Performance Characteristics Research Articles

Design of A PFR For the Production of 1,000,000 Tons Per Year of Ethyl Acetate from Esterification of Acetic Acid and Ethyl Alcohol

The research considered the design or size of a plug flow reactor for the production of 1,000,000 tons of ethyl acetate per year from the esterification of acetic acid and ethyl alcohol in the presence of an acid catalyst. The PFR design models for volume, height, diameter, space time, space velocity, quantity of heat generated, quantity of heat generated per unit volume of the reactor as well as the temperature effect models were developed using the conservation principle of mass and energy at steady state operation of the reactor. The developed models were simulated using MATLAB at initial feed and operating temperature of 299.830k and 343.15k respectively and fractional conversion variation between 0 to 0.95 at an interval of 0.05. At a maximum conversion of 0.95, the PFR size specification for volume, height, diameter, space time, space velocity, quantity of heat generated and the quantity of heat generated per unit volume of the reactor was 15.2774m3, 4.2691m, 2.1346m, 2.9956sec., 0.3338sec-1, 12821.5800j/s and 839.2536j/sm3 respectively. The effect of the operating parameters on the performance or functional parameters of the reactor are presented in profiles as shown in figure 2 to 12 and the profile behaviour or trend were in agreement with process behaviour of PFR steady state operation in various literatures. The research have shown that in order to ensure sustainability and continuous production of ethyl acetate to meet the global demand of the economic and viable product, the plug flow reactor have demonstrated a good performance characteristics as a reacting media for the esterification process especially in the energy efficiency of the process as well as the product yield.

The Effects of Shrimp Waste Added to Broiler Diets on Growth Performance, Slaughter and Carcass Characteristics, Intestinal Morphology, Bone Traits, and Fatty Acids in the Meat.

Recycling animal waste is crucial for the circular economy, promoting environmental and sustainability. This study aimed to assess the impact of shrimp waste added to broiler diets on growth performance, slaughter and carcass characteristics, intestinal morphology, bone traits, and fatty acids in the meat. In the study, 315 ROSS-308 male broiler chicks were utilised as the animal subjects. The experiment consisted of five groups based on the timing and amount of shrimp (Penaeus vannamei) waste addition to their diet (Control [C], 1% added the first 11 days [1% FED], 1% added during fattening [1% DF], 2% added during the first 11 days [2% FED], 2% added during fattening [2% DF]). The differences in body weight, body weight gain, total feed intake and total feed conversion ratio, carcass parameters, relative internal organ weights, and fatty acids of thigh and breast meat among the groups were found to be statistically insignificant (p > 0.05). The addition of shrimp waste to the diet only significantly affected the VH/CD ratio in the jejunum, with the C group showing a lower ratio (p < 0.05). Adding shrimp waste to the diet only affected the seedor index of the femur among the characteristics of the leg bones, and an interaction between the period and the group was observed for this trait (p < 0.05). According to the results, up to 2% shrimp waste can be added to the diet without adversely affecting broiler performance, carcass quality, villus and bone properties, and fatty acid composition. The use of shrimp waste in feed can benefit the broiler industry and protect to environment.

Productive Performance and Carcass Characteristics of Broiler Chickens Fed on Diets with Different Protein, Energy Levels, and Essential Oils During the Warm Season in Dry Tropics

This study evaluated the productive performance and carcass traits of broiler chickens during the warm season in dry tropical conditions. Two hundred, 1-day-old chicks were used. Birds were fed on reduced (RED) and standard (STD) diets, and two essential oils (EOs) levels, 0 and 200 ppm. The RED diets were formulated with 10% less energy and 10% less protein than STD diets. In the starter phase, weight gain was greater (p &lt; 0.01) in birds fed STD than birds fed RED. In the starter phase, productive variables were not affected (p ≥ 0.14) by EOs. In the finisher phase, greater feed intake (p = 0.02) and higher weight gain (p = 0.04) were observed in chickens on STD. Feed conversion ratio was similar (p = 0.97) for STD and RED. Throughout this study (1–42 d), greater feed intake (p = 0.02) and higher weight gain (p &lt; 0.01) were found in chickens on STD. Feed conversion ratio was similar (p = 0.51) for STD and RED. Broiler chickens on EO-supplemented diets had better feed conversion (p ≥ 0.08). Hot carcass weight was greater (p &lt; 0.01) in birds on STD. Greater yields of leg-thigh (p = 0.01), back (p = 0.01), and wings (p &lt; 0.01) were observed in RED. Carcass yields, breast yield, pH, and meat temperature were not influenced (p ≥ 0.14) by nutrient concentrations in the diet. Carcass evaluations were not affected (p ≥ 0.11) by EOs. Body temperature was lower (p = 0.03) in birds receiving RED, however EOs had no effect (p ≥ 0.22) on body temperature. For the length of the study, at 20:00 h, broiler chickens fed on RED diets showed lower (p = 0.04) body temperatures. In conclusion, broiler chickens were under heat stress during the study, and body temperatures were reduced in chickens fed on RED diets or with EOs. Diet modification or EO-supplementation may improve feed conversion, though RED diets may have a negative effect on weight gain or carcass values.

Into the Revolution of NanoFusion: Merging High Performance and Aesthetics by Nanomaterials in Textile Finishes

AbstractThe field of technical textiles has grown significantly during the last two decades, with a focus on functionality rather than aesthetics. However, the advancement of NanoFusion technology provides a novel potential to combine better functionality and aesthetic value in textile finishes. NanoFusion incorporates nanoparticles into textile treatments to improve waterproofing, stain resistance, durability, and breathability. This is performed without affecting the textile's visual appeal or aesthetics and may even improve them. This textile finishing revolution is expected to impact industries such as athletics, outdoor clothing, car upholstery, and luxury fashion. It offers cutting‐edge functionality while maintaining style and design integrity. Furthermore, the use of nanoparticle textile coatings opens up new opportunities for personalization and modification. Manufacturers and designers can now experiment with different color combinations, patterns, and textured finishes while maintaining performance characteristics. NanoFusion technology has the potential to transform the textile industry by providing hitherto unattainable levels of performance and aesthetics. This study reviews the current state of the art in nanofinishes for garment textiles, focusing on their many varieties, techniques, mechanisms, and applications. In addition, it addresses significant concerns such as sustainability and the environmental footprint, paving the way for a new era in textile manufacturing.

3D in-system calibration method for PET detectors.

Light-sharing detector designs for positron emission tomography (PET) systems have sparked interest in the scientific community. Particularly, (semi-)monoliths show generally good performance characteristics regarding 2D positioning, energy-, and timing resolution, as well as readout area. This is combined with intrinsic depth-of-interaction (DOI) capability to ensure a homogeneous spatial resolution across the entire field of view (FoV). However, complex positioning calibration processes limit their use in PET systems, especially in large-scale clinical systems. This work proposes a new 3D positioning in-system calibration method for fast and convenient (re-)calibration and quality control of assembled PET scanners. The method targets all kinds of PET detectors that achieve the best performance with individual calibration, including complex segmented detector designs. The in-system calibration method is evaluated and empirically compared to a state-of-the-art fan-beam calibration for a small-diameter proof of concept (PoC) scanner. A simulation study evaluates the method's applicability to different scanner geometries. A PoC scanner geometry of 120mm inner diameter and 150mm axial extent was set up consisting of five identical finely segmented slab detectors (one detector under test and four collimation detectors). A 2 2Na point source was moved in a circular path inside the FoV. Utilizing virtual collimation and by selecting gamma rays incident approximately perpendicular to the detector normal of the detector under test, training data was created for the training of a 2D positioning model with the machine-learning technique gradient tree boosting (GTB). Data with oblique ray angles was acquired in the same measurement for subsequent angular DOI calibration. For this, a 2D position estimate in the detector under test was calculated first. On this basis, the DOI label was calculated geometrically from the ray path within the detector to finally establish up to 3D training data. With a mean absolute error (MAE) of 0.8 and 1.19mm full-width at half maximum (FWHM) along the planar-monolithic slab dimension, the in-system methods performed similarly within 1% to the fan-beam collimator results. The DOI performance was at ∼90% with 1.13mm MAE and 2.47mm FWHM to the fan-beam collimator. Analytical calculations suggest an improved performance for larger scanner geometries. The functionality of the 3D in-system positioning calibration method was successfully demonstrated with the measurements within a PoC scanner configuration with similar positioning performance as the bench-top fan-beam setup. The in-system calibration method can be used to calibrate and test fully assembled PET systems to enable more complex light-sharing detector architectures in, for example, large PET systems with many detectors. The acquired data can further be used for more complex energy and time calibrations.

Prospective, multi-site evaluation of the Cepheid Xpert Xpress CoV-2 plus test on nasal and nasopharyngeal swabs.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to cause millions of infections and tens of thousands of deaths per year in the United States. While the FDA authorized hundreds of SARS-CoV-2 tests during the public health emergency, significantly fewer have made the transition to being cleared or approved. There continues to be a need for FDA-authorized point-of-care SARS-CoV-2 testing that can be performed by untrained users. We conducted a large prospective study of the Cepheid Xpert Xpress CoV-2 plus test for detection of SARS-CoV-2 in both nasal and nasopharyngeal swabs by trained and untrained users. The assay demonstrated excellent clinical performance characteristics and, as a result of this study, was cleared by the FDA.

Experimental Characterization of a Bladeless Air Compressor

Abstract The Tesla compressor is an innovative technology that offers a unique approach to fluid compression. Unlike traditional compressors that use rotating blades, bladeless compressors utilize closely spaced disks to create compression. The purpose of this article is to design a prototype Tesla air compressor with optimal design parameters and investigate the performance and loss characteristics based on numerical analysis and experimental demonstration. The prototype model has been numerically investigated at different rotational speeds, and the results have been compared with those obtained in experiments. Computational fluid dynamics (CFD) simulations indicate that the rotor-only efficiency is greater than 90% at very low mass flowrates, while the coupling of the rotor and volute leads to a total-to-static efficiency of approximately 58% (without losses) at 14 g/s. At a nominal mass flow of 4 g/s, the highest total-to-static pressure ratio would be around 1.27. Experimental results indicate leakage losses greatly reduce net mass flow, while pressure ratio values are in good agreement with CFD predictions. During this experiment, a maximum isentropic efficiency of 32.4% is measured. Indeed, the prototype included ventilation and leakage losses, which were not modeled in the CFD analysis. It is remarkable that the compressor does not show any unstable behavior down to zero mass flow (closed valve test), where the CFD and the experiment show consistent pressure ratios. An estimation of the losses from end-wall friction and leakage flow is carried out using numerical simulations at different exit radial clearances. Increasing radial clearance results in an increase in leakage and end-wall power loss, the latter being driven mainly by the axial clearance with the casing, which remained unchanged. To minimize leakage, a Teflon ring has been used as a first measure. Numerical calculations have indicated that the leakage rate is approximately 6 g/s at design speed. A brush seal-type solution can improve the sealing system to reduce leakage.

Board Performance of Fisheries Graduates: Logistic Regression Analysis for Curriculum Enhancement

This study investigates the factors affecting the board performance of Bachelor of Science in Fisheries (BSFi) graduates in the fisheries technologists licensure exams in a specific region of the Philippines. The impetus for this research arose from observed variations in exam performance among graduates, prompting an examination of educational and institutional influences on success. The study used a purposive sampling technique to gather data from 138 respondents across State Universities and Colleges (SUCs) who took their first licensure exam from October 2018 to October 2023. A validated online survey questionnaire assessed academic performance, teaching methods, curriculum, faculty qualifications, library resources, laboratory facilities, and student characteristics. Logistic regression analysis was employed to analyze the relationship between these independent variables and licensure exam performance. The findings of this study are of profound importance, as they reveal strong correlations between faculty qualifications and exam outcomes, emphasizing the need for continuous professional development. Moreover, the study identifies improved laboratory facilities and a robust curriculum as critical factors contributing to student success. These insights have the potential to significantly impact stakeholders, informing them about essential areas for intervention and improvement. Ultimately, they aim to elevate the educational experience and licensure performance of BSFi graduates, thus supporting their professional trajectories in the fisheries sector.

Investigation of an Ammonia-Fueled SOFC-mGT Hybrid System: Performances Analysis and Comparison With Natural Gas-Based System

Abstract Hybrid systems (HS) are highly attractive in power generation due to their potential for higher power outputs and efficiencies by integrating different technologies. Among solid oxide fuel cell (SOFC) plants, the SOFC-Micro-Gas Turbine (mGT) system is particularly innovative. In this setup, the SOFC replaces the mGT combustion chamber, with an afterburner completing fuel combustion before the expander. Various configurations and control systems have been explored over the years, and prototypes have demonstrated satisfactory efficiency. However, these systems have predominantly used NG and Biogas, which do not achieve zero carbon emissions. The growing global demand for carbon-free energy production is increasing, highlighting the importance of alternative fuels in the power generation sector: among them, thanks to its chemical and physical properties, ammonia is gaining more and more interest. This work investigates an innovative ammonia-to-power system based on an SOFC-mGT HS, focusing on thermodynamic parameters, system features, and technical and environmental challenges. A MATLAB/Simulink model, built on a validated HS model fueled by NG, was developed to analyze the new system configuration. This configuration replaces the SOFC prereformer with an ammonia cracker, allowing for the exploration of anode gas recirculation effects and optimal system design. Key operating parameters such as anodic recirculation factor, fuel utilization, performance, and gas turbine characteristics are discussed. Finally, a comparison is made between hybrid systems and mGTs powered by methane, biogas, and ammonia.

Conversion of CO2 into Synthetic Motor Fuels

The process of CO2 conversion into synthetic hydrocarbons including the stages of synthesis gas production on the catalyst NIAP 06-06 and hydrocarbon synthesis by the Fischer-Tropsch method on a bifunctional zeolite-containing catalyst has been investigated. Experimental studies of the process of catalytic conversion of CO2 into synthesis gas were carried out in order to obtain gas with the ratio of H2/CO close to the required ratio for Fischer-Tropsch synthesis. The possibility of obtaining gasoline and diesel fractions of hydrocarbons with a high content of isomeric structures that increase the performance characteristics of motor fuels has been shown. The yield of hydrocarbons C5+ with 1 m3 of initial CO2 and H2 at the synthesis temperature of 220 °C is found to be 44.5 g.

First principle atomistic modelling of magnetic tunnel junction (MTJ) to enhance its tunnel magneto-resistance (TMR) ratio

Abstract This paper investigates the impact of electrode materials on the Tunnel Magneto-Resistance (TMR) ratio of Magnetic Tunnel Junction (MTJ) device. Four different structures of MTJ have been simulated by using cobalt (Co), Nickel (Ni), Iron (Fe) and two alloy materials of nickel-iron (NiFe) and cobalt-iron (CoFe). These materials have been used as ferromagnetic electrodes. Mulliken population and transmission spectrum observed in both parallel and antiparallel configurations of these devices to understand the spin transport properties and Tunnel Magneto-Resistance (TMR) ratio has been estimated. The first principal study was performed based on density function theory (DFT) and Non-equilibrium Green’s Function (NEGF) computational methods using the QuantumATK simulation tool to study properties such as band structure, the density of states (DOS), Spin Transfer Torque (STT), I-V characteristics and TMR. This study explores how different electrode materials affect the Tunnel Magneto-Resistance (TMR) ratio in Magnetic Tunnel Junction (MTJ) devices. With these results, it is observed that cobalt-based MTJ devices (that is Co-MgO-Fe and CoFe-MgO-CoFe) exhibit higher TMR ratio as compared to Nickel- and Iron-based MTJ devices (that is NiFe-MgO-NiFe and Ni-MgO-Fe). As Cobalt has a high spin polarization this property makes it suitable for use in spintronics devices like MTJs, where the manipulation of electron spins is essential for data storage and information processing. These findings can be employed to improve the performance characteristics of the MTJ-based Random Access Memory (MRAM) in the field of spintronics.

Benchmarking Big Data Systems: Performance and Decision-Making Implications in Emerging Technologies

Systems for graph processing are a key enabler for insights from large-scale graphs that are critical to many new advanced technologies such as Artificial Intelligence, Internet of Things, and blockchain. In this study, we benchmark another two widely utilized graph processing systems, Apache Spark GraphX and Apache Fink, concerning the key performance criterion by means of response time, scalability, and computational complexity. We demonstrate our results which show the capability of each system for real-world graph applications, and hence, providing a quantitative understanding to select the system for our purpose. GraphX’s strength was in processing batch in-memory workloads typical of blockchain and machine learning model optimization, while Flink excelled in processing stream data, which is timely and important to the IoT world. These performance characteristics emphasize how the capabilities of graph processing systems can match the requirements for the performance of different emerging technology applications. Our findings ultimately inform practitioners about system efficiencies and limitations, but also the recent advances in hardware accelerators and algorithmic improvements aimed at shaping the new graph processing frontier in diverse technology domains.

Evaluation of Guanidinoacetic Acid Supplementation on Finishing Beef Steer Growth Performance, Skeletal Muscle Cellular Response, and Carcass Characteristics.

This study elucidated the effects of dosage-dependent guanidinoacetic acid (GAA) supplementation on growth performance, muscle responses, and carcass characteristics in finishing beef steers. Thirty crossbred Red Angus beef steers (395 ± 28.09kg) were randomly assigned one of three treatments during a 146-day feedlot study: basal diet without GAA supplementation (CONTROL), 1g of GAA per 100kg of BW daily (LOWGAA), and 2g of GAA per 100kg of BW daily (HIGHGAA). Individual feed intake was monitored daily, growth performance parameters were collected every 28 days, and longissimus muscle (LM) biopsies occurred every 56 days. In biopsied LM, greater (P = 0.048) mRNA expression of IGF-1 was observed in LOWGAA steers on d 112 compared to the CONTROL group. LOWGAA steers also exhibited greater expression of myosin heavy chain (MHC) I compared to CONTROL steers (P < 0.05) and MHC IIA compared to both CONTROL and HIGHGAA treatment groups (P < 0.01) on d 112. GAA supplementation resulted in no change in carcass characteristics, serum and LM tissue metabolites, LM composition, and Warner-Bratzler shear force (WBSF) values (P > 0.05). Data collected from this study demonstrate the influence of GAA supplementation on the gene expression of MHC isoforms and their role in skeletal muscle growth, differentiation, and muscle fiber-typing.

A study on the internal vortex structure within a single-blade pump via numerical methods and particle image velocimetry experiments

This study investigates the performance and internal flow characteristics of a single-blade centrifugal pump through a comprehensive analysis integrating performance tests, Particle Image Velocimetry (PIV) tests, and numerical simulations. Across the operational speed range of 1470–2940 rpm, the predicted pump (head-flow rate curve)performance error between the numerical simulation results and the test results of the pump underrated flow conditions is found to be only 3.4%, demonstrating the high accuracy of the selected numerical method in predicting both performance metrics and internal flow structures. Key findings highlight the presence of significant circumferential and axial secondary flows in the region where the blade wraps back, resulting in the formation of high-intensity vortex structures and subsequent energy dissipation. The interaction of the blade's trailing jet with the volute casing's tongue induces periodic changes in the intensity and spatial size of these vortex structures. Furthermore, pronounced reverse vortex pairs are identified within the volute casing, attributed to axial non-uniformity in impeller outflow. These vortex pairs are associated with the preferential accumulation of solid particles, potentially contributing to wear in the volute casing of single-blade centrifugal pumps. The revelation of the evolution characteristics of vortex structure in single-blade centrifugal pumps provides theoretical support for reducing pressure pulsation and radial force of single-blade centrifugal and provides a potential solution to the technical difficulties of low efficiency and poor stability of single-blade centrifugal pumps. Overall, this study provides valuable insights into optimizing the design and operational efficiency of single-blade centrifugal pumps by elucidating their complex flow dynamics and performance characteristics under varying operational conditions.

Towards improving the characteristics of high-energy pyrazines and their N-oxides.

Based on the methods of quantum chemistry and atom-atom potentials, the molecular and crystal structure of a number of high-energy pyrazines was modeled: unsubstituted diazines, as well as fully nitrated 1,4-diazabenzenes, their oxides and polymorphs. The enthalpies of formation, densities of molecular crystals, and some performance characteristics of these compounds were determined. The parameters of decomposition of substances were estimated. It has been established that tetranitropyrazine-1,4-dioxide has maximum energy content and excellent performance characteristics, which determine the prospects for using this compound as a high-energy one in the considered series of compounds. In this work, DFT calculations were conducted through the software Gaussian 09 using B3LYP functional with basis set aug-cc-PVDZ and the Grimme dispersion correction D2. For crystal structure optimization, the atom-atom potential methods with PMC program (Packing of Molecules in Crystal) were used. Charges for molecular electrostatic potential were fitted by FitMEP and enthalpies of formation in gas phase were assessed by G3B3.

Monitoring the Wake of Low Reynolds Number Airfoils for Their Aerodynamic Loads Assessment

Experimental investigations are carried out to explore the aerodynamic performance and vortex shedding characteristics of S5010 and E214 airfoil-based wings to provide guidance for the design of MAVs and other low-speed vehicles. Force and wake shedding frequency measurements are carried out in a subsonic wind tunnel in the Reynolds number (Re) range of 4 × 104 - 1 × 105. The measurements with increasing Re show that the slope of the lift curve in the linear region increases by 14% for S5010, while this increment is 11% for E214. The peak lift coefficient of both airfoils reduces with reducing Re. For lower pitch angles, the influence of Re on drag coefficients is less significant, but at higher angles, the drag increases as the Re drops. Unlike pre-stall mountings, the pitch-down propensity of the airfoil enhances in the post-stall region for high Re flows. Moreover, the frequency of shed vortices reduces with rising angle of attack at a given Re. In contrast, the Strouhal number almost remains constant with varying Re at a fixed angle of attack. For S5010 and E214 airfoils, the Strouhal number is noticed to vary between 0.68 - 0.36 and 0.58 - 0.36, respectively, for pitch angle variation of 12°- 28°. The airfoils show a higher Strouhal number than the bluff body wakes, but this difference decreases for high angles of attack mountings. This finding reveals that the wake structure of the airfoil at a high post-stall angle behaves as bluff body wakes.

Experimental investigation on diesel engine performance and emission characteristics using waste cooking oil blended with diesel as biodiesel fuel

Biodiesel production from waste cooking oil is a potential feedstock to alternative fuel sources. Produced alternative fuel sources were to have a strong emphasis on energy efficiency to substitute the declining world supply of fossil fuels while also improving emission characteristics in diesel engine applications. The development of industrialization and mechanization causes increased fossil fuel consumption and its usage. This study aimed at an experimental investigation of biodiesel blended fuel combustion efficiency for single-cylinder diesel engines under varying engine loads at constant engine speed 1500 rpm. The transesterification process was used to produce biodiesel from waste cooking oil using NaOH as catalysts. Biodiesel reaction takes place with oil to methanol ratio of 6:1 at 60 °C reaction temperature for 90 min with 600 rpm stirring speed while 90% yield gained. Eight sample biodiesel blends were prepared with percentage value B5%, B10%, B15%, B20%, B25%, B30%, B35%, B40% v/v and B100% to investigate the effect of biodiesels on engine performances. The experimental result reveals that the mixed biodiesel blends have lower average value in terms of brake torque, brake power, and brake thermal efficiency than diesel fuels as a percentage of 16.79%, 4.08%, and 27.9% respectively. In addition, the average BSFC of biodiesel blends was increased by 4.8% than baseline diesel fuel. Related to exhaust gases emission test results were shows that the average CO and HC emissions decreased by 52.2% and 60% with increasing loads and blends and the increment of CO2 and NOx by 28.1% and 45.4% respectively than baseline fuel with increasing blends and loads. Biodiesel derived from waste cooking oil was less costly and environmentally friendly and viable to substitute petro-diesel.

Tensor based approach for tooth contact analysis of planar and spatial gearing contact

This paper presents a new method for analyzing gear tooth contact, leveraging tensor notation and discrete differential geometry. Existing analytical and numerical methods often face challenges in convergence and computational efficiency. Our proposed approach involves defining a novel tensor notation and applying it to the gear tooth contact kinematics problem. By discretizing the tooth surfaces and using tensor operations, we can accurately determine the kinematics, path of contact, and transmission error of the gear pair. To validate our approach, we compared its results with those obtained from commercial software, KISSsoft and KiMOS. The results demonstrated high accuracy, with mean absolute errors below 0.08 for specific sliding, 0.003 for sliding factor, and 0.1μm for transmission error. Furthermore, we applied our method to analyze non-involute gear types, such as S-gears, pin gearing and cosine gears. Our findings revealed the kinematic performance and contact characteristics of these gear types, providing valuable insights for gear design and optimization. In conclusion, the proposed tensor-based approach offers a promising alternative for gear tooth contact analysis, providing accurate and efficient results for a wide range of gear types.

A Nonaxial-Type Swirling Cavitating Nozzle for Exploiting Natural Gas Hydrate

Summary Natural gas hydrates (NGHs) have garnered widespread attention in the new energy sector, owing to their efficient and clean combustion properties. NGHs are ice-like substances formed by methane and water under high-pressure and low-temperature conditions, abundantly deposited in seabeds and frozen soil of highlands on Earth. However, the rock shelves of NGH reservoirs are mostly fragile and sparsely colloidal. Traditional mechanical mining methods can easily cause rock-shelf collapses, leading to mining accidents. Long-term indoor experiments and pilot mining projects have shown that cavitating nozzles can provide a feasible solution to the problem of efficient mining of NGHs. To further improve the efficiency of cavitating nozzle mining for NGHs, we have optimized and designed a nonaxial-type swirling cavitating nozzle (NASCN) based on traditional swirling cavitating nozzles (SCNs). Both numerical simulations and indoor experiments have verified the higher mining performance of this nozzle. In the numerical simulation experiments, we analyzed the cavitation performance, erosion performance, and energy consumption characteristics of different cavitating nozzles using the mixture multiphase flow model and the renormalization group (RNG) k-ε turbulence model. In the indoor experiments, we utilized a jet erosion experimental device for NGHs to analyze the erosion effects of different cavitating nozzles on hydrate samples. The results of these experiments indicate that the NASCN reduces energy consumption by 12% compared with traditional nozzles when there is little difference in cavitation performance and erosion performance. Moreover, under similar energy consumption, the NASCN improves erosion efficiency by 35.2% compared with traditional nozzles. These results demonstrate that the NASCN has good application value in the mining engineering of NGHs.

Influence of laminated porous cathode structure on the performance and mass transfer of Li[sbnd]O2 batteries

The porous cathode is a crucial component of LiO2 batteries, and its porous structure significantly impacts the battery's performance. In this study, a stacked porous cathode was fabricated via roller pressing. The influence of the cathode structure on the battery performance and mass transfer characteristics were examined using experimental and simulation methods. The structural characteristics, electrochemical properties, and overall battery performance of the stacked porous cathode were analyzed. Furthermore, the effects of the cathode structure on mass transfer within the cathode and battery performance were explored through numerical simulation. The results indicate that when the mass ratio of CNTs to ACET on the diaphragm side is 5:1, the cathode exhibits optimal structural parameters, with an average pore size of 24 nm and a maximum pore volume of 0.85564 cm3/g. Concurrently, the battery demonstrates an exceptionally high area specific capacity of 30.35 mAh/cm2. Integrating the simulation findings, it was observed that adjusting the structural parameters of the cathode enhances material transfer efficiency, thereby improving battery performance.