Pellet Surface Research Articles

Experimental exploration of potassium compounds in the vicinity of a burning biomass pellet: From near-surface to downstream

The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm3, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the devolatilization stage, the release of all three potassium species was observed, with each of them accounting for ∼1/3; while in char oxidation stage, the release of KOH was dominant, but the release intensity was strongly influenced by the local oxygen content. The results from different measurement heights showed there was a notable difference in potassium release profiles of different potassium species over the near-surface area, where the detected potassium forms were the best representative of the originally released forms of potassium. For a period of time during the devolatilization stage, only K(g) was detected in the near-surface area, and the concentration was significantly lower than the downstream area where KOH and KCl coexisted. This suggested that a large amount of potassium might leave the pellet as organic-K, which cannot be detected by the PF-TDLAS method. During char oxidation stage, the total potassium concentration at the near-surface area was also lower than the downstream area, but it was due to the lack of oxygen at the measurement position. A potassium release mechanism during the devolatilization stage of biomass combustion was proposed based on the experimental measurements, and the results also indicated the importance of spatially resolved measurement.

Generalized effectiveness factor correlations for nickel catalyst pellets under low-pressure steam methane reforming conditions

In this study, generalized correlations are proposed to predict the effectiveness factors of nickel-based catalyst pellets used in low-pressure steam methane reforming (SMR) systems suitable for small-scale fuel cell applications. Previously, the authors have shown that over 99 % of the total reaction occurs within a thin layer of 0.2 mm thickness from the surface of porous Ni catalyst pellets. Thus, by developing the correlations based on the 0.2-mm-thick active reaction thickness, the proposed effectiveness factor correlations are applicable to catalyst pellets of various shapes used in the low-pressure SMR process. The method of using these effectiveness factor correlations for analyzing fixed-bed SMR systems is also addressed, along with the method for considering the variations in the catalyst properties.

Effect of Kaolin Addition on Combustion Behavior of Zhundong Coal Pellet Using Flame Emission Spectroscopy

ABSTRACT Kaolin, as an adsorbent, has been proven to be effective in inhibiting sodium release during high alkali coal combustion thereby alleviating severe slagging and fouling problems. Understanding the co-firing behavior of Zhundong coal with kaolin additives is essential for Zhundong coal utilization. In this study, the effect of kaolin additive on the combustion behavior of two Zhundong coals with different Na contents was investigated based on image analysis and flame emission spectroscopy (FES) method. Spectral and image results were able to distinguish the three stages of coal combustion. The addition of kaolin impacted all combustion stages for both types of coal. The results show the volatile combustion time of the blended coal sample was shortened, while the char burnout time was prolonged, which was attributed to the ash suppression effect. The two coals presented similar decrease trends with different blending ratios in terms of sodium concentration, pellet surface temperature, and thermal radiation. However, the changes were no longer evident after the blending ratio reached 8% and 12%. The replacement of combustible components in the coal by the kaolin altered the mineral fraction of the ash and thus affected the heat and mass transfer. Combining the online measurement results and the analysis of the ash fusion characteristics, the suggested addition of kaolin was 8% and 12% respectively.

Hydrogen storage and ignition properties of pelletized catalyzed magnesium

Catalyzed magnesium (MgH2+1mol%Nb2O5) can quickly absorb hydrogen even at room temperature, but there is a risk of ignition due to reaction with oxygen when handled in the atmosphere. In this study, we attempted to suppress ignition by pelletizing catalyzed magnesium powder. In addition, the effect of pelletizing conditions on the hydrogen storage properties of catalyzed magnesium was investigated. The pellets were formed at a forming pressure from 140 MPa to 1400 MPa. The higher the pelletizing pressure, the more the particles adhered to each other, and it was confirmed that an adhered layer of about 5 μm was formed on the pellet surface. This is thought to have reduced the pathway for gas molecules to penetrate from the pellet surface to the interior, resulting in a decrease in the hydrogen absorption rate and ignitability.

Calcium-Magnesium-Aluminosilicate (CMAS) corrosion resistance of high entropy rare-earth phosphate (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4: A novel environmental barrier coating candidate

Single phase (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4 was synthesized, and its thermal properties and CMAS resistance were investigated to explore its potential as an environmental barrier coating (EBC) candidate. The high entropy phosphate (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4 displays a lower thermal conductivity (2.86 W m−1 K−1 at 1250 K) than all the single component xenotime phase rare-earth phosphates. Interaction of (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4 pellets with CMAS at 1300 °C led to the formation of a dense and uniformed Ca8MgRE(PO4)7 reaction layer, which halted the CMAS penetration into the bulk pellet. At 1400 and 1500 °C the (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4-CMAS corrosion showed CMAS penetrating beyond the reaction layer into the bulk pellet via the grain boundaries, and SiO2 precipitates remaining at the pellet surface. The effects of duration, temperature, and compositions on the resistance against CMAS corrosion are discussed within the context of optimizing materials design and performance of high entropy rare-earth phosphates as candidates for advanced EBC applications.

Investigation of Plasma Propagation in Packed-Bed Dielectric Barrier Discharge Based on a Customized Particle-in-Cell/Monte Carlo Collision Model

This study investigates the propagation dynamics of plasma streamers in a packed-bed dielectric barrier discharge using a 2D particle-in-cell/Monte Carlo collision model. To accurately simulate the high-intensity discharge and streamer propagation mechanism at atmospheric pressure, additional algorithms for particle merging and a new electron mechanism are incorporated into the traditional particle-in-cell/Monte Carlo collision model. To validate the accuracy of this improved model, qualitative comparisons are made with experimental measurements from the existing literature. The results show that the speed of streamer propagation and the distribution of plasma are strongly influenced by the dielectric constant of the packed pellet, which is commonly used as a catalyst. In cases with a moderate dielectric constant, the presence of a strong electric field between the pellet and dielectric layer on the electrode significantly enhances the discharge. This enables the streamer to propagate swiftly along the pellet surface and results in a wider spread of plasma. Conversely, a very high dielectric constant impedes streamer propagation and leads to localized discharge with high intensity. The improved model algorithms derived from this research offer valuable insights for simulating high-density plasma discharge and optimizing plasma processing applications.

Structural and enhancement of electrical properties of BFO-LFO solid solution

To synthesizes the polycrystalline perovskite ceramic compounds (That is, (BiFeO3)1-x + (LaFeO3)x, having x = 0.0, 0.1, 0.2 and 0.3) (BFO-LFO), by using an elevated temperatures solid state reaction technique. Powder X-Ray diffraction (P-XRD) was employed for structural analysis to validate the creation of single phase materials and the phase structure of BFO-LFO changing from rhombohedral to tetragonal. The morphological characteristics of the surface of ceramic composite pellets were examined by using a scanning electron microscopy at the ambient temperature, which revealed a uniform arrangement of grains with very little porosity and varying sizes on the samples' surface. At various temperatures (25-500 °C), the frequency-temperature connection of dielectric and electric characteristics was studied utilizing dielectric and complex impedance spectroscopy. Both grains and grain boundaries have been demonstrated to have a substantial impact on the electrical sensitivity of the materials. All BFO-LFO samples exhibited a negative temperature coefficient of resistance.

Biomineralization of calcium phosphates functionalized with hydroxyapatite-binding peptide

Functionalization of calcium phosphates with biomimetic peptides is a promising strategy to increase cellular response for bone tissue repair. In this work, biphasic calcium phosphate pellets were functionalized with the hydroxyapatite-binding peptide pVTK by dropping a suspension of the peptide on the pellet surface. The bioactivity tests were performed in vitro by using McCoy culture medium. Cytotoxicity tests were also performed to assess cell viability. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with field emission gun (FEG-SEM). The results showed that functionalization with the biomimetic peptide was most effective in inducing precipitation of bone-like apatite on the pellets surface, when compared to the control groups (two positive control groups and one negative control group). Cytotoxicity tests showed that all samples are biocompatible but the pellets with peptide showed the highest values of cell viability.

Effect of sample pretreatment on pelletization and performance of laser-induced breakdown spectroscopy for predicting key soil properties

Laser-induced breakdown spectroscopy (LIBS) is a promising analytical technique for determining soil properties in a rapid, cost-effective, and environmentally friendly manner. However, an optimal sample pretreatment method that enhances sample homogeneity for improved prediction accuracy is needed. In this study, the effect of different sample pretreatments on pelletization of soil samples, and prediction of texture and soil organic carbon (SOC) content, was assessed. Four pretreatments, namely 2 mm, 200 μm, and 100 μm sieved, and milled pretreatment, were applied to 133 soil samples representing a wide variability in texture and SOC content range. Visual assessment of soil pellet surface quality was done where poor surfaces, deemed unsuitable for LIBS measurement, were separated from the good-surface pellets. Partial least square regression (PLSR) models for the pretreatments across the investigated soil properties were compared, followed by interval partial least square regression (iPLSR), to evaluate potential improvements in the accuracy of the prediction models. The ratio of performance to interquartile distance (RPIQ) was used to rank the PLSR models for each pretreatment across the soil properties. The 100 μm pretreatment had the highest number of good-surface pellets followed by the 2 mm pretreatment, and lastly the 200 μm and milled pretreatments, which were comparable. The milled pretreatment achieved the best model for sand prediction (RPIQ = 7), followed by the 2 mm pretreatment for clay prediction (RPIQ = 2.5), 100 μm pretreatment for silt prediction (RPIQ = 2), and the milled pretreatment for SOC prediction (RPIQ = 1). A reduction in RMSEP of 31%, 23%, and 11% for the prediction of sand, SOC, and silt content, respectively was achieved by the milled pretreatment while the 100 μm pretreatment recorded a 15% reduction in RMSEP for the prediction of silt content. Overall, PLSR performed better than iPLSR for the prediction of texture (apart from clay) and SOC. These results show that sample pretreatment that involves sieving, or milling, influences the pellet surface quality and the prediction accuracy of texture and SOC content.

An effective way for the simultaneous valorization and treatment of olive mill wastewater by means of a photocatalytic process

This work hereby illustrates how to valorize olive mill wastewater (OMW) with a photocatalytic process able to produce hydrogen and simultaneously break down the polluting load of this waste. To achieve this objective, a comparison between the performances of commercial TiO2 and home-made sol–gel TiO2 on olive mill wastewater was first carried out. The hydrogen production and the ability of the catalyst to remove the organic matter present in wastewater were considered, with particular attention to the best combination (in terms of processing time and experimental phase sequence) between the anoxic phase (for the hydrogen production) and the oxidative phase (for the degradation of the organic residue). Once the best combination was identified, the photocatalyst in powder form was transferred on the surface of polystyrene pellets in order to make the catalyst easily separable and recyclable. The photocatalytic activity tests demonstrated that the proposed photocatalyst showed very good stability after ten reuse cycles, even in the presence of real OMW (with dilution 1:70), assuring a hydrogen production of about 16954 μmol/L. During the tests, the liquid samples were analyzed also with UHPLC technique that evidenced the phenol degradation and the presence of only hydroquinone as by-product.

Polyvinylpyrrolidone Nanofibers Incorporating Mesoporous Bioactive Glass for Bone Tissue Engineering.

Composite biomaterials that combine osteoconductive and osteoinductive properties are a promising approach for bone tissue engineering (BTE) since they stimulate osteogenesis while mimicking extracellular matrix (ECM) morphology. In this context, the aim of the present research was to produce polyvinylpyrrolidone (PVP) nanofibers containing mesoporous bioactive glass (MBG) 80S15 nanoparticles. These composite materials were produced by the electrospinning technique. Design of experiments (DOE) was used to estimate the optimal electrospinning parameters to reduce average fiber diameter. The polymeric matrices were thermally crosslinked under different conditions, and the fibers' morphology was studied using scanning electron microscopy (SEM). Evaluation of the mechanical properties of nanofibrous mats revealed a dependence on thermal crosslinking parameters and on the presence of MBG 80S15 particles inside the polymeric fibers. Degradation tests indicated that the presence of MBG led to a faster degradation of nanofibrous mats and to a higher swelling capacity. The assessment of in vitro bioactivity in simulated body fluid (SBF) was performed using MBG pellets and PVP/MBG (1:1) composites to assess if the bioactive properties of MBG 80S15 were kept when it was incorporated into PVP nanofibers. FTIR and XRD analysis along with SEM-EDS results indicated that a hydroxy-carbonate apatite (HCA) layer formed on the surface of MBG pellets and nanofibrous webs after soaking in SBF over different time periods. In general, the materials revealed no cytotoxic effects on the Saos-2 cell line. The overall results for the materials produced show the potential of the composites to be used in BTE.

Modeling of Core-shell Catalytic Pellets of Inert Shell with Various Morphologies for Series Reactions

Modeling of core-shell catalytic pellets with inert shell was performed assuming three different particle shapes such as sphere, cylinder, and slab. For isothermal irreversible first order reaction, A→B, analytical solutions of intra-particle concentration of reactant were derived by solving reaction-diffusion equations, considering thickness of catalytically active core (r2), when the pellets were immersed in infinitely large medium. Unlike conventional pellets or core-shell pellets with inert core, effectiveness factor (η) was affected by r2 as well as ratio of effective diffusivity in inert shell and active core (Υ), and η could be enhanced by increasing Υ. η increased in the order of sphere > cylinder > slab due to surface area per unit volume of medium, and η increased with increasing Biot number (Bi), because of decreased external film resistance. For series reaction, A→B→C, transient change of the concentration of starting reactant (CA) and intermittent product (CB) in bulk fluid of reactor could be predicted by solving material balance equations assuming pseudo-steady state approximation and equal value of Thiele modulus for both reactions in batch reactor and CSTR. When B is desirable product, CB increased by increasing Υ and decreasing r2. Similar to conventional pellets, CB in batch reactor decreased by increase of distribution coefficient of B on surface of pellet, KB, due to increased adsorption, and increased in the order of sphere < cylinder < slab, similar to conventional pellets. In CSTR, CB at steady state could be enhanced by decreasing amount of catalyst and Thiele modulus (Φ), implying that performance of reactor can be controlled by adjusting various reaction parameters. From numerical solutions of reaction diffusion equations for series reactions, the effect of r2 and Υ were also confirmed from transient value of CA and CB in exit stream calculated by finite element method.

Structural analysis and properties of novel Terbium Samarium Zirconate functional ceramic

Synthesis and characterization of Terbium Samarium Zirconate (TbSmZr2O7) is reporting for the first time. XRD analysis along with Raman spectroscopy revealed that citrate-nitrate combustion synthesized TbSmZr2O7 powder and sintered sample crystallize in defect-fluorite structure with Fm3‾m space group. This composition lies at the pyrochlore-defect fluorite phase boundary. TEM analysis showed that the powder particles are in size range between 3 nm and 9 nm. FESEM image showed a well-sintered pellet surface with a grain size distribution between 0.1 μm and 2 μm. TbSmZr2O7 has an optical band gap of 1.66 eV and has an indirect allowed mechanism of optical transition. Due to intrinsic defect structure, TbSmZr2O7 exhibits photoluminescence with excitation bands at 270 nm and 313 nm and emission bands at 364 nm and 400 nm. Impedance spectroscopic analysis established that from 400 °C to 900 °C TbSmZr2O7 is a pure oxide ion conductor with a conductivity value of 1.9 × 10−3 S/cm at 900 °C.

Oxidative dissolution of (U,Ce)O2 materials in aqueous solutions containing H2O2

Homogeneous and heterogeneous U1-xCexO2 (with 0≤ x≤ 0.25) materials were prepared via wet and dry chemistry routes, respectively before being submitted to dynamic leaching experiments. The feeding solution containing 0.20 mmol.L−1 H2O2 was kept under air and renewed to guarantee the stability of H2O2 during the experiment. Normalized alteration rates were determined from U concentration in the leachates. For homogeneous (U,Ce)O2 materials, the dissolution rate was divided by a factor of 3 when increasing the Ce content from 0.08 to 0.25. Surface characterizations revealed that studtite precipitated all over UO2 pellet surface and only on the UO2 grains of heterogeneous U0.92Ce0.08O2 samples. The behaviour of this heterogeneous material was similar to that observed for (U,Pu)O2 in the same conditions, which revealed the reliability of cerium as a plutonium analogue.

2D(r,θ) Simulations of the HBC-4 Power-to-Melt Experiment with the Fuel Performance Code ALCYONE

This paper presents 2D(r, θ ) simulations of the HBC-4 power-to-melt experiment performed with the fuel performance code ALCYONE. The HBC-4 experiment is one of the two test cases selected for the simulation exercise on past fuel melting experiments of the Power to Melt and Maneuverability (P2M) project. The ramp terminal level (RTL) at peak power node (PPN) has been estimated at 66 kW·m−1 by gamma scanning and 70 kW·m−1 based on online measurements of thermal fluxes. The fuel burnup at PPN was close to 60 GWd/tU−1. The cladding failed during the short holding time at a RTL of 40 s. Fuel melting took place at the pellet center, and in particular, in front of clad cracks. In this paper, simulations of the HBC-4 power-to-melt experiment are performed using an updated version of the 2D(r, θ ) scheme of ALCYONE where half of the fuel pellet is described. This configuration allows for the modeling of clad failure by iodine stress corrosion cracking and of its consequences on fuel pellet deformation. The modeling of fuel melting relies on thermochemical equilibrium calculations performed with the OpenCalphad Gibbs Energy Minimizer and the Thermodynamics of Advanced Fuels International Database. The simulation without clad failure indicates that the solidus is reached during the HBC-4 experiment but not the liquidus. The simulation with clad failure leads to a small increase in the fuel temperature that is sufficient to reach the liquidus at the pellet center, in agreement with postirradiation examination (PIE). The impact of water ingress in the rod and vaporization at the pellet surface is discussed, showing that it could explain the pronounced swelling of the fuel pellet reported from the PIE.

In-situ construction of multifunctional interlayer enabled dendrite-free garnet-based solid-state batteries

Garnet-based Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is a prospective solid-state electrolyte with fast ionic mobility and distinguished chemical/electrochemical stabilities toward Li metal. However, Li dendrite propagated within LLZTO bulk is one of the main obstacles to the practical application of solid-state batteries. Herein, we propose to inhibit Li dendrite growth through in-situ construction of a multifunctional interlayer of Li2S/LiSn alloy achieved via a conversion reaction of SnS layer coated on the surface of the LLZTO pellet. DFT calculation reveals that the interfacial contact of LLZTO and Li is considerably improved via Li2S/LiSn interlayer, consequently contributing to a low interfacial impendence (5.1 Ω cm2). Furthermore, the electronic insulativity of LLZTO is also meliorated to suppress electron tunneling. As a result, with effectively restraining the Li dendrite, the Li|LLZTO@Li2S/LiSn|Li symmetrical battery exhibits a superb long-term Li plating/stripping performance over 1500 h and 700 h under 0.2 and 0.4 mA cm−2, respectively. Furthermore, the LFP|LLZTO@Li2S/LiSn|Li full battery displays notable cycling performance (99.8% capacity retention after 100 cycles at 1 C) and rate properties (160.6 mAh g−1 at 0.1 C and 116.3 mAh g−1 at 1 C). This facile and effective method may provide a feasible strategy for eliminating the interfacial issue and achieving dendrite-free solid-state Li metal batteries.

Ratiometric Luminescent Thermometer Based on the Lanthanide Metal–Organic Frameworks by Thermal Curing

The high-performance optical thermometer probes are of great significance in diverse areas; lanthanide metal-organic frameworks (Ln-MOFs) are a promising candidate for luminescence temperature sensing owing to their unique luminescence properties. However, Ln-MOFs have poor maneuverability and stability in complex environments due to the crystallization properties, which then hinder their application scope. In this work, the Tb-MOFs@TGIC composite was successfully prepared using simple covalent crosslinking through uncoordinated -NH2 or COOH on Tb-MOFs reacting with the epoxy groups on TGIC {Tb-MOFs = [Tb2(atpt)3(phen)2(H2O)]n; H2atpt = 2-aminoterephthalic acid; phen = 1,10-phenanthroline monohydrate}. After curing, the fluorescence properties, quantum yield, lifetime, and thermal stability of Tb-MOFs@TGIC were remarkably enhanced. Meanwhile, the obtained Tb-MOFs@TGIC composites exhibit excellent temperature sensing properties in the low-temperature (Sr = 6.17% K-1 at 237 K), physiological temperature (Sr = 4.86% K-1 at 323 K), or high-temperature range (Sr = 3.88% K-1 at 393 K) with high sensitivity. In the temperature sensing process, the sensing mode of single emission changed into double emission for ratiometric thermometry owing to the back energy transfer (BenT) from Tb-MOFs to TGIC linkers, and the BenT process enhanced with the increase of temperature, which further improved the accuracy and sensitivity of temperature sensing. Most notably, the temperature-sensing Tb-MOFs@TGIC can be easily coated on the surface of polyimide (PI), glass plate, silicon pellet (SI), and poly(tetrafluoroethylene) plate (PTFE) substrates by a simple spraying method, which also exhibited an excellent sensing property, making it applicable for a wider T range measurement. This is the first example of a postsynthetic Ln-MOF hybrid thermometer operative over a wide temperature range including the physiological and high temperature based on back energy transfer.

Combustion and mass loss behavior and characteristics of a single biomass pellet positioning at different orientations in a fixed bed reactor

This study aims to investigate the combustion characteristics and mass loss behaviors of rice straw and wheat straw biomass pellets experimentally in a laboratory fixed bed combustor under various operating conditions. High-speed photography was used to record images of the combustion process, and a sensitive balance was utilized for recording the particle mass history during the combustion process in addition to K-type thermocouples for temperature measurements. For both materials, the single pellet was exposed to various air temperatures and different flow rates of air. The orientation of the biomass pellet was positioned at various angles from 0 (horizontal), 30°, 45°, 60° (inclined), and 90° (parallel) to the hot air stream at different flow rates. Both glowing reactions and flameless ignition have been noticed in all experiments at all pellet orientations. All pellets experienced low and high luminosity volatiles without flames, followed by a bright radish color and short-lived combustion of the chars. Although the volatile contents of the two materials are identical, the volatile combustion duration of wheat straw (17–258 s) is less than that of rice straw (20–300 s), which could be due to differences in particle sizes, shapes, and structural compositions. The results also show that increased air temperatures lessen the time it takes for volatile and char to ignite and burn off. It also raises the temperature of surface ignition. Starting from the horizontal position and increasing the orientation angle of the pellet, the volatile and char ignition times increase up to 30° and then drop up to 90°, with angle 45° giving the lowest value. The same pattern was also noticed for volatile and char burnout times. The pellet horizontal position (0°) exhibits reduced combustion and mass loss (%) time intervals. The order of increasing the maximum temperature at the pellet surface was 30° > 60° > 90° angles. Increasing the air temperature reduces the times of char combustion, devolatilization, volatile burnout, and char burnout. As the air flow rate increases, the effect on the combustion parameters alternates between increasing and decreasing values.

In-situ constructed SnO2 gradient buffer layer as a tight and robust interphase toward Li metal anodes in LATP solid state batteries

Li1.3Al0.3Ti1.7(PO4)3 (LATP), of much interest owing to its high ionic conductivity, superior air stability, and low cost, has been regarded as one of the most promising solid-state electrolytes for next-generation solid-state lithium batteries (SSLBs). Unfortunately, the commercialization of SSLBs is still impeded by severe interfacial issues, such as high interfacial impedance and poor chemical stability. Herein, we proposed a simple and convenient in-situ approach to constructing a tight and robust interface between the Li anode and LATP electrolyte via a SnO2 gradient buffer layer. It is firmly attached to the surface of LATP pellets due to the volume expansion of SnO2 when in-situ reacting with Li metal, and thus effectively alleviates the physical contact loosening during cycling, as confirmed by the mitigated impedance rising. Meanwhile, the as-formed SnO2/Sn/LixSn gradient buffer layer with low electronic conductivity successfully protects the LATP electrolyte surface from erosion by the Li metal anode. Additionally, the LixSn alloy formed at the Li surface can effectively regulate uniform lithium deposition and suppress Li dendrite growth. Therefore, this work paves a new way to simultaneously address the chemical instability and poor physical contact of LATP with Li metal in developing low-cost and highly stable SSLBs.

Multiphysics simulation of VVER-1200 fuel performance during normal operating conditions

Nuclear fuel performance modeling and simulation are critical tasks for nuclear fuel design optimization and safety analysis under normal and transient conditions. Fuel performance is a complicated phenomenon that involves thermal, mechanical, and irradiation mechanisms and requires special multiphysics modules. In this study, a fuel performance model was developed using the COMSOL Multiphysics platform. The modeling was performed for a 2D axis-symmetric geometry of a UO2 fuel pellet in the E110 clad for VVER-1200 fuel. The modeling considers all relevant phenomena, including heat generation and conduction, gap heat transfer, elastic strain, mechanical contact, thermal expansion, grain growth, densification, fission gas generation and release, fission product swelling, gap/plenum pressure, and cladding thermal and irradiation creep. The model was validated using a code-to-code evaluation of the fuel pellet centerline and surface temperatures in the case of constant power, in addition to validation of fission gas release (FGR) predictions. This prediction proved that the model could perform according to previously published VVER nuclear fuel performance parameters. A sensitivity study was also conducted to assess the effects of uncertainty on some of the model parameters. The model was then used to predict the VVER-1200 fuel performance parameters as a function of burnup, including the temperature profiles, gap width, fission gas release, and plenum pressure. A compilation of related material and thermomechanical models was conducted and included in the modeling to allow the user to investigate different material/performance models. Although the model was developed for normal operating conditions, it can be modified to include off-normal operating conditions.