Severe Operating Conditions Research Articles

Probabilistic reliability model of electrical motors in submersible well pumping units used in the uranium mining by in-situ leaching

Relevance. A submersible electric motor is the most vulnerable component of an electric centrifugal pumping unit used in in-situ leaching uranium mining. The accuracy of calculating the need for new electric motors directly affects the profitability of the uranium production. Aim. Development of a probabilistic reliability model for a submersible electric motor that provides the calculation of its failure probability for the upcoming period of time and allows estimating with sufficient accuracy the number of motors required to replace the failed ones. Methods. Statistical methods, survival analysis, statistical hypothesis testing. Results and conclusions. The authors conducted a study of three probabilistic reliability models for electric motors of submersible well pumping units used in in-situ leaching uranium mining. As a result of the study, the maximum likelihood estimates of model parameters were determined for each model; the adequacy of the models under study was checked based on nonparametric goodness-of-fit tests. Despite the fact that the test results did not allow excluding any of the considered models, a model based on a mixture of two Weibull distributions was selected as a probabilistic reliability model demonstrating higher consistency with real data, compared to the other models. At the same time, the analysis of the components of the mixture distribution indicated the presence of a group of electric motors with an uncharacteristically low time-to-failure value compared to the average value calculated for the entire set of equipment under study, and made it possible to estimate the share of such motors, which amounted to 8% of the total population. Possible reasons explaining such heterogeneity of data, according to the authors, are hidden manufacturing defects or more severe operating conditions in which some submersible electric motors operate.

Experimental investigation and thermodynamic description of the Ni-Mo-Y ternary system

Nickel-based superalloys are extensively utilized in aerospace engines, marine gas turbines, and other environments with severe operating conditions. The phase relations of the Ni-Mo-Y ternary system were experimentally studied across the entire composition range at 800 °C and 1000 °C using scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Thirteen three-phase regions were confirmed at 800 °C, and eleven three-phase regions were observed at 1000 °C. No ternary compound was observed at these temperatures. In addition, the experimental results indicate that molybdenum (Mo) has almost no solubility in the binary compounds found in the Ni-Y binary system. Furthermore, the primary solidification phases and the solidification process of typical alloys were investigated, and three different primary solidification phases were found. Based on the experimental results, thermodynamic calculations for the Ni-Mo-Y system were performed through the CALPHAD technique. The experimental results agree well with the calculated, a set of self-consistent thermodynamic parameters for the Ni-Mo-Y ternary system was obtained in the present work.

New characterization models for macroscopic chemical-hydrodynamic behavior of catalytic cracking riser-reactor with interactive patterns of severe operating conditions using CFD calculations

BackgroundFCC is the core of refining technologies for production of high-valued chemicals including, light olefins, and fuels. Global capacity of catalytic cracking unites is projected to grow from 14.4 to 15.8 million barrels per day from 2022 to 2026. Moreover, global production of 57 % ethylene, 42 % propylene and 69 % butylene is based on deep/fluid catalytic cracking. Therefore, optimization of catalytic cracking process is our indispensable industrial approach. MethodsThis study is optimization of industrial catalytic cracking unit for maximizing the yield of light gases, gasoline and gasoil conversion using CFD calculations. Hydrodynamic behavior and performance of the riser-reactor was investigated at severe operating conditions, including feed temperature, catalyst temperature and catalyst to oil ratio (CTO) in the range of 788–903 K, 813–1013 K and 6–18, respectively. New characterization models were proposed for macroscopic chemical-dynamic behavior of the process. Models validated with ANOVA analysis, RSM methodology. Significant findingsResults showed that the maximum products yield and gasoil conversion occur between 4 and 8 s. It was obtained that the maximum yield of nearly 12 wt% light gases, 38–39 wt% gasoline and 54 % conversion is possible for this geometry of industrial unit via optimization of operating conditions. Coefficients of obtained models and interactive patterns of operating conditions showed that CTO is the most influential parameter on riser-reactor performance.

High Entropy Alloys as High Performance Catalysts for Electrolytic Water Splitting

Renewable energy driven electrolytic water splitting is a required technology for low-carbon hydrogen production to achieve the goal of net-zero CO2 emission by 2050. This technology also serves as a necessary energy storage route to resolve the intolerable intermittency and unreliability issues of renewable energies. The prevailing of this hydrogen production technology however is restricted by the high cost of electricity. Consequently, developments of cost–effective highly efficient and stable electrocatalysts to drive the electrolytic water splitting reactions are the key. In terms of catalyst developments, mono-component systems are first explored, followed by multi–component systems, taking advantages of possible positive synergy between constituent components. Recently, a new class of multi-component catalyst systems, entropy-stabilized materials, including alloys, oxides, sulfides, phosphides, etc., emerges and is demonstrated promising performances toward electrocatalysis. In light of the variable and flexible element compositions, entropy-stabilized materials provide infinite and enormous potentials for the design of promising electrocatalysts. The key is to maximize the synergy between constituent components. High entropy alloys (HEA), defined as alloys composed of five or more major metallic elements, have been under intensive and extensive development in past fifteen years for their extraordinary mechanical, magnetic, corrosion, and catalytic properties. Herein, an equi–molar FeCoNiCuMo HEA on nickel foam was developed as a breakthrough catalyst for electrocatalytic water splitting, in terms of both activity and stability, in pH-universal media and in severe industrial operation conditions. Furthermore, a new catalytic phenomenon is discovered. Two different catalytic mechanisms function simultaneously on different constituents of the catalyst, and the synergistic interactions between the two categorical domains leads to catalytic kinetics faster than the theoretical limit set by a single rate-limiting step, Tafel step of the Volmer-Tafel route. A new kinetic model is developed to predict a new theoretical lower limit of Tafel slopes of 15 mV/dec based on a synergistic interaction between the two categorical domains of the high entropy alloy catalyst. This new development proves that the theoretical lower limit of Tafel slope of 30 mV/dec posed for the Volmer-Tafel mechanism functioning on a single component catalyst can be further reduced to 15 mV/dec through synergistic interactions between two categorical domains of a multi-component catalyst. It is demonstrated that high entropy materials, composed of five or more atomically/molecularly well-mixed major components, are intrinsically promising candidates for realization of quantum leaps in catalytic performances of catalysts.

Effect of Ni Addtion on Electroless Cu for High Density Interconnect PCB Substrate

Introduction Nowadays, high-density interconnect (HDI) printed circuit board (PCB) substrates have been widely applied to high-end electronics to meet the increasing input and output (I/O) density and small footprint area. Micro-via, a tiny structure buried among build-up layers that provide electrical interconnection is a key component in the HDI substrate. However, the preparation of micro-via is facing new challenges. It is not only required that the size of the micro-via scales down to meet the increased interconnect density, but also that the micro-via should withstand severe operating conditions in different scenarios. Therefore, it is of great importance to improve the quality of micro-vias during processing and manufacturing. The micro-via structure is a sandwich structure that is processed by electroless Cu plating and Cu electrolyte plating sequentially, and thus the quality of the electroless Cu layer can significantly affect the reliability of micro-via. In this work, we mainly focused on the electroless Cu plating process and investigated the effect of the electroless Cu deposition speed on the quality of the micro-via structure. SIM and HR-TEM characterizations were employed to investigate the micro-structure inside the electroless Cu layer. Materials and Method In this study, we used the common alkaline ion catalyst method to prepare the electroless Cu layer. The electroless Cu plating and electrolyte Cu plating was conducted on a PCB Resin Coated Copper (RCC) substrate that was cleaned by soft etching in an acid condition. The surface is then pre-dipped in an anionic solution, and palladium ions were adsorbed using an alkaline ion catalyst. The electroless Cu processes adopted in a reaction bath that consists of Cu resource (CuSO4·5H2O), complexing agent (KNaC4H4O6·4H2O) and reductant (HCHO). The whole reaction was conducted in the alkaline condition with a PH of 12.5, and the thickness of the electroless Cu deposition was controlled at around 0.20 µm. NiSO4 is selected as the Ni precursor to alter the Ni concentration in the reation bath. The contents of Ni addition were selected as 50 %, 100 %, 200 % and 300% of a conventional process at a bath temperature of 27 ºC. The thickness of the plated Cu layer was measured by a gravimetric method. Results and discussion TEM observation was used to identify the structure at the interface. Fig. 1 shows the TEM observation of the sample with 50 % and 200 % Ni concentrate. There are some nanovoids found at the interface between the Cu substrate and electroless Cu, which is arguably due to hydrogen generated during electroless Cu plating. The sample with a higher reaction speed has more nanovoids. It can be due to that the higher reaction speed can generate more hydrogen bubbles in the bath that can attach to the electroless Cu layer, leading to nanovoids as shown in Fig. 1. The samples prepared at different bath temperatures are under investigation to illustrate that the reaction speed can significantly affect the Cu electroless layer quality. Conclusions In this work, we investigated the Ni effect in electroless Cu on the RCC substrate. It is found that the higher Ni incorporation can lead to massive nanovoids generation and fine Cu grains in the electroless layer, which is a potential risk for the reliability of the HDI substrate. By reducing the Ni incorporation content, the number of nanovoids can be effectively reduced. Figure 1

Development and fault-tolerant control of a distributed piezoelectric stack actuator

Piezoelectric stack actuator (PSA) has attracted widespread attention in aerospace applications. However, the severe operating conditions would bring certain risks to PSA, leading to decreased performance or even failure. The conventional PSA structure lacks adaptability in the event of a complete failure occurring within the piezoelectric stack layer (PSL) due to its centralized design and driving method. To address the reliability challenges inherent in PSAs, this paper proposes a novel distributed PSA (DPSA) by means of mechanical and electrical dispersion. Additionally, dual-redundant PSLs are integrated into the DPSA as backups, providing hardware redundancy for active fault-tolerant control (FTC). Building upon this foundation, an sliding mode observer (SMO)-based fault detector for DPSA is developed to facilitate fault reconstruction. Subsequently, an active FTC strategy, comprising dual-SMO-based fault detectors and a tracking controller, is introduced to effectively manage faults and reallocate control resources. Comprehensive experiments under various fault scenarios are carried out to assess the performance of the SMO-based fault detector and FTC strategy. The results demonstrate that the proposed fault detector and FTC strategy promptly detect faults and efficiently restore the DPSA to a stable state, thereby ensuring effective trajectory tracking even in the presence of faults.

Fatigue Strength Improvement of Laser-Directed Energy Deposition 316L Stainless Steel with In Situ Ultrasonic Rolling by Preliminary Investigation.

In this study, to improve the fatigue strength of the LDED (laser-directed energy deposition) 316L stainless steel, an in situ ultrasonic rolling technology is developed to assist the laser-directed energy deposition process (LDED-UR). The microstructural characteristics and fatigue behavior are comprehensively discussed. The results show that the average size of pores of the LDED-UR alloy is about 10.2 μm, which is much smaller than that of the LDED alloy (34.1 μm). Meanwhile, the density of the LDED alloy is also enhanced from 98.26% to 99.27% via the in situ ultrasonic rolling. With the application of the in situ ultrasonic rolling, the grains are transformed into fully equiaxed grains, and their average grain size is greatly reduced from 84.56 μm to 26.93 μm. The fatigue limit of the LDED-UR alloy is increased by 29% from 210 MPa (LDED alloy) to 270 MPa, which can be ascribed to the decreased porosity and the fine grains. In particular, the crack initiation site of the LDED alloy is located at the surfaces, while it is nucleated from the sub-surface for the LDED-UR alloy. This is mainly attributed to the compression residual stress induced by the in situ ultrasonic rolling. This research offers a valuable understanding of the failure mechanisms in additively manufactured metals, guiding the development of effective strategies to improve their fatigue threshold under severe operating conditions.

Robust Ru/Ce@Co Catalyst with an Optimized Support Structure for Propane Oxidation.

Short carbon chain alkanes, as typical volatile organic compounds (VOCs), have molecular structural stability and low molecular polarity, leading to an enormous challenge in the catalytic oxidation of propane. Although Ru-based catalysts exhibit a surprisingly high activity for the catalytic oxidation of propane to CO2 and H2O, active RuOx species are partially oxidized and sintered during the oxidation reaction, leading to a decrease in catalytic activity and significantly inhibiting their application in industrial processes. Herein, the Ru/Ce@Co catalyst is synthesized with a specific structure, in which cerium dioxide is dispersed in a thin layer on the surface of Co3O4, and Ru nanoparticles fall preferentially on cerium oxide with high dispersity. Compared with the Ru/CeO2 and Ru/Co3O4 catalysts, the Ru/Ce@Co catalyst demonstrates excellent catalytic activity and stability for the oxidation of propane, even under severe operating conditions, such as recycling reaction, high space velocity, a certain degree of moisture, and high temperature. Benefiting from this particular structure, the Ru/Ce@Co (5:95) catalyst with more Ce3+ species leads to the Ru species being anchored more firmly on the CeO2 surface with a low-valent state and has a strong potential for adsorption and activation of propane and oxygen, which is beneficial for RuOx species with high activity and stability. This work provides a novel strategy for designing high-efficiency Ru-based catalysts for the catalytic combustion of short carbon alkanes.

Two-dimensional stiffness identification by inversion of local wavenumbers based on artificial neural network

Impact and fatigue damages in carbon fiber reinforced polymers (CFRP) are unavoidable in severe operating conditions, which will lead to the stiffness properties degrading and redistributing in space. The local wavenumbers of guided waves at a specific point depend on the stiffness at that spatial location. Therefore, the two-dimensional stiffness properties can be determined by inversion of local wavenumbers. In this paper, the relationship between the local wavenumbers and the stiffness coefficients was established by the artificial neural network (ANN) method. For each spatial point, based on the semi-analytical finite element (SAFE) method, the wavenumbers (inputs of ANN) with different frequencies can be obtained at given stiffness coefficients (outputs of ANN). Furthermore, the accuracy of the ANN method was validated by the finite element model. Results show that the predicted two-dimensional stiffness coefficients of the damaged region are close to the true ones, thus demonstrating the accuracy of the two-dimensional stiffness identification method.

Boosting Selective Nitrogen Oxidation to Nitric Acid by Synergizing Cobalt Phthalocyanine on Carbon Nitride Surface

AbstractThe Ostwald process, which is producing HNO3 for commercial use, involves the catalytic oxidation of NH3 and a series of chemical reactions conducted under severe operating conditions. Due to their energy‐intensive nature, these activities play a major role in greenhouse gas emissions and global energy consumption. In response to the urgent requirements of the global energy and environmental sectors, there is an increasingly critical need to develop novel, highly efficient, and environmentally sustainable methods. Herein, CoPc/C3N4 electrocatalyst, integrating CoPc nanotubes with C3N4 nanosheets, is shown. The CoPc/C3N4 electrocatalyst demonstrates yield rate of 871.8 µmol h−1 gcat−1 at 2.2 V, with corresponding Faradaic efficiency (FE) of 46.4% at 2.1 V, which notably surpasses that of CoPc. Through a combination of experimental investigations and density functional theory (DFT) calculations, this study shows that CoPc anchored on C3N4 effectively simplifies the adsorption and activation of chemically inactive nitrogen molecules. The improved catalytic activity for composite system may be the reason of re‐distribution of charges over the CoPc, tuning the valence orbital of Co center due to the presence of 2D layer of C3N4. This mechanism significantly lowers the energy barrier required for critical breaking of inert N2, ultimately leading to a significant improvement in N2 oxidation efficiency.

High-Performance Cobalt Chalcogenides for Oxygen Reduction Reaction

Abstract: The oxygen reduction reaction (ORR) is vital to numerous energy conversion technologies, such as fuel cells and metal-air batteries. Moreover, to enhance the overall efficacy and durability of these devices, it is crucial to develop catalysts that are both effective and economical. Among the many explored catalyst materials, cobalt chalcogenides have attracted considerable interest due to their unique properties and exceptional ORR performance. This review focuses on the synthesis methods, structural characteristics, and electrochemical performance of high-performance cobalt chalcogenides as catalysts for the ORR. In addition, the influence of various synthetic parameters on the catalytic activity and stability of cobalt chalcogenides is investigated. Also addressed are the effects of defects, doping, and surface modification on the ORR performance of cobalt chalcogenides. In addition, the use of cobalt chalcogenides in practical fuel cell devices is discussed, along with their outstanding performance as ORR catalysts in both acidic and alkaline environments. The durability and long-term stability of cobalt chalcogenides under severe operating conditions are evaluated, indicating their potential commercial applications. Finally, the field of cobalt chalcogenides for ORR challenges and prospects are outlined. This review proposes strategies for further enhancing their catalytic activity, selectivity, and durability, such as interface engineering and synergistic combinations with other catalyst materials. For researchers working on the development of next-generation ORR catalysts and the practical implementation of cobalt chalcogenides for sustainable energy applications, the insights garnered from this review are invaluable.

Aluminum-distribution-dependent microstructural evolution of NCA cathodes: Is aluminum homogeneity really favorable?

Despite extensive research, the optimal synthesis method and Al concentration for fabricating high-performance Li[NixCoyAl1−x−y]O2 (NCA) cathodes remain to be established. This study provides an in-depth analysis of NCA cathodes prepared using different synthesis methods and Al fractions. Al overdoping (3 mol%) during coprecipitation generates a homogeneous Al distribution in the cathode active material, whereas supplying excess Al during calcination induces a hierarchical spatial arrangement. Interestingly, different Al distributions and concentrations produce strikingly different cathode microstructures, which greatly affect the electrochemical performance of the cathode. Contrary to the common belief that homogeneous Al doping is critical for optimal cycling performance, the electrochemical performance of the cathode is maximized by grain-boundary-segregated Al ions. The proposed Li[Ni0.925Co0.042Al0.033]O2 cathode demonstrates superior cycling performance, retaining 74.1 % of its initial capacity after 1000 cycles in a full cell despite cycling under severe operating conditions (3 C and 45 °C). These findings redefine the fundamental contribution of the elemental distribution to the engineering of cathode microstructures, thereby providing a viable approach for developing high-performance Ni-rich NCA cathodes for advanced Li-ion batteries.

Coupling a nonlinear finite element mooring model with an overset CFD solver for dynamic analysis of floating structures in waves

An accurate prediction of motion responses of a moored floating structure requires high-fidelity coupled analysis between the structure and its mooring system in waves, which involves both mooring line dynamics and fluid dynamics. In this paper, we develop a nonlinear finite element dynamic mooring analysis module that allows large axial stretching of mooring lines under the open source CFD framework OpenFOAM, and couple it with an Overset CFD solver to establish a fully coupled finite element mooring-CFD analysis model for floating structures. The coupled model is advantageous over existing models in that it is able to deal with large axial mooring stretching and complex mesh motions induced by significant structure responses under severe operating conditions. The developed dynamic mooring analysis method is firstly validated against publicly available data. In order to validate the coupled model, a series of experimental tests were carried out for a semi-submersible platform moored by eight catenary lines under different operating conditions, including free decay, regular and irregular wave tests. The dynamic responses of the floating structure and mooring tension are analyzed and compared with experimental data. Results show that numerically predicted structure responses and mooring tension are generally in good agreement with experimental measurements. Meanwhile, the strongly nonlinear large-amplitude resonant motions generated by the interaction of irregular waves with the moored floating structure are also investigated. Comparisons reveal that the coupled model can accurately predict the resonant spectral peaks of the structure responses, indicating that the it is capable of simulating large-amplitude motions of moored floating structures. The coupled model developed in this paper can be further applied to study the survivability of moored floating structures under harsh sea conditions.

Energy storage density enhancement in paraffin phase change material emulsions: A comparative study with two different base fluids

This investigation examined the thermophysical properties of emulsions comprising paraffin 56/58 phase change material (PCM) dispersed in water and ethylene glycol (60 wt%) aqueous solution to optimize energy storage density for low-temperature thermal applications. Dynamic Light Scattering analysis revealed a uniform dispersion of paraffin 56/58 PCM droplets in the basefluids, with an average diameter of approximately 150 nm achieved by incorporating sodium dodecyl sulfate surfactant. The latent heat of fusion for emulsions containing paraffin 56/58 PCM in ethylene glycol (60 wt%) exhibited values of 37.5/41.7, 58.5/63.9, 73.8/75.43, and 93/90.25 J/g for concentrations of 20, 30, 40, and 50 wt%, respectively, during melting/solidification phases. Furthermore, the highest energy storage densities of 306.95 and 361.3 kJ/kg were attained at a PCM concentration of 50 wt% in ethylene glycol (60 wt%) and water-based emulsions, respectively, surpassing those of similar working fluids. It is also indicated that water-based paraffin 56/58 PCMs offer superior energy storage density. However, under severe operating conditions such as extreme temperatures, ethylene glycol (60 wt%) based paraffin 56/58 emulsions demonstrate greater suitability, as the evaporation and freezing points of the basefluid can be adjusted by modulating the ethylene glycol concentration ratio.

Effect of manganese and vanadium additions on the microstructures and two-body abrasive wear behaviors of Fe–B hardfacing alloys

Fe–B wear-resistant alloys often exhibit brittleness and suboptimal wear resistance, making them unsuitable for severe operational conditions. In this study, we incorporated ferromanganese powder and ferrovanadium powder were compounded into the Fe–B wear-resistant alloy by plasma cladding technology. The results indicate that the addition of a minor percentage of vanadium, such as about 2 wt%, does not induce any changes in the phase composition. The alloy layer primarily consists of (Mn,Fe)2B and γ-Fe, with vanadium predominantly dissolving in the primary (Mn,Fe)2B phase. This dissolution enhances the toughness of the hard phase and refines the grain structure. At around 4 wt% vanadium, a spherical VB phase precipitates. This inclusion elevates the impact toughness of the alloy layer. The impact toughness of the high manganese content with 4.69 wt% vanadium is the highest, up to 39.11 J/cm2, which is about 30 %higher than that of the sample without vanadium. As vanadium content rises, both the hardness and wear resistance of the alloy layer improve. The most optimal performance was observed with a manganese content of 20.15 wt% and vanadium at 4.69 wt%, achieving a hardness of 65.5 HRC and wear amounts of 48.1 mg (24 N load) and 85.0 mg (48 N load).

Innovative Approaches to Sustainable Ammonia Synthesis under Mild Conditions

AbstractAmmonia is one of the most important chemicals in the world because it is a feedstock for fertilizer production and, moreover, it has been proposed as a convenient storage media for renewable H2. Currently, it is produced by Haber‐Bosch process, which entails harsh operation conditions and a high carbon footprint, rendering the process difficult to be run by renewable energy. Therefore, substituting the conventional Haber‐Bosch process by other approach less energy‐intensive and carbon‐free is an urgent need. A milder process for ammonia synthesis will enable the implementation of smaller distributed plants more aligned with renewable energies. For this reason, there is a plethora of current research focusing on the development of suitable catalysts with higher activity and selectivity for nitrogen reduction and processes that will work under less severe operating conditions or even at ambient conditions. Some of the most relevant research approaches are here revised and compared.

Mechanical Analysis of the Quasi-Static and Dynamic Composite Action in PV Modules with Viscoelastic Encapsulant.

The mechanical analysis of photovoltaics and building integrated photovoltaics is a key step for their optimal design and certification, and requires careful consideration, alongside solar power, durability and functionality issues. The solar cells are encapsulated in thin interlayers that are usually composed of a viscoelastic Ethylene-Vinyl Acetate compound, and protected by thin glass and/or plastic layers. This paper investigates the out-of-plane bending response of a full-scale commercial PV module and focuses attention on the shear bonding efficiency of the thin encapsulant for quasi-static and dynamic mechanical considerations. The parametric analytical analysis, carried out in this study for a laminated glass plate, highlights the possible consequences of the viscoelastic shear coupling on the cross-section load-bearing demand in the covers. As a direct effect of severe operational conditions (i.e., ageing, non-uniform/cyclic thermal gradients, humidity, extreme mechanical/thermal loads, etc.) the shear rigidity and adhesion of these films can suffer from repeated/progressive modification and even degradation, and thus induce major stress and deflection effects in the out-of-plane mechanical response of the PV module components. The minimum shear bond efficiency required to prevent mechanical issues is calculated for various configurations of technical interest. Accordingly, it is shown how the quasi-static and dynamic mechanical performance of the system modifies as a function of a more rigid or weak shear coupling.

Holistic Characterization of MgO-Al2O3, MgO-CaZrO3, and Y2O3-ZrO2 Ceramic Composites for Aerospace Propulsion Systems

Aerospace propulsion systems are among the driving forces for the development of advanced ceramics with increased performance efficiency in severe operation conditions. The conducted research focused on the mechanical (Young’s and shear moduli, flexural strength, hardness, and fracture toughness), thermal (thermal conductivity and coefficient of thermal expansion), and electric (dielectric properties) characterization of MgO-Al2O3, MgO-CaZrO3, and stable YSZ ceramic composites. The experimental results, considering structural and functional traits, underscore the importance of a holistic understanding of the multifunctionality of advanced ceramics to fulfill propulsion system requirements, the limits of which have not yet been fully explored.

Effects of the geometrical parameters on rectification characteristics of convergence angle throttle orifice plates

Under severe operating conditions, the conventional porous plates are rendered ineffective in rectifying the spiral turbulence generated during the steam flow and pressure adjustment process by the primary pressure-reducing valve (PPRV). To address this limitation, an innovative throttle plate with a convergent angle structure is proposed based on the conventional uniformly distributed porous plate in this study. The design aims to rectify the spiral turbulence generated after PPRV and elucidate its formation mechanism. However, there is currently no clear understanding or reliable prediction method for the pressure loss coefficient due to various structural factors influencing the rectification characteristics and pressure drop properties of the converging angle structure throttle orifice plate. This lack of knowledge severely hampers practical applications of this new plate in pressure-reducing desuperheating devices. To address this issue, the present study investigates the underlying mechanisms governing the rectification characteristics and flow resistance properties of a throttle orifice plate with a converging angle structure through experimental investigations and numerical simulations. The focus is on geometric parameters including the converging angle (θ), orifice diameter (d), throttle diameter ratio (β), and plate thickness (h). The findings suggest that the incorporation of a converging angle structure throttle orifice plate is advantageous in achieving effective rectification of spiral turbulence in the secondary pressure pipeline of the pressure-reducing desuperheating device. This modification reduces the required channel distance for enhancing unstable flow, diminishes velocity non-uniformity, and augments the rectification and control capabilities of the medium.

Design optimization of noise reduction for labyrinth control valve in secondary circuit flow regulation system

The labyrinth control valve has been widely used in the secondary circuit flow regulation system of nuclear power field for good pressure reduction and cavitation suppression characteristics. The design of the labyrinth channel is a key to realizing pressure regulation and cavitation suppression for the labyrinth control valve. However, an unreasonable labyrinth flow channel design will be challenging to meet the requirements and aggravate the noise problem under severe operating conditions. This paper proposes a hybrid labyrinth flow channel structure (HLS) that combines the traditional labyrinth flow channel (TLS) and orifice plate structure. The cavitation volume and maximum flow velocity are used as evaluation parameters of the labyrinth flow channel noise. The flow characteristics analysis show that compared with the TLS, the HLS can reduce flow velocity, decrease cavitation volume, improve transmission loss, and lower sound power levels. In addition, the influence between the HLS structural parameters and the noise evaluation parameters is clarified by correlation coefficient analysis. A low noise HLS based on the adaptive NSGA-II algorithm is established. The experimental results indicate that the optimized HLS reduces air noise by 4.21 dB(A) compared to the TLS. The optimized HLS can effectively reduce noise, and help the design of low noise labyrinth flow channels for nuclear power field.