• Journal of ILASS-Korea
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• v.13 no.4
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• pp.206-211
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• 2008

In this research, combustion and spray characteristics were investigated experimentally in a constant volume chamber by applying bio-diesel fuel to a common-rail system in which precise control is available for utilizing environmentally friendly properties of bio-diesel fuel. The experiment was conducted at fuel temperatures $20^{\circ}C$ and $-20^{\circ}C$ to investigate combustion characteristics of bio-diesel fuel provoking problems in fluidity specially in a low temperature. For the visualization, the experiment was carried out under various conditions of ambient pressure, injection pressure and fuel temperature. The test was made by three different types of diesel fuels, conventional diesel, BD20 and BD100. In summary, this research aims to investigate combustion characteristics in the application of bio-diesel fuels and compare the results with performance of conventional diesel fuel. This experimental data may provide fundamentals of spray and combustion of bio-diesel fuels at a low temperature and contribute to the development of bio-diesel engines in future.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.732-742
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• 2002

This paper presents twin spray characteristics of two impinging F-O-O-F type injectors in which fuel and oxidizer impinge on each other to atomize under the various conditions. The droplet size and velocity in the impinging spray flow field were measured using PDPA. The droplet size and velocity were investigated at the mixture ratios of 1.5, 2.0, 2.47 and 3.0 for four injectors in which two single F-O-O-F injectors were arranged at the intervals of 20.8, 31.2, 41.6 and 62.4mm respectively. In general, the arithmetic mean diameter, SMD and standard deviation of droplet size in the interaction area (X=0 and Y=0mm) were smaller, while the axial velocity in the interaction area was slightly higher. An empirical correlation is obtained for the (D$\_$10/)$\_$D//(D$\_$10/)$\_$c/ value under the assumptions of two identical droplets and these with different size and velocity. The droplets with low Weber numbers below 40 have possibility to coalesce, while those over 40 tend to disintegrate after impingement in the interaction area.

• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.451-459
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• 2012

Background: In Korea, a healthy 36-year-old man developed acute interstitial pneumonitis soon after inhaling a waterproofing spray which he had applied at home to his outdoor jacket. Objectives: The objectives of this study were to review cases of varying degrees of respiratory toxicity and poisoning in connection with the use of waterproofing spray and summarize major reasons for cases of poisoning. Methods: We searched articles reporting on a combination of a waterproofing agent and/or respiratory symptoms, including acute respiratory syndrome, lung injury, pneumonia, pulmonary toxicity, and respiratory disease. Results: We reviewed a number of cases of varying degrees of respiratory toxicity and poisoning resulting from inhalation of waterproofing spray containing fluorocarbon co-polymer, solvents and propellants reported in a variety of countries. The literature searches concluded that among the ingredients of waterproofing agents, fluorinated polymer may cause acute respiratory health effects. Conclusion: Environmental policy should be implemented in order to prevent consumers from using household and industrial products including waterproofing agents. In addition, a national surveillance system should be created to collect cases of poisoning caused by the use of consumer products.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.357-362
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• 2015

There is potential method to utilize the liquid carbon dioxide ($LCO_2$) in coal gasification plants. The $LCO_2$ could be used to effectively transport coal particles instead of conventional carrier such as liquid water ($H_2O$) particularly in wet-fed gasifier. However, there is a lack of fundamental study on the atomization behavior of $LCO_2$ coal slurry under high pressure condition. In this study, the flashing spray characteristics of a coal mixture with $LCO_2$ was examined during a throttling process by using a flow visualization system. The spray of coal water slurry which is in the Rayleigh-type break up mode was significantly different. This difference indicates that the coal water slurry did not effectively transport the coal, as compared to $LCO_2$ coal slurry.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.23-30
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• 2015

The scanning quality can be influenced by reflective abilities of a surface. Transparency and glossiness of a surface can highly limit the scanning results. Various techniques have been developed to solve problems of reflective and transparent surfaces. As one of the most feasible and convenient solutions, a thin layer of coating with proper specifications is sprayed on surface for eliminating the problems of the surfaces. As the main goal is to keep the object geometry unchanged, then it is important to coat the surface with layers less than one micrometer in thickness. For this purpose, a newly designed atomization-based spray system has been developed and tested in sets of experiments to study its efficiency on scanning results while objects with the surface are in use. This paper presents the spray design process and then studies and compares the 3D scanning results of the surfaces coated with atomization-based and aerosol sprays.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.110-115
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• 2005

Plasma Transferred Arc Spray process was used to make modified surface for wear and corrosion resistant by using Co system powder type alloy. The modified surface was produced by changing only spray current and other process variables were constant. The current range was from 80 amp to 140 amp as inclosing 20 amp. It was appeared that the geometrical shape, microstructures and microhardness of the modified surface were affected by the different cooling rate of base metal. The modified surface that produced by 120 amp current exhibited the fine microstructure and the highest microhardness number impling good surface characteristics. It was also found that the spray current affected the width but not the height of the bead as increasing current.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.334-339
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• 2008

An closed cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The purpose of this study is to evaluate thermal performance of heat exchanger at various conditions and to provide design datebase. The experimental study regarding heat exchanger for closed cooling tower was conducted. Experimental apparatus consists of constant temperature bath, water pump, spray nozzle, heat exchanger, fan, and date acquisition system. Heat transfer rates at various air velocitys, water flow rates, two different spray modes were measured and heat transfer coefficient were calculated to compare the thermal performances. This study provides that the heat transfer coefficient increases with increasing spray water flow rate and with increasing air velocity. The wet mode was more effective than dry mode for closed cooling tower to this study.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.763-768
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• 2001

Molybdenum-based thermal spray powder is widely used for coating the moving parts of the internal combustion engines due to its excellent wear resistance. A composite powder of the $Mo_{40}(Al_{1-x}Si_x)_{60}$ system was synthesized using the SHS method. The synthesized bulk was pulverized and specially treated to produce thermal spray powder. It was found that the synthesis reaction consisted of two-steps: the formation of $Al_8/Mo_3$ and the formation of Mo(Al,Si)$_2$. Both the temperature and the rate of the SHS reaction linearly increased with the increase of the value of x in $Mo_{40}(Al_{1-x}Si_x)_{60}$, The temperature and the rate of the reaction were also affected by the compacting density of the specimens, exhibiting the maximum valves at 62% and 60%, respectively. Since spherical shape is advantageous to the thermal spraying process, shape-control of the powder was attempted with PVA as a binding additive, resulting in the successful production of almost perfectly spherical powder of 80 $\mu\textrm{m}$ Ø$(d_{50})$ mean particle size.

• Journal of ILASS-Korea
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• v.22 no.2
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• pp.96-102
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• 2017

In order to reduce the NOx, SCR technology is most suitable. In this study, we focused on studying the injector part of urea-SCR system. When stoichiometric 1 mole of urea is injected, 2 moles of $NH_3$ are created. $NH_3$ causes a SCR reaction by reacting with NOx. However, urea is decomposed by the side reaction of coming out HNCO, deposit formation is formed. In this study, it was to design a nozzle that can spray the optimal spray flow rate. Test nozzle used in this experiment is efferverscent type. The result of the experiment, liquid flow rate was confirmed to be that they are dominated by the exit orifice diameter. The area ratio is defined by ratio of the area of exit orifice hole and that of aerorator. The droplet size was measured by varying the area ratios. In addition, it was also confirmed that there is no change of the liquid flow rate and air flow rate to change the aerorator at the same exit orifice. Further, It was confirmed that the droplet size was relatively uniform even though the area ratio was different. Finally, there is little change in the SMD that air flow rate increases in 0.3 or more ALR.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.205-211
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• 2018

Y-jet nozzle has various advantages over other twin-fluid nozzles and are used in industrial boilers. However, it costs large energy consumption because of assisted air and its design is complex. The Y-jet nozzle is consisted of a liquid and gas port and a mixing chamber. The diameter of the port and the length of the mixing chamber greatly affect spray and atomization characteristics, therefore, they are the most important factors in nozzle design. In this study, The experimental setup is consisted of a laboratory scale spray system. The characteristics of the Y-jet nozzle according to the design parameters were observed. As a result, it was found that the length of the mixing chamber did not have effect on the flow rate and the choking condition. The droplet size was measured using a Malvern type measuring device. In addition, measurements were conducted in the front and the right directions of the nozzles. Based on the results, the SMD View Ratio is defined. It is the asymmetrical design characteristics of the Y-jet nozzle.