• 한국가스학회지
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• 제19권6호
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• pp.1-7
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• 2015

지구온난화와 화석연료 고갈 문제의 해결을 위하여 대체 연료 개발에 많은 노력을 하고 있다. 암모니아(NH3)는 수소와 마찬가지로 탄소를 포함하고 있지 않으면서 대표적인 수소 캐리어이다. 또한, 상온에서 0.6 MPa 정도의 압력을 가하면 액상을 유지할 수 있어 LPG 충전인프라를 그대로 사용가능한 장점이 있다. 본 연구는 암모니아를 가솔린과 함께 혼소시켰으며, 혼소 비율에 따른 엔진 성능을 비교하였다. 암모니아와 가솔린의 혼소를 위하여 가솔린 인젝터와 암모니아용 인젝터를 각각 사용하였으며, 암모니아는 액상으로 분사시켰다. 암모니아-가솔린 혼소 엔진의 최대 장점은 가솔린 대체량에 비례하여 이산화탄소 배출량을 크 게 감소시킬 수 있다는 것이다. 하지만 암모니아-가솔린 혼소율에 따라 연소가 불안정한 구간이 있었으며, 암모니아 혼소 비율 0.7 이상에서는 연소 불안정성 증가로 인해 토크와 NOx 배출량이 감소하고, THC 배출량이 급증하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.711-714
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• 2008

The objective of this paper is to know the characteristics of pressure through a simplified typical carburetor used in small engines at the different throttle opening conditions. The carburetor is the device responsible for creating the right air-fuel mixture according to the different engine operating conditions. It is activated by the static or the dynamic pressure. The carburetor dummy is geometrically similar of LPG brush-cutter engine's diaphragm carburetor and is made of acrylic. Suction system gives body to crankcase vacuum using the vacuum pump and throttle opening conditions are controled by transfer device. Carburetor venturi throat and fuel charging tube diameter is each 20mm, 4.1mm. The result of the work presents an unprecedented phenomenon of suction pressure variation inside the carburetor venturi. It is predicted that these unprecedented pressure variation be caused by minor losses; sudden contraction or expansion, open or partially closed and so on.

• 유공압시스템학회논문집
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• 제4권3호
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• pp.13-21
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• 2007

A forklift is a motive machine powered by LPG, diesel engine or electric motors. The internal combustion engine type forklift is equipped with automatic transmission to meet the required drive load as well as the easy operation of the vehicle. This paper deals with the shift control and endurance test controller which is developed for the functional test of the newly designed automatic transmission on a dynamometer test bench. Its major function is to control the proportional solenoid currents, which is directly related to clutch pressures, for the given reference current trajectory during shift and sequential operation of shift schedule designed for the durability test at each gear. It also has the ability to monitor all the necessary test data through RS232 communication and log them to disk files. The current controller of embedded system is designed from the identified dynamics of solenoid coil and the current reference can be easily modified with a user interface software on PC so as to match the shift data by experiments.

• 한국가스학회지
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• 제27권3호
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• pp.52-58
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• 2023

지구 기상이변에 대해 탄소중립의 중요성이 대두됨에 따라 무탄소 연료인 수소의 에너지원으로서의 활용도 역시 증대되고 있다. 일반적으로 수소는 연료전지(FC, Fuel Cell)에 활용되고 있으나, 이는 연소를 기반으로 하는 내연기관(ICE, Internal Combustion Engine)에도 활용될 수 있다. 특히 연료전지만으로 수소 활용 및 인프라 확장이 어려운 때에 이미 생산 측면이나 공급 측면에서 인프라가 기 구축되어 있는 내연기관은 수소 에너지 저변 확대에 큰 도움을 줄 수 있다. 다만 수소를 연소기반으로 활용할 경우 고온에서 공기 중 질소가 산소와 반응하여 유해배기물질인 질소산화물(NOx, Nitrogen Oxides)이 생성될 수 있는 단점은 존재한다. 특히 냉간 (Cold Start) 운전 영역시 포함될 EURO-7 배기규제의 경우 워밍업(Warm-up) 과정에서 발생하는 배기배출물의 저감을 위한 노력도 필요하다. 따라서 본 연구에서는 2 L급 수소 직접분사방식 전기점화 (SI, Spark Ignition) 엔진을 활용하여 냉각수를 상온에서 88 ℃로 워밍업하는 과정에서 질소산화물 및 연료소모율의 변화 특성을 살펴보았다. 특히 수소는 기존의 가솔린, 천연가스, 액화석유가스(LPG, Liquified Petroleum Gas)와 달리 가연범위(Flammable range)가 넓기 때문에 공기과잉률(Excessive air ratio)을 희박하게 조절할 수 있다는 장점이 있다. 이에 본 연구에서는 워밍업하는 과정에 있어서 공기과잉률을 1.6/1.8/2.0으로 변화하여 그 결과를 분석하였다. 본 실험의 결과는 워밍업 시 공기과잉률이 희박해질수록 시간당 질소산화물의 배출이 적고, 열효율도 상대적으로 높으나 최종 온도까지 도달 시간이 길어짐에 따라 누적 배출량 및 연료소모율은 악화될 수도 있음을 시사한다.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.410-419
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• 2015

In this study, the roadability, fuel economy and emission characteristics were evaluated for a natural gas converted vehicle. The results are as follows; Not only the shortage of power was observed in stall test, but also large deterioration of acceleration performance was exposed in roadability. Compared to the original LPG system, the acceleration is 76% in start acceleration and 45 ~ 65% in overtaking acceleration, especially the decline became larger when air conditioner is at work. Furthermore, because the mapping data, which controls the injection depending on driving condition, do not match up with injection system, the failure of air-fuel ratio feedback control occurs resulting from the large gap between the required and the really supplied amount of fuel. This failure cause the exhaust gas to emit without catalytic conversion and the fuel economy based on the fuel heat value to get worse 22% in the mode test and 16% in road test respectively. In addition, the existing injection system does not secure enough fuel at the starting so that it may lead to the fail of clod start, the deterioration of hot start and inharmonic of engine at the idle after start.

• 한국대기환경학회지
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• 제24권1호
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• pp.72-82
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• 2008

Benzene is a very harmful and toxic compound known as human carcinogen by all routes of exposure. Owing to the risky feature of benzene, several countries such as Japan, UK and EU have established the ambient air quality standard and protect from that risk of it. Korea also has designated it as one of the criteria air pollutants and established the concentration limit ($5\;{\mu}g/m^3$) in the air and is going to apply the standard from 2010. Benzene is emitted from various sources such as combustion plants, production processes, waste treatment facilities and also automobiles. Mobile source is known as one of the major emission sources of benzene. In this study, we estimated the domestic emissions of benzene from mobile source and compared the results with those of advanced countries. Mobile source was divided into 2 categories, Le., on-road source and non-road source. The total emissions of benzene from mobile source were estimated as 3,106 tons/yr and 1,612 tons/yr was emitted from on-road source and 1,494 tons/yr was from non-road source. Emission ratio of benzene from on-road source showed that 80.0% was from passenger cars, 10.1% was from taxis, 7.2% was from light-duty vehicles, 2.5% was from heavy-duty vehicles and 0.2% was from buses. In the case of non-road source, the distribution showed that 66.3% was from construction machineries, 14.5% was from locomotives, 11.7% was from ships, 7.1% was from agriculture equipments and 0.5% was from aircrafts. The cold-start emissions were estimated as 942 tons/yr and this value was almost 1.5 times greater than that for hot engine emissions (608 tons/yr). In addition, the fuel-based distribution was 65.9%, 31.1% and 2.8% from gasoline, LPG and diesel vehicles, respectively. The emission ratio from mobile source occupied 65% and 30% of total benzene emissions in USA and UK, respectively. In case of Korea, the emission ratio of benzene from mobile source occupied 29% (15% from on-road source, 14% from non-road source) which showed similar value with UK.