• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.860-865
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• 2012

Although biomass syngas is very low calorific gas, it is utilized by means of dual fuel combustion technology in the fields of industrial furnace and boiler as a substitute oil technology. The basic structure of duel fuel combustion burner is designed so that low caloric gas fuel is supplied around an oil burner in the middle. In the present study, three types of mixing burners were manufactured to conduct performance experiment. Low caloric gas was evenly distributed around the oil burner and the method of changing the angle of gas nozzle was applied. CO generation decreased according to the increase of the amount of air for combustion. In addition, the shapes and colors of flame changed according to the proportions of gas and oil used. Remained flame after combustion was from the lack of atomization at the exit of oil burner. Although it was difficult to maintain the optimum air ratio due to different required air ratio for oil and syngas, stable combustion was able to maintained within excess oxygen concentration of 4.7~8.2%. From this study, it was shown that the oil atomization at the exit of fuel oil nozzle was promoted by the increased rate of syngas combustion and the CO concentration in flue gas lower than only fuel oil combustion.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.230-237
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• 2012

Engine makers are lately interested in the gas engine development as the alternative for diesel engine in order to cope the rise of oil price and the environmental regulation. So, STX has developed the 1.6MW gas engine which was converted from 22HLX diesel engine. The gas engine developed with precombustion chamber, which has good performance of 21bar BMEP at engine speed 1000rpm and low $NO_X$ emission of 50ppm at 15% oxygen composition, has been developed recently. Especially, it has a good thermal efficiency of 45% and a reduction efficiency of green house gas($CO_2$) emission of 25% than a conventional diesel engine.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.674-680
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• 2014

Monitoring systems of informations for ship performance have become important gradually for economical management of existing ship. Monitoring of NOx emission from marine diesel engines is one of them. The measurement of NOx emission, however has been many difficulties due to technical and costly problems. A monitoring by prediction method of NOx on-board ship according to sailing condition of ship could be an useful method. In this paper, it is discussed about modified method of one-zone model which has been utilized usually for analyzing the combustion process. The modified method is able to calculate the temperature of burned region from the result by one-zone model. Influences which excess air ratio during combustion process affected for the gas temperature and NOx emission were investigated. From the results variation of excess air ratio during combustion process could be estimated inversely through the comparison with measurement of NOx emission.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.52-58
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• 2023

With the increasing awareness of the importance of carbon neutrality in response to global climate change, the utilization of hydrogen as a carbon-free fuel source is also growing. Hydrogen is commonly used in fuel cells (FC), but it can also be utilized in internal combustion engines (ICE) that are based on combustion. Particularly, ICEs that already have established infrastructure for production and supply can greatly contribute to the expansion of hydrogen energy utilization when it becomes difficult to rely solely on fuel cells or expand their infrastructure. However, a disadvantage of utilizing hydrogen through combustion is the potential generation of nitrogen oxides (NOx), which are harmful emissions formed when nitrogen in the air reacts with oxygen at high temperatures. In particular, for the EURO-7 exhaust regulation, which includes cold start operation, efforts to reduce exhaust emissions during the warm-up process are required. Therefore, in this study, the characteristics of nitrogen oxides and fuel consumption were investigated during the warm-up process of cooling water from room temperature to 88℃ using a 2-liter direct injection spark ignition (SI) engine fueled with hydrogen. One advantage of hydrogen, compared to conventional fuels like gasoline, natural gas, and liquefied petroleum gas (LPG), is its wide flammable range, which allows for sparser control of the excessive air ratio. In this study, the excessive air ratio was varied as 1.6/1.8/2.0 during the warm-up process, and the results were analyzed. The experimental results show that as the excessive air ratio becomes sparser during warm-up, the emission of nitrogen oxides per unit time decreases, and the thermal efficiency relatively increases. However, as the time required to reach the final temperature becomes longer, the cumulative emissions and fuel consumption may worsen.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.38-46
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• 2023

Carbon neutrality policies have been strengthened to reduce emissions, and the importance of technology road maps has been emphasized. In the global industrial boiler market, carbon neutrality is implemented through fuel diversification of methane-hydrogen mixture gas. However, various problems such as flashback and flame unstability arise. There is a limit to implementing the actual system as it remains in the early stage. Therefore, it is necessary to secure the source technology of methane-hydrogen hybrid combustion system applicable to industrial fields. In this study, control program for methane-hydrogen fuel conversion was developed to expect various parameters. After determining the hydrogen mixing ratio and the input air flow, the fuel conversion control algorithm was constructed to get the parameters that achieve the target oxygen concentration in the exhaust gas. LabVIEW program was used to derive correlations among hydrogen mixing rate, oxygen concentration in exhaust gas, input amount of air and heating value.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.04a
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• pp.9-14
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• 1999

1. LPG 온풍기는 용량 16$\times$$10^4$ ㎉ 건타입가스버너, 연소부 및 열교환부, 6개의 50kgLPG탱크와 자동절체기, 가스메타, 배관으로 구성하였다. LPG 온풍기의 이론연소효율은 91%, $CO_2$ 배출량은 11.74%, CO배출량은 0ppm, 과잉공기비는 1.16, 배기가스온도는 253$^{\circ}C$, 온풍온도는 8$0^{\circ}C$로서 우수한 성능으로 나타났다. 2. LPG온풍기에서 배출되는 배기가스중의 $CO_2$ 를 온실로 공급하기 위하여 $CO_2$ 공급기를 제작하여 배출가스연도에 부착하였다. $CO_2$ 공급기는 흡입형 시로코팬(1200㎥/h)과 차단문으로 이루어졌다. 1-2W형 300평 온실내의 $CO_2$ 농도를 1000ppm으로 올리기 위해서는 $CO_2$ 공급기를 약 1시간 정도 운전시켜야 할 것으로 판단되었다. 3. LPG온풍기와 경유온풍기의 경제성 비교분석에 의하면 현 시점의 경유 가격 242원, LP가스 가격 435원을 기준으로 연간소요비용은 각각 5,392,430원, 5,299,917원으로 경유온풍기가 10만원 정도 경제적이지만 탄산가스 시용비용, 탄산가스 공급으로 인한 작물의 수량증대 및 고품질 생산물을 고려한다면 LPG온풍기 사용이 더 경제적이라 사료된다.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.235-244
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• 2001

Liquefaction may be caused by sudden decrease in the soil strength under undrained conditions. This loss of soil strength is related to the development of excess pore pressures. During this study, fines content affects the maximum and minimum void ratios are investigated. The results of static and cyclic triaxial test on silty saturated sands are presented. These tests are performed to evaluate liquefaction strength and static and cyclic behavior characteristics. The samples are obtained from Saemangeum and drying on air. The main results are summarized as follows : 1) The maximum and minimum void ratio lines follow similar trends. 2) Maximum and minimum void ratios are established at 20~30% fines content. 3) As confining pressures and overconsolidation ratio are increased, the resistance to liquefaction are increased. 4) Instability friction angles are increased with increasing initial relative density. 5) The resistance to liquefaction are decreased with increasing effective stress ratio.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.253-259
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• 2013

In the present study, the characteristics of combustion phenomena and NOx emission in the OFA-type tangentially injected coal-fired boiler have been investigated numerically in order to find the effect of geometrical variation on the performance of the boiler. For these, numerical analyses of turbulent flow, chemical reaction, and radiation heat transfer are performed by using the computational fluid dynamics method. The predicted results clearly show that NOx formation highly depends on the combustion processes, the temperature and species concentrations. In addition, the optimum conditions for both the maximum NOx reduction and highest boiler efficiency can be obtained by considering the amount of supplied air and the injection angle at OFA, and modifying the boiler configuration. It is also found that the variation of supplied air at OFA is more effective than that of the injection angle for reducing the NOx emission, within the present operating conditions.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.1-10
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• 2023

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.21-27
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• 2015

In order to meet the current emission regulations (EURO-6), it is necessary to significantly reduce $CH_4$ and $NO_X$ emissions. This study investigated the effect of a reduction in the valve overlap on the combustion and emission characteristics of a hydrogen-compressed natural gas engine under a part-load operating condition. The combustion and emission characteristics were analyzed for each fuel using the original camshaft and an altered camshaft with reduced valve overlap. The results showed that the thermal efficiency was decreased and the fuel flow was increased when using the altered camshaft. The $CO_2$ and $CH_4$ emissions were increased as a result of the reduced thermal efficiency. Under lean operating conditions, the $NO_X$ emission was decreased compared with one of the conventional camshaft. Thus, under the same fuels and operating conditions, it had a harmful influence on the emission characteristics and thermal efficiency.