• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.1005-1013
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• 2010

This study was conducted to assess the spray control of flash boiling with mixed fuel in consideration of HCCI (Homogeneous Charge Compression Ignition) engine condition. Mixed fuel existing in two phase regions can control the process of mixture formation under low temperature and density by using the spray resulting from flash boiling which is able to induce rapid evaporation of fuel spray as well as the evaporation of high boiling point component. Because HCCI engine injects the fuel early under ambient conditions, it can facilitate the chemical control of ignition combustion and physical control such as breakup and atomization of liquid fuel by flash boiling of mixed fuel which consists of highly ignitable light oil and highly volatile gasoline. This study was conducted by performing video processing after selected composition and molar fraction of the mixed fuel as major parameters and photographed Schlieren image and Mie scattered light corresponding to the flash boiling phenomenon of the fuel spray that was injected inside a constant volume vessel. It was found that flash boiling causes significant changes in the spray structure under relatively low temperature and density. Thus, we analyzed that the flash boiling spray can be used for HCCI combustion by controlling the mixture formation at the early fuel injection timing.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.99-103
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• 2005

This study focused on the use of orimulsion in industrial combustion systems. Orimulsion is a bitumen-in-water emulsified fuel, which contains a thirty percent water. Orimulsion has relatively high levels of sulfur and nitrogen compared to many fuel oils, and has been the subject of much debate regarding the environmental impacts of its use. The goal of this research is to analyse the effect of flash spray combustion characteristics of orimulsion on NOx and particulate material reduction. For the flash spray of orimulsion, it is heated by $150^{\circ}C$. The effects of fuel heating temperatures on NOx and particulate material emissions were investigated experimentally. As the fuel temperature was increased, NOx and particulate material concentrations in flue gas were decreased.

• Journal of ILASS-Korea
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• v.5 no.1
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• pp.30-40
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• 2000

The characteristics of liquefied butane spray are expected to be different from conventional diesel fuel spray, because a kind of flash boiling spray is expected when the back pressure is below the saturated vapor pressure of the butane(0.23MPa at 298K). The ambient pressure was held at a pressure above(0.37MPa) and below(0.15MPa) the fuel vapor pressure. The axial velocities, radial velocities, and size distributions in butane sprays were measured with PDPA(Phase Doppler Particle Analyzer) system. The PDPA measurement showed a smaller SMD at the 0.15MPa chamber pressure, compared to the 0.37MPa case. Log-hyperbolic density function for the droplets size distribution can be fitted to the experimental results of a liquefied butane spray.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.466-474
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• 2004

The characteristics of liquefied butane spray are expected to be different from conventional diesel fuel spray, because a flash boiling spray is expected when the surround pressure is below the saturated vapor pressure of the butane(0.23MPa 98K). The axial velocities. radial velocities. and size distributions in butane sprays were measured with PDPA(Phase Doppler Particle Analyzer) system. Sprays were macroscopically observed by using the high speed camera in case that the surround pressure is 0.37MPa and 0.15MPa. respectively. Compared with the conventional spray. the reversed results were investigated when the surround pressure is below the saturated vapor pressure of the butane.

• Journal of the Korean Society of Visualization
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• v.20 no.2
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• pp.38-44
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• 2022

Due to increasingly strict emission regulations for carbon-based fuels in the shipping industry, there is a significant motivation to investigate the alternative fuel. Ammonia is one of the attractive alternative fuels as a carbon-free fuel. Since ammonia has different properties such as high vapor pressure and low boiling point compared to conventional fuels, further research into ammonia spray behavior is important. In this work, the spray characteristics of ammonia and other fluids (ethanol, n-decane) were compared by using numerical simulation. The results show that the spray characteristics of ammonia differs from those of the others due to the occurrence of flash boiling. The narrow-dispersed spray with accelerated velocity at the center have been observed for ammonia. It is also found that droplets of ammonia achieve smaller diameter with more uniform distribution, leading to better atomization behavior compared to the others.

• Journal of ILASS-Korea
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• v.11 no.2
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• pp.81-88
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• 2006

The spray characteristics of the rotating fuel injection system were investigated. The special test rig was devised to get the spatial and momentary droplet information. This experimental apparatus consists of a high-speed motor, a shaft, a rotating fuel nozzle and an acrylic case. Spray droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and instantaneous velocity field was measured by 1'IV (Particle Image Velocimetry) system. At the same time, spray visualization was performed by using ND-YAG laser-based flash photography. From these two different laser diagnostic techniques, we could get spatial and instantaneous spray information fur rotating fuel injection system. The results presented in this paper indicate that spray characteristics such as droplet size, velocity and spray pattern were strongly influenced by rotational speed.

• Journal of ILASS-Korea
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• v.13 no.2
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• pp.65-72
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• 2008

It is recognized that alternative fuel such as dimethyl ether (DME) has better combustion polluting characteristics than diesel fuel, even though the cetane number of DME is almost the same as that of diesel. Characteristics of DME spray were observed experimentally under various ambient conditions using a constant volume chamber and a common-rail injection system. N-dodecane and LPG fuel sprays were also observed under same conditions of DME spray. Using spray images from backlight scattering and Mie scattering, characteristics of fuel sprays such as penetration and spray volume were visualized and quantitatively measured. The measurements showed that the penetration of early period decreased remarkably, because evaporation of alternative fuels became prosperous by the influence of flash boiling phenomenon under the condition of the low temperature and pressure compared with n-dodecane. The penetration of DME and LPG spray received the influence of temperature more largely in comparison with low density, because the specific surface area increased by atomizing in high density.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.32-42
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• 2023

In this study, spray characteristics of n-heptane and propane were investigated under different injection pressure using various imaging techniques such as Mie-scattering, DBI (diffuse back-illumination), and Schlieren imaging techniques. NI compact RIO system was used to control a test injector. Spray penetration length, length-to-width ratio and number of black pixels were calculated by using MATLAB software to compare spray characteristics of each fuel. Longer spray penetration length and higher length-to-width ratio were observed in propane spray because of flash boiling caused by high saturated vapor pressure. Spray collapse occurred in propane spray due to the high plume-to-plume interaction. Moreover, rapid evaporation occurred in propane spray, so that nozzle tip wetting could not be observed. Rapid evaporation of propane also caused fewer residual droplets compared to n-heptane spray. Therefore, propane is advantageous in reducing the generation of soot emission from large droplets that are not atomized. However, additional evaluation should be conducted considering combustion efficiency and the possibility of deposits by nozzle tip icing during fuel injection.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.35-39
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• 2019

The shielding effectiveness (SE) of the EMI spray coating film was measured in a three-dimensional structure. The shielding effectiveness was measured by AST D4935 using coaxial type TEM cell. A standard sample of the cylindrical slab is fabricated to measure the shielding effectiveness using the ASTM D4935. At this time, spray coating was performed by bonding a three-dimensional structure with NAND flash memory to a standard sample. In the case of spray coating, it was uniformly coated not only on the horizontal plane but also on the vertical plane of the three-dimensional structure. As a result of measurement, shielding effectiveness of maximum 59 dB was measured in a three-dimensional structure similar to the case without three-dimensional structure. As a result, it was confirmed that the spray coating can be uniformed even in the three-dimensional structure.

• Journal of ILASS-Korea
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• v.13 no.3
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• pp.149-155
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• 2008

An experimental study was performed to understand spray characteristics of the rotary atomizer for the slinger combustor. In this fuel injection system, fuel is injected and atomized in the combustor by centrifugal forces to engine shaft. The experimental apparatus consists of a high speed rotational spindle, rotary atomizer, pressure tank and acrylic case. The droplet size and velocity were measured by PDPA (phase Doppler particle analyzer), and spray was visualized by using high speed camera and Nd:Yag laser-based flash photography. From the test results, the droplet size (SMD) is largely affected by rotational speed, mass flow rate and the number of orifice. As the experimental results, we could understand the spray characteristics of the rotary atomizer for the slinger combustor and obtain the optimum shape of the rotary atomizer which is suitable for the small gas turbine engine.