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Search Results (815)

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Keywords = spraying pressure

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28 pages, 2057 KiB  
Article
Design and Fabrication of a Cost-Effective, Remote-Controlled, Variable-Rate Sprayer Mounted on an Autonomous Tractor, Specifically Integrating Multiple Advanced Technologies for Application in Sugarcane Fields
by Pongpith Tuenpusa, Kiattisak Sangpradit, Mano Suwannakam, Jaturong Langkapin, Alongklod Tanomtong and Grianggai Samseemoung
AgriEngineering 2025, 7(8), 249; https://doi.org/10.3390/agriengineering7080249 - 5 Aug 2025
Abstract
The integration of a real-time image processing system using multiple webcams with a variable rate spraying system mounted on the back of an unmanned tractor presents an effective solution to the labor shortage in agriculture. This research aims to design and fabricate a [...] Read more.
The integration of a real-time image processing system using multiple webcams with a variable rate spraying system mounted on the back of an unmanned tractor presents an effective solution to the labor shortage in agriculture. This research aims to design and fabricate a low-cost, variable-rate, remote-controlled sprayer specifically for use in sugarcane fields. The primary method involves the modification of a 15-horsepower tractor, which will be equipped with a remote-control system to manage both the driving and steering functions. A foldable remote-controlled spraying arm is installed at the rear of the unmanned tractor. The system operates by using a webcam mounted on the spraying arm to capture high-angle images above the sugarcane canopy. These images are recorded and processed, and the data is relayed to the spraying control system. As a result, chemicals can be sprayed on the sugarcane accurately and efficiently based on the insights gained from image processing. Tests were conducted at various nozzle heights of 0.25 m, 0.5 m, and 0.75 m. The average system efficiency was found to be 85.30% at a pressure of 1 bar, with a chemical spraying rate of 36 L per hour and a working capacity of 0.975 hectares per hour. The energy consumption recorded was 0.161 kWh, while fuel consumption was measured at 6.807 L per hour. In conclusion, the development of the remote-controlled variable rate sprayer mounted on an unmanned tractor enables immediate and precise chemical application through remote control. This results in high-precision spraying and uniform distribution, ultimately leading to cost savings, particularly by allowing for adjustments in nozzle height from a minimum of 0.25 m to a maximum of 0.75 m from the target. Full article
(This article belongs to the Special Issue Implementation of Artificial Intelligence in Agriculture)
15 pages, 2015 KiB  
Article
Optimization of Dust Spray Parameters for Simulated LiDAR Sensor Contamination in Autonomous Vehicles Using a Face-Centered Composite Design
by Sungho Son, Hyunmi Lee, Jiwoong Yang, Jungki Lee, Jeongah Jang, Charyung Kim, Joonho Jun, Hyungwon Park, Sunyoung Park and Woongsu Lee
Appl. Sci. 2025, 15(15), 8651; https://doi.org/10.3390/app15158651 (registering DOI) - 5 Aug 2025
Abstract
Light detection and ranging (LiDAR) provides three-dimensional environmental information that is critical for maintaining the safety and reliability of autonomous driving systems. However, dust accumulation on the LiDAR window can cause detection errors and degrade performance. This study determined the optimal spray conditions [...] Read more.
Light detection and ranging (LiDAR) provides three-dimensional environmental information that is critical for maintaining the safety and reliability of autonomous driving systems. However, dust accumulation on the LiDAR window can cause detection errors and degrade performance. This study determined the optimal spray conditions for accumulating dust to evaluate LiDAR sensor cleaning performance. A primary optimization experiment using spray pressure, spray speed, spray distance, and the number of sprays as variables showed that spray pressure and number of sprays had the most significant influence on the kinetic energy and distribution of dust particles. Notably, the interaction between spray distance and number of sprays—related to curvature effects—was identified as a key variable increasing process sensitivity. A supplementary experiment, which added spray angle as a variable, indicated that while spray pressure remained the most significant factor, spray angle and number of sprays had an indirect influence through interaction terms. Both experiments used the same response variable (point cloud data) interactions to stepwise analyze particle transfer and spatial diffusion. The resulting optimal conditions offer a standard basis for evaluating LiDAR cleaning performance and may help improve cleaning efficiency and maintenance strategies. Full article
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16 pages, 1659 KiB  
Article
Ricinus communis L. Leaf Extracts as a Sustainable Alternative for Weed Management
by Aline Mazoy Lopes, Lucas Kila Ribeiro, Maurício Ricardo de Melo Cogo, Lucas Mironuk Frescura, Marcelo Barcellos da Rosa, Alex Schulz, Flávio Dias Mayer, Ederson Rossi Abaide, Marcus Vinícius Tres and Giovani Leone Zabot
Sustainability 2025, 17(15), 6942; https://doi.org/10.3390/su17156942 - 30 Jul 2025
Viewed by 181
Abstract
Weeds pose a significant challenge to agricultural productivity, requiring control strategies that are both effective and environmentally sustainable. Therefore, this study evaluated the inhibitory potential of aqueous extracts from Ricinus communis L. leaves to manage the weeds Oryza sativa L. (weedy rice) and [...] Read more.
Weeds pose a significant challenge to agricultural productivity, requiring control strategies that are both effective and environmentally sustainable. Therefore, this study evaluated the inhibitory potential of aqueous extracts from Ricinus communis L. leaves to manage the weeds Oryza sativa L. (weedy rice) and Cyperus ferax. Extracts were obtained through pressurized liquid extraction using water as the solvent. Bioassays were conducted during pre- and post-emergence stages by foliar spraying 15 and 30 days after sowing (DAS). The effect of extraction time (1–30 min) on inhibitory efficacy was also assessed. Chemical profiles of the extracts were characterized using high-performance liquid chromatography. The extracts significantly inhibited seed germination, with suppression rates reaching 92.7%. Plant growth was also diminished, particularly with earlier treatments (at 15 DAS), resulting in reductions of up to 32% and 53% in shoot length, and 69% and 73% in total dry mass for O. sativa L. and C. ferax, respectively. Mortality rates of O. sativa L. and C. ferax reached 64% and 58%, respectively. Phenolic compounds were identified in the extracts, and higher concentrations were observed at shorter extraction times. These findings underscore the potential of R. communis L. leaf extracts as an ecologically sustainable alternative for weed management, providing an effective and natural approach that may reduce reliance on synthetic herbicides and mitigate their environmental impact. Full article
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29 pages, 6486 KiB  
Article
Optimisation of Atomisation Parameters of Gas–Liquid Two-Phase Flow Nozzles and Application to Downhole Dust Reduction
by Jianguo Wang, Xinni He and Shilong Luo
Processes 2025, 13(8), 2396; https://doi.org/10.3390/pr13082396 - 28 Jul 2025
Viewed by 251
Abstract
Considering the serious hazard of respiratory dust in underground coal mines and the low efficiency of traditional dust-reduction technology, this study optimizes the atomisation parameters of the gas–liquid two-phase flow nozzle through numerical simulation and experimental testing, and designs an on-board dust-reduction system. [...] Read more.
Considering the serious hazard of respiratory dust in underground coal mines and the low efficiency of traditional dust-reduction technology, this study optimizes the atomisation parameters of the gas–liquid two-phase flow nozzle through numerical simulation and experimental testing, and designs an on-board dust-reduction system. Based on the Fluent software (version 2023 R2), a flow field model outside the nozzle was established, and the effects of the air supply pressure, gas-phase inlet velocity, and droplet mass flow rate on the atomisation characteristics were analyzed. The results show that increasing the air supply pressure can effectively reduce the droplet particle size and increase the range and atomisation angle, and that the dust-reduction efficiency is significantly improved with the increase in pressure. The dust-reduction efficiency reached 69.3% at 0.6 MPa, which was the economically optimal operating condition. Based on the parameter optimization, this study designed an annular airborne gas–liquid two-phase flow dust-reduction system, and a field test showed that the dust-reduction efficiency of this system could reach up to 86.0%, which is 53.5% higher than that of traditional high-pressure spraying, and that the dust concentration was reduced to less than 6 mg/m3. This study provides an efficient and reliable technical solution for the management of underground coal mine dust and guidance for promoting the development of the coal industry. Full article
(This article belongs to the Section Chemical Processes and Systems)
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31 pages, 5261 KiB  
Review
Wear- and Corrosion-Resistant Coatings for Extreme Environments: Advances, Challenges, and Future Perspectives
by Subin Antony Jose, Zachary Lapierre, Tyler Williams, Colton Hope, Tryon Jardin, Roberto Rodriguez and Pradeep L. Menezes
Coatings 2025, 15(8), 878; https://doi.org/10.3390/coatings15080878 - 26 Jul 2025
Viewed by 716
Abstract
Tribological processes in extreme environments pose serious material challenges, requiring coatings that resist both wear and corrosion. This review summarizes recent advances in protective coatings engineered for extreme environments such as high temperatures, chemically aggressive media, and high-pressure and abrasive domains, as well [...] Read more.
Tribological processes in extreme environments pose serious material challenges, requiring coatings that resist both wear and corrosion. This review summarizes recent advances in protective coatings engineered for extreme environments such as high temperatures, chemically aggressive media, and high-pressure and abrasive domains, as well as cryogenic and space applications. A comprehensive overview of promising coating materials is provided, including ceramic-based coatings, metallic and alloy coatings, and polymer and composite systems, as well as nanostructured and multilayered architectures. These materials are deployed using advanced coating technologies such as thermal spraying (plasma spray, high-velocity oxygen fuel (HVOF), and cold spray), chemical and physical vapor deposition (CVD and PVD), electrochemical methods (electrodeposition), additive manufacturing, and in situ coating approaches. Key degradation mechanisms such as adhesive and abrasive wear, oxidation, hot corrosion, stress corrosion cracking, and tribocorrosion are examined with coating performance. The review also explores application-specific needs in aerospace, marine, energy, biomedical, and mining sectors operating in aggressive physiological environments. Emerging trends in the field are highlighted, including self-healing and smart coatings, environmentally friendly coating technologies, functionally graded and nanostructured coatings, and the integration of machine learning in coating design and optimization. Finally, the review addresses broader considerations such as scalability, cost-effectiveness, long-term durability, maintenance requirements, and environmental regulations. This comprehensive analysis aims to synthesize current knowledge while identifying future directions for innovation in protective coatings for extreme environments. Full article
(This article belongs to the Special Issue Advanced Tribological Coatings: Fabrication and Application)
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12 pages, 828 KiB  
Communication
Enhanced Protein Extraction from Auxenochlorella protothecoides Through Synergistic Mechanical Cell Disruption and Alkaline Solubilization
by Jun Wei Ng, Sze Ying Lee, Tong Mei Teh, Melanie Weingarten and Md. Mahabubur Rahman Talukder
Foods 2025, 14(15), 2597; https://doi.org/10.3390/foods14152597 - 24 Jul 2025
Viewed by 229
Abstract
Microalgae proteins are increasingly recognized in the food and nutraceutical industries for their functional versatility and high nutritional value. Mild alkaline treatment is commonly used for cell wall degradation and intracellular protein solubilization, consequently enhancing the protein extraction yield. The findings of this [...] Read more.
Microalgae proteins are increasingly recognized in the food and nutraceutical industries for their functional versatility and high nutritional value. Mild alkaline treatment is commonly used for cell wall degradation and intracellular protein solubilization, consequently enhancing the protein extraction yield. The findings of this study reveal that alkaline treatment alone, even at higher NaOH concentration (up to 0.3 M) and treatment time (up to 90 min), was ineffective (max. 2.4% yield) for the extraction of protein from Auxenochlorella protothecoides biomass. This challenge was significantly reduced through synergistic application of mechanical cell disruption using high-pressure homogenization (HPH) and alkaline solubilization. Single-pass HPH (35 k psi) alone without alkaline treatment led to 52.3% protein solubilization from wet biomass directly harvested from culture broth, while it was only 18.5% for spray-dried biomass. The combined effect of HPH and alkaline (0.1 M NaOH) treatment significantly increased protein extraction yield to 68.0% for a spray-dried biomass loading of 50 g L−1. Through replacing spray-dried biomass with wet biomass, the requirement of NaOH was reduced by 5-fold to 0.02 M to achieve a similar yield of 68.1%. The process integration of HPH with the mild alkaline solubilization and utilization of wet biomass from culture broth showed high potential for industrialization of microalgae protein extraction. This method achieves high extraction yield while reducing alkaline waste and eliminating the need for energy-consuming drying of biomass, thereby minimizing the environmental impact. Full article
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16 pages, 4298 KiB  
Article
Investigation of Flame Structure and PAHs’ Evolution in a Swirl-Stabilized Spray Flame at Elevated Pressure
by Wenyu Wang, Runfan Zhu, Siyu Liu, Yong He, Wubin Weng, Shixing Wang, William L. Roberts and Zhihua Wang
Energies 2025, 18(15), 3923; https://doi.org/10.3390/en18153923 - 23 Jul 2025
Viewed by 282
Abstract
Swirl spray combustion has attracted significant attention due to its common usage in gas turbines. However, the high pressure in many practical applications remains a major obstacle to the deep understanding of flame stability and pollutant formation. To address this concern, this study [...] Read more.
Swirl spray combustion has attracted significant attention due to its common usage in gas turbines. However, the high pressure in many practical applications remains a major obstacle to the deep understanding of flame stability and pollutant formation. To address this concern, this study investigated a swirl spray flame fueled with n-decane at elevated pressure. Planar laser-induced fluorescence (PLIF) of OH and polycyclic aromatic hydrocarbons (PAHs) were used simultaneously, enabling the distinction of the locations of OH, PAHs, and mixtures of them, providing detailed information on flame structure and evolution of PAHs. The effects of swirl number and ambient pressure on reaction zone characteristics and PAHs’ formation were studied, with the swirl number ranging from 0.30 to 1.18 and the pressure ranging from 1 to 3 bar. The data suggest that the swirl number changes the flame structure from V-shaped to crown-shaped, as observed at both atmospheric and elevated pressures. Additionally, varying swirl numbers lead to the initiation of flame divergence at distinct pressure levels. Moreover, PAHs of different molecular sizes exhibit significant overlap, with larger PAHs able to further extend downstream. The relative concentration of PAH increased with pressure, and the promoting effect of pressure on producing larger PAHs was significant. Full article
(This article belongs to the Special Issue Challenges and Opportunities in the Global Clean Energy Transition)
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24 pages, 4099 KiB  
Article
Dynamic Control of Coating Accumulation Model in Non-Stationary Environment Based on Visual Differential Feedback
by Chengzhi Su, Danyang Yu, Wenyu Song, Huilin Tian, Haifeng Bao, Enguo Wang and Mingzhen Li
Coatings 2025, 15(7), 852; https://doi.org/10.3390/coatings15070852 - 19 Jul 2025
Viewed by 302
Abstract
To address the issue of coating accumulation model failure in unstable environments, this paper proposes a dynamic control method based on visual differential feedback. An image difference model is constructed through online image data modeling and real-time reference image feedback, enabling real-time correction [...] Read more.
To address the issue of coating accumulation model failure in unstable environments, this paper proposes a dynamic control method based on visual differential feedback. An image difference model is constructed through online image data modeling and real-time reference image feedback, enabling real-time correction of the coating accumulation model. Firstly, by combining the Arrhenius equation and the Hagen–Poiseuille equation, it is demonstrated that pressure regulation and temperature changes are equivalent under dataset establishment conditions, thereby reducing data collection costs. Secondly, online paint mist image acquisition and processing technology enables real-time modeling, overcoming the limitations of traditional offline methods. This approach reduces modeling time to less than 4 min, enhancing real-time parameter adjustability. Thirdly, an image difference model employing a CNN + MLP structure, combined with feature fusion and optimization strategies, achieved high prediction accuracy: R2 > 0.999, RMSE < 0.79 kPa, and σe < 0.74 kPa on the test set for paint A; and R2 > 0.997, RMSE < 0.67 kPa, and σe < 0.66 kPa on the test set for aviation paint B. The results show that the model can achieve good dynamic regulation for both types of typical aviation paint used in the experiment: high-viscosity polyurethane enamel (paint A, viscosity 22 s at 25 °C) and epoxy polyamide primer (paint B, viscosity 18 s at 25 °C). In summary, the image difference model can achieve dynamic regulation of the coating accumulation model in unstable environments, ensuring the stability of the coating accumulation model. This technology can be widely applied in industrial spraying scenarios with high requirements for coating uniformity and stability, especially in occasions with significant fluctuations in environmental parameters or complex process conditions, and has important engineering application value. Full article
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17 pages, 3443 KiB  
Article
Influence of Dissipated Energy on the Bonding Strength of Cold-Sprayed Titanium Coatings on Selected Metallic Substrates
by Medard Makrenek
Materials 2025, 18(14), 3355; https://doi.org/10.3390/ma18143355 - 17 Jul 2025
Viewed by 250
Abstract
Modern nanoindentation equipment allows for highly precise measurements of mechanical properties such as hardness and elastic modulus, generating detailed load–unload curves using advanced techniques and specialised software. In this study, titanium coatings were deposited on various metallic substrates using cold gas spraying. Before [...] Read more.
Modern nanoindentation equipment allows for highly precise measurements of mechanical properties such as hardness and elastic modulus, generating detailed load–unload curves using advanced techniques and specialised software. In this study, titanium coatings were deposited on various metallic substrates using cold gas spraying. Before deposition, the spraying parameters (temperature, pressure, velocity, and distance) were statistically optimised using the Taguchi method, reducing the number of experiments required from 81 to 9. This approach allowed the identification of optimal spray conditions (T = 731.0 °C, p = 33.0 bar, V = 343.6 mm/s, d = 35.5 mm), which were then applied to substrates including brass, steel, titanium, Al7075, copper, magnesium, and Al2024. Mechanical characterisation included hardness (H), reduced modulus (E), coating adhesion, and dissipated energy, calculated from the area of the load–unload hysteresis loop. Each coating–substrate combination underwent 36 nanoindentation tests, and adhesion was evaluated by pull-off tests. The initial results showed a poor correlation between adhesion and conventional mechanical properties (χ2 of 17.1 for hardness and 16.2 for modulus, both with R2 < 0.24). In contrast, the dissipated energy showed an excellent correlation with adhesion (χ2 = 0.52, R2 = 0.92), suggesting that dynamic deformation mechanisms better describe bonding. This introduces a new perspective to predict and optimise cold-spray adhesion in industrial applications. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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20 pages, 9695 KiB  
Article
Numerical Investigation on Flow and Thermal Characteristics of Spray Evaporation Process in Boiler Desuperheater
by Jianqing Wang, Baoqing Liu, Bin Du, Kaifei Wu, Qi Lin, Bohai Liu and Minghui Cheng
Energies 2025, 18(14), 3734; https://doi.org/10.3390/en18143734 - 15 Jul 2025
Viewed by 200
Abstract
The spray evaporation process in the boiler desuperheater involves complex droplet behaviors and fluid–thermal coupling, and its temperature distribution characteristics greatly affect the performance and safety of industrial processes. To better understand the process characteristics and develop the optimal desuperheater design, computational fluid [...] Read more.
The spray evaporation process in the boiler desuperheater involves complex droplet behaviors and fluid–thermal coupling, and its temperature distribution characteristics greatly affect the performance and safety of industrial processes. To better understand the process characteristics and develop the optimal desuperheater design, computational fluid dynamics (CFDs) was applied to numerically investigate the flow and thermal characteristics. The Eulerian–Lagrangian approach was used to describe the two-phase flow characteristics. Both primary and secondary droplet breakup, the coupling effect of gas–liquid and stochastic collision and coalescence of droplets were considered in the model. The plain-orifice atomizer model was applied to simulate the atomization process. The numerical model was validated with the plant data. The spray tube structure was found to greatly affect the flow pattern, resulting in the uneven velocity distribution, significant temperature difference, and local reverse flow downstream of the orifices. The velocity and temperature distributions tend to be more uniform due to the complete evaporation and turbulent mixing. Smaller orifices are beneficial for generating smaller-sized droplets, thereby promoting the mass and heat transfer between the steam and droplets. Under the same operating conditions, the desuperheating range of cases with 21, 15, and 9 orifices is 33.7 K, 32.0 K, and 29.8 K, respectively, indicating that the desuperheater with more orifices (i.e., with smaller orifices) shows better desuperheating ability. Additionally, a venturi-type desuperheater was numerically studied and compared with the straight liner case. By contrast, discernible differences in velocity and temperature distribution characteristics can be observed in the venturi case. The desuperheating range of the venturi and straight liner cases is 38.1 K and 35.4 K, respectively. The velocity acceleration through the venturi throat facilitates the droplet breakup and improves mixing, thereby achieving better desuperheating ability and temperature uniformity. Based on the investigation of the spray evaporation process, the complex droplet behaviors and fluid–thermal coupling characteristics in an industrial boiler desuperheater under high temperature and high pressure can be better understood, and effective guidance for the process and design optimizations can be provided. Full article
(This article belongs to the Special Issue Computational Fluid Dynamics (CFD) for Heat Transfer Modeling)
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27 pages, 3720 KiB  
Article
Thermal Management in Multi-Stage Hot Forging: Computational Advances in Contact and Spray-Cooling Modelling
by Gonzalo Veiga-Piñeiro, Elena Martin-Ortega and Salvador Pérez-Betanzos
Materials 2025, 18(14), 3318; https://doi.org/10.3390/ma18143318 - 15 Jul 2025
Viewed by 510
Abstract
Innovative approaches in hot forging, such as the use of floating dies, which aim to minimise burr formation by controlling material flow, require precise management of die geometry distortions. These distortions, primarily caused by thermal gradients, must be tightly controlled to prevent malfunctions [...] Read more.
Innovative approaches in hot forging, such as the use of floating dies, which aim to minimise burr formation by controlling material flow, require precise management of die geometry distortions. These distortions, primarily caused by thermal gradients, must be tightly controlled to prevent malfunctions during production. This study introduces a comprehensive thermal analysis framework that captures the complete forging cycle—from billet transfer and die closure to forging, spray-cooling, and lubrication. Two advanced heat transfer models were developed: a pressure- and lubrication-dependent contact heat transfer model and a spray-cooling model that simulates fluid dispersion over die surfaces. These models were implemented within the finite element software FORGE-NxT to evaluate the thermal behaviour of dies under realistic operating conditions. These two new models, contact and spray-cooling, implemented within a full-cycle thermal simulation and validated with industrial thermal imaging data, represent a novel contribution. The simulation results showed an average temperature deviation of just 5.8%, demonstrating the predictive reliability of this approach. This validated framework enables accurate estimation of thermal fields in the dies, and offers a practical tool for optimising process parameters, reducing burr formation, and extending die life. Moreover, its structure and methodology can be adapted to various hot forging applications where thermal control is critical to ensuring part quality and process efficiency. Full article
(This article belongs to the Special Issue Advanced Computational Methods in Manufacturing Processes)
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18 pages, 7681 KiB  
Article
Microstructure, Phase Components, and Tribological Properties of Al65Cu20Fe15 Quasicrystal Coatings Deposited by HVOF
by Sherzod Kurbanbekov, Tulkinzhon Gaipov, Pulat Saidakhmetov, Alibek Tazhibayev, Sherzod Ramankulov, Sattarbek Bekbayev, Arai Abdimutalip and Dilnoza Baltabayeva
Lubricants 2025, 13(7), 297; https://doi.org/10.3390/lubricants13070297 - 6 Jul 2025
Viewed by 456
Abstract
Quasicrystalline coatings based on Al65Cu20Fe15 are of increasing interest as potential alternatives to conventional wear-resistant materials due to their unique structural and tribological properties. This study explores the influence of air pressure during high-velocity oxy-fuel (HVOF) spraying on [...] Read more.
Quasicrystalline coatings based on Al65Cu20Fe15 are of increasing interest as potential alternatives to conventional wear-resistant materials due to their unique structural and tribological properties. This study explores the influence of air pressure during high-velocity oxy-fuel (HVOF) spraying on the phase composition, morphology, and wear behavior of Al65Cu20Fe15 coatings deposited on U8G tool steel. Coatings were applied at a fixed spraying distance of 350 mm using three air pressures (1.9, 2.1, and 2.3 bar), with constant propane (2.0 bar) and oxygen (2.1 bar) supply. X-ray diffraction analysis identified the formation of Al78Cu48Fe14 and Al0.5Fe1.5 phases, while scanning electron microscopy revealed a dense, uniform microstructure with low porosity and homogeneous element distribution across all samples. Tribological testing using the ball-on-disk method showed wear track widths ranging from 853.47 to 952.50 µm, depending on the air pressure applied. These findings demonstrate that fine-tuning the air pressure during HVOF spraying significantly influences the structural characteristics and wear resistance of the resulting quasicrystalline coatings, highlighting their promise for advanced surface engineering applications. Full article
(This article belongs to the Special Issue Wear and Friction of High-Performance Coatings and Hardened Surfaces)
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23 pages, 4667 KiB  
Article
An Experimental Study on the Charging Effects and Atomization Characteristics of a Two-Stage Induction-Type Electrostatic Spraying System for Aerial Plant Protection
by Yufei Li, Qingda Li, Jun Hu, Changxi Liu, Shengxue Zhao, Wei Zhang and Yafei Wang
Agronomy 2025, 15(7), 1641; https://doi.org/10.3390/agronomy15071641 - 5 Jul 2025
Viewed by 336
Abstract
To address the technical problems of broad droplet size spectrum, insufficient atomization uniformity, and spray drift in plant protection unmanned aerial vehicle (UAV) applications, this study developed a novel two-stage aerial electrostatic spraying device based on the coupled mechanisms of hydraulic atomization and [...] Read more.
To address the technical problems of broad droplet size spectrum, insufficient atomization uniformity, and spray drift in plant protection unmanned aerial vehicle (UAV) applications, this study developed a novel two-stage aerial electrostatic spraying device based on the coupled mechanisms of hydraulic atomization and electrostatic induction, and, through the integration of three-dimensional numerical simulation and additive manufacturing technology, a new two-stage inductive charging device was designed on the basis of the traditional hydrodynamic nozzle structure, and a synergistic optimization study of the charging effect and atomization characteristics was carried out systematically. With the help of a charge ratio detection system and Malvern laser particle sizer, spray pressure (0.25–0.35 MPa), charging voltage (0–16 kV), and spray height (100–1000 mm) were selected as the key parameters, and the interaction mechanism of each parameter on the droplet charge ratio (C/m) and the particle size distribution (Dv50) was analyzed through the Box–Behnken response surface experimental design. The experimental data showed that when the charge voltage was increased to 12 kV, the droplet charge-to-mass ratio reached a peak value of 1.62 mC/kg (p < 0.01), which was 83.6% higher than that of the base condition; the concentration of the particle size distribution of the charged droplets was significantly improved; charged droplets exhibited a 23.6% reduction in Dv50 (p < 0.05) within the 0–200 mm core atomization zone below the nozzle, with the coefficient of variation of volume median diameter decreasing from 28.4% to 16.7%. This study confirms that the two-stage induction structure can effectively break through the charge saturation threshold of traditional electrostatic spraying, which provides a theoretical basis and technical support for the optimal design of electrostatic spraying systems for plant protection UAVs. This technology holds broad application prospects in agricultural settings such as orchards and farmlands. It can significantly enhance the targeted deposition efficiency of pesticides, reducing drift losses and chemical usage, thereby enabling agricultural enterprises to achieve practical economic benefits, including reduced operational costs, improved pest control efficacy, and minimized environmental pollution, while generating environmental benefits. Full article
(This article belongs to the Section Agricultural Biosystem and Biological Engineering)
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24 pages, 19539 KiB  
Article
Effects of Circumferential and Interaction Angles of Hydrogen Jets and Diesel Sprays on Combustion Characteristics in a Hydrogen–Diesel Dual-Fuel CI Engine
by Qiang Zhang, Zhipeng Li, Yang Xu and Xiangrong Li
Sustainability 2025, 17(13), 6059; https://doi.org/10.3390/su17136059 - 2 Jul 2025
Viewed by 318
Abstract
This study investigates the impact of circumferential angle (φ) and interaction angle (θ) between hydrogen jets and diesel sprays in a co-axial hydrogen–diesel injector on combustion and emissions in a hydrogen–diesel dual-fuel engine using 3D CFD simulations. The results demonstrate that a co-axial [...] Read more.
This study investigates the impact of circumferential angle (φ) and interaction angle (θ) between hydrogen jets and diesel sprays in a co-axial hydrogen–diesel injector on combustion and emissions in a hydrogen–diesel dual-fuel engine using 3D CFD simulations. The results demonstrate that a co-axial dual-layer nozzle design significantly enhances combustion performance by leveraging hydrogen jet kinetic energy to accelerate fuel–air mixing. Specifically, a co-axial alignment (φ = 0°) between hydrogen and diesel sprays achieves optimal combustion characteristics, including the highest in-cylinder pressure (20.92 MPa), the earliest ignition timing (−0.3° CA ATDC), and the maximum indicated power of the high-pressure cycle (47.26 kW). However, this configuration also results in elevated emissions, with 29.6% higher NOx and 34.5% higher soot levels compared to a φ = 15° arrangement. To balance efficiency and emissions, an interaction angle of θ = 7.5° proves most effective, further improving combustion efficiency and increasing indicated power to 47.69 kW while reducing residual fuel mass. For applications prioritizing power output, the φ = 0° and θ = 7.5° configuration is recommended, whereas a φ = 15° alignment with a moderate θ (5–7.5°) offers a viable compromise, maintaining over 90% of peak power while substantially lowering NOx and soot emissions. Full article
(This article belongs to the Special Issue Green Shipping and Operational Strategies of Clean Energy)
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22 pages, 13594 KiB  
Article
Numerical Modelling of the Multiphase Flow in an Agricultural Hollow Cone Nozzle
by Paweł Karpiński, Zbigniew Czyż and Stanisław Parafiniuk
Appl. Sci. 2025, 15(13), 7214; https://doi.org/10.3390/app15137214 - 26 Jun 2025
Viewed by 230
Abstract
In the field of agriculture, various types of pesticides are used to control crop pests. These chemical agents are applied using nozzles with different geometries. Regardless of their configuration and operational liquid parameters, the applied liquid jet encounters issues with wind drift and [...] Read more.
In the field of agriculture, various types of pesticides are used to control crop pests. These chemical agents are applied using nozzles with different geometries. Regardless of their configuration and operational liquid parameters, the applied liquid jet encounters issues with wind drift and penetration efficiency. Therefore, it is necessary to optimize the spraying process. In this study, 3D numerical calculations were performed using computational fluid dynamics (CFD). A two-phase flow model based on the volume of fluid (VOF) method was used to simulate the mixing of water and air. The k-ω SST turbulence model was adopted to capture vortex phenomena. A hollow cone nozzle geometry, commonly used in orchards, was selected. Simulations allowed the analysis of pressure, velocity, and turbulence kinetic energy (TKE) in selected cross-sections. Results show that the maximum velocity of the liquid jet at the nozzle outlet exceeded 23 m/s, with the highest TKE reaching 35 m2/s2 in the vortex chamber. The computed spray cone angle was approximately 88°, while the experimental value was 80°, and the simulated mass flow rate differed by 16.7% from the measured reference. The critical flow region was identified between the vortex insert and the ceramic stem, where the highest gradients of pressure and velocity were observed. Full article
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