• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.62-67
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• 2019

This study was focused on the design and the performance analysis of integral Hot BoP for recovering waste heat from high-temperature exhaust gas in 2 kW class solid oxide fuel cell (SOFC). The hot BoP system was consisted of a catalytic combustor, air preheater and steam generator for burning the stack exhaust gas and for recovering waste heat. In the design of the system, the maximum possible heat transfer was calculated to analyze the heat distribution processes. The detail design of the air preheater and steam generator was carried out by solving the heat transfer equation. The hot BoP was fabricated as a single unit to reduce the heat loss. The simulated stack exhaust gas which considered SOFC operation was used to the performance test. In the hot BoP performance test, the heat transfer rate and system efficiency were measured under various heat loads. The combustibility with the equivalent ratio was analyzed by measuring CO emission of the exhaust gas. As a result, the thermal efficiency of the hot BoP was about 60% based on the standard heat load of 2 kW SOFC. CO emission of the exhaust gas rapidly decreased at an equivalent ratio of 0.25 or more.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.173.2-173.2
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• 2011

대체 에너지 자원 중 폐기물의 소화 가스를 이용한 바이오가스 발전은 이산화탄소에 비해 온실효과 영향력에 21배에 해당하는 메탄가스를 연료로 사용하여 환경부하를 저감시키고 에너지를 생산한다. 바이오가스에 포함된 $H_2S$는 연소 후 $SO_2$형태로 발생되는데 $SO_2$는 수분과 반응을 하게 되면 $H_2SO_4$등의 강한 산성을 띄는 물질로 생성되어 배관 및 발전기에 손상을 주고 저온부식현상을 유발하게 하며, 동물이나 인체에 노출되면 기관지 수축현상이 일어나 호흡기에 영향을 주는 질식성을 띄는 가스이다. 축산바이오가스에 포함된 $H_2S$의 함유량과 가스엔진의 연소 시 배출되는 $SO_2$ 배기가스 성분의 관련성을 검증하기 위해 60-65%의 $CH_4$와 30-35%의 $CO_2$ 성분의 바이오가스를 50kW급 발전기에서 사용하였고 연소 후 배출되는 가스 성분을 분석하였다.

• Journal of Energy Engineering
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• v.18 no.2
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• pp.136-140
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• 2009

Vehicle idle has become an increasing quality concern for automobile manufacturers because of its impact on customer satisfaction. As demand for better fuel economy increases, automobile manufacturers are continuously looking for any benefits from different driving conditions. Combustion variability in spark ignition engines was recognized that the stability of engine at idle is affected by the factors of fuel injection timing, ignition timing and air-fuel ratio. Therefore in this research, the results will be shown the effects of stability and the variations at idle according to fuel injection timing, ignition timing and air-fuel ratio as the basic parameters.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.283-290
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• 2010

The main goal of this study is to examine the use of a hybrid -fuel lean reburning system with air staging for $NO_X$ reduction. The experimental variables include the reburn fuel fraction, sizes of reburn- fuel-injection nozzles, oxygen enrichment ratio, and location of reburn- fuel- injection. The effect of the flow field induced by air- staging combustion on $NO_X$ reduction is considered, and then, the $NO_X$ reduction rate is compared with only fuel lean reburning system. On the basis of the effectiveness of each De-$NO_X$ process, the advantage of using the hybrid reburning system with air staging is determined and discussed.

• Journal of Energy Engineering
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• v.17 no.3
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• pp.153-160
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• 2008

The combustion behaviors of the blends of Korean anthracite, bituminous coal and their blends were studied with a thermogravimetric analyzer. Concerning the burning profiles of the anthracite-bituminous coal blends in TGA, it has been observed the independent burning of two coals without any interaction between two coals. With the blends of 50% anthracite with 50% bituminous coal in weight basis, the combustion tests in a utility boiler have been carried out for the analysis of the combustion and operational characteristics by increasing the power output from 134 MW to 197 MW. The stable combustion has been observed in a boiler. With the increase of power output, the exhaust gas temperature was exceeded the design value of $430^{\circ}C$, so the combustion air was taken from atmosphere instead of the boiler penthouse.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.413-418
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• 2012

A modified VIStA (Vortex Inertial Staged Air) burner has been developed and applied to a once-through type boiler. The secondary air is supplied through a swirler instead of nozzles, which stabilizes the flame and reduces carbon monoxide (CO) emissions. However, the modification increases the emission of nitrogen oxides (NOx). To balance emissions of the two pollutants, a divided flame was adopted. An air damper was installed to control the distribution of air to each combustion chamber, and three types of flame dividers were studied. The effects of the air-fuel ratio and combustion load on the NOx formation were investigated. The divided flame was found to reduce the NOx emission up to 25%, while keeping the CO to less than 10 ppm.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.58-64
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• 2016

The main engine of a vehicle is used an common rail diesel engine for improving the efficiency of the whole load area. However, the generator engines is still used mechanical fuel injection valve drive cams. In addition, most of generator engines is applied a part-load operation of less than 50%. Therefore, diesel engine of vehicle set at 100% load is necessary to readjust in order to perform efficient operation because of part-load operation. In this study, the objective is to report the results of the part-load fuel consumption improvement by injection timing readjust to identify the operational characteristics of a generator engine currently operated in the facilities.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.45-51
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• 2015

In order to meet the enforced emission regulations and reduce fuel consumption, various new technologies are employed in engines. The problem of NOx emissions under a lean mixture condition should be solved, because a lean-burn direct-injection engine can realize stable lean combustion with a stratified mixture, which results in improvements in fuel economy and emissions. This study investigated the effects of intake and exhaust valve timing changes on the performance and emission characteristics of a lean-burn LPG direct-injection engine. Under a partial-load operating condition without throttling, an increase in the intake valve opening led to an increase in NOx emissions due to an increase in the amount of excess air. The fuel consumption deteriorated with an increase in the exhaust valve opening due to a decrease in the expansion work and an increase in the pumping loss.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.45-53
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• 2022

In order to improve the emission of diesel engines, natural gas-diesel dual fuel combustion compression ignition engines are in the spotlight. In particular, a reactivity controlled compression ignition (RCCI) combustion strategy is investigated comprehensively due to its possibility to improve both efficiency and emissions. With advanced diesel direct injection timing earlier than TDC, it achieves spontaneous reaction with overall lean mixture from a homogeneous mixture in the entire cylinder area, reducing nitrogen oxides (NOx) and particulate matter (PM) and improving braking heat efficiency at the same time. However, there is a disadvantage in that the amount of incomplete combustion increases in a low load region with a relatively small amount of fuel-air. To solve this, sensitive control according to the diesel injection timing and fuel ratio is required. In this study, experiments were conducted to improve efficiency and exhaust emissions of the natural gas-diesel dual fuel engine at low load, and evaluate combustion stability according to the diesel injection timing at the operation point for power generation. A 6 L-class commercial diesel engine was used for the experiment which was conducted under a 50% load range (~50 kW) at 1,800 rpm. Two injectors with different spray patterns were applied to the experiment, and the fraction of natural gas and diesel injection timing were selected as main parameters. Based on the experimental results, it was confirmed that the brake thermal efficiency increased by up to 1.3%p in the modified injector with the narrow-angle injection added. In addition, the spray pattern of the modified injector was suitable for premixed combustion, increasing operable range in consideration of combustion instability, torque reduction, and emissions level under Tier-V level (0.4 g/kWh for NOx).

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.252-258
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• 2009

Engine bench tests has been done on a common-rail diesel engine with bio-diesel fuel to study effects of B100 and B20 on output power, fuel consumption and emissions. Test results show that B100 and B20 could reduce PM, HC, CO emission and smoke, but power decrease, fuel consumption increase and NOx increase obviously, B100 reduce PM and DS with $50%{\sim}70%$ and $80%{\sim}85%$ compared with diesel fuel, while B20 reduce PM and DS with $25%{\sim}35%$ and $30%{\sim}40%$. NOx of B100 and B20 increase $5%{\sim}20%$ compare to diesel.