• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.205-214
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• 2002

The reaction of gas-phase atomic hydrogen with hydrogen atoms chemisorbed on a silicon surface is studied by use of the classical trajectory approach. Especially, we have focused on the mechanism changes with the hydrogen surface coverage difference. On the sparsely covered surface, the gas atom interacts with the preadsorbed hydrogen atom and adjacent bare surface sites. In this case, it is shown that the chemisorption of H(g) is of major importance. Nearly all of the chemisorption events accompany the desorption of H(ad), i.e., adisplacement reaction. Although much less important than the displacement reaction, the formation of $H_2(g)$ is the second most significant reaction pathway. At gas temperature of 1800 K and surface temperature of 300 K, the probabilities of these two reactions are 0.750 and 0.065, respectively. The adsorption of H(g) without dissociating H(ad) is found to be negligible. In the reaction pathway forming $H_2$, most of the reaction energy is carried by $H_2(g)$. Although the majority of $H_2(g)$ molecules are produced in sub-picosecond, direct-mode collisions, there is a small amount of $H_2(g)$ produced in multiple impact collisions, which is characteristic of complex-mode collisions. On the fully covered surface, it has been shown that the formation of $H_2(g)$ is of major importance. All reactive events occur on a subpicosecond scale, following the Eley-Rideal mechanism. At gas temperature of 1800 K and surface temperature of 300 K, the probability of the $H_2(g)$ formation reaction is 0.082. In this case, neither the gas atom trapping nor the displacement reaction has been found.

• 한국수소및신에너지학회논문집
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• 제28권2호
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• pp.174-180
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• 2017

Recently, the world faces the environmental problem such as air pollution due to harmful gas discharged from car and abnormal climate due to the green-house gases increased by the discharge of $CO_2$. Compressed Natural Gas (CNG), one of alternative for this problem, is less harmful, compared to the existing fossil fuel, as gaseous fuel, and less carbon in fuel ingredients and carbon dioxide generation rate relatively favorable more than the existing fuel. However, CNG fuel has the weakness of slow flame propagation speed and difficult fast burn. On the other hand, hydrogen does not include carbon in fuel ingredients, and does not discharge harmful gas such as CO and HC. Moreover, it has strength of quick burning velocity and ignition is possible with small ignition energy source and it's has wide Lean Flammability Limit. If using this hydrogen with CNG fuel, the characteristics of output and discharge gas is improved by the mixer's burning velocity improved, and, at the same time, is possible to have stable lean combustion with the reduction of $CO_2$ expected. Therefore, this research tries to identify the characteristics of engine and emission gas when mixing CNG fuel and hydrogen in each portion and burning them in spark igniting engine, and grasp the lean combustion limit and emission gas characteristics according and use it as the basic data of hydrogen-CNG premixed engine.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.203-206
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• 2005

The objective of study on composite cylinder for alternative fuel vehicle is to develop safe, efficient, and commercially viable, on-board fuel storage system for the fuel cell vehicle or natural gas vehicle that use highly compressed gaseous fuel such as hydrogen or natural gas. This study presents the whole procedure of development and certification of a type 3 composite cylinder of 207bar service pressure and 70 liter water capacity, which includes design/analysis, processing of filament winding, and validation through various testing and evaluation. Design methods of liner configuration and winding patterns are presented. Three dimensional, nonlinear finite element analysis techniques are used to predict burst pressure and failure mode. Design and analysis techniques are verified through burst and cycling tests. The full qualification test methods and results for validation and certification are presented.

• 한국대기환경학회지
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• 제16권1호
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• pp.61-68
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• 2000

Gas-phase hydrogen peroxide(H2O2) concentrations were measured to investigate it's distribution in the ambient air in downtown Seoul(Kwanghwamum and Mullae-dong). These measurements were made during four season, from April 30, 1998 to January 29, 1999, using Cold Trap and HPLC. Measurements were also made of other photochemical oxidants and trace gases(O3, NO2, CO and SO2) and meteorological parameters(relative humidity, temperature, solar radiation and wind speed). The mean of all observations was 0.10 ppbv and the range measured was below the level of detection(>0.01 ppbv) to 0.47ppbv. The higher seasonal mean concentrations showed during the summer(0.21 ppbv) and concentrations of H2O2 showed a diurnal variation with maximum concentrations in the afternoon(12:30∼14:00). The results from the corrrelation analysis showed that the concentration of gaseous H2O2 is strongly dependent on the other air pollutants(NO2, CO and O3) and meteorological parameters(relative humidity, temperature and solar radiation.)

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2000년도 춘계학술대회 논문집
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• pp.110-111
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• 2000

대기중 가스상 $H_2O_2$(Hydrogen Peroxide)는 액상 화학반응과 기상 라디칼반응사이에 연결고리의 역할을 할 뿐만 아니라, 대기중의 $SO_2$를 $H_2SO_4$로 산화시키는 산화제로서 구름, 안개, 이슬 및 빗물의 산화에 중요한 역할을 담당한다. 또한 가스상 $H_2O_2$는 연쇄종결자와 $HO_2$.(hydroperoxyl radical)농도의 지표로서 광화학 스모그에 있어 중요한 화학종이기도 하다. $H_2O_2$농도의 증가는 결국 대기의 산화율 및 속도를 증가시키고 대류권내의 액상중에서 $H_2SO_4$ 생성을 가속화시킨다는 것은 이미 잘 알려져 있는 사실이다. (중략)

• 대한화학회지
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• 제7권2호
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• pp.115-121
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• 1963

Aliphatic hydrocarbon gases from rubber pyrolysis have been identified by gas chromatography with tetraethyleneglycol dimethylether column. Rubbers used in this work are polyisoprene, SBR, NBR, polybutadiene, buthyl rubber, polychloroprene and polyurethane rubber. The chromatogram is characteristic for each polymer. Author proposes a method of identification of synthetic rubbers by gas chromatograph of pyrolyzed gas. Sample is pyrolyzed at $450^{\circ}C$ under nitrogen or more effectively helium and gaseous portion, which eliminated liquid condensate, is passed to the column. The appearance of exclusively large peak of isoprene, isobutylene and carbon dioxide shows the presence of polyisoprene, polyisobutylene and polyurethane, respectively. Large peak of butadiene will appear in case of polybutadiene, SBR and NBR, but SBR can be identified through the styrene peak in gas chromatogram of liquid pyrolyzate and NBR can be identified by the evolution of hydrogen cyanide during pyrolysis. Polychloroprene is identified by the evolution of hydrogen chloride. This method could be applied to the identification of copolymer or polymer blend.

• 한국추진공학회지
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• 제25권6호
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• pp.1-11
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• 2021

층류화염편 라이브러리에 대한 효율적인 계산과정을 개발하기 위하여 초임계 압력조건의 기체수소/액체산소 연소기에 대해 인공신경망을 이용한 기계학습과정이 적용되었다. 학습성능과 계산효율성에 근거한 최적의 계산과정을 찾기 위하여 은닉층에 대한 ReLU와 쌍곡탄젠트 함수의 25가지 조합이 선택되었다. 정확성이 우수한 높은 학습성능을 얻는데 쌍곡탄젠트 활성화함수가 적절하였다. 인공신경망의 학습성능을 개선하기 위해서 학습데이터 변환이 제안되었다. 4개의 은닉층에 최적의 노드를 배치할 때 학습성능 및 계산비용 관점에서 모두 효율적인 것으로 나타났다. 층류화염편 라이브러리의 보간법보다 인공신경망을 사용하는 경우 전체 계산시간은 37%, 시스템 메모리는 99.98% 감소되었다.

• 한국항공우주학회지
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• 제36권11호
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• pp.1094-1103
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• 2008

수소나 탄화수소 계열 연료의 비정상 연소에 의해 발생된 데토네이션 파와 같은 이동 하중이 특정한 속도로 파이프 내부에서 전파하는 경우를 고려한다. 파이프 내부를 통과하는 데토네이션 파의 속도는 굽힘파의 활성화 정도와 큰 변형을 일으키는 공진이 발생할 가능성을 결정한다. 본 연구에서는 데토네이션 파가 파이프 내부를 통과할 때의 변위의 이론적해와 공진현상이 일어날 조건을 설명하였다. 또한 이론적 결과를 다중물질간의 간섭을 고려한 DNS를 통하여 이론의 정당성을 증명하였다. 이 정당성을 기반으로 하여 보다 더 실제적인 상황에서 일어날 수 있는 경우에 대하여 고려하였다. 본 연구의 결과를 바탕으로 일반적인 원자력, 화학, 설비 산업에서 발생할 수 있는 수소나 탄화수소 관련 폭발에 의한 사고들을 예방할 수 있을 것으로 기대된다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.237-240
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• 2002

Micro catalytic reactors are alternative propulsion device that can be used on a nano satellite. When used with a monopropellant, $H_2O_2$, a micro catalytic reactor needs only one supply system as the monopropellant reacts spontaneously on contact with catalyst and releases heat without external ignition, while separate supply lines for fuel and oxidizer are needed for a bipropellant rocket engine. Additionally, $H_2O_2$ is in liquid phase at room temperature, eliminating the burden of storage for gaseous fuel and carburetion of liquid fuel. In order to design a micro catalytic reactor, an appropriate catalyst material must be selected. Considering the safety concern in handling the monopropellants and reaction performance of catalyst, we selected hydrogen peroxide at volume concentration of 70% and perovskite redox catalyst of lantanium cobaltate doped with strondium. Perovskite catalysts are known to have superior reactivity in reduction-oxidation chemical processes. In particular, lantanium cobaltate has better performance in chemical reactions involving oxygen atom exchange than other perovskite materials. In the present study, a process to prepare perovskite type catalyst, $La_{0.8}Sr_{0.2}CoO_3$, and measurement of its propellant decomposition performance in a test reactor are described.

• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1737-1743
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• 2002

We have studied the dynamics of energy-rich hydrogen molecules produced on a graphite surface through H(g) + H(ad)/C(gr) → $H_2$ + C(gr) at thermal conditions mimicking the interstellar medium using a classical trajectory procedure. The recombination reaction of gaseous H atom at 100 K and the adsorbed H atom on the interstellar graphite grains at 10 K efficiently takes place on a subpicosecond time scale with most of the reaction exothermicity depositing in the product vibration, which leads to a strong vibrational population inversion. The molecules produced in nearly end-on geometry where H(g) is positioned below H(ad) rotate clockwise and are more highly rotationally excited. but in low-lying vibrational levels. The rotational axis of most of the molecule rotating clockwise is tilted from the surface normal by more than 30°, the intensity peaking at 35°. The molecules produced when H(ad) is close to the surface rotate counter-clockwise and are weakly rotationally excited, but highly vibrationally excited. These molecules tend to align their rotational axes parallel to the surface. The number of molecules rotating clockwise is eight times larger than that rotating counter-clockwise.