• Journal of the Korean Society of Combustion
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• v.13 no.1
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• pp.10-16
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• 2008

Numerical simulations of freely propagating premixed flames burning mixtures of methane and chlorinated hydrocarbons in fuel are performed at atmospheric pressure in order to understand the effect of chlorinated hydrocarbons on the formation of nitrogen oxide. A detailed chemical reaction mechanism is used, the adopted scheme involving 89 gas-phase species and 1017 elementary forward reaction steps. Chlorine atoms available from chlorinated hydrocarbons inhibit the formation of nitrogen oxides by lowering the concentration of radical species. The reduction of NO emission index calculated with thermal or prompt NO mechanism is not linear and is probably related to the saturation effect as $CH_3Cl$ addition is increased, In the formation or consumption of nitrogen oxide, the $NO_2$ and NOCl reactions play an important role in lean flames while the HNO reactions do in rich flames. The molar ratio of Cl to H in fuel has an effect on the magnitude of NO emission index.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.981-986
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• 2015

As the seriousness of global environment pollution is gaining increasing public attention, research into greenhouse gas emissions of ships is being carried out globally. At a domestic level, however, in a number of significant fields such research has not been conducted to date. This study examined countermeasures for the reduction of $CO_2$ emission in the fields of electronic control engines, trim optimization, propeller polishing, hull cleaning, and anti-fouling paint using an actual sea-going vessel. Selected countermeasures were applied during sea trials of the ship and the effect of specific fuel oil consumption analyzed. It was found that each countermeasure resulted in a decrease of fuel consumption of 1~5%. The energy efficiency operational indicator (EEOI) was calculated and found to also be improved by 1~5%. Further research into the EEOI of domestic shipping is planned to enhance conformance with international environmental regulations and improve global competitiveness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1163-1168
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• 2011

Compared with the spark-ignition gasoline engine, the compression-ignition diesel engine has reduced fuel consumption due to its higher thermal efficiency. In addition, this reduction in the fuel consumption also leads to a reduction in $CO_2$ emission. Diesel engines do not require spark-ignition systems, which makes them less technically complex. Thus, diesel engines are very suitable target engines for using biofuels with high cetane numbers. In this study, the spray characteristics of biofuels such as vegetable jatropha oil and soybean oil were analyzed and compared with those of diesel oil. The injection pressures and blend ratios of jatropha oil and diesel oil (BD3, BD5, and BD20) were used as the main parameters. The injection pressures were set to 500, 1000, 1500, and 1600 bar. The injection duration was set to $500{\mu}s$. Consequently, it was found that there is no significant difference in the characteristics of the spray behavior (spray angle) in response to changes in the blend ratio of the biodiesel or changes in the injection pressure. However, at higher injection pressures, the spray angle decreased slightly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.335-342
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• 2012

Nowadays, automobile manufacturers are focusing on the reduction of exhaust-gas emissions because of the harmful effects on humans and the environment, such as global warming by greenhouse gases. Gasoline direct injection (GDI) combustion is a promising technology that can improve fuel economy significantly compared to conventional port fuel injection (PFI) gasoline engines. In the present study, ultra-lean combustion with an excess air ratio of over 2.0 is realized with a spray-guided-type GDI combustion system, so that the fuel consumption is improved by about 13%. The level of exhaust-gas emissions and the operation performance with the multiple injection strategy and exhaust-gas recirculation (EGR) are examined in comparison with the emission regulations and from the point of view of commercialization.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.181-187
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• 2008

Recently, alternative fuels are drawing more attentions due to the increasing need for lower emission characteristics and fuel consumption rate in automotive engines. The GTL(gas to luquid) is the one of most favored candidates. It has higher cetane number(more than 75) and almost negligible sulphur and aromatic contents. Therefore, enhanced emission characteristics are expected even in the application in diesel engines without any modification. In this study, the cylinder pressure and heat release, emission characteristics with fuel injection timings are compared between diesel and GTL fuel in the single cylinder diesel engine. Noticeable reduction in PM, THC and CO emission are observed due to lower sulphur and aromatic contents in GTL. Also, the ignition delay decreased due to higher cetane number of GTL, which slightly decreased the amount of NOx emissions. With the retards of main injection timing, NOx decreases more for the case of GTL, while the level of THC and CO emissions still remains lower than the case of diesel. Therefore, there is much room for the control of injection timing for NOx reduction without sacrificing THC and CO emissions. With the retards of main injection timing, Small size distribution of PM became lager and there amount increased. But from all conditions, size distribution of PM for the case GTL was lower than Diesel.

• Journal of the Korean Society of Safety
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• v.39 no.2
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• pp.75-86
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• 2024

Hydrogen has been selected as one of the key technologies for reducing CO₂ emissions to achieve carbon neutrality by 2050. However, hydrogen safety issues should be fully guaranteed before the commercial and widespread utilization of hydrogen. Here, a bow-tie risk assessment is conducted for the hydrogen fuel supply system in a gas turbine power plant, which can be a mass consumption application of hydrogen. The bow-tie program is utilized for a qualitative risk assessment, allowing the analysis of the causes and consequences according to the stages of accidents. This study proposed an advanced bow-tie method, which includes the barrier criticality matrix and visualized maps of quantitative risk reduction. It is based on evaluating the importance of numerous barriers for the extent of their impact. In addition, it emphasizes the prioritization and concentrated management of high-importance barriers. The radar chart of a bow tie allows the visual comparison of risk levels before/after the application of barriers (safety measures). The risk reduction methods are semi-quantitatively analyzed utilizing the criticality matrix and radar chart, and risk factors from multiple aspects are derived. For establishing a secure hydrogen fuel storage system, the improvements suggested by the bow-tie risk assessment results, such as 'Ergonomic equipment design to prevent human error' and 'Emergency shutdown system,' will enhance the safety level. It attempts to contribute to the development and enhancement of an efficient safety management system by suggesting a method of calculating the importance of barriers based on the bow-tie risk assessment.

• Journal of Drive and Control
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• v.9 no.1
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• pp.10-17
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• 2012

Nowadays, the demand of energy saving is increasing more and more while the natural resources have been exhausted. Besides, the emission gas caused by vehicles has been being a serious environment problem. Therefore, many studies have been carried out, especially focusing on braking energy regeneration, in order to save energy as well as reduce emission of mobile vehicles. In this paper, we propose a closed-loop hydrostatic transmission for braking energy regeneration with two configurations to reduce the energy consumption by recovering the braking energy. The effectiveness of the proposed system was verified by simulation. The simulation results indicated that the pressure coupling configuration gave better performance in comparison to flow coupling configuration about 40.8%, 61.7% and 53.8% reduction of fuel consumption in 10 mode, 10 mode modified profile and highway schedules, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1238-1243
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• 2022

The International Maritime Organization is at the forefront of strengthening gas emission regulations for ships globally. The Korean government needs to apply measures to reduce emissions, such as setting a basic roadmap for greenhouse gas reduction. In addition, there is an urgent need to introduce a new efficient propulsion system that can reduce gas emissions. This includes applications to fishing vessels, which account for 90.6% of the greenhouse gas emissions from ships sailing along domestic coasts. In this study, an electric-combined propulsion system applicable to domestic coastal fishing vessels was developed. The target ship to which the electric-combined propulsion system could be applied was selected. A simulation system was constructed using MATLAB/Simulink to compare the expected fuel consumption when applying the developed complex electric propulsion system to the propulsion system mounted on the selected target fishing vessel. Through simulations, the differences in fuel consumption between the mechanical propulsion system and the electric hybrid propulsion system (both when charging and not charging the battery on land) were confirmed. The results show that fuel consumption can be decreased by approximately 13% and 16% when applying the electric-combined propulsion system.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.363-369
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• 2000

Due to environmental problem for reduction in fuel consumption, vehicle emission and etc., many automotive makers are trying to reduce the weight of the vehicle. The most effective way to reduce the weight of vehicle is to use lighter materials, aluminum, plastics. Aluminum Space Frame has many advantages in weight reduction, body stiffness, ease of model change and so on. So, most of automotive manufacturers are attempting to develope Aluminum Space Frame body. For these reasons, we have developed Aluminum Intensive Vehicle based on steel monocoque body with Hyundai Motor Company. We achieved about 30% weight reduction, the stiffness of our model was higher than that of conventional steel monocoque body. In this paper, with optimization using FEM analysis, we could get more weight reduction and body stiffness increase. In the long run, we analyzed by means of simulation using PAM-CRASH to evaluate crush and crash characteristic of Aluminum Intensive Vehicle in comparison to steel monocoque automotive.

• Journal of Energy Engineering
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• v.18 no.4
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• pp.230-238
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• 2009

We study about small gas engine and fuel cell CHP (Combined Heat and Power) as the technologies for energy conservation and $CO_2$ emissions reduction. Korea government plans to use them in near future. This study quantitatively analyzed energy consumption and $CO_2$ emissions reduction potential of small CHP instead of existing electric power plant (coal steam, combined cycle and oil steam) using LEAP (Long-range Energy Alternative Planning system) as energy-economic model. Three future scenarios are discussed. In every scenario similar condition for each CHP is used. Alternative scenario I: about 6.34% reduction in $CO_2$ emissions is observed in 2019 due to increase in amount of gas engine CHP and fuel cell CHP while coal use in thermoelectric power plant is almost stagnant. In alternative scenario II: a small 0.8% increase in $CO_2$ emission is observed in 2019 keeping conditions similar to alternative scenario I but using natural gas in combined cycle power plant instead of coal. During alternative scenario II overall $CO_2$ emission reduction is observed in 2019 due to added heat production from CHP. Alternative scenario III: about 0.8% reduction in $CO_2$ emissions is observed in 2019 using similar CHP as AS I and AS II. Here coal and oil are used in thermoelectric power plant but the quantity of oil and coal is almost constant for next decade.