• Journal of Hydrogen and New Energy
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• v.18 no.2
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• pp.171-181
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• 2007

Blending effects of hydrogen and water vapor on flame structure and NOx emission behavior are numerically studied with detailed chemistry in methane-air counterflow diffusion flames. The composition of fuel is systematically changed from pure methane and pure hydrogen to the blending fuels of methane-hydrogen-water vapor through the molar addition of $H_2O$. Flame structure is changed considerably for hydrogen-blending methane flames and hydrogen-blending methane flames diluted with water vapor in comparison to pure methane flame. These complicated changes of flame structures also affect NOx emission behavior considerably. The changes of thermal NO and Fenimore NO are analyzed for various combinations of the fuel composition. Importantly contributing reaction steps to thermal NO and Fenimore NO are addressed in pure methane, hydrogen-blending methane flames, and hydrogen-blending methane flames diluted with water vapor.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1116-1123
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• 2021

Oil spilled in seawater undergoes physical and chemical changes as well as biological degradation through various weathering processes, such as evaporation, diffusion, dispersion, emulsification, dissolution, oxidation, and sedimentation. Evaporation is one of the most immediate and prompt weathering processes, and it has the greatest influence on majority of pollutants. In this study, the evaporation characteristics of different oil samples were studied; the volatilization characteristics of gasoline, kerosene, and diesel were compared at average seawater (25 ℃) and near-equator (35 ℃) temperatures. The oil samples were pre-treated and then collected at regular intervals. Gas chromatography-mass spectrometry analysis was performed, and the changes in the amount of the hydrocarbons were calculated.

• Journal of Hydrogen and New Energy
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• v.21 no.6
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• pp.513-518
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• 2010

In the present work the second-order perturbation solutions of the simple physical model for liquid pool spreading is obtained for the case of instantaneous spill. To generalize the solution governing equations are non-dimensionalized, and two dimensionless parameters, dimensionless evaporation rate and aspect ratio of the initial pool, are identified to control the governing equations. The dimensional governing equations have three parameters. The second-order solution improves fairly the first-order solution for the pool volume.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.937-944
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• 2004

An experimental study has been conducted to evaluate the effects of $CO_2$ on heat transfer from oxygen-enriched hydrogen flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which was mounted on top of the furnace. Five different oxidizer compositions were prepared by replacing $N_2$ with $CO_2$. In a steady state, the total as well as radiative heat flux from the flame to the wall of furnace have been measured using a heat flux meter. Temperature distribution in furnace also has been measured and compared. By increasing $CO_2$ proportion in the oxidizer, the convection played a more significant role rather than radiation. Overall temperature in the furnace was seen to be decreased, while the total heat flux has increased.

• The Safety technology
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• no.198
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• pp.26-28
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• 2014

2년 전인 지난 2012년 9월 27일 경북 구미4공단에 소재한 휴브글로벌에서 불화수소가 누출되는 사고가 발생했다. 이 사고로 근로자 5명이 사망하고 23명이 부상을 당했다. 사고 후 불화수소가 공기를 통해 대량 퍼지면서 인근 지역도 막대한 피해를 입었다. 사고는 안전관리측면에서 많은 허점을 드러냈다. 사업장은 물론 관할 소방서, 구미시 모두에서 화학사고에 대한 대응 매뉴얼과 협조체계가 제대로 구축되지 않아 피해의 확산을 막지 못했다. 너무나 허술한 화학사고 대응체계의 현실에 구미시민은 물론 전 국민이 분노했다. 이에 정부는 화학물질관리 및 사고대응 시스템 전면에 대한 대대적인 개선에 돌입했다. 그리고 그 결과물이 지난해 12월 초 모습을 드러냈다. 관계부처, 지자체, 소방당국, 안전보건공단까지 한데 모여 효과적인 화학사고 예방과 대응을 전담하는 화학재난 합동방재센터가 전국에서 처음으로 구미에 문을 연 것이다. 그로부터 반년이 흐른 지금 구미에는 어떤 변화가 생겼을까. 달라진 화학재난 안전관리체계를 확인해보고자 구미119화학구조센터를 찾아가봤다.

• The Magazine of the IEIE
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• v.30 no.1
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• pp.43-49
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• 2003

이동 전자기기 혹은 이동 전원에 적용 가능한 휴대용 Fuel Cell에 필요한 재료는 놀은 전력을 요구하는 주택용이나 무공해 자동차용 및 대형발전 장비용 Fuel Cell과는 다르게 이해되어야 한다. 휴대용 Fuel Cell은 상온, 상압에서 작동되어야 하고 Fuel Cell의 효율을 높이기 위한 여러가지 주변 장치들이 제거 혹은 소형화 되어야 하므로, 이러한 열악한 조건에 적합한 재료의 개발이 필수적이다. 본 논문에서는 휴대용 Fuel Cell이 요구하는 촉매층, 확산전극, 수소이온 전도막 재료 및 Stack 혹은 Cell Pack의 개념에 대해 설명하고자 하며, 본 연구소에서 개발한 소형 PEMFC(MEA : 400㎽/㎠-무가습 수소/공기, 1 Bar, 30℃, Membrane: 0.1S/㎝; Stack : 40W)와 소형 DMFC (MEA : 50㎽/㎠-5M 메탄올 Passive, 상온 ; MEA : 100㎽/㎠ 2M 메탄올-Active, 1Bar, 상온 ; Membrane : Hybrid : Cell Pack : 2W)와 관련한 기술내용 및 상용화 전망에 대하여 언급하였다.

• Journal of ILASS-Korea
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• v.15 no.4
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• pp.182-188
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• 2010

Significant real fluid behaviors including rapid property changes take place where high pressure combustion devices such as rocket engines. The flamelet model is the reliable approach to account for the real fluid effects. In the present study, the flamelet equations are extended to treat the general fluids over transcritical and supercritical states. The real fluid flamelet model is carried out for the gaseous hydrogen and cryogenic liquid oxygen flames at the wide range of thermodynamic conditions. Based on numerical results, the precise discussions are made for effects of real fluid, pressure, and differential diffusion on the local flame structure.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.58-59
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• 1995

기체 분리용 무기분리막은 고분자막과 비교하여 열 및 구조적 안정성이 우수하므로, 석탄가스화반응 혼합기체중의 기체분리 등 고온 또는 고압공정에 적합한 분리방법으로서 주목되고 있다. 기체의 분리를 위한 무기재료막은 크게 다공성막과 비다공성막으로 나눌 수 있으며, 이 중 비기공 성막의 경우 높은 선택도를 가지나 투과도가 낮아 경제성이 떨어지는 것으로 평가되고 있다. 한편, 기존의 다공성막의 경우 투과도는 높으나 기체의 분리가 혼합기체중 각 기체의 분자량의 차이에 의존하는 Knudsen 확산에 제한되는 낮은 선택도를 갖는 단점이 있다. 따라서 다공성막의 기공을 특정기체의 선택도가 우수한 촉매물질등으로 개선하여 비기공성막에 비해 우수한 투과도를 갖고, 기공성막에 비해 향상된 선택도를 보이는 복합막의 연구가 활발히 추진되고 이\ulcorner. 본 연구는 솔젤법에 의해 제조된 팔라듐 함침 알루미나 지지막의 기공을 침투$\cdot$증착(Soaking and Vapor-deposition)법에 의해 개선하여 기체의 투과도를 높게 유지하면서 수소의 선택성을 향상시키는 것을 목적으로 하였다.

• Journal of Hydrogen and New Energy
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• v.14 no.3
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• pp.195-206
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• 2003

Polymer electrolyte membrane fuel cells(PEMFC) are very interesting power source due to high power density, simple construction and operation at low temperature. But they have problems such as high cost, improvement of performance and effect of temperature. This problems can be approached using mathematical models which are useful tools for analysis and optimization of fuel cell performance and for heat and water management, in this paper, transient model consists of various energy terms associated with fuel cell operation using the mass and energy balance equation. And water transfer in the membrane is composed of back diffusion and electro-osmotic drag. The temperature calculated by transient model approximately agreed with the temperature measured by experiment in constant current condition.

• Journal of Hydrogen and New Energy
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• v.27 no.3
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• pp.264-269
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• 2016

A simple dry chemical approach was developed in order to load palladium (Pd) as a promoter on Pt/gas diffusion electrode (GDE) for polymer electrolyte membrane fuel cell (PEMFC). Palladium(II) bis (acetylacetonate), $Pd(acac)_2$ was sublimed, penetrated into Pt/GDE and then reduced to Pd nanoparticles simultaneously without any reducing agent and any solvent in a glass reactor of $N_2$ atmosphere at $180^{\circ}C$ for 3, 5 and 15 min. Pd distribution was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), and I-V curve was estimated by using a unit cell with $5{\times}5cm^2$ active area.