• 한국안전학회지
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• 제23권2호
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• pp.1-6
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• 2008

The present study investigates on improvement of inhalation efficiency of hood in ventilation system for elimination of industrial dust. The hood, one of local exhaust ventilation system, has an important function to inhale a pollution source such as harmful dust and industrial waste. In this study, in order to improve the inhalation efficiency of the industrial hood, a new device named "gas-guide-device" was attached to inside of hood. The thermal fluid commercial code "Phoenics ver 3.1" was used to analyze the flow velocity distribution at the hood inlet and around the hood after gas-guide-device was installed. And the flow velocity on each position inside and around the hood was actually measured using the hot wire type anemometer under the same condition as that of numerical analysis. Also, in order to identify the optimum shape of gas-guide-device, numerical analysis and experiments are performed under various conditions and their results are presented. The results of this study revealed that the hood attached with gas-guide-device was higher the inhalation efficiency than that for without one and can be possible to improve the capture velocity of the industrial dust. And the optimum shape of gas-guide-device was identified that the ratio of two sizes of gas-guide-device, X to Y, has 4 to 6 on the basis of the hood size in use and the width (b) of gas-guide-device.

• 해양환경안전학회지
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• 제23권5호
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• pp.541-548
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• 2017

본 연구에서는 해양플랜트설비 건조 현장에서 사용되고 있는 기존 고온 오일 플러싱 장비에 대한 성능개선을 위해 기존의 플러싱 장치에 사용되던 오일에 질소가스를 혼합한 고온 오일 플러싱 시스템에 대하여 국제표준화기구 코드(ISO code)를 기준으로 이론적 연구를 수행하였다. 연구를 위해 오일-질소가스 혼합유체 플러싱 시스템 공정을 설계 후 청정성능에 영향을 주는 혼합유체의 혼합비율, 온도, 레이놀즈수 및 액상분율 등에 대한 공정모사 결과도 분석하였다. 그 결과 관 직경과 가스상의 체적분률이 일정한 상태에서 혼합유체의 체적유량이 증가될수록 수평 유압배관 입출구의 액상분율 차이 ${\Delta}{\alpha}_L$ 값은 증가하게 되고 배관길이 방향의 위치에 따라 오일과 질소가스 기포 사이의 상분포가 달라짐을 확인했다. 이러한 상분포의 변화는 오일-질소가스 혼합유체 플러싱 시스템의 청정성능에도 커다란 영향을 줄 것으로 예상된다.

• 오토저널
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• 제13권2호
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• pp.67-87
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• 1991

The computer program which predicts the gas exchange process of multi-cylinder 4-Stroke cycle spark-ignition engine, can be great assistance for the design and development of new engine. In this study, the computer program was developed to predict the gas exchange process of multi-cylinder four stroke cycle spark ignition engine including intake and exhaust systems. When gas exchange process is to be calculated, the evaluation of the variation of the thermo-dynamic properties with time and position in the intake and exhaust systems is required. For the purpose, the application of the generalized method of characteristics to the gas exchange process is known as one of the method. The simulation model developed was investigated to the analysis of the branch system of multi-cylinder. The models used were the 2-zone expansion model and single zone model for in cylinder calculation and the generalized method of characteristic including area change, friction, heat transfer and entropy gradients for pipe flow calculation. The empirical constants reduced to least number as possible were determined through the comparison with the experimented indicator diagram of one particular operation condition and these constants were applied to other operating condition. The predicted pressures in cylinder were compared with the experimental results over the wide range of equivalence ratio and ignition timing. The predicted values have shown good agreement with the experimental results. The thermodynamic properties in the intake and exhaust system were predicted over the wide range of equivalence ratio and ignition timing. The obtained results can be summarized as follows. 1. Pressures in the exhaust manifold have a little influence on the equivalence ratio, a great influence on the ignition timing. 2. Pressures in the inlet manifold are nearly unchanged by the equivalence ratio and the ignition timing. 3. In this study, the behaviors of the exhaust temperature, gas in the exhaust manifold were ascertained.

• 해양환경안전학회지
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• 제28권2호
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• pp.385-393
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• 2022

수소는 지구 온난화의 주범인 온실가스(GHG) 배출을 감소시키고 선박용 친환경 연료로서 대두되고 있다. 수소는 가연 하한계(Lower Flammability Limit, LFL)가 4 ~ 75 %이고 폭발 위험성이 큰 물질이다. 그래서 선박용으로 사용되려면 누출에 대비한 안전성이 충분히 확보되어야 한다. 본 연구에서는 수소탱크 저장실에서 수소 누출이 발생한 경우, 급·배기구의 면적 변화가 환기 성능에 미치는 영향을 분석하였다. 급·배기구의 면적은 1A = 740 mm × 740 mm이며 저장실 표면에 크기 및 위치 변경이 쉽도록 설정하였다. CFD 상용 소프트웨어인 ANSYS CFX ver 18.1을 이용하여 급·배기구의 면적을 1A, 2A, 3A, 5A로 변경하였고, 면적 변화에 따른 저장실 내의 수소 몰분율을 분석하였다. 그 결과 급기구 면적이 배기구 면적 증가에 비해 누출 수소의 농도를 더 감소시켰으며 단일 급기구보다 최소 2A 이상에서 환기 성능이 향상되었다. 급기구의 면적이 증가할수록 수소 층화가 저장실 상부부터 균일하게 형성되었지만 LFL 범위는 벗어나 있었다. 그러나 배기구는 면적을 단순히 증가하는 것만으로는 환기 성능에 미치는 영향은 미비하였다.

• 융복합기술연구소 논문집
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• 제3권1호
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• pp.31-35
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• 2013

Unsteady fluid dynamics analysis of flow characteristics inside a Metal DPF system is done using a commercial CAE software, CFD-ACE+. The time profiles of both temperature and pressure of exhaust gas are given as initial conditions. It was found that the position of connecting pipes and the numbering of exhaust gases did not affect the flow uniformity. The presence of a DPF resulted in the significant flow nonuniformity effect on the flow characteristics at the inlet of the DPF. Present results can be applied to the selection of optimal geometry that produces uniform flow characteristics inside a DPF system.

• 한국대기환경학회지
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• 제12권2호
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• pp.131-139
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• 1996

The developent of ceramic combustor is being increased beca- use of the excellent physical properties of ceramic material, that is, high-resistant strength, high emissivity power and high corrosin-resistance. Ceramic combustor has been interested in the application of ultra-lean combustion for low NO$_{x}$ emission and gaseuos waste incineration with good combustion. This experimental study was conducted to investigate the combustion and emission characteristics of wall recess type ceramic combustor with equivalence ratio, mixture flow velocity and wall recess depth as parameters. The results in this study are as follows: 1. Wall recess played a important role to extend flame stability region. 2. The peak temperature of gas was peoportional to equivalence ratio, mixture flow velocity and wall recess depth. 3. The static pressure of mixing chamber and inlet temperature depended on the position of flame zone. 4. NO reduction was achieved by lean mixture without lower combustibility.y.

• 한국응용과학기술학회지
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• 제17권2호
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• pp.83-88
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• 2000

The VOCs(Volatile Organic Compounds) is one of the major cause for the atmosphere pollution. Breakthrough behavior of benzene and toluene in adsorption bed packed with activated carbon was experimentally studied. Composition and temperature of the gas flowing in the bed was measured and breakthrough curves for each component was obtained. Breakthrough time of benzene was earlier than that of toluene due to relatively weak adsorptivity. The relationship between breakthrough time and flow rate was obtained. The shape of temperature change with time was dependent on the position in the bed. Temperature changed faster and sharper in the inlet than in the outlet. It was noted that breakthrough behavior could be affected by the heat transfer properties.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.585-589
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• 2008

This study is performed to analyze the fluid flow about 150mm shower heads of semiconductor device. Under the air pressure, the ideal gas of moving fluid is injected as 5m/s velocity into inlet of shower heads and the flow distribution in shower heads is measured according to pitch of plasma distribution device. As results, the maximum and minimum value of fluid velocity are investigated with their position. The velocity values at outlet are also studied. From two experiment using the plasma distribution device, the results of CFD are compared with the experimental results. That results shows stable flow of fluid in that case of corrected design from CFD.

• 한국분무공학회지
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• 제9권2호
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• pp.9-17
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• 2004

The performance characteristics of lean burn system in gasoline engine are mainly affected by the air-fuel mixture in cylinder, gas exchange process of manifold system, exhaust emission of engine, and the electronic engine control system. In order to obtain the effect of performance factors on the optimum conditions of lean burn engine, this study deal with the behavior of mixture formation, gas flow characteristics of air, flow and evaporation analysis of spray droplet in cylinder, vaporization and burning characteristics of lean mixture in the engine, and the control performance of electronic engine control system. The optimum flow conditions were investigated with the swirl and tumble flows in the combustion chamber with swirl control valve. The performance characteristics and optimum condition of flow field in intake system were analyzed by the investigation of inlet flow of air and combustion stabilization on cylinder.

• Journal of Advanced Marine Engineering and Technology
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• 제40권10호
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• pp.916-921
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• 2016

It is possible for humans to breathe underwater using dissolved oxygen. However, unlike fish, humans need large amounts of oxygen to breathe underwater. Water generally contains small amounts of dissolved oxygen. To get enough dissolved oxygen from water, great volumes of it should be supplied into a separation device. If exhalation gases are used, the amounts of water supplied into the membrane can be decreased. However, the characteristics of exhalation gases after passage through the separation device need to be investigated. To reuse the exhalation gases, the concentration of carbon dioxide should be decreased. A compressor is needed to supply the exhalation gases because of the high pressure generated in the membrane inlet. However, compressors require a lot of power and are heavy, so it is not proper to get the portable separation device. A system without the compressor is needed. If the pressure of the position mixed from the exhalation is less than atmosphere, the compressor is not needed. In this thesis, characteristics of the gases which are mixed with exhalation gases and separated from water after passing the membrane are investigated. The compositions of carbon dioxide, oxygen, and nitrogen are measured with the gas chromatography. The effects of water and exhalation gas flow rates on characteristics of gases separated from water after the membrane are showed.