scholarly journals Air-Core-Liquid-Ring (ACLR) Atomization: Influences of Gas Pressure and Atomizer Scale Up on Atomization Efficiency

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 139 ◽  
Author(s):  
Marc Wittner ◽  
Heike Karbstein ◽  
Volker Gaukel
Keyword(s):  
Energy Input ◽  
Scale Up ◽  
Gas Pressure ◽  
Orifice Diameter ◽  
Internal Mixing ◽  
Atomization Efficiency ◽  
Droplet Sizes ◽  
Reference Parameter ◽  
Liquid Ring ◽  
Gas Pressures

Air-core-liquid-ring (ACLR) atomizers present a specific type of internal mixing pneumatic atomizers, which can be used for efficient atomization of high viscous liquids. Generally, atomization efficiency is considered as a correlation between energy input and resulting droplet size. In pneumatic atomization, air-to-liquid ratio by mass (ALR) is commonly used as reference parameter of energy input. However, the pressure energy of the atomization gas is not considered in the calculation of ALR. In internal mixing ACLR atomizers, it can be assumed that this energy contributes to liquid disintegration by expansion of the gas core after exiting the atomizer. This leads to the hypothesis that droplet sizes decrease with increasing gas pressure at constant ALR. Therefore, the use of volumetric energy density (EV) as a reference parameter of energy input was investigated at different gas pressures between 0.4 and 0.8 MPa. Furthermore, scale up-related influences on the atomization efficiency of ACLR atomization were investigated by use of an atomizer with enlarged exit orifice diameter. We can conclude that EV can be applied as a reference parameter of ACLR atomization processes with different gas pressures. However, within the range investigated no clear influence of gas pressure on atomization efficiency was found. Up-scaling of ACLR atomizers allows production of similar droplet sizes, but atomization efficiency decreases with increasing exit orifice diameter.

Pressure Assisted Sintering of an Aluminium Alloy

2009 ◽  
Vol 618-619 ◽  
pp. 627-630
Author(s):  
Stephen J. Bonner ◽  
Graham B. Schaffer ◽  
Ji Yong Yao
Keyword(s):  
Aluminium Alloy ◽  
Gas Flow ◽  
Isothermal Holding ◽  
Horizontal Tube ◽  
Elevated Pressure ◽  
Nitrogen Pressure ◽  
Gas Pressure ◽  
Densification Rate ◽  
Conventional Press ◽  
Gas Pressures

An aluminium alloy was sintered using a conventional press and sinter process, at various gas pressures, to observe the effect of sintering gas pressure on the densification rate. Compacts of aluminium alloy 2712 (Al-3.8Cu-1Mg-0.7Si-0.1Sn) were prepared from elemental powders and sintered in a horizontal tube furnace under nitrogen or argon at 590°C for up to 60 minutes, and air cooled. The gas flow was adjusted to achieve specific gas pressures in the furnace. It has been found that increasing the nitrogen pressure at the start of the isothermal holding stage to 160kPa increased the densification rate compared to standard atmospheric pressure sintering. Increasing the nitrogen pressure further, up to 600kPa, had no additional benefit. The densification rate was increased significantly by increasing the gas pressure to 600kPa during both heating and isothermal holding. Under argon the elevated pressure did not increase the densification rate. Results seem to suggest that the beneficial effect of the elevated pressure on the rate of densification is related to nitride formation.

A Study on Gas Pressure for Superplastic Forming of Titanium Alloy Bellows

2005 ◽  
Vol 475-479 ◽  
pp. 3051-3054 ◽  
Author(s):  
Gang Wang ◽  
Jun Chen ◽  
X.Y. Ruan
Keyword(s):  
Titanium Alloy ◽  
Thin Shell ◽  
Deformation Theory ◽  
Shell Theory ◽  
Superplastic Forming ◽  
Gas Pressure ◽  
Forming Process ◽  
Compressive Axial Load ◽  
Thin Shell Theory ◽  
Gas Pressures

The complex superplastic forming (SPF) technology applying gas pressure and compressive axial load is an advanced forming method for bellows made of titanium alloy, which forming process consists of the three main forming phases namely bulging, clamping and calibrating phase. The influence of forming gas pressure in various phases on the forming process are analyzed and models of forming gas pressure for bellows made of titanium alloy are derived according to the thin shell theory and plasticity deformation theory. Using model values, taking a two-convolution DN250 bellows made of Ti-6Al-4V titanium alloy as an example, a series of superplastic forming tests are performed to evaluate the influence of the variation of forming gas pressure on the forming process. According to the experimental results models are corrected to make the forming gas pressures prediction more accurate.

Effect of Sputtering Gas Pressure and Bias Voltage on Mechanical Properties of TiN Coating Deposited by DC Magnetron Sputtering

2004 ◽  
Author(s):  
Hirotaka Tanabe ◽  
Yoshio Miyoshi ◽  
Tohru Takamatsu ◽  
Hitoshi Awano ◽  
Takaaki Yamano
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Magnetron Sputtering ◽  
Bias Voltage ◽  
Adhesive Strength ◽  
Gas Pressure ◽  
Dc Magnetron Sputtering ◽  
Tin Films ◽  
Bombarding Energy ◽  
Gas Pressures

The mechanical properties of TiN films deposited on carbon steel JIS S45C by reactive dc magnetron sputtering under three sputtering gas pressures, 0.5Pa, 0.8Pa, and 1.76Pa were investigated. The residual stress once increased and then decreased with increasing bias voltage at 0.5Pa and 0.8Pa, but increased monotonously at 1.76Pa. These variations could be explained by the variations of the bombarding energy of a sputtered ion at each gas pressure. The variations of hardness and toughness correlated with the variation of residual stress. The variation of adhesive strength also could be explained by the variation of the bombarding energy with a model proposed in this study. A specific wear rate was also investigated, and it was found that to increase not only the hardness but also the adhesive strength is necessary to improve the wear resistance of TiN films.

Gas Pressure Dependence of Photon Emission Accompanying Fracture of Polycrystalline MgO in Nitrogen

2006 ◽  
Vol 317-318 ◽  
pp. 313-316 ◽  
Author(s):  
Tadashi Shiota ◽  
Yasuo Toyoshima ◽  
Kouichi Yasuda ◽  
Yohtaro Matsuo
Keyword(s):  
Pressure Dependence ◽  
Room Temperature ◽  
Photon Emission ◽  
Gas Discharge ◽  
Gas Pressure ◽  
The Other ◽  
Experimental Conditions ◽  
Infrared Photon ◽  
Gas Pressures

The photon emission accompanying fracture of a polycrystalline MgO was investigated at room temperature under N2 gas pressures from 10-4 to 105 Pa. At fracture, the ultraviolet, visible and infrared photon emissions instantaneously increased, and then rapidly decreased in most of the experimental conditions. However, in a N2 gas pressure of around 100 Pa, their peak counts lasted for about 10 milliseconds, and the amount of the UV photon emission was fifteen times larger than those obtained in the other N2 gas pressures. This abrupt increment in the emission was explained by the luminescence due to N2 gas discharge according to the classical Townsend’s theory. In conclusion, the photon emission accompanying fracture of a polycrystalline MgO mainly originated from the excited defects as reported by the authors previously, but the N2 gas discharge had a supplementary effect on the emission around a specific N2 gas pressure.

scholarly journals A Method for the Segregation of Emulsion Inner Phase Droplets Using Imbibition Process in Porous Material

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 110
Author(s):  
Mariola M. Błaszczyk ◽  
Łukasz Przybysz
Keyword(s):  
Energy Input ◽  
Economic Cost ◽  
Minimal Energy ◽  
Environmental Footprint ◽  
Small Droplet ◽  
Dispersive Systems ◽  
Internal Phase ◽  
Oil In Water ◽  
Droplet Sizes ◽  
Energy Consuming

The process of forming an emulsion is an energy-consuming process. The smaller the internal phase droplets we want to produce and the closer the droplets are in size to each other (monodisperse), the more energy we need to put into the system. Generating energy carries a high economic cost, as well as a high environmental footprint. Considering the fact that dispersive systems are widely used in various fields of life, it is necessary to search for other, less-energy-intensive methods that will allow the creation of dispersive systems with adequate performance and minimal energy input. Therefore, an alternative way to obtain emulsions characterized by small droplet sizes was proposed by using an imbibition process in porous materials. By applying this technique, it was possible to obtain average droplet sizes at least half the size of the base emulsion while reducing the polydispersity by about 40%. Oil-in-water emulsions in which vegetable oil or kerosene is the oily phase were tested. The studies were carried out at three different volume concentrations of the emulsions. Detailed analyses of diameter distributions and emulsion concentrations are presented. In addition, the advantages and limitations of the method are presented and the potential for its application is indicated.

scholarly journals Thermodynamic Characteristics of Methane Adsorption of Coal with Different Initial Gas Pressures at Different Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Tingting Cai ◽  
Zengchao Feng ◽  
Yulong Jiang ◽  
Dong Zhao
Keyword(s):  
Adsorption Process ◽  
Thermodynamic Characteristics ◽  
Methane Adsorption ◽  
Gas Pressure ◽  
Adsorption Heat ◽  
Mathematical Function ◽  
Adsorption Time ◽  
Free Gas ◽  
Different Temperatures ◽  
Gas Pressures

The adsorption of methane in coal depends on both pressure and temperature, and the adsorption gas content decreases as the temperature rises while increases as the pressure increases. When the gas molecule switches between the free state and adsorbed state, energy exchange is accompanied. To study the thermodynamic characteristics (adsorption heat, adsorption content, and adsorption time) of the methane adsorption of coal, the isothermal methane adsorption experiments of coal with different initial free gas pressures at different temperatures (30–90°C) were conducted. In this paper, a well-defined mathematical function of the adsorption heat was established on the basis of the actual gas state equation, Boltzmann energy distribution theory, and the two-state energy model, and the function was verified by the experimental data. The results show that the mathematical function of the adsorption heat can well describe the relationship among the adsorption heat, temperature, and initial free gas pressure in the closed adsorption system, and the adsorption heat involves the initial free gas pressure. The greater the initial free gas pressure, the less the adsorption heat is. In the adsorption process with different initial free gas pressures at different temperatures, the real-time free gas content increases with time and the adsorption system shows desorption process generally. For the adsorption process with the same initial free gas pressure, the adsorption time increases with the rising temperature. For the adsorption process with different initial free gas pressures at the same temperature, the greater the initial free gas pressure, the shorter the adsorption time it takes to reach an equilibrium state. The results help to understand the thermodynamic characteristics and the heat and mass transfer of methane in coal adsorption.

scholarly journals Mechanical Behavior and Permeability Evolution of Coal under Different Mining-Induced Stress Conditions and Gas Pressures

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2677
Author(s):  
Zetian Zhang ◽  
Ru Zhang ◽  
Zhiguo Cao ◽  
Mingzhong Gao ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Triaxial Compression ◽  
Volumetric Strain ◽  
Coal Mass ◽  
Gas Pressure ◽  
Stress Conditions ◽  
Permeability Evolution ◽  
Compression Tests ◽  
Induced Stress ◽  
Conventional Triaxial Compression ◽  
Gas Pressures

The gas permeability and mechanical properties of coal, which are seriously influenced by mining-induced stress evolution and gas pressure conditions, are key issues in coal mining and enhanced coalbed methane recovery. To obtain a comprehensive understanding of the effects of mining-induced stress conditions and gas pressures on the mechanical behavior and permeability evolution of coal, a series of mining-induced stress unloading experiments at different gas pressures were conducted. The test results are compared with the results of conventional triaxial compression tests also conducted at different gas pressures, and the different mechanisms between these two methods were theoretically analyzed. The test results show that under the same mining-induced stress conditions, the strength of the coal mass decreases with increasing gas pressure, while the absolute deformation of the coal mass increases. Under real mining-induced stress conditions, the volumetric strain of the coal mass remains negative, which means that the volume of the coal mass continues to increase. The volumetric strain corresponding to the peak stress of the coal mass increases with gas pressure in the same mining layout simulation. However, in conventional triaxial compression tests, the coal mass volume continues to decrease and in a compressional state, and there is no obvious deformation stage that occurs during the mining-induced stress unloading tests. The theoretical and experimental analyses show that mining-induced stress unloading and gas pressure changes greatly impact the deformation, failure mechanism and permeability enhancement of coal.

Primary Breakup of Liquid Jet in an Annular Passage in Crossflow of Air

2015 ◽  
Author(s):  
Deepak Kumar ◽  
Abhijit Kushari ◽  
Jeffery A. Lovett ◽  
Saadat Syed
Keyword(s):  
Reynolds Number ◽  
Momentum Flux ◽  
Initial Conditions ◽  
Axial Direction ◽  
Orifice Diameter ◽  
Liquid Jet ◽  
Momentum Ratio ◽  
Formation Zone ◽  
Primary Breakup ◽  
Droplet Sizes

This paper presents an experimental study of primary breakup of liquid jet in an annular passage in a cross flow of air at a fixed Mach number of 0.12, at atmospheric pressures. The experiments were conducted for various velocities of liquid jet from 1.417 m/s to 7.084 m/s (based on orifice diameter = 1 mm) and the corresponding liquid-air momentum flux ratios varied from 1 to 25. The droplet sizes and velocities were measured using a Phase Doppler Particle Analyzer (PDPA) downstream of the liquid inlet port along the axial direction at the centerline of the annular passage along the plane of injection. Observed droplet sizes and velocity variations at different momentum flux ratios, in the axial direction, show three distinct zones. The first zone is the ligament formation zone represented by large variation in droplet Reynolds number with momentum ratio. The second zone is the primary droplet formation zone in which a fairly monotonic decrease in droplet size and droplet acceleration due to the breakup is observed. However, the Reynolds number of the droplets is almost invariant with momentum ratio. The third zone is where the spray attains the critical state where the size and velocity does not vary in the axial direction and the variation in size in this zone with the momentum ratio is primarily due to the initial conditions established in the ligament formation zone.

scholarly journals Axial Blast Type Discharge Chamber with Moving Electrode

2019 ◽  
Vol 6 (3) ◽  
pp. 227-230
Author(s):  
M. E. Pinchuk ◽  
A. V. Budin ◽  
N. K. Kurakina ◽  
A. G. Leks
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Gas Dynamics ◽  
Gas Flow ◽  
Discharge Chamber ◽  
Gas Pressure ◽  
Current Amplitude ◽  
Experimental Stand ◽  
Design Changes ◽  
Gas Pressures

The paper presents some results concerning electrophysical and gas-dynamics parameters of high-curent arc in axial blast discharge chamber. The experimental stand and numerical model were modified for axial gas flow type. Some design changes are described in the paper. The experiments were carried out for gas pressures of 1.0-6.0 MPa with current amplitude of 25-150 kA. The current half-period was of 1.0-10.0 ms. The contacts moved apart to the distance of 3-4 cm due to gas pressure boost in the chamber. OpenFOAM package with the library swak4foam was used for numerical simulation.

Gas Penetration of Pit Membranes in the Xylem of Rhododendron as the Cause of Acoustically Detectable Sap Cavitation

1985 ◽  
Vol 12 (5) ◽  
pp. 445 ◽  
Author(s):  
DS Crombie ◽  
MF Hipkins ◽  
JA Milburn
Keyword(s):  
Structural Damage ◽  
Gas Permeability ◽  
Mechanical Damage ◽  
Gas Pressure ◽  
Water Films ◽  
Detached Leaves ◽  
Gas Penetration ◽  
Xylem Conduits ◽  
Gas Pressures

The gas pressure required to force sap from Rhododendron stems was investigated. Sap was expressed from stems, and stem permeability to gas increased, at pressures of 1.3-3.5 MPa. We interpret the changing of permeability as a removal of water films in the pores of the pit membranes which normally limit the length of xylem conduits. Similar pressure differences exist across the pit membranes separating gas and sap-filled conduits when cavitation occurs in Rhododendron. It is suggested that cavitation in detached leaves and shoots of Rhododendron occurs when gas penetrates the pit membranes. The increase in the gas permeability of xylem subjected to high gas pressures was reversed by a soaking in water. It could not therefore have been a consequence of mechanical damage, caused when xylem conduits are subjected to high gas pressures, because such structural damage would be irreversible.

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