Fault Tree Analysis of Dust Suppression Mechanism in a Spray System with Wetting Agent

By using the fault tree analysis in reliability theory as the systematical analysis approach, the dust suppression mechanism in a spray system with wetting agent is shown in a logic tree and some graphical models. From these diagrams, all factors related to the spray system and their cause and effect relationship can be seen clearly. Based on the built logic tree, several mathematical models and new ideas for expressing the dust suppressing efficiency in the spray system are put forward. The significance of all factors related to the efficiency of suppressing dust is qualitatively described. Furthermore, the new concepts, such as, the effective reaction time between dust particle and droplet, the expansion phenomenon of laden dust droplet, the functions of volatile and the relative size distribution efficiency of wetting agent are presented. All this richenes the existing mechanism of dust abatement by spraying wetting agent. At last, several problems that need to be further investigated are also suggested in the paper.

Modeling and Experiments of Spray System for Cable Painting Robot

Many cable-stayed bridges have been built in the world in the past decades,and cable-stayed structures have been adopted in many large constructions.The cable painting robot is safe and economically efficient for stay cable maintenance.In order to satisfy the need for spraying cables in high attitude,an automatic cable spray system for cable painting robots is presented in this paper.Using the β distribution,paint thickness distribution on a cylinder surface is modeled.The spray gun's number,angle and movement are analyzed to get coat evenness.Then a robotic spray system engineering prototype has been developed,which includes a cable electric running climbing base,a spray cover,four airless spray guns and a pressurized paint container.Experiments indicate that four airless spray guns can guarantee good coat quality for general stay cables.The field tests have been successfully conducted on Nanpu Bridge,Shanghai.

Experimental investigation on effective aerosol scavenging using different spray configurations with pre-injection of water mist for Fukushima Daiichi decommissioning

During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting methods.During the cutting process,aerosol particles are expected to be generated at the submicron scale.It has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying methods.Therefore,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays.In this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist.The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist.The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.

Spray Characteristics of Non-Circular Nozzle in Air-Assisted Injection System

In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-0.6 MPa and the spray volume of 1000-5000 mL/h. Elliptical nozzle and triangular nozzle are classified as non-circular geometries. The spray cone angle was measured by processing the spray image captured by a CCD camera. The measured spray cone angles of the circular nozzles were analyzed, and the axis switching phenomenon of minor plane of elliptical nozzle was found during the test. Among the three shapes of nozzles, the elliptical nozzle had the largest spray cone angle, and the triangular nozzle had the smallest. The velocity field obtained depended on the PIV system. The results show that for axial velocity, elliptical orifice spray has greater kinetic energy and smaller droplet size under the same working parameters. Compared with the circular and elliptical nozzles, triangular orifice reached maximum spray velocity the fastest, but its velocity decay was the fastest. For radial velocity, away from the axis, the spray velocity of the elliptical orifice was less affected by the injection parameters, and the velocity was less than that of circular orifice and triangle orifice. Increasing air pressure will weaken radial propagation. The increase of liquid spraying rate had no remarkable effect on the increase of spraying rate. The results of particle size analysis show that the particle size of the non-circular orifice is reduced compared with that of the circular orifice, which promotes the breakup of droplets to a certain extent and enhances the atomization effect.

Spray pyrolysis feasibility of tungsten substitution for cobalt in nickel-rich cathode materials

Cobalt(Co)serves as a stabilizer in the lattice structure of high-capacity nickel(Ni)-rich cathode materials.However,its high cost and toxicity still limit its development.In general,it is possible to perform transition metal substitution to reduce the Co content.However,the traditional coprecipitation method cannot satisfy the requirements of multielement coprecipitation and uniform distribution of elements due to the differences between element concentration and deposition rate.In this work,spray pyrolysis was used to prepare LiNi_(0.9)Co_(0.1-x)W_(x)O_(2)(LNCW).In this regard,the pyrolysis behavior of ammonium metatungstate was analyzed,together with the substitu-tion of W for Co.With the possibility of spray pyrolysis,the Ni-Co-W-containing oxide precursor presents a homogeneous distribution of metal elements,which is beneficial for the uniform substitution of W in the final materials.It was observed that with W substitution,the size of primary particles decreased from 338.06 to 71.76 nm,and cation disordering was as low as 3.34%.As a consequence,the pre-pared LNCW exhibited significantly improved electrochemical performance.Under optimal conditions,the lithium-ion battery assembled with LiNi_(0.9)Co_(0.0925)W_(0.0075)O_(2)(LNCW-0.75mol%)had an improved capacity retention of 82.7%after 200 cycles,which provides insight in-to the development of Ni-rich low-Co materials.This work presents that W can compensate for the loss caused by Co deficiency to a cer-tain extent.

HVOF-sprayed HAp/S53P4 BG composite coatings on an AZ31 alloy for potential applications in temporary implants

Bioactive thermal spray coatings produced via high-velocity oxygen fuel spray(HVOF)from hydroxyapatite(HAp)and bioactive glasses(BG)have the potential to be employed on temporary implants due to the ability of both HAp and BG to dissolve and promote osseointegration,considering that both phases have different reaction and dissolution rates under in-vitro conditions.In the present work,75%wt.HAp-25%wt.S53P4 bioactive glass powders were HVOF-sprayed to obtain HAp/S53P4 BG composite coatings on a bioresorbable AZ31 alloy.The study is focused on exploring the effect of the stand-off distance and fuel/oxygen ratio variation as HVOF parameters to obtain stable structural coatings and to establish their effect on the phases and microstructure produced in those coatings.Different characterization techniques,such as scanning electron microscopy,X-ray diffraction,and Fourier transform infrared spectroscopy,were employed to characterize relevant structural and microstructural properties of the composite coatings.The results showed that thermal gradients during coating deposition must be managed to avoid delamination due to the high temperature achieved(max 550℃)and the differences in coefficients of thermal expansion.It was also found that both spraying distance and oxygen/fuel ratio allowed to keep the hydroxyapatite as the main phase in the coatings.In addition,in-vitro electrochemical studies were performed on the obtained HAp/S53P4 BG composite coatings and compared against the uncoated AZ31 alloy.The results showed a significant decrease in hydrogen evolution(at least 98%)when the bioactive coating was applied on the Mg alloy during evaluation in simulated body fluid(SBF).

Effect of cold rolling deformation on microstructure evolution and mechanical properties of spray formed Al−Zn−Mg−Cu−Cr alloys

The impact of cold rolling deformation,which was introduced after solid solution and before aging treatment,on microstructure evolution and mechanical properties of the as-extruded spray formed Al−9.8Zn−2.3Mg−1.73Cu−0.13Cr(wt.%)alloy,was investigated.SEM,TEM,and EBSD were used to analyze the microstructures,and tensile tests were conducted to assess mechanical properties.The results indicate that the D1-T6 sample,subjected to 25%cold rolling deformation,exhibits finer grains(3.35μm)compared to the D0-T6 sample(grain size of 4.23μm)without cold rolling.Cold rolling refines the grains that grow in solution treatment.Due to the combined effects of finer and more dispersed precipitates,higher dislocation density and smaller grains,the yield strength and ultimate tensile strength of the D1-T6 sample can reach 663 and 737 MPa,respectively.In comparison to the as-extruded and D0-T6 samples,the yield strength of the D1-T6 sample increases by 415 and 92 MPa,respectively.

Simulation Study on the Heat Transfer Characteristics of a Spray-Cooled Single-Pipe Cooling Tower

The current study focuses on spray cooling applied to the heat exchange components of a cooling tower.An optimization of such processes is attempted by assessing different spray flow rates and droplet sizes.For simplicity,the heat exchanger of the cooling tower is modeled as a horizontal round tube and a cooling tower spray cooling model is developed accordingly using a computational fluid dynamics(CFD)software.The study examines the influence of varying spray flow rates and droplet sizes on the heat flow intensity between the liquid layer on the surface of the cylindrical tube and the surrounding air,taking into account the number of nozzles.It is observed that on increasing the spray flow strength,the heat flow intensity and extent of the liquid film in the system are enhanced accordingly.Moreover,the magnitude of droplet size significantly impacts heat transfer.A larger droplet size decreases evaporation in the air and enhances the deposition of droplets on the round tube.This facilitates the creation of the liquid film and enhances the passage of heat between the liquid film and air.Increasing the number of nozzles,while maintaining a constant spray flow rate,results in a decrease in the flow rate of each individual nozzle.This decrease is not favorable in terms of heat transfer.

Investigation of the Film Formation in Dynamic Air Spray Painting

To accurately predict the film thickness distribution during dynamic spraying performed with air guns and support accordingly the development of intelligent spray painting,the spray problem was analyzed numerically.In particular,the Eulerian-Eulerian approach was employed to calculate the paint atomization and film deposition process.Different spray heights,spray angles,spray gun movement speeds,spray trajectory curvature radii,and air pressure values were considered.Numerical simulation results indicate that the angle of spray painting significantly affects the velocity of droplets near the spray surface.With an increase in the spraying angle,spraying height and spray gun movement speed,the maximum film thickness decreases to varying degrees,and the uniformity of the film thickness also continuously worsens.When the spray gun moves along an arc trajectory,at smaller arc radii,the film thickness on the inside of the arc is slightly greater than that on the outside,but the impact on the maximum film thickness is minimal.Increasing air pressure expands the coating coverage area,results in finer atomization of paint droplets,and leads to a thinner and a more uniform paint film.However,if the pressure is too high,it can cause paint splattering.Using the orthogonal experimental method,multiple sets of simulation calculations were conducted,and the combined effects of spraying height,spray angle,and spray gun movement speed on the film thickness distribution were comprehensively analyzed to determine optimal configurations.Finally,the reliability of the numerical simulations was validated through dynamic spray painting experiments.

Effects of plasma spraying process on microstructure and mechanical properties of Cr_(2)AlC/410 composite coatings

To investigate the influences of Cr_(2)AlC mass fraction and supersonic plasma spraying process on the microstructure and mechanical properties of Cr_(2)AlC reinforced 410 stainless steel composite coatings,the coatings containing different mass fractions of Cr_(2)AlC were prepared and investigated.The composite coating exhibited low porosity and high adhesion strength.The addition of Cr_(2)AlC significantly enhanced the hardness of the composite coatings through particle strengthening.However,when the mass fraction of Cr_(2)AlC was 20%,the aggregation of Cr_(2)AlC resulted in a strong decrease in the coating preparation efficiency,as well as a decline in adhesion strength.In the supersonic plasma spraying process,the Ar flow rate mainly influenced the flight velocity of the particles,while the H_(2) flow rate and the current mainly affected the temperature of the plasma torch.Consequently,all of them influenced the melting degree of particles and the quality of the coating.The lowest porosity and the highest hardness and adhesion strength could be obtained when the Ar flow rate is 125 L/min,the H_(2) flow rate is 25 L/min,and the current is 385 A.

Preparation and Properties of Spray Polyurea Elastomer for Aquaculture Foam Floating Balls

[Objectives] This study was conducted to develop a polyurea elastomer which can be sprayed on the surface of expanded polystyrene (EPS) floating balls, so as to improve the surface strength and service life of the floating balls. [Methods] The effects of the types and amounts of isocyanate, chain extenders and polyether polyols on the gelation rate, adhesion and wear resistance of polyurea elastomer were investigated, and it was finally determined the preparation process of polyurea elastomer using liquid isophorone diisocyanate (IPDI) and amino-terminated polyether (D2000) as the main raw materials, dimethylthiotoluene diamine (E300) as the chain extender and silica as the wear resistance modifier through two-step solution polymerization of prepolymerization and chain extension. [Results] The physical properties and chemical resistance tests of spray polyurea elastomer showed that it had good physical properties and acid and alkali resistance, and could meet the requirements of spraying and protection of EPS floating ball surface in marine environment. [Conclusions] Polyurea elastomer coating can improve the aging resistance, wear resistance and acid and alkali resistance of EPS floating balls, and prevent them from being fragile and floating randomly to form marine floating garbage which results in "white pollution".

Effect of Spray Rails on Takeoff Performance of Amphibian Aircraft

Amphibian aircraft have seen a rise in popularity in the recreational and utility sectors due to their ability to take off and land on both land and water, thus serving a myriad of purposes, such as aerobatics, surveillance, and firefighting. Such seaplanes must be aerodynamically and hydrodynamically efficient, particularly during the takeoff phase. Naval architects have long employed innovative techniques to optimize the performance of marine vessels, including incorporating spray rails on hulls. This research paper is dedicated to a comprehensive investigation into the potential utilization of spray rails to enhance the takeoff performance of amphibian aircraft. Several spray rail configurations obtained from naval research were simulated on a bare Seamax M22 amphibian hull to observe an approximate 10% - 25% decrease in water resistance at high speeds alongside a 3% reduction in the takeoff time. This study serves as a motivation to improve the design of the reference airplane hull and a platform for detailed investigations in the future to improve modern amphibian design.

Designing an Experimental Device for Swinging Excitation Spray Cooling

In this paper,we introduce the design principle of the oscillating excited spray cooling experimental device.We then designed an oscillating excited spray cooling experimental device.By using the device,the swaying motion can be realized through the control system,and the motion of the droplet under different vibration frequencies can be observed.By measuring the liquid flow rate and pressure,the changes in liquid flow rate,pressure,and temperature with time under different vibration frequencies were studied.The trajectory of the droplet and the temperature distribution of the droplet under different vibration frequencies could be observed.The device has a simple structure,is easy to control,and can achieve continuous observation of the spray cooling process.

Design of precision variable-rate spray system for unmanned aerial vehicle using automatic control method

In order to reduce the use of chemical pesticides in crop plant protection and improve the utilization efficiency of pesticides,it is necessary to study advanced application machinery and application techniques.The use of unmanned aerial vehicle(UAV)for pesticide spraying has the characteristics of less application,strong penetrability,wide applicability and flexible operation scheduling,and has gradually become one of the important development directions in the field of aviation plant protection.However,the operation process of the UAV is often affected by meteorological factors and human manipulation,resulting in poor actual operation with inaccurate spray volume and uneven application.Therefore,to improve the stability and uniformity of the application of the plant protection UAV under variable operating conditions,in this paper a real-time control method was proposed for the application flow rate,and a precision variable-rate spray system was designed based on single-chip microcomputer and micro diaphragm pump that can controls the flow rate of the pump in real time with the changes of the operating state.The response s-peed of the variable-rate spray system was tested.The average control response time of the system was 0.18 s,and the average stability time of the pump flow change was 0.75 s.The test results showed that the system has a quick response to the working state and the adjustment of the target flow of the pump can be quickly completed to realize the variable-rate spray function.The research results can provide a reference for the practical application of plant protection UAV variable-rate spray system.

Development of Energy-storing High Pressure Spray Cooling System

The greenhouse has been increasingly used in the breeding industry. However, the high temperature inside the greenhouse in summer has not been effectively addressed. The spray cooling system sprays tiny droplets into the air. Thus the water molecules will be vaporized, absorbing heat and reducing ambient temperature. It is the only cooling method that can be used to cool the uneasily-sealed flexible greenhouse. We developed an energy-storing high pressure spray cooling system. The ordinary water pump is used as the source of high-pressure water. The partial kinetic energy is stored in the energy-storing tubes. When the water pump is stopped, the energy produced by releasing the compressed air can still be used to maintain the spray. And thus the use-cost and systematic wear would be reduced. The cooling system only requires 1 kilowatt hour of power per day. It has been widely used in summer to cool the breeding sheds. After a recent continuous improvement, its functions have been extended to disinfection, removing dust, humidifying and immunizing animals. In addition, it can also be used for the cooling and humidifying of squares, venues and streets in summer. The energy-storing high pressure spray cooling system has a broad application prospect.

An Investigation of the Effects of Wave State and Sea Spray on an Idealized Typhoon Using an Air-Sea Coupled Modeling System

In this study, the impact of atmospherewave coupling on typhoon intensity was investigated using numerical simulations of an idealized typhoon in a coupled atmospherewaveocean modeling system. The coupling between atmosphere and sea surface waves considered the effects of wave state and sea sprays on airsea momentum flux, the atmospheric lowlevel dissipative heating, and the wavestateaffected sea spray heat flux. Several experiments were conducted to examine the impacts of wave state, sea sprays, and dissipative heating on an idealized typhoon system. Results show that considering the wave state and seasprayaffected seasurface roughness reduces typhoon intensity, while including dissipative heating intensifies the typhoon system. Taking into account sea spray heat flux also strengthens the typhoon system with increasing maximum wind speed and significant wave height. The overall impact of atmospherewave coupling makes a positive contribution to the intensification of the idealized typhoon system. The minimum central pressure simulated by the coupled atmospherewave experiment was 16.4 hPa deeper than that of the control run, and the maximum wind speed and significant wave height increased by 31% and 4%, respectively. Meanwhile, within the area beneath the typhoon center, the average total upward airsea heat flux increased by 22%, and the averaged latent heat flux increased more significantly by 31% compared to the uncoupled run.

Fuel Spray Dynamic Characteristics of GDI High Pressure Injection System

In order to improve the fuel consumption and exhaust emission for gasoline engines,gasoline direct injection（GDI） system is spotlighted to solve these requirements.Thus,many researchers focus on the investigation of spray characteristics and the fuel formation of GDI injector.This paper presents a complete numerical and experimental characterization of transient gasoline spray from a high pressure injection system equipped with a modern single-hole electric controlled injector in a pressurized constant volume vessel.The numerical analysis is carried out in a one-dimensional model of fuel injection system which is developed in the AVL HYDSIM environment.The experimental analyses are implemented through a self-developed injection rate measurement device and spray evolution visualization system.The experimental results of injection rate and spray dynamics are taken to tune and validate the built model.The visualization system synchronize a high speed CMOS camera to obtain the spray structure,moreover,the captured images are taken to validate the injector needle lift process which is simulated in the model.The reliability of the built model is demonstrated by comparing the numerical results with the experimental data.The formed vortex structure at 0.8 ms is effectively disintegrated at 6.2 ms and the spray dynamics become rather chaotic.The fuel flow characteristics within injector nozzle extremely influence the subsequent spray evolution,and therefore this point should be reconsidered when building hybrid breakup GDI spray model.The spray tip speed reach the maximum at 1.18 ms regardless of the operation conditions and this is only determined by the injector itself.Furthermore,an empirical equation for the spray tip penetration is obtained and good agreement with the measured results is reached at a certain extent.This paper provides a methodology for the investigation of spray behavior and fuel distribution of GDI engine design.

Sprayed separation membranes: A systematic review and prospective opportunities

Membrane separation technology has been taken up for use in diverse applications such as water treatment,pharmaceutical,petroleum,and energy-related industries.Compared with the design of membrane materials,the innovation of membrane preparation technique is more urgent for the development of membrane separation technology,because it not only affects physicochemical properties and separation performance of the fabricated membranes,but also determines their potential in industrialized application.Among the various membrane preparation methods,spray technique has recently gained increasing attention because of its low cost,rapidity,scalability,minimum of environmental burden,and viability for nearly unlimited range of materials.In this Review article,we summarized and discussed the recent developments in separation membranes using the spray technique,including the fundamentals,important features and applications.The present challenges and future considerations have been touched to provide inspired insights for developing the sprayed separation membranes.

Phase Transition in Superconducting Thin Films of Tl System Employing a One-Zone Furnace and Deposited by Spray Pyrolysis

A study of the phase transitions in superconducting thin films of the Thallium-Barium-Calcium-Copper (TBCCO) system is carried out. In particular, it was got the Tl-1223 phase. For this purpose, and using the ultrasonic spray pyrolysis technique, Barium-Calcium-Copper precursor films were first obtained. Upon deposition of the precursor films, and as a second step, they were thallium (Tl) diffused in the one-zone furnace at 860°C. This methodology resulted in superconducting films that showed a phase transition as follows: Tl-2223 → Tl-2223 + Tl-2212 → Tl-2212 → Tl-1223, achieved between 2 and 7 hours of thallium diffusion. The evidence of the phase transitions was corroborated by the experimental results of X-ray diffraction, energy dispersive spectroscopy and resistance-temperature measurements.

Influence of Spray Gun Position and Orientation on Liquid Film Development along a Cylindrical Surface

A method combining computationalfluid dynamics(CFD)and an analytical approach is proposed to develop a prediction model for the variable thickness of the spray-induced liquidfilm along the surface of a cylindrical workpiece.The numerical method relies on an Eulerian-Eulerian technique.Different cylinder diameters and positions and inclinations of the spray gun are considered and useful correlations for the thickness of the liquidfilm and its distribution are determined using various datafitting algorithms.Finally,the reliability of the pro-posed method is verified by means of experimental tests where the robot posture is changed.The provided cor-relation are intended to support the optimization of spray-based coating applications.