• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.165-172
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• 1999

Landfill gas has merely half heating value compared with liquified natural gas but can be greatly utilized as a commercial fuel. The authors have examined emission characteristics as well as measured burning velocity of LFG mixed gas which contains plenty of $CO_{2}$. With the viewpoint of fuel utilization, flame stability could be one of important characteristics of LFG. In this study, the comparison experiments are conducted between $CH_{4}$ and LFG for searching the region of flame stabilization based upon the flame blowout at maximum fuel stream velocity. As a result, it is found that stabilization region of LFG is not improved with that of $CH_{4}$ in non-swirl/or weak swirl jet diffusion flame. However, it is also known that flame stability is hardly affected by inert gas in the strong swirl with considering widened flame stabilization region of LFG rather than LNG.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.128-131
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• 2004

The composite mesoporous ceramic membranes were prepared with ${\gamma}$-alumina and poly (2, 6-dimethyl-l, 4-pyphenylene oxide) (PPO) on the surface of the macroporous $\alpha$-alumina ceramic membranes and the permeation results were compared with those of the $\alpha$-alumina membrane for large-scale applications. In the results of the transport experiments, the ceramic membranes gave high gas permeances mainly due to Knudsen diffusion and surface diffusion as an additional mechanism. And, the polymer modification increased the permeances of the strongly adsorbing gas components. In this study the modifications of alumina ceramic membranes could increase the gas permeation performances especially for the strongly absorbing gas components.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.207-210
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• 2005

In this paper, a two-dimensional cross-channel model was applied to investigate influence of the gas diffusion layer(GDL) property and flow field geometry in the anode side for proton exchange membrane fuel cell(PEMFC). The GDL is made of a porous material such as carbon cloth, carbon paper, or metal wire mesh. To the simplicity, the GDL is represented as a block of material containing numerous pathways through which gaseous reactants and liquid water can pass. The purpose of present work was to study the effect of the GDL thickness and the porosity, and flow field geometry by computational fluid dynamics(CFD)

• 설비공학논문집
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• 제27권5호
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• pp.241-246
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• 2015

Cellular foamed insulation such as polyurethane foam ages and degrades the thermal conductivity. Aging of foam is a result from the diffusion of gases, initially consisting of $CO_2$ but eventually replaced by air from the environment. The variation of the cell gas content with time is primarily influenced by the increase of thermal conductivity of the cellular foam. The weight of foam also changes as the gas diffuses and exchanges. In this study, a weight measurement method has been proposed to evaluate the effective diffusion coefficients of $CO_2$ and Air, $D_{CO2}=7.08504E-11$ and $D_{air}=4.86086E-12$, respectively and are compared with the gas analysis method.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.149-155
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• 2002

A promising new approach to achieve low pollutants emission and improvement of flame stabilities is tested experimentally using a hybrid cyclone jet combustor employing both premixed and diffusion combustion mode, Three kind of nozzles are used for LNG(Liquified Natural Gas) as a fuel. The combustor is operated by two method, One is ATI(Air Tangential Injection) mode, generated swirl flow by air as general swirl combustor, and the other is PTI(Premixed gas Tangential Injection) mode, The PTI mode consists of diffusion flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion flame. The results showed that the stable region of the PTI mode is more larger than the ATI mode. In addition, the reduction of NOx emission in PTI mode, as compared with that for the ATI mode is at least 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, the cyclone jet combustor has high performance of flame stability.

• 분석과학
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• 제8권4호
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• pp.683-689
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• 1995

Electrochemical reduction of carbon dioxide under high pressure on Fe electrodes and a gas diffusion electrode containing Pt catalyst (Pt-GDE) had been investigated. Formic acid was formed on Fe electrode with a faradaic efficiency of 60% at a current density of $120mA\;cm^{-2}$ under 30 atm of $CO_2$. Hydrocarbons such as $CH_4$, $C_2H_6$, $C_3H_6$, $1-C_4H_8$, and $n-C_5H_{12}$ are also formed. The distribution of hydrocarbons followed well the Schultz-Flory distribution. $CH_4$ was formed efficiently as the main reduction product on Pt-GDE.

• 멤브레인
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• 제27권2호
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• pp.167-181
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• 2017

그래핀 기반 소재는 높은 가공성과 초박성으로 인하여 분리막 소재로서 각광받고 있다. 본 연구에서는, 스핀 코팅법을 이용하여 제조된 산화그래핀 분리막의 기체 투과 거동을 평가하였다. 산화그래핀 분리막의 구조는 산화그래핀의 크기와 산화그래핀 용액의 pH 조절을 통하여 조절될 수 있다. 산화그래핀의 크기가 작을수록 굴곡률이 작아짐에 따라 분리막의 기체 투과도 및 선택도가 증가하는 경향을 보인다. 또한 산화그래핀에서의 기체 투과 거동은 적층된 산화그래핀 사이의 채널크기에 따라 영향을 받는다. 특히 산화그래핀 분리막의 좁은 기공과 이산화탄소 선택적인 산화그래핀 자체의 특성으로 인하여 산화그래핀 분리막은 이산화탄소에 대한 높은 투과도 및 선택성을 가지며, 이는 이산화탄소 포집에 적합한 특성을 가진다. 이러한 산화그래핀 분리막의 특이한 기체 투과 거동은 흡착-촉진 확산 거동(표면 확산 기작)으로 설명될 수 있다. 본 연구를 통하여 이산화탄소 선택성 분리막 소재 설계와 슬릿 형태의 기공과 적층 구조를 가진 분리막을 통한 기체 투과 거동 연구가 활발히 이루어질 것으로 기대한다.

• 한국유체기계학회 논문집
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• 제12권1호
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• pp.16-21
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• 2009

In the last five years, 91 accidents from portable gas ranges and non-refillable metallic gas cartridges have occurred. The gas cylinder installed with a relief valve was developed to prevent an explosive accident from the gas cartridge. In this study it was carried out to evaluate the safety of a gas cylinder mounted with a relief valve which can prevent an explosion. Under the real using condition and the extreme condition the gas cylinder is heated with an electric heater. Simultaneously, the operating pressure is checked and the suitability of releasing flux is evaluated. And the possibility of fire or explosion was tested when the gas was released from the relief valve at the real using condition. Using a numerical simulation method, the diffusion of butane gas released from a relief valve was visualized.

• 대한기계학회논문집B
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• 제37권8호
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• pp.767-773
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• 2013

본 연구는 높은 압력으로 체결되어 있는 고분자전해질연료전지(PEMFC) 스택의 구성부품중 가장 크게 변형되는 가스확산층(GDL)의 공극률과 기체투과율의 변화를 제시하였다. 압축하중에 따른 체적변화를 실험을 통하여 측정하고 기존에 제시된 관계식을 이용하여 공극률과 기체투과율의 변화을 예측하였다. 또한 물의 배출을 향상시키기 위하여 첨가되는 PTFE 가 압축상태의 GDL 의 공극률과 기체투과율에 미치는 영향을 연구하였다. 물질전달에 직접 영향을 미치는 기체투과율은 PTFE 가 많이 포함된 GDL에서 급격하게 감소하였다. 결과적으로 같은 압축하중으로 체결하는 경우 GDL 의 PTFE 함량에 따라서 공극네트워크를 통한 물질전달은 크게 달라질 수 있다. 본 결과를 이용하면 GDL 에서의 전달현상에 대한 개선된 상관식을 개발할 수 있고 그로 인하여 모델링의 정확성을 향상시킬 수 있다.

• 한국해양공학회지
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• 제28권6호
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• pp.517-526
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• 2014

The leakage of cryogenic LNG through cracks in the insulation membrane of an LNG carrier causes the hull structure to experience a cold spot as a result of the heat transfer from the LNG. The hull structure will become brittle at this cold spot and the evaporated natural gas may potentially lead to a hazard because of its flammability. This paper presents a computational model for the LNG flow and heat diffusion in an LNG insulation panel subject to leakage. The temperature distribution in the insulation panel and the speed of gas diffusion through it are simulated to assess the safety level of an LNG carrier subject that experiences a leak. The behavior of the leaked LNG is modeled using a multiphase flow that considers the mixture of liquid and gas. The simulation model considers the phase change of the LNG, gas-liquid multiphase interactions in the porous media, and accompanying rates of heat transfer. It is assumed that the NO96-GW membrane storage is composed of glass wool and plywood for the numerical simulation. In the numerical simulation, the seepage, heat diffusion, and evaporation of the LNG are investigated. It is found that the diffusion speed of the leakage is very high to accelerate the evaporation of the LNG.