• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.202-206
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• 2007

Plasma assisted combustion is an old subject for the combustion society, but recently, the subject is refocused partly because techniques for non-thermal plasmas are progressed significantly, and partly because there are lots of applications which need to be overcome by a new reaction technology. In the present study, we have developed plasma assisted burner (plasma burner), which can be used as a heating source in a diesel particulate filter system. The burner can bum 20 - 60 cc/min of diesel fuel with 50 lpm of fresh air in an exhaust pipe of 2.0 liter diesel engine. Using 20 cc/min of diesel fuel, an exhaust temperature for 2.0 liter disel engine can be raised up to around $600^{\circ}C$ for the range of engine speeds is idle - 3,000 rpm. The characteristics of the plasma burner are reported, and the possible operating mechanism of it will be discussed based on the effects of an electric field and a plasma on flames.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.327-334
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• 2004

Spectroscopic and electrostatic probe measurements were made to examine plasma characteristics with or without a metal plate for a 10-㎾-class direct-current arcjet Heat fluxes into the plate from the plasma were also evaluated with a Nickel slug and thermocouple arrangement. Ammonia and mixtures of nitrogen and hydrogen were used. The NH$_3$ and $N_2$+3H$_2$ plasmas in the nozzle and in the downstream plume without a plate were in thermodynamical nonequilibrium states. As a result, the H-atom electronic excitation temperature and the $N_2$ molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NH molecule-rotational excitation temperature did not show an axial decrease. Each temperature was kept in a small range in the plume without a plate except for the NH rotational temperature for NH$_3$ gas. On the other hand, as approaching the plate, the thermodynamical nonequilibrium plasma came to be a temperature-equilibrium one because the plasma flow tended to stagnate in front of the plate. The electron temperature had a small radial variation near the plate. Both the electron number density and the heat flux decreased radially outward, and an increase in H$_2$ mole fraction raised them at a constant radial position. In cases with NH$_3$ and $N_2$+3H$_2$ a large number of NH radical with a radially wide distribution was considered to cause a large amount of energy loss, i.e., frozen flow loss, for arcjet thrusters.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.547-554
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• 2002

We are facing the serious environmental pollution difficulties such as acid rain, green house effects, etc. The gaseous matter NOx, SOx, VOCs which are regarded as main factors for these current pollutions are mainly emitted from power plants and vehicles. Therefore several leading countries are regulating the emissions strictly, especially the exhaust emissions from a Diesel engine without an aftertreatment device. The objective of this study is to find out soot and NO removal characteristics focused on the emissions of a Diesel engine by using nonthermal plasma for each engine speeds and loads. Electrostatic precipitator(wire-to-plate type reactor) is used for soot removal. Radicals generated from outer air and put into a mixing chamber in the end of exhaust line are used for NO removal. Concentration of exhaust emissions is analyzed from the gas analyzer(KaneMay) and FTIR to estimate by-products.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1115-1118
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• 2003

A great part of flint fuel is Hydrogen and carbon's combination. they should be generated steam and carbon gas when combine with oxygen for perfect combustion in the inside of engine, but the pollutive material especially NOx and Soot are exhausted, even though fuel is combine perfectly. In this paper the characteristics of exhaust material from diesel engine is investigated for the corona discharge-EGR hybrid plasma reactor, which combined corona discharge with EGR system. NOx is decreased in all load and applied voltage to plasma reactor. However Soot is increased as increasing EGR rate and it is decreased as increasing applied voltage.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.82-88
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• 2008

The diesel engine of the merchant ship has been aperated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of law quality, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for both corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.39-46
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• 2007

The technique of $NH_3$ SCR (selective catalytic reduction) assisted by plasma oxidation has been applied to a 2,000 cc diesel engine. The present combined $deNO_x$ process consists of two steps. The first step is that about 50% of emitted NO from the engine is oxidized to $NO_2$ in a plasma oxidation process. The second step is that NO and $NO_2$ are simultaneously reduced to $N_2$ in the $NH_3$ SCR process. The engine test results showed that the $deNO_x$ rates of the present combined process are higher than those of conventional SCR process by 20%. Such a high performance of the combined process is noticeable especially, when the exhaust temperature are relatively low, i.e., $170-220^{\circ}C$. To provide a feasibility of the present technique the effects of operating conditions, such as an electrical input energy, an exhaust gas temperature, an initial NO concentration, and the amount of hydrocarbon addition, were discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.35-42
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• 2001

The diesel engine exhaust gas is know as one of the causes to produce photochemical smog, which causes damage on environmental. However, due to the high thermal efficiency and low carbon dioxide emission, the usage of a diesel engine is prevailed. In this study, the DC non-thermal plasma technology used to the particulate matter (PM) aftertreatment. The exhaust gas characteristics and energy density were investigated on the dynamometer test bed and chassis dynamometer with CVS-75 mode in a passenger diesel car. It was reported that the smoke removal efficiency has around the 70% in the dynamometer test with 80W energy consumption and the PM removal efficiency has the 68% in the real car test. The NOx also reduced the 20% according to electrode type respectively. Considering these results, plasma technology is one of the ways to simultaneously removing method the particulate matter (PM) and NOx.

• Journal of the Semiconductor & Display Technology
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• v.16 no.2
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• pp.75-78
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• 2017

We reports improved monitoring performance of Self plasma-optical emission spectroscopy (SP-OES) by augmenting a by-pass tube to a conventional straight (or single) tube type self plasma reactor. SP-OES has been used as a tool for the monitoring of plasma chemistry indirectly in plasma process system. The benefits of SP-OES are low cost and easy installation, but some semiconductor industries who adopted commercialized SP-OES product experiencing less sensitivity and slow sensor response. OH out-gas chemistry monitoring was performed to have a direct comparison of a conventional single type tube and a by-pass type tube, and fluid dynamic simulation on the improved hardware design was also followed. It is observed faster pumping out of OH from the chamber in the by-pass type SP-OES.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.40-47
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• 2002

Because UV wavelength lights can activate photocatalysts, plasma is used as a light source of a photocatalytic reactor. Even though plasma has good intensity for photo reaction, substrate of catalyst coating was limited by the geometry of plasma generator. Usually bead type substrate was used for a pack bed type reactor. Honeycomb monolith type substrate was used with UV lamps instead plasma, due to the light penetration the honeycomb monolith length was too short to show good activity In this study a photocatalytic reactor, which is using a honeycomb monolith substrate, was investigated with plasma as an activation light source. As a parametric study the effects of 1311owing factors on plasma generation and power consumption are examined; supply voltage, substrate length, environment condition, catalyst loading and ratio. Using the test results, the practicability test was done with simulated synthetic gases representing bad smells and automotive exhaust gases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.262-270
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• 2004

Basic experiments were carried out using the THT-IV low-power Hall thruster to examine the influences of magnetic field shape and strength, and acceleration channel length on thruster performance and to establish guidelines for design of high-performance Hall thrusters. Thrusts were measured with varying magnetic field and channel structure. Exhaust plasma diagnostic measurement was also made to evaluate plume divergent angles and voltage utilization efficiencies. Ion current spatial profiles were measured with a Faraday cup, and ion energy distribution functions were estimated from data with a retarding potential analyzer. The thruster was stably operated with a highest performance under an optimum acceleration channel length of 20 mm and an optimum magnetic field with a maximum strength of about 150 Gauss near the channel exit and with some shape considering ion acceleration directions. Accordingly, an optimum magnetic field and channel structure is considered to exist under an operational condition, related to inner physical phenomena of plasma production, ion acceleration and exhaust plasma feature. A new Hall thruster was designed with basic research data of the THT-IV thruster. With the thruster with many considerations, long stable operations were achieved. In all experiments at 200-400 V with 1.5-3 mg/s, the thrust and the specific impulse ranged from 15 to 70 mN and from 1100 to 2300 see, respectively, in a low electric power range of 300~1300 W. The thrust efficiency reached 55 %. Hence, a large map of the thruster performance was successfully made. The thermal characteristics were also examined with data of both measured and calculated temperatures in the thruster body. Thermally safe conditions were achieved with all input powers.