe and Al,and Fe/Al composite fuels had a larger specific surface area than pure Al,which could better improve the reactivity of pure Al.Besides,the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored.The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder.Especially,the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder.Hence,Fe/Al composite fuels are expected to be widely used in solid propellants.
基金supports from the National Natural Science Foundation of China (Nos.12132005,12102094 and 12135008)the Shanghai Sailing Program (21YF1402200)the foundation from the Science and Technology on Reactor System Design Technology Laboratory.
文摘A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.
文摘New powdered sorbent Lignosorb based on the hydrophobized hydrolysis lignin has been developed at the Belarusian State University. Hydrolysis lignin is a commercial waste product of biomass processing in the hydrolysis production of ethanol. In spite of the various proposals for hydrolysis lignin usage, the wide application has not found yet. Special area of hydrophobized hydrolysis lignin usage as a sorbent for oil spills removal and oil products waste recovery is discussed. Lignosorb, thanks to the rather high bulk density, can be applied manually or mechanically by conventional sprayers. It does not sink after oil adsorption and transforms liquid oil film on the water surface into the solid mass. The solid product is a complete mass and is easily collected from the surface of water. Lignosorb when blended with oil products waste in the volume forms the granular free-running product. The rheological properties of the Lignosorb suspensions in oil products at different sorbent to oil product ratio have been estimated. Saturated by different oil products Lignosorb one can granulate or pellet and utilize as a composite solid fuel including the co-firing regime of combustion. It has the higher heating value of 32.1 - 38.8 MJ/kg while the coal has 20.9 - 30.1 MJ/kg. It has been shown that composite fuel burning has less longstanding inflammation stage, more long stable burning stage and less longstanding phase of smoldering in the comparison to wood and Lignosorb burning.
基金funded by the Shanghai Academic/Technology Research Leader(Project No.21XD1432000).
文摘The coating layers of Tri-structural Isotropic Particles(TRISO)serve to protect the kernel and act as barriers to fission products.Sintering aids in the silicon carbide matrix variably react with TRISO coating layers,leading to the destruction of the coating layers.Investigating how carbon content affects element diffusion in silicon carbide-based TRISO composite fuel is of great significance for predicting reactor safety.In this study,silicon carbide-based TRISO composite fuels with different carbon contents were prepared by adding varying amounts of phenolic resin to the silicon carbide matrix.X-ray Diffraction(XRD)and Scanning Electron Microscopy(SEM)were employed to characterize the phase composition,morphology,and microstructure of the composite fuels.The elemental content in each coating layer of TRISO was quantified using Energy-Dispersive X-ray Spectroscopy(EDS).The results demonstrated that the addition of phenolic resin promoted the uniform distribution of sintering aids in the silicon carbide matrix.The atomic percentage(at.%)of aluminum(Al)in the pyrolytic carbon layer of the TRISO particles reached its lowest value of 0.55%when the phenolic resin addition was 1%.This is because the addition of phenolic resin caused the Al and silicon(Si)in the matrix to preferentially react with the carbon in the phenolic resin to form a metastable liquid phase,rather than preferentially consuming the pyrolytic carbon in the outer coating layer of the TRISO particles.The findings suggest that carbon addition through phenolic resin incorporation can effectively mitigate the deleterious reactions between the TRISO coating layers and sintering aids,thereby enhancing the durability and safety of silicon carbide-based TRISO composite fuels.
文摘An enhanced thermal conductivity UO2-BeO composite nuclear fuel was studied. A methodology to generate ANSYS （an engineering simulation software） FEM （finite element method） thermal models of enhanced thermal conductivity oxide nuclear fuels was developed. The results showed significant increase in the fuel thermal conductivities and have good agreement with the measured ones. Thus BeO is one of the promising candidates for fabricating two-phase high thermal conductivity ceramic nuclear fuels with UO2. The reactor performance analysis showed that the decrease in centerline temperature was 250-350 K depending on different fabrication methods for the UO2-BeO composite fuel, and thus we can improve nuclear reactors＇ performance and safety, and high-level radioactive waste generation for the existing and next generation nuclear reactors.
基金This work was financially supported by the Swedish Science Council(Vetenskapsradet)under grant number 2019-04156by the Swedish Foundation for Strategic Research(SSF,Stiftelsen for Strategisk Forskning)under grant number ID17-0078as well as in the SUNRISE center with financial support from SSF under Grant No.ARC19-0043.
文摘The temperature-dependent effective thermal conductivity of UN-X-UO_(2)(X=Mo,W)nuclear fuel composite was estimated.Following the experimental design,the thermal conductivity was calculated using Finite Element Modeling(FEM),and compared with analytical models for 10%,30%,50%,and 70%(in mass)uncoated/coated UN microspheres in a UO_(2) matrix.The FEM results show an increase in the fuel thermal conductivity as the mass fraction of the UN microspheres increases from 1.2 to 4.6 times the UO_(2) reference at 2,000 K.The results from analytical models agree with the thermal conductivity estimated by FEM.The results also show that Mo and W coatings have similar thermal behaviors,and the coating thickness influences the thermal conductivity of the composite.At higher weight fractions,the thermal conductivity of the fuel composite at room temperature is substantially influenced by the high thermal conductivity coatings approaching that of UN.Thereafter,the thermal conductivity from FEM was used in the fuel thermal performance evaluation during LWR normal operation to calculate the maximum centerline temperature.The results show a significant decrease in the fuel maximum centerline temperature ranging from−94 K for 10% UN to−414 K for 70%(in mass)UN compared to UO_(2) under the same operating conditions.
文摘Proton irradiation with a primary ion energy of 2 MeV was used to simulate radiation damage in UN and(U,Zr)N fuel pellets.The pellets,nominally at room temperature,were irradiated to peak levels of 0.1,1,10 dpa and 100.0 dpa resulting in a peak hydrogen concentration of at most 90 at.%.Microstructure and mechanical properties of the samples were investigated and compared before and after irradiation.The irradiation induced an increase in hardness,whereas a decrease in Young’s modulus was observed for both samples.Microstructural characterization revealed irradiation-induced cracking,initiated in the bulk of the material,where the peak damage was deposited,propagating towards the surface.Additionally,transmission electron microscopy was used to study irradiation defects.Dislocation loops and fringes were identified and observed to increase in density with increasing dose levels.The high density of irradiation defects and hydrogen implanted are proposed as the main cause of swelling and consequent sample cracking,leading simultaneously to increased hardening and a decrease in Young's modulus.
