Spray Conditions Research Articles

A Randomized Controlled Trial Examining the Effect of Topical Refrigerant Spray on the Perception of an Instantaneous Noxious Stimulus

Topical refrigerant spray is commonly used with routine hand injections despite mixed evidence about its efficacy in reducing the pain experience. We hypothesize that the use of topical refrigerant spray decreases the pain experience of an instantaneous noxious stimulus. Eighty adult volunteer participants were enrolled in the study. We constructed an instrument using the smooth end of a Kirschner wire mounted to the spring of a ballpoint pen to apply an instantaneous noxious stimulus to the long (middle) finger proximal nail fold. Participants completed two trials and were randomized to receive the topical refrigerant spray before either the first or second stimulus and on either the left or right side. Participants were asked to rate the pain of each experience using an 11-point Likert scale and indicate which condition they preferred, if any. The mean pain ratings for the spray and no-spray conditions were 2.0 and 4.3, respectively, giving a mean difference of-2.3 (P < .001, α = 0.05). Subgroup analysis showed no significant effect of sex or medical versus nonmedical occupation (P = .28 and .11 respectively) on the mean difference in pain rating between the two conditions. Participants who received the spray first had a higher mean difference in pain rating (2.7) than that in those who received it second (1.9). Fifty-nine participants preferred the spray, whereas 21 participants either preferred no spray or had no preference (P < .0001). The use of topical refrigerant spray significantly decreased the perception of pain from an instantaneous noxious stimulus. A significant majority of participants also preferred the topical refrigerant spray condition. The use of topical refrigerant spray for painful procedures, such as needle insertions, may improve the overall patient experience. Therapeutic I.

Asymmetric Spray Characteristics According to Y-Jet Nozzle Orifice Shape and Spray Conditions.

The Y-jet nozzle is a twin-fluid nozzle that has a larger operating range and simpler structure than other twin-fluid nozzles. Furthermore, it offers outstanding atomization quality even at low flow rates, mak ing it simple to atomize viscous liquids. However, because of the structure of the Y-jet nozzle, having an asymmetrical spray pattern is limited. Most existing experimental studies focused on the orifice diameter and mixing tube length. In this study, two types of elliptical nozzles and one type of circular nozzle were tested. We found that the elliptical nozzle's asymmetric spray characteristics are different from those of the circular type. Furthermore, it was demonstrated that the spray characteristics were different even in ellipsoids, with only the major and minor axes differing.

Particle-based approach for modeling phase change and drop/wall impact at thermal spray conditions

The ability to model the impact of small, high-velocity molten droplets on a cold substrate is a key to designing the thermal spray process. Such drop-wall interactions involve complex phenomena such as droplet splash, phase change, solidification, substrate melting, and re-solidification. In this study, a particle-based approach, Smoothed Particle Hydrodynamics (SPH), is used to simulate the impact of molten droplets on a cold substrate at the thermal spray conditions, i.e., small droplets with high temperature and velocities. A solidification model is developed to simulate the phase change of the droplet and substrate. The present SPH method is validated against the experimental results using tin droplets on stainless-steel and aluminum substrate, and copper droplet on copper substrate. The histories of the spread factor, the substrate temperature, and the splat height at the impingement point are validated. A parametric study on the impact of the high melting point molybdenum droplets on different substrate materials (including tin, stainless steel, zinc, yttrium stabilized zirconia, and aluminum) is performed. The temporal evolution of the solidification interface and the height/thickness of the solidified splat are reported. Temperature distributions across the splat, substrate, and the corresponding melting/re-solidification are investigated. It was found that the cooling rates for the same impingement velocity were nearly the same for the same substrate regardless of the initial substrate temperatures but were higher for higher impingement velocities. A modified Biot number and thermal diffusivity were used to describe the heat transfer characteristics of the splat substrate combination. Results show that a higher modified Biot number for the splat-substrate combination indicates a faster cooling of the splat and a higher maximum substrate temperature. Furthermore, a substrate with high thermal diffusivity also causes heat at the impingement location to be dissipated quickly, resulting in a fast-cooling rate and accelerated solidification.

Investigation of Upgraded Technology for Plasma Spraying of Bronze Powder Using the Combined Process with Hydrocarbon Additions

The object of the research is thermal spray process for the formation of metal coating from bronze powder in plasma-fuel variant, using direct current (DC) electric arc plasma torch, on steel samples. The aim of the work was to investigate and develop the technology for plasma-fuel spraying of functional coatings (for wear-resistant and antimicrobial applications) on machine-building and medical purpose pieces with increased process capacity and moderate energy consumptions in a comparison with conventional thermal spray technologies with use of inert and oxygen-free gas media. During the study, using experimental and thermodynamic estimation methods, the thermal and chemical parameters of the process under the spraying conditions at ambient pressure were characterized, which made it possible to determine the area of preferred regimes of the developed technology. On the modernized testing unit for plasma spraying of metal powders with power of up to 40 kW, operating using a controlled combination of three types of gases – technical nitrogen and propane-butane (LPG) with compressed air, the measurement and optimization of the operating and constructive/assembling parameters of the system for aluminum bronze coating spraying were established. In this case, the experiments were carried out using the designed fuel intensifier, which is joined with the PP-25 arc plasma torch, as well as additional technological equipment (protective shroud). For samples of the resulting coatings with a thickness of 100 to 450 mm from the bronze material, testing of phase composition and some parameters of the resulting coatings on steel products was carried out. Operating capacity of the proposed process reaches 7–15 kg/h for bronze powder when using a moderate power of the torch – up to 35–40 kW and a limited flow rate of hydrocarbon gas (for example, LPG of the SPBT grade) – 0.1–0.35 kg/h. Analysis of the energy efficiency parameters of the developed technology, as well as its calculated technical characteristics, in a comparison with plasma and combined equipment of a similar purpose, showed that it has an advantage in terms of target indicators, in particular, in terms of energy consumption and total energy efficiency of the spraying unit, not less than 20–30 %. This makes it to proceed later to the stage of application of this technology into production based on a new process for the metal coating formation, in particular with antimicrobial properties, with improved energy efficiency of the process.

Critical storage conditions of pequi pulp microparticles and kinetics of degradation of nutritional properties

AbstractThe understanding of water sorption behavior and the determination of glass transition temperature (Tg) is essential in stability studies of dried foods, to determine their best storage or processing condition. Water sorption isotherm and glass transition temperature of spray‐dried pequi pulp microparticles were evaluated to obtain storage critical condition of spray dried pequi pulp, which was 25 °C and 62% of relative humidity (RH). Water sorption isotherm at 25 °C was determined by static gravimetric method, using saturated salt solutions, while Tg by differential scanning calorimetry. Total carotenoids, antioxidant capacity, lipid oxidation, and color parameters were evaluated throughout 120 days at 25 and 35 °C and RH of 23 and 43% to determine the powder kinetic degradation. All quality parameters presented decay during storage. Total carotenoids and antioxidant capacity by ferric reduction antioxidant power method exhibited a second‐order kinetic, while antioxidant capacity by DPPH assay and lipid oxidation a first and zero‐order kinetics, respectively. Both temperature and RH negatively affected nutritional properties. The storage condition that better preserved the desirable characteristics of spray‐dried pequi pulp microparticles was 25 °C and RH of 23%.Practical ApplicationsOne of the greatest challenges for the food industry is to extend food stability against environmental factors. Especially for those food components very unstable such as pigments, antioxidant components, flavor, and so forth. The sample we used for this study was pequi fruit which has high potential in the food industry because of its sensory and nutritional qualities due to the phytochemicals present in the fruit, such as carotenoids and vitamins A and C. However, pequi is highly perishable and generally susceptible to degradation reactions. We successfully applied microencapsulation for pequi pulp protection and showed the environmental conditions that will preserve its functional properties for longer periods. Our results are relevant to extending the bioactive properties of food components.

Microstructural evolution and tribological behavior of suspension plasma sprayed CuO as high-temperature lubricious coatings

Suspension plasma spraying (SPS) was used to produce three different CuO coatings by varying spray distance and solid loading within the suspension. The low spray distance (30 mm) and high solid loading (20 wt%) in the suspension resulted in the deposition of dense coatings as compared to other spray conditions (i.e., a distance of 40 mm and solid loading of 10 wt%). The tribological performance of the dense coating was investigated at 25 °C and 300 °C under dry sliding conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman analysis were used to characterize the coating, and corresponding wear tracks to determine the wear mechanisms. The results showed that the friction coefficient of the CuO coating decreased from 0.7 at 25 °C to 0.46 at 300 °C. Similarly, the wear rate at 300 °C decreased by 50% compared to the wear rate at 25 °C. Ex-situ analysis showed an increased oxygen content on the worn surfaces at 300 °C and the formation of a smooth uniform tribofilm. At 25 °C, a thicker transfer film was observed on the counterface, which leads to a different velocity accommodation mode and, thus, relatively high friction.

Numerical Simulation of Solidification Structures Influenced by Cooling Spraying and Process Parameters Based on Cellular Automaton Finite‐Element Model

A cellular automaton finite‐element coupling model is developed to investigate the influences of the solidification structure of a continuous casting slab by the state of the cooling spray and process conditions. The model is validated. The solidification structure is simulated for different cooling spray schemes, superheat degrees, and casting speeds. The grain growth and distribution of the continuous casting slab near the corner area are sensitive to the cooling spray. As the distance of the nozzle from the surface of the continuous casting slab increases, the radii of the columnar and equiaxed grains tend to increase near the corners. The distribution of a columnar‐to‐equiaxed grain transition near the corner area gradually moves toward the core of the slab as the distance of the nozzle from the continuous casting slab decreases. At a casting speed of 1.2 m min−1 and superheat degree of 20 °C, the best nozzle height from the surface of the continuous casting billet is 234.5 mm. The casting speed and superheat significantly affect the grain radius. With the increase in the casting speed and decrease in the degree of superheat, the average grain radius decreases, while the equiaxed grain area increases.

Experimental and numerical research on flow characteristics of inlet particle separator for aero-engine under the influence of water film

An aero-engine must be able to operate in all-weather conditions, which requires the aircraft to be safe throughout the flight even in bad weather. Excessive intake of rainwater can induce stall and surge of compressor and flameout of combustion chamber, which will lead to the loss of power of the engine. In rainy weather, water come into the engine inlet protection device, which directly determines the compressor inlet conditions and will further affect the compressor working condition and the matching features. In this paper, special attention was paid to the experimental characteristics of aero turbo-shaft engine inlet particle separator (IPS) and the numerical study employing ANSYS-CFX under water spraying condition. Based on the phenomenon of water film forming on the wall surface of the IPS and the experimental data under different water spraying conditions, combined with the predictions from CFD study, an empirical model of water film flow on the wall surface has been developed. The results indicate that in the case of high water ingestion, droplets will inevitably form water film on the wall after entering the IPS. Due to the viscous resistance of wall water film and its influence on the airflow boundary layer, the flow state inside the IPS will change. By establishing a wet wall water film model, the flow characteristics near the wall are closer to the experimental state. The total pressure loss prediction error was reduced from 24.8% to 5.2% and 26.4% to 5.7% under the uniform water spraying rate of 2.93% and 4.84%, respectively.

Advanced diamond-reinforced metal matrix composite (DMMC) coatings via HVAF process: Effect of particle size and nozzle characteristics on tribological properties

High-velocity air fuel (HVAF) spraying is a versatile and cost-effective platform to fabricate wear resistant coatings. In this work, deposition of Nickel–Phosphorus cladded diamond feedstock is explored as a greener alternative to realize highly wear resistant large-area coatings. To the best of authors knowledge. this is the first study that has utilized HVAF technique for developing wear resistant Ni–P coatings reinforced with diamond (NCD). This work also aims to understand the effect of particle size by using coarse (20–30 μm) and fine NCD (10–15 μm) particles as feedstock. The importance of utilizing appropriate processing conditions was also highlighted by using two different nozzle configurations, for which the two powder particle sizes exhibited considerable differences in terms of microstructure, phase characteristics and mechanical properties. Further, the effect of annealing on the above coating characteristics was also examined, and it is shown that optimal spraying conditions can preclude the need for post-treatment. Furthermore, the as-deposited and annealed coatings were subjected to sliding wear tests to assess their tribological performance. Post-wear analysis performed on worn surfaces revealed the associated wear mechanisms. The results ensuing from this work lay the foundation for realizing new generation of HVAF sprayed wear resistant Ni–P/diamond composite coatings for diverse applications.

Singularly narrow size distributions of 200 nm polystyrene latex spheres determined by high resolution mobility analysis

A high-resolution differential mobility analyzer (DMA) is used for the first time to study the mobility distribution of Polystyrene Latex (PSL) particles. We investigate in particular some unique, nominally 200 nm and 100 nm PSL particles, known by other methods to be unusually monodisperse. The suspensions are electrosprayed after adding ammonium acetate to a concentration of 10 mmol/L. Mobility analysis is carried out after charge reduction with a second electrospray of the opposite polarity. The 200 nm particles typically produce two narrow peaks, with relative intensities that depend on electrospray parameters. Under the most favorable spraying conditions achieved, the more mobile peak becomes dominant, is narrowest, and has a repeatable mobility; we attribute it provisionally to the unpolluted suspended particles. The less mobile peaks are substantially more variable but never entirely removed. We initially attributed them to attachment of involatile solutes in the suspension to the atomized PSL particles; however, this hypothesis is put in doubt by later observations. The measured relative width of the mobility distribution for the most mobile peak is FWHMZ = (1.65 ± 0.08) %. This translates into a width for the diameter distribution FWHMd = (1.09 ± 0.05) % or standard deviation σd = (0.46 ± 0.02) %, by far the most monodisperse polymeric submicron particle suspension so far reported. Concentrations of ammonium acetate of 100 mmol/L and 40 mmol/L were also tested in order to reduce residue attachment by forming smaller initial electrosprayed drops. These higher salinities, however, led to capillary clogging, apparently because the narrow electrospraying jet precludes the passage of the PSL particles. The 100 nm particles gave a wider variation in mean diameter and size distribution depending on electrospraying parameters, perhaps because of the suspension's considerably larger content of involatile solutes. Unlike the 200 nm particles, no spraying condition was found under which a precisely repeatable size distribution could be achieved for the 100 nm particles. However, the data do point to an estimated upper bound on the size distribution width of FWHMd ≈ 3 % (σd ≈ 1.3 %), which is uniquely narrow for particles of this size.

Self‐Repairing Coating with Excellent Mechanical Properties by Compatibility Epoxy Resin‐Loaded Polyurea Formaldehyde Microcapsule

Polymer coating is one of the most widely used methods to inhibit metal corrosion. However, the continuous generation and aggregation of microcracks inside the coating eventually lead to cracking or damage at the macro level, which greatly damage the mechanical and protective properties of the coating. Therefore, the polyurea‐formaldehyde microcapsules loaded with epoxy resin repair agent in the resin matrix are mixed and dispersed. When microcracks are generated inside the coating, the extension and expansion of microcracks would cause the microcapsules to rupture, thereby releasing the repair agent. The repair agent fills the microcracks under the siphon effect and then repair the microcracks, thereby restoring its mechanical properties, corrosion resistance, and appearance. The weight fraction of microcapsules on the internal bonding strength and anticorrosive performance of the scratched samples are studied under tensile test and salt spray condition, which reveal the coatings with microcapsules in the range of 15–20 wt%, demonstrate the best performance. It is worth noting that the research provides some theoretical support and practical guidance for the study of metal anticorrosive coatings with self‐healing function.

Influence of Pre-Milling of Cr3C2-25 NiCr Spray Powder on the Fatigue Life of HVOF-Sprayed Coating on ASTM A516 Steel Substrate

The aim of the present investigation is to evaluate the influence of the powder size of Cr3C2-25NiCr spraying powder on the fatigue behavior of HVOF-sprayed coating on the ASTM A516 steel substrate. Conventional commercial Cr3C2-25NiCr spraying powder was previously treated through high-energy milling. The crystallite sizes of milled powders were measured by X-ray diffraction and transmission electronic microscopy. Three different powder formats of the same Cr3C2-25NiCr composite were subjected to HVOF spraying to produce (i) a Milled-Coating (from high-energy milled spray powder), (ii) an Original-Coating (from conventional commercial spray powder), and (iii) a 50%-50% mixture of both (Milled + Original-Coating). The same spraying conditions were adopted for all the assessed cases. The sprayed coatings were investigated through the Knoop hardness test and SEM-EDS analysis. In addition, 3-point bending fatigue tests were conducted at different stress levels up to 107 cycles. The coating morphology and roughness effects on fatigue behavior were analyzed. The Cr3C2-25NiCr milled coating presented a lower fatigue life above the fatigue limit and a higher fatigue limit than other coatings; this outcome could be attributed to its lower surface roughness and finer grain size microstructure.

Skin Application of Menthol Enhances Maximal Isometric Lifting Performance.

Abstract Over, DM, Arjomandkhah, N, Beaumont, JD, Goodall, S, and Barwood, MJ. Skin application of menthol enhances maximal isometric lifting performance. J Strength Cond Res 37(3): 564–573, 2023—Topical application of menthol to the skin improves perception (i.e., makes subjects feel cooler) and changes submaximal neuromuscular recruitment facilitating force generation. We explored the effect of menthol (0.2% concentration; sprayed on the legs), on perception and maximal, dynamic (DLT) and isometric (IMLT) (weight) lifting tasks. Nine resistance-trained male subjects (mean ± SD: 24 ± 5 years; 75.7 ± 8.8 kg; 174 ± 10 cm; 5 repetition maximum deadlift [5RM] 132.3 ± 28.5 kg) were tested using a repeated measures design; we hypothesized that performance would improve. Before completing the DLT (i.e., deadlift performance 75% 1RM) and a midthigh pull dynamometer IMLT, subjects were sprayed with (∼125 ml) of menthol or control spray. Performance, electromyography (root mean squared [rmsEMG], rectus femoris [RF], biceps femoris [BF], and medial gastrocnemius [MG]), perceptions (leg thermal sensation [TSlegs] and comfort [TClegs] and perceived exertion [RPE] and readiness to train), heart rate, and skin temperature were measured. Data were compared using analysis of variance (effect size ) and t test to a 0.05 alpha level supported by Bayesian analysis. Dynamic lifting task performance was unchanged, although BF rmsEMG was higher (i.e., greater muscle activation in final [10th] repetition). Isometric lifting task force production was higher in the menthol spray (148 ± 30 kgf) condition (control spray 140 ± 30 kgf; p = 0.035, = 0.444) with corresponding higher rmsEMG (BF 3.8 ± 1.46 vs. control spray 2.9 ± 0.34 V; p = 0.049, = 0.403). TSlegs was lower after menthol spray before IMLT; subjects felt slightly cool. Menthol spray enhances isometric weightlifting performance with corresponding changes in neuromuscular activity, partially supporting our hypothesis.

Microwave-Osmo-Dehydro-Freezing and Storage of Pineapple Titbits—Quality Advantage

Osmotic dehydration is a pre-treatment given prior to finish drying or freezing preservation to improve quality and/or minimize the damaging effects on quality parameters, by partially reducing the moisture content of the sample. Pineapple titbits were partially dried using microwave assisted osmotic dehydration under continuous flow medium spray condition (MWODS) and then frozen with or without a sodium alginate–calcium chloride-based edible coating. The effects of MWODS pre-treatment and edible coating on the quality parameters of pineapple titbits frozen and stored at −20 °C for 10 and 50 days were evaluated after thawing. Both treatments (MWODS and alginate) resulted in superior quality products as compared to the control sample. MWODS, with its advantages over the conventional osmotic dehydration (COD) of rapid and higher moisture removal (16% in 10 min vs. 4 h in COD), while limiting solids gain (2.5% MWODS vs. 4.5% in COD), resulted in improved quality over the control during the frozen storage. The sodium alginate–calcium chloride edible coating treatment further reduced the drip loss in MW-osmo-dehydro-frozen pineapple titbits, possibly due to the effect of the calcium cross linked firming of the fruit texture. Both resulted in enhanced appearance, color and textural properties.

Droplet Penetration Model Based on Canopy Porosity for Spraying Applications

Analysing the penetration and droplet deposition characteristics in the canopy of fruit trees is critical for optimising the operational parameters of air-assisted spraying equipment, achieving precise application of chemicals, and improving the effectiveness of fruit tree pest and disease control. We used a mobile LIDAR system to detect the tree canopy characteristics and optical porosity and conduct wind tunnel experiments to investigate the interaction between the tree canopy, the airflow field, and the droplet penetration ratio in the canopy of fruit trees. The results show that the relative wind velocity decreases rapidly during canopy penetration, and that the minimum value occurs at the back of the canopy. The smaller the optical porosity, the greater the reduction in wind velocity is. The quadratic exponential regression model had the highest coefficient of determination (R2) (0.9672) and the lowest root mean square error (RMSE) (5.56%). This paper provides information on optimising the spraying parameters, improving the pesticide utilisation rate, and selecting the optimum spraying conditions and application parameters.

Physiological and growth responses of cacao to glyphosate exposure

Herbicide drift phytotoxicity is a problem in plantation crops due to application failures and unfavorable spray conditions. With the increased use of glyphosate in cacao plantations in Ghana, there are concerns about the effect on cacao growth and productivity from doses that potentially could be expected from drift. The aim of this study was to evaluate the physiological and growth response of young cacao plants exposed to glyphosate. Two field experiments were conducted in randomized blocks, with four replications. Glyphosate was applied at rates 0 to 720 g a.e. ha−1. Crop injury, shikimate accumulation, chlorophyll content, quantum efficiency of PSІІ (Fv/Fm), height, and stem diameter were evaluated. Increased glyphosate rates increased crop injury and shikimate accumulation and decreased chlorophyll content, quantum efficiency of PSІІ (Fv/Fm), and plant growth. Glyphosate rates 360 g a.e. ha−1 or higher resulted in >60% foliar injury and more than 10-fold increase in shikimate accumulation. Glyphosate reduced chlorophyll content to <10 and Fv/Fm to <0.35 at the highest rates. Glyphosate rates ≥180 g a.e. ha−1 reduced height and stem diameter of plants and caused reductions in stand count. Thus, cacao showed sensitivity to glyphosate, and severe injury impaired plant growth.

Effect of the microstructure of suspension plasma-sprayed thermal barrier coatings on their thermal cycling damage

The suspension plasma spray (SPS) technique has recently attracted attention due to the variety of microstructures achievable using submicron spray particles mixed with a solvent to form a suspension. Thermal barrier coatings (TBCs) with a columnar microstructure can be obtained using SPS. Because of its unique columnar microstructure achieving high strain tolerance, a top coat sprayed using this technique can efficiently suppress thermal cycling damage in SPS–TBCs. However, there are few reports on the effect of microstructure on the damage behavior of SPS–TBCs with a columnar structure. In this study, the effect of the top coat microstructure on the thermal cycling fatigue of SPS–TBCs was investigated. The size of the complex oxide formed on the top coat–bond coat interface and the length of the cracks at the interface (formed as a result of thermal cycling) increase with the column diameter in the top coat of SPS–TBCs. The thermal spray conditions affect the thermal cycling fatigue life of SPS–TBCs. The SPS–TBC with fine columnar structure exhibits superior thermal cycling fatigue life.

Wetting and deposition characteristics of air-assisted spray droplet on large broad-leaved crop canopy.

Precision and efficient pesticide spraying is an important part of precision agriculture, banana is a large broad-leaved plant, with pests and diseases, has a high demand for spraying and pest control. The purpose of this study was to clarify the wettability of different pesticides on the banana leaf surface, and the effects of nozzle type and working parameters on the deposition distribution performance under air-assisted spray conditions. The wettability test results of different pesticides on banana leaf surfaces showed that the wettability of the adaxial side was always stronger than that of the abaxial side, the smaller the surface tension of the droplets, the better the wettability on the surface. The spray experiment was carried out on the previously developed air-assisted sprayer with the latest developed intelligent variable spray control system. Three types of nozzles were used to spray with different combinations of working parameters. The deposition distribution performance on the banana leaf surface was obtained by image processing using a self-compiled program. The experimental results show that the nozzle type, wind speed, and spray pressure have significant effects on the deposition distribution performance. Through the study of the interaction and coupling effect of nozzle type and working parameters on the spray droplet deposition distribution on both sides of banana leaves, the results show that under the conditions of hollow cone nozzle, 0.5Mpa spray pressure and 3-5m/s wind speed, the spray coverage and droplet density are in the optimal state. This is mainly due to the low spray pressure and/or wind speed is not enough to make the banana leaves vibrate and improve the performance of pesticide deposition. excessive spray pressure and/or wind speed will cause large deformation of banana leaves and make them airfoil stable, which reduces the surface deposition performance. It is of great significance for promoting sustainable and intelligent phytoprotection.

Artificial neural network models for phase equilibrium predictions under engine trans/supercritical spray conditions

Engine spray models based on phase equilibrium have made great progress in simulating trans/supercritical engine spray processes, but there are inherent weaknesses in terms of efficiency and stability for the conventional phase equilibrium algorithm due to the iterative schemes for solving complex nonlinear equations. The low efficiency of the conventional algorithm limits the amount of detail that can be considered in the simulation, while the instability may lead to unphysical results or even simulation divergence. In this work, a method based on artificial neural networks (ANNs) was developed as a potential alternative to the conventional algorithm applied in the engine spray models to achieve fast and robust phase equilibrium calculations. Three ANNs were constructed, including isothermal-isobaric-ANN (TPn-ANN), isenthalpic-isobaric-ANN (HPn-ANN) and adiabatic-mixing-temperature-ANN (AMT-ANN). The latter two models combined with TPN-ANN can be applied to heat and mass transfer flow and adiabatic mixing problems, respectively, to achieve the prediction of phase equilibrium temperature, phase stability and phase splitting. The current work shows that the ANN method leads to significant efficiency improvements while maintaining almost the same accuracy as the conventional algorithm. Analysis of execution time for a high-fidelity n-dodecane spray simulation shows that the conventional phase equilibrium calculation can take up to 70% of total computational time, which can be reduced to negligible levels with the current proposed ANN approach.

An Experimental Method for Evaluating Ammonia Emission Rates of Bio-Curtain

Bio-curtain (i.e., curtain) is a permeable cover equipped with a spraying system for ammonia (NH3) control in a swine facility. Previous studies investigated the NH3 reduction effects primarily based on concentration units. It is challenging to determine the actual efficiency because of the large amount of air discharged through the large surface of the curtain, and external wind rapidly dilutes and disperses the exhausted air. Therefore, this study investigates a technique to evaluate the NH3 reduction effect of the curtain in terms of emission rate. We constructed a metallic cover with a single hole around the curtain to gather the air discharged through it. The NH3 reduction effect was calculated by comparing the NH3 emission rate that was monitored in the barn exhaust fan and at the single hole of metallic cover during the non-spray and spray treatments inside the curtain at the maximum and minimum operating rate of the barn’s exhaust fan. NH3 emission rates declined both non-spray and spray at the minimum operation rate of the barn exhaust fan, but the reduction effect was higher in spray conditions than non-spray. Accumulating NH3-absorbed water inside the curtain under the low ventilation of the exhaust fan caused these circumstances.