• 항공우주시스템공학회지
• /
• 제11권2호
• /
• pp.9-15
• /
• 2017

제올라이트 촉매를 이용한 에탄올의 연소 성능 향상 가능성과 질소산화물 및 일산화탄소 배출 특성을 검증하기 위해 촉매 반응 생성물, 에탄올, 케로신을 연료로 사용하여 마이크로 가스터빈 엔진 구동실험을 수행하고 그 결과를 비교하였다. 촉매 반응 생성물의 추력은 케로신의 추력보다 낮았으나 에탄올을 사용했을 때에 비해 평균적으로 5% 정도 향상되었다. 촉매 반응 생성물의 질소산화물과 일산화탄소 배출량은 전반적으로 케로신에 비해 매우 낮게 측정되었다. 결론적으로 제올라이트 촉매를 이용하여 에탄올을 개질하는 경우, 에탄올의 친환경성을 유지하면서 엔진성능을 개선할 수 있는 가능성을 확인하였다.

• 한국가스학회지
• /
• 제5권1호
• /
• pp.45-51
• /
• 2001

촉매연소는 근래 들어 산업용 및 가정용의 다양한 분야에 적용되고 있는 환경친화적인 기술로서 본 연구는 고온용 촉매제조기술과 촉매연소기 개발을 중점적으로 수행하여 이를 상용화된 콘덴싱 보일러에 적용하는 데 그 목표를 두었다. 고온용 촉매로는 귀금속 팔라듐(Pd)을 사용하여 담체인 알루미나$(Al_{2}O_{3})$와 지르코니아$(ZTO_{2})$에 일정 중량비로 담지하였고, 천연가스 연소시 촉매의 활성을 비긴 분석하였다. 그 결과 $Pd/Al_{2}O_{3}\;=\;4$가 활성이나 내구성에서 우수한 것으로 나타났다. 그리고 기존의 콘덴싱 보일러에 적용되고 있는 판형 연소기(Plate-type combustor)를 시험모델로 촉매성능 및 연소성능을 파악하였고, 이를 토대로 연소면적을 증가시킨 원통형 촉매연소기(Cylindrical-type catalyst combustor)를 개발하였다. 또한, 원통형 촉매연소기를 적용한 콘덴싱 보일러의 촉매연소 성능실험을 통하여 결정한 노즐 5.95mm와 오리피스 21mm로 최적의 연소상태를 갖는 25,000 kcal/hr 촉매연소식 콘덴싱 보일러를 개발하였다.

• 한국자동차공학회논문집
• /
• 제8권6호
• /
• pp.40-50
• /
• 2000

In this study, as a means of increasing engine power, turbocharging was applied to the gasoline engine of a light passenger car which was originally naturally aspirated. Also the catalytic convertor was applied to improve the exhaust emission characteristics. The comparison of the performance characteristics between the burbocharged engine with catalytic convertor and the naturally aspirated engine was made over the wide range of operating conditions. The results showed considerable increase of the output performances at full load condition by trubocharging while slight losses were observed at part load conditions.

• 한국수소및신에너지학회논문집
• /
• 제31권5호
• /
• pp.444-452
• /
• 2020

This study investigated the cathode catalyst of direct borohydride/hydrogen peroxide fuel cells for space exploration. Various catalysts such as Au, Ag, and Ni were supported on multiwalled carbon nanotubes (MWCNTs). Various techniques, such as transmission electron microscopy, Brunauer-Emmett-Teller method, scanning electron microscopy, and X-ray diffraction were conducted to investigate the characteristics of the catalysts. Fuel cell tests were performed to evaluate the performance of the catalysts. Ag/MWCNTs exhibited better catalytic activity than the Ni/MWCNTs and better catalytic selectivity of the Au/MWCNTs. Ag/MWCNTs presented good catalytic activity and selectivity even at an elevated operating temperature. The performance of Ag/MWCNTs was also stable for up to 60 minutes.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.49-54
• /
• 2006

The present study conducted a numerical modeling on the diesel SCR (selective catalytic reduction) system using ammonia as a reductant over vanadium-based catalysts $(V_2O_5-WO_3/TiO_2)$. Transient modeling for ammonia adsorption/desorption on the catalyst surface was firstly carried out, and then the SCR reaction was modeled considering for it. In the current catalytic reaction model, we extended the pure chemical kinetic model based on laboratory-scale powdered-phase catalyst experiments to the chemico-physical one applicable to realistic commercial SCR reactors. To simulate multi-dimensional heat and mass transfer phenomena, the SCR reactor was modeled in two dimensional, axisymmetric domain using porous medium approach. Also, since diesel engines operate in transient mode, the present study employed an unsteady model. In addition, throughout simulations using the developed code, effects of space velocity on the DeNOx performance were investigated.

• Carbon letters
• /
• 제28권
• /
• pp.105-110
• /
• 2018

Owing to their scalability, flexible operation, and long cycle life, vanadium redox flow batteries (VRFBs) have gained immense attention over the past few years. However, the VRFBs suffer from significant polarization, which decreases their cell efficiency. The activation polarization occurring during vanadium redox reactions greatly affects the overall performance of VRFBs. Therefore, it is imperative to develop electrodes with numerous catalytic sites and a long cycle life. In this study, we synthesized heteroatom-rich carbon-based freestanding papers (H-CFPs) by a facile dispersion and filtration process. The H-CFPs exhibited high specific surface area (${\sim}820m^2g^{-1}$) along with a number of redox-active heteroatoms (such as oxygen and nitrogen) and showed high catalytic activity for vanadium redox reactions. The H-CFP electrodes showed excellent electrochemical performance. They showed low anodic and cathodic peak potential separation (${\Delta}E_p$) values of ~120 mV (positive electrolyte) and ~124 mV (negative electrolyte) in cyclic voltammetry conducted at a scan rate of $5mV\;s^{-1}$. Hence, the H-CFP-based VRFBs showed significantly reduced polarization.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.120-127
• /
• 2017

로켓 등급의 고농도 과산화수소는 촉매 분해를 통해 높은 온도의 산소와 수증기를 발생하며, 이와 같은 성질을 이용하여 우주 추진 기술로 사용된 바 있다. 본 연구에서는 과산화수소의 촉매 분해를 이용한 수중 추진 시스템 관련 문헌 조사 및 개념 설계를 진행했다. 과산화수소 분해 가스를 분사하는 분사기 설계의 경우 로켓 노즐 설계 방식과 유사하게 진행했으며, 두 종류의 형태로 엔진 설계를 진행했다. 환형의 형태의 가스 분사기를 갖는 엔진을 제작하여 수중 환경에서 작동 시험을 수행했으며, 엔진 노즐 출구의 면적에 따른 성능 변화를 관찰했다. 향후 중앙에서 가스를 분사하는 방식의 엔진을 제작하여 성능 평가를 수행할 예정이다.

• 한국환경과학회지
• /
• 제15권3호
• /
• pp.221-227
• /
• 2006

Oxidative TCE decomposition over $TiO_2$-supported single and complex metal oxide catalysts has been conducted using a continuous flow type fixed-bed reactor system. Different types of commercial $TiO_2$ were used for obtaining the supported catalysts via an incipient wetness technique. Among a variety of titanias and metal oxides used, a DT51D $TiO_2\;and\;CrO_x$ would be the respective promising support and active ingredient for the oxidative TCE decomposition. The $TiO_2-based\;CrO_x$ catalyst gave a significant dependence of the catalytic activity in TCE oxidation reaction on the metal loadings. The use of high $CrO_x$ contents for preparing $CrO_x/TiO_2$ catalysts might produce $Cr_2O_3$ crystallites on the surface of $TiO_2$, thereby decreasing catalytic performance in the oxidative decomposition at low reaction temperatures. Supported $CrO_x$-based bimetallic oxide systems offered a very useful approach to lower the $CrO_x$ amounts without any loss in their catalytic activity for the catalytic TCE oxidation and to minimize the formation of Cl-containing organic products in the course of the catalytic reaction.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 제33회 추계학술대회논문집
• /
• pp.74-77
• /
• 2009

본 연구에서는 과산화수소/케로신 촉매 점화기의 최적 설계를 위하여 점화기 설계와 운용 조건에 따른 점화 특성을 확인하였다. 그 결과 촉매대의 출구 면적은 분해된 가스가 쵸킹이 발생하지 않도록 충분하여야 하며, 케로신은 촉매대 중앙에서 미립화가 잘되도록 분무하여야 함을 확인하였다. 또한 점화기를 운용하는데 있어 예열이 없을 경우 과산화수소를 약 3초 정도 리드해야 하며, 퍼지는 케로신 공급과 같거나 늦게 공급하는 것이 바람직함을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 추계학술대회 초록집
• /
• pp.92.1-92.1
• /
• 2011

Anode off-gas of high temperature fuel cells such as MCFC contains a significant amount of combustible components like hydrogen, carbon monoxide and methane according to fuel utilization ratio of the fuel cell stack. Thus, it is important to fully burn anode off-gas and utilize the generated heat in order to increase system efficiency and reduce emissions as well. In the present study, 25 kW catalytic combustor has been developed for the application to a load-following 300kW MCFC system. Mixing and combustion characteristics have been experimentally investigated with the catalytic combustor. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study has been focused on the experimental investigation on the combustion characteristics of multiple catalysts having different structures and compositions. Results show that the exhaust emissions are highly dependent on the catalyst loading and the ratio of catalytic components. Test results at load-following conditions are also shown in the present study.