• Journal of Advanced Marine Engineering and Technology
• /
• 제26권5호
• /
• pp.554-564
• /
• 2002

A newly designed combustion chamber of diesel engine with a modified piston crown was prepared for the purpose of investigation for reduction of NO emission. It was intended to realize 2-stage combustion that is to keep fuel rich condition during early stage of combustion and fuel lean condition during next stage. The engine was tested on various conditions concerning exhaust gas emissions especially about NO emission and simultaneously fuel consumption rate. It was found that the engine with 2-stage combustion type piston emits significantly low NO at various speed and torque compared with conventional engines, but it raised points at issue in CO and smoke emissions with fuel consumption rate. The increasing of injection pressure on 2 stage combustion type diesel engine affects on CO and smoke emission considerably to reduce but slightly on NO to increase. The effect of 2-stage combustion was better at low speed than at high speed.

• Journal of Advanced Marine Engineering and Technology
• /
• 제24권2호
• /
• pp.57-62
• /
• 2000

The effect of exhaust gas recirculation(EGR) on the characteristics of exhaust gas emissions, and SFC are experimentally investigated by four-cylinder, four-cycle and direct injection marine diesel engine. In order to reduce the soot contents in the recirculated exhaust gas to intake system of the engines, a soot removal system of a cylinderical-type scrubber is specially designed and manufactured for the experimental system. (1) SFC is increased in downward convex curve style with increasing excess air ratio, it is increased with increasing EGR rate at the same excess air ratio. (2) NOx emission is reduced in downward convex curve style with increasing excess air ratio, it is reduced with increasing EGR rate at the same excess air ratio. (3) Soot emission is decreased in downward convex curve style with increasing excess air ratio, it is reduced with increasing EGR rate at the same excess air ratio. (4) CO emission is increased in nearly straight line style with increasing excess air ratio, it is increased with increasing EGR rate at the same excess air ratio. (5) HC emission is not constant tendency with increasing excess air ratio, it is increased with increasing EGR rate at the same excess air ratio.

• 멤브레인
• /
• 제25권3호
• /
• pp.268-275
• /
• 2015

침지식 분리막 모듈에서 공기강도에 따른 분리막 위치에 대한 오염을 조사하였다. 분리막의 충진밀도가 낮은 곳에서 높은 유체 유속을 나타내었으며, 유체 속도는 기-액 주입률에 비례하였다. 전단응력은 기-액 주입률 및 유체 유속에 비례하였다. 비가역오염($R_{ir}$)은 흡입 압력이 가까운 부분에서 가장 높게 나타났다(position 1). 비가역오염에 대한 저항과 분리막 고유 저항의 비($R_{ir}/R_m$) 및 비가역오염에 대한 저항과 가역오염의 저항의 비($R_{ir}/R_r$)도 position 1에서 가장 높게 조사되었다. 비가역오염($R_{ir}$)은 흡입 압력이 높은 곳인 position 1에 오염물질이 축적되어진 결과이다. 분리막 위치에 따른 오염현상은 모듈 디자인 최적화에 중요한 인자임을 알았다.

• 에너지공학
• /
• 제14권1호
• /
• pp.54-61
• /
• 2005

한국형 신형원자로1400(APR1400)은 3983MWt급의 2×4 루프 개량형 가압경수로(PWR)로서 대형 냉각재상실사고 발생시 안전주입수의 원자로용기 직접주입(DVI) 방식을 채택하고 있으며, 안전주입수탱크(SIT) 내부에 유량조절기(Fluidic Device, FD)를 장착하고 있다. 본 연구에서는 신형원자로 1400의 안전주입계통에 새로이 적용된 주요 특징 중 하나인 유량조절기에 대하여 최적안전해석코드인 TRAC-M/F90, 3.782버전을 이용한 성능평가 및 민감도 분석을 수행하였다. 연구결과 유량조절기가 안전주입수의 원자로 유입을 적절하게 조절하고 있음을 확인하였으며, 안전주입수탱크 내부의 압축질소체적 감소가 안전 주입수체적 감소에 비하여 노심의 급냉 완료 시점을 빠르게 하였다. 또한 안전주입계통의 전체 저항계수(K factor)가 최소 또는 최대일 때 노심의 급냉 완료 시점은 평균값인 경우보다 다소 늦어졌으나, 피복재 최고온도(PCT)는 상대적으로 큰 차이가 발생하지 않았다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
• /
• pp.23-30
• /
• 1998

The stabilization characteristics of diffusion flame formed in the wake of a cylindrical flame holder were investigated. Distribution of turbulence intensity, concentration distribution of combustion gas, and ion currents were measured. The turbulence intensity in the wake of cylindrical- game holder is increased with increase of diameter or blockage ratio of grid. If the auxiliary fuel is injected into recirculation zone, the concentration of $C_3H_8$ is high, but the concentration of $CO_2$ is low at the boundary of recirculation zone. The region with highest average value of ion currents in the middle of flame is moved to the upstream side by the turbulent components of main stream. The flame mass with partially active reaction is moved fast for uniform flow and turbulence generator G3, but the flame mass with relatively slow reaction is moved slowly for turbulence generator G1.

• 광물과 암석
• /
• 제36권4호
• /
• pp.221-232
• /
• 2023

탄소중립을 위한 이산화탄소 저감 기술 및 대체 에너지에 대한 수요가 계속 증가하고 있다. 팔리고스카이트(palygorskite)는 리본 구조를 가지는 점토광물로 넓은 표면적의 나노크기의 공극을 가지고 있어, 지구온난화의 주범인 이산화탄소(CO₂)를 포집하고 친환경 대체 에너지인 수소(H₂)를 저장할 수 있는 물질로 제안된 바 있다. 이번 논문에서는 대정준 몬테 카를로(grand canonical Monte carlo) 시뮬레이션을 사용하여 팔리고스카이트 나노공극으로의 CO₂ 및 H₂ 분자의 흡착 등온선과 기작에 대한 기초연구의 예비 결과를 보고한다. 실온에서 기체의 분압 관련 변수인 화학 포텐셜(chemical potential)의 증가에 따라 나노공극에 흡착되는 CO₂ 및 H₂ 함량은 증가하였다. CO₂와 비교하여, H₂의 흡착은 더 높은 화학 포텐셜, 즉 높은 에너지가 필요하였다. 이론 계산으로 얻은 나노공극에서의 평균 제곱 변위(mean squared displacement)는 CO₂ 보다 H₂가 훨씬 높았으며 기존 실험 결과와 일치했다. CO₂는 나노공극에서 일렬로 배열된 반면, H₂는 매우 불규칙한 배열을 보였다. 이번 연구 방법은 CO₂ 및 H₂를 저장 가능한 지구물질 광물을 찾는 개발연구뿐만 아니라, 지중환경에서 유체와 광물의 반응을 근본적으로 이해하는 데 기여할 것으로 기대한다.

• Journal of Korean Society for Atmospheric Environment
• /
• 제17권E4호
• /
• pp.157-162
• /
• 2001

Jet Bubbling Reactors(JBRs) were operated for the removal of SO$_{x}$ in flue gases produced from many electric power plants. However, many JBR flue gas desulfurization (FGD) facility faced a decrease of SO$_{x}$ removal efficiency and an increase of scale problems with continuous operations. We increased alkalinity of the SO$_{2}$ absorbing medium by adding the dibasic acids (DBAs) to solve these problems more effectively. The SO$_{2}$ removal efficiency, the purity of CaCO$_{3}$ and COD of the wastewater was measured to identify the addition effects of DBAs (150, 200, 250, and 400 ppm) for 2hr in a day into the JBR attached to the large-scale power plants (400 MW$\times$3). Addition of the DBAs resulted in the improvement of the SO$_{2}$ removal efficiency from 2 to 5% and the purity of the gypsum from 1 to 2%; these improvement were due to the alkalinity increase of the absorbing medium and the reduction of a proportion of un-reacted CaCO$_{3}$, respectively. Also, the scale problems formed by un-reacted CaCO$_{3}$ inside the reaction zone of the JBR were substantially reduced. Even though the effluent COD of the wastewater slightly increased from 10~15 to 18~36 mg/l and the erosion problems in the injection pump and duct occurred, this method of increasing SO$_{2}$ removal efficiency by adding the DBAs could be considered as a profitable approach.ach.

• 한국자동차공학회논문집
• /
• 제14권4호
• /
• pp.1-11
• /
• 2006

The aim in this study is to develop the combined EGR system with a non-thermal plasma reactor for reducing exhaust emissions and improving fuel economy in turbo intercooler ECU common-rail diesel engines. In this study, the characteristics of soot, CO and $CO_2$ emissions under four kinds of engine loads are experimentally investigated by using a four-cycle, four-cylinder, direct injection type, water-cooled turbo intercooler ECU common-rail diesel engine with a combined plasma exhaust gas recirculation(EGR) system operating at three kinds of engine speeds. The EGR and non-thermal plasma reactor system are used to reduce $NO_x$ emissions, and the non-thermal plasma reactor and turbo intercooler system are used to reduce soot and THC emissions. The plasma system is a flat-to-flat type reactor operated by a plasma power supply. The fuel is sprayed by pilot and main injections at the variable injection timing between BTDC $15^{\circ}$ and ATDC $1^{\circ}$ according to experimental conditions. It is found that soot emissions with increasing EGR rate are increased, but are decreased as the applied electrical voltage of the non-thermal plasma reactor is elevated at the same engine speed and load. Results also show that CO and $CO_2$ emissions are increased as EGR rate is elevated, and CO emissions are increased, but $CO_2$ emissions are decreased as the applied electrical voltage of the non-thermal plasma reactor is elevated at the same engine speed and load.

• 대한지하수환경학회지
• /
• 제6권4호
• /
• pp.159-170
• /
• 1999

초정지역에서 산출되는 탄산수에 대한 수리화학적 연구를 수행하였다. 초정탄산수는 낮은 pH(5.0~5.8). 높은 이산화탄소함량($Pco_2$＜$10^{0.31}$atm). 높은 TDS 함량을 갖는 것으로 특징되며. 화학적으로 Ca-$HCO_3$형에 속한다. 탄산수의 화학적특성은 지하수가 심부로 순환하는 과정에서 심부기원의 이산화탄소와의 반응을 통하여 탄산수가 형성되었음을 지시하며. 낮은 pH를 갖는 탄산수는 물-암석(화강암) 반응이 활발히 진행되면서 지화학적으로 진화된 것으로 판단된다. 또한 높은 $NO_3$함량은 탄산수가 천부로 상승되는 과정에서 주변지하수와 혼합된 특성을 지시한다. 초정 탄산수의 진화과정은 이산화탄소의 공급. 물-암석반응 및 혼합작용으로 설명할 수 있다. 이러한 진화과정을 열역화적으로 확인하고자 지화학 반응을 PHREEQC를 이용하여 모델링하였다. 비록 모델링은 사장석자의 반응에 국한되었지만. 탄산수의 진화과정에서 pH 및 Ca와 Na함량 변화양상에 대한 타당한 설명을 제시하고 있다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
• /
• pp.93-96
• /
• 2005

High temperature furnace such as Steam power plant and incinerator contribute considerable part of NOx generation and face urgent demand of De-NOx system. Reducing agents are necessary to use De-NOx system. In this study mixing caused by direct injection of reducing agent solution spray into flue gas duct was measured. Carbonated water was used as tracer and simulated agent because ammonia as a reducing agent is not proper to experiment. Mixing and evaporation must occur simultaneously and quickly enough to achieve desirable efficiency. To achieve that, the angle of attack of static mixer and the location is simulated and $CO_2$ concentration is measured.