• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.81-86
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• 2005

The purpose of this study is to develop venturi type after-burner in order to obtain pollutant reduction effect and find the best stable combustion condition. For this purpose, through a flow analysis, the shape of venturi type was made and flame holder locations were also decided by measuring chemical species at before and after the after-burner. Also, various chemical species concentration were measured at changing the induced air rates and the oxygen for oxygen enrichment for the solution the problems of much oxygen flow rate and the flame stability range. As results of this study, a flow distribution and the purification effect was excellent at venturi contraction 0.5 and flame holder location 12mm below the center of Venturi throat. On the purification characteristics, we found that pollutants reduction was effective when area ratio and oxygen are increased. But there are suitable quantities due to the flame shape change and combustion efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.165-176
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• 1996

The flow field and spray characteristics for loop scavenged type 2stroke engine having pancake shape was numerically computed using KIVA-Ⅱ code. The cylinder has 1intake port, 2side intake ports and 1exhaust port with induced flow angle 25 deg. In engine calculation, the chop techniques is used to strip or add planes of cells across the mesh adjacent to the TDC and the BDC(ports parts) for preventing the demand of exceed time during the computation, providing a control on cell height in the squish region. The modified turbulent model including the consideration of the compressibility effect due to the compression and expansion of piston was also used. The case of 25 deg.(injection angle) which is opposite to scavenging flow direction shows better the distribution of droplets and the evaporation rate of droplets compared to other cases(0 deg., - 25 deg.). When injection pressure was increased, the spray tip penetration became longer. When injection pressure was increased, the interaction between the upward gas velocity and spray droplets strongly cause. Thus the breakup of droplets is strongly occurred and the evaporation rate of droplets was found to be better.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.852-859
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• 2000

The emission in the exhaust gas from diesel engine is effected by the fuel spray characteristics. The spray of D.I. diesel engine impinges on a piston cavity and a cylinder wall. It is very important to know exactly the distribution and behavior of the spray inside cylinder. The objective of this study is to develop more accurate evaporation model. The EPISO code was used to analyze the flow characteristics in the engine. The Wakil model and the Faeth model are applied to the EPISO code to analyze the behavior of impinging spray. And also experimental and numerical analysis were carried out. The spray behavior characteristics were investigated by changing injection pressure, ambient pressure and temperature. The behavior of impinging spray was strongly effected by the change of ambient pressure and temperature. The effects of evaporation and rebounding droplet should be considered.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.12
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• pp.979-985
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• 2007

Spray combustion characteristics of the conducting fuel electrospray has been studied for clean combustion technology. The electrospraying multiplexed system which can maintain the characteristics of the cone-jet mode is able to obtain charged micro droplets with high flow rate. In addition, they have monodisperse distribution during operating the electrospray in the cone-jet mode. The multiplexed grooved nozzle system with the extractor was applied to this experimental device set up. The stable grooved mode can be generated by the grooved nozzle and this electrospray system was applied to the diffusion combustion. It is the first step to discover the diffusion combustion characteristics of the electrospray, In case of the single grooved nozzle electrospray the diffusion flames are occurred at each Jet of grooved mode and they are quite stable. The exhaust gas analysis was indicated that there is the critical point which can make very stable diffusion combustion

• Clean Technology
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• v.25 no.1
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• pp.19-32
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• 2019

As regional air pollution gets worse by the sulfur oxides emitted from various types of vessels passing through the many countries, the International Maritime Organization establishes the emission control areas and regulates sulfur dioxide in those areas. In order to satisfy these regional regulations, the fuel selection method and the exhaust gas post-treatment device are applied to the ships. Due to the economic reasons, the post-treatment method of exhaust gas for reducing the amount of sulfur oxides discharged is mainly preferred. The scrubber which is dominantly used in the ships are the spray type system where the sprayed liquid drops used for capturing the soluble sulfur dioxides in the exhaust gas. The performance of the spray type system depends on the size distribution of the sprayed droplets. In order to evaluate this performance, we designed counterflow type scrubber and cyclone scrubber and evaluated the desulfurization efficiency and the amount of droplet evaporation according to the size of each droplet by using computational fluid dynamics. The Eulerian-Eulerian analysis method was used because the scrubber had a gas-liquid two-phase flow inside the scrubber. When the diameter of the droplet was $100{\mu}m$, $300{\mu}m$, $500{\mu}m$ and $700{\mu}m$. As a result, both of scrubbers showed high desulfurization efficiency and low evaporation amount at $500{\mu}m$ and $700{\mu}m$.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.72-79
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• 2000

In recent, occupational diseases in harmful working places become a social issue. It is the well-known fact that a respiration in polluted working places exert a serious effect on health of workers. Accordingly, the cutting off contaminants air originally is the best way to improve working environments. In these cases, ventilation systems should be essentially installed to dilute or exhaust the contaminated indoor air. In this study, we investigated the characteristics of ventilation system of the noxious gas in working indoor places with natural ventilation by using COMET. The numerical simulations were carried out the natural ventilation with two phase(air, dust). For turbulent flow, Reynolds stresses were closed by the standard $\kappa$-$\varepsilon$ model. The results are as follows ; 1) In the natural exhaust in the working place, the flows of the central region have a more rapid velocity vector than the right and left one. 2) Numerical results show that the distribution of contaminants concentration have greater influence on convection than the case of diffusion by government of velocity vectors. 3) To observe the velocity variation with distance, three location of distance are considered. As results, it shows that the velocity are 0.075(m/s) at y=5(m), 10(m) and mean concentration are raised 10.6% at y=5(m), 10(m). 4) We have presented the useful data for the adequate counterplan in the harmful working places by carrying out the various investigation of the natural ventilation.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.14-21
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• 2007

In order to enhance combustion efficiency, oxygen-enriched combustion is used by increasing the oxygen ratio in the oxidizer. However, since the flame temperature increases, NOx formation in the furnace seriously increases for low oxygen enrichment ratio. In this case, reburning is a useful technology for reducing nitric oxide. In this research, experimental studies have been conducted to evaluate the hybrid effects of reburning/selective non-catalytic reaction (SNCR) and reburning/air staging on NOx formation and also to examine heat transfer characteristics in various oxygen-enriched LPG flames. Experiments were performed in flames stabilized by a co-flow swirl burner, which were mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and NOx generation were observed to increase by low level oxygen-enriched combustion, but due to its hybrid effects of reburning, SNCR and Air staging, NOx concentration in the exhaust have decreased considerably.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.1
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• pp.41-48
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• 2014

A urea-SCR system suffers from some issues associated with the ammonia slip phenomenon, which mainly occurs because of the shortage of evaporation and thermolysis time, and this makes it difficult to achieve an uniform distribution of injected urea. A numerical study was therefore performed by changing such various parameters as installed injector angle and application and angle of mixer to enhance evaporation and the mixing of urea water solution with exhaust gases. As a result, various parameters were found to affect the evaporation and mixing characteristics between exhaust gas and urea water solution, and their optimization is required. Finally, useful guidelines were suggested to achieve the optimum design of a urea-SCR injection system for improving the DeNOx performance and reducing ammonia slip.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3125-3134
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• 2010

Three-way catalyst durability in the Korea requires 5 years/80,000km in 1988 but require 10 years/120,000km after 2002. Domestic three-way catalyst satisfies exhaust gas conversion efficiency or pressure drop etc. but don't satisfy thermal durability. Three-way catalyst maintains high temperature in interior domain but maintain low temperature on outside surface. This study evaluated thermal durability of three-way catalyst by thermal flow and structure analysis and the procedure is as followings. Thermal flow parameters ranges were determined by vehicle test and basic thermal flow analysis. Response surface for rear catalyst temperature was constructed using the design of experiment (DOE) for thermal flow parameters. Thermal flow parameters for rear catalyst temperature in vehicles examination were predicted by desirability function. Temperature distribution of three-way catalyst was estimated by thermal flow analysis for predicted thermal flow parameters.

• Journal of Power System Engineering
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• v.19 no.6
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• pp.68-74
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• 2015

NOx emission has been controlled because it is a major cause of the acid rain and effects considerably on formation and destruction of ozone. A SCR system on diesel engine is necessary to clear TierIII, because IMO(International Maritime Organization) plans on tightening regulations to TierIII at $1^{st}$ January 2016. In this study, flow analysis was accomplished with ANSYS Fluent program so that the SCR system would be retrofitted in training ship KAYA and the temperature distributions of exhaust gas in SCR sytem were investigated after it was installed. As a result, it was confirmed that pressure and velocity distributions in SCR system were depended on pipe line shapes, then it was designed as the pressure was lower. The temperature differential between 1 and 3 point was $15^{\circ}C$ because of evaporative latent heat of urea and the temperature of 4 point after catalyst was increased by $5^{\circ}C$ than 3 point because of exothermic reaction.