• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1212-1221
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• 2010

최근 선박은 연료절감과 배기가스 감축을 위한 고효율 친환경 동력발생장치에 대한 요구가 증대되고 있다. 이에 따라 오염물질의 배출이 매우 작고, 소음 진동이 거의 없으며, 발전효율이 높은 연료전지가 차세대 선박용 동력원으로 관심의 초점이 되고 있다. 본 연구에서는, 과거부터 현재까지의 세계 조선산업과 선박용 엔진시장의 동향을 고찰함으로써 미래의 세계 선박용 연료전지 시장을 분석해 보고자 한다. 이를 위해 연간 선박수주량 및 선박건조량을 예측함으로써 2018년까지의 연도별 총선박량을 전망한다. 또한 과거의 선박수주량과 엔진주문량을 비교, 분석함으로써 미래의 엔진주문량을 예측하고, 이를 바탕으로 연료전지 시장을 전망한다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권2호
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• pp.273-279
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• 2006

The performance of an autothermal thermophilic aerobic digestion (ATAD) system was studied to determine if nitrogen loss, as ammonia, was affected by an exhaust gas condenser. The system was run with and without a condenser while treating $8m^3$ of piggery slurry for 8 days. The system with a condenser (SWC) maintained the reactor temperatures above $40^{\circ}C$ for 2 days during the 8 days run, while the system without a condenser (SWOC) remained above $40^{\circ}C$ for 6 days. The SWC maintained the reactor temperatures mostly at mesophilic conditions while the SWOC at thermophilc conditions. Differences in operation conditions for the two runs were mainly caused by differences in atmospheric temperatures. Soluble chemical oxygen demand (SCOD) and volatile solids (VS) removal efficiencies of the SWC (SCOD: 62%, VS: 41%) were higher than those of the SWOC (SCOD: 40%, VS: 20%). The total Kjeldal nitrogen (TKN) removal efficiency of the SWC (7%) was less than that of the SWOC (25%). The concentration of total volatile fatty acids (VFA) in the SWC was observed to be lower than the threshold value of 0.23 g total VFA/L after 6 days, while the SWOC progressed below the threshold value after 3 days. No offensive odor emissions were observed in either run, which suggest that the use of the ATAD system may be a good odor removal strategy.

• 대한기계학회논문집
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• 제16권9호
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• pp.1736-1743
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• 1992

본 연구에서는 기화기부착 4행정 4기통 전기점화기관을 사용하여 흡기관내 액 막흐름에 의한 연료의 불균일화가 기관의 연소특성과 배기특성에 미치는 영향을 규명 하는데 궁극적인 목적을 두고 우선, 연소특성을 해석하기 위하여 비교적 고가인 연소 해석 시스템을 개발하는데 1차적인 목적으로 하였으며, 시험제작한 연소해석 시스템으 로 액막흐름의 가시화 및 배기가스 농도측정과 지압선도 해석을 행하여 구조적으로 대 칭인 1번과 4번 실린더의 연소특성과 배기특성을 비교 검토하였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.81-86
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• 2005

The purpose of this study is to develop venturi type after-burner in order to obtain pollutant reduction effect and find the best stable combustion condition. For this purpose, through a flow analysis, the shape of venturi type was made and flame holder locations were also decided by measuring chemical species at before and after the after-burner. Also, various chemical species concentration were measured at changing the induced air rates and the oxygen for oxygen enrichment for the solution the problems of much oxygen flow rate and the flame stability range. As results of this study, a flow distribution and the purification effect was excellent at venturi contraction 0.5 and flame holder location 12mm below the center of Venturi throat. On the purification characteristics, we found that pollutants reduction was effective when area ratio and oxygen are increased. But there are suitable quantities due to the flame shape change and combustion efficiency.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.520-524
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• 2000

A ejector system is one of the fluid machinery, which has been mainly used as an exhaust pump or a vacuum pump. The ejector system has often been pointed out to have only a limited efficiency because it is driven by pure shear action and the mixing action between primary and secondary streams. In the present work, numerical simulations were conducted to investigate the effects of the geometry and the mass flow ratio of supersonic ejector-diffuser systems on their mixing performance. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations, and the standard ${\kappa}-{\varepsilon}$ turbulence model was used to close the governing equations. The flow fields of the supersonic ejector-diffuser systems were investigated by changing the ejector throat area ratio and the mass flow ratio. The existence of the second throat strongly affected the shock wave structure inside the mixing tube as well as the spreading of the under-expanded jet discharging from the primary nozzle, and served to enhance the mixing performance.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1309-1316
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• 2003

A premixed-compression-ignition engine has been studied to improve the efficiency and to decrease exhaust emissions. However those systems have some difficulties for controlling combustion process. Radical is an activated chemical species formed by a chemical chain reaction between reactant and product. When the chain reactions occur, the energy bond of species is broken easily by the released radicals. The combustion chamber of the premixed-compression-ingnition engine is consist of a main chamber with lean premixture and a subchamber with rich premixture. Those are connected by narrow cylinderical connections. With ignition start in the subchamber, many different kinds of radical is jetted into the main chamber. The premixed gas in main chamber is quickly burned up by the radical ignition in multi-pionts. In this paper, the combustion phenomena in a constant volume combustor having a radical injector are numerically analyzed. The some constants in the reaction rate equation are adjusted by the experimental results tested in the same geometrical chamber. The code is applied on the two combustors in a wide range of equivalence ratio. The results show that the burning time is much shorter in the combustor having radical injector.

• 한국분무공학회지
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• 제24권4호
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• pp.178-184
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• 2019

Diesel engines have the advantages of higher thermal efficiency and lower CO2 emissions than gasoline engines, but have the disadvantages that particulate matter (PM) and nitrogen oxides (NOx) emissions are greater than those of gasoline engines. In particular, nitrogen oxides (NOx) emitted from diesel engines generates secondary ultrafine dust (PM2.5) through photochemical reactions in the atmosphere, which is fatal to humans. In order to reduce nitrogen oxides (NOx), pre-treatment systems such as EGR, post-treatment systems such as LNT and Urea SCR have been actively studied. The Urea SCR consists of an injection device injecting urea agent and a catalytic device for reducing nitrogen oxides (NOx). The nitrogen oxide (NOx) reduction performance varies greatly depending on the urea uniformity in the exhaust pipe. In this study, spray characteristics according to the spray hole structure were confirmed, and the influence of spray uniformity on spray characteristics was studied through engine evaluation.

• 농촌계획
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• 제21권1호
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• pp.19-28
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• 2015

As environmental concerns including climate change drive the strong regulations for car exhaust emissions, electric vehicles attract the public eye. The purpose of this study is to identify rural areas vulnerable for charging infrastructures based on the spatial distributions of the current gas stations and provide the target dissemination rates for promoting electric cars. In addition, we develop various scenarios for finding optimal way to expand the charging infrastructures through the administrative districts data including 11,677 gas stations, the number of whole national gas stations. Gas stations for charging infrastructures are randomly selected using the Monte Carlo Simulation (MCS) method. Evaluation criteria for vulnerability assessment include five considering the characteristic of rural areas. The optimal penetration rate is determined to 21% in rural areas considering dissemination efficiency. To reduce the vulnerability, the charging systems should be strategically installed in rural areas considering geographical characteristics and regional EV demands.

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

• Journal of Biosystems Engineering
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• 제28권1호
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• pp.27-34
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• 2003

Present combustion engines have reached almost at the limit of development due to the fundamental structural problems. This study was carried out to propose a new concept internal combustion engine which has great potential advantages to the conventional engines. Proposed new concept engine is a kind of rotary engine. A rotor is rotating concentrically in a cylinder which is divided into two partitioning valves. and it makes four compartments in the cylinder. The volumes of each of four compartments are changing continuously with the rotor movement, and performs the functions of intake, compression. expansion and exhaust simultaneously. The results of this study can be summarized as follows. 1. Expected theoretical thermal efficiency is 44.9 percent at the condition of 1000rpm and compression ratio of 8.0. which is almost the same as that of the conventional engines. i.e., piston and Wankel rotary engine. 2. The new concept engine has 2. working strokes in every revolution. Therefore. the new concept engine can reduce the specific weight and volume than four-stroke piston engine. 3. The torque variation is very small. therefore minimal noise and vibration are expectable. 4. The new concept engine can reduce mechanical energy loss than piston engine because neither crank mechanism nor eccentrical motion exists.