• Journal of the Korean Institute of Gas
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• v.23 no.1
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• pp.12-18
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• 2019

Exhaust gas recirculation method is widely used among various methods for reducing nitrogen oxides in automobile engines and incinerators. In the present study, the computational fluid dynamic analysis was accomplished to derive the optimal location of air nozzle exit position by changing its position in a venturi tube for the maximum flue gas recirculation effect. In addition, the flue gas recirculation characteristics with a cone at the exit of air nozzle was elucidated with flue gas recirculation flow rate ratio and mixed gas exit temperature. When the air nozzle exit position was changed from the start position (z = 0) to the end position (z = 0.6m) of the exhaust gas recirculation exit pipe, the change of streamline and temperature distribution in the venturi tube was observed. The exhaust gas recirculation flow rate and the average temperature at the mixed gas exit position was quantitatively compared. From the present study, the optimal location of air nozzle exit position for the maximum flue gas recirculation flow rate ratio and maximum mixed gas exit temperature is z = 0.15m (1/4L). In addition, when the cone is installed at the outlet of the air nozzle, the velocity of the air nozzle outlet is increased, the flue gas recirculation flow rate was increased by about 2 times of the flow rate without cone, and the mixed gas exit temperature is increased by $116^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.518-524
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• 2013

In this study, we conducted a study on characteristics of exhaust gas emissions from boiler when water-bunker oil mixed by homogenizer was burned in boiler. The results showed that NOx concentration and CO concentration of the homogenized bunker oil was decreased by 19% and 54% compared to pure bunker oil pretreatment was not being performed. And, in the case of water-bunker A oil, the NOx concentration was decreased with increasing water mixing ratio in bunker A oil. In particular, the NOx concentration in exhaust gas of 20 %water-80 %bunker A oil decrease by 45 % compared with pure bunker-A. However, the CO concentration in exhaust gas of 20 %water-80 %bunker A oil shows irregular changes. This means that the mixing of water more than a certain amount can cause a decrease in combustion performance. From this result, it can be found that critical mixing ratio of water in bunker A oil for normal combustion is 15% in this study. Deposition amount of soot that is collected in the vicinity of the chimney was decreased with increasing water mixing ratio.

• Journal of Biosystems Engineering
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• v.8 no.2
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• pp.49-61
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• 1983

U shape multitube heat exchanger was equipped in the flue to recover the exhaust heat from the boiler system. The fluids of the exhaust heat recovery equipment were the flue gas as the hot fluid, and the water as the cold fluid. The flow geometry of the fluids was cross flow - two pass, the hot fluid being mixed and the cold fluid unmixed. The results of the theoretical and the experimental analysis and the economic evaluation are summarized as follows. 1) The heat exchanger effectiveness and the temperature efficiency of the hot fluid were about 35% when the fuel consumption rate was 140 - 150 L/15min. The temperature efficiency for the cold fluid ranged from 3.0% to 4.5%. The insulation efficiency ranged from 85% to 98%, which was better than the KS air preheater insulation efficiency of 90%. 2) The relationship between the fuel consumption rate, F, and the outlet temperature, $T_{h2}$, of the flue gas from the heat exchanger was $T_{h2}$ = 0.927F + 110. In order to prevent the low temperature corrosion from the coagulation of $SO_3$, it is necessary to maintain the fuel consumption rate above 82 L/15min. 3) The ratio of the exhaust heat from the boiler system to the total energy consumption was about 14.5%. With the installation of the exhaust heat recovery equipment, the energy recovery ratio to the exhaust heat was about 25%. Accordingly, about 3.6% of the total fuel consumption was estimated to be saved. 4) Economic analysis indicated that the installation of the exhaust heat recovery equipment was feasible to save the energy, because the capital reocvery period was only 10 months when the fuel consumption rate was 80 L/15min. 4 months when it was 160 L/15min. 5) Based on the theoretical and the experimental analysis, it was estimated to save the energy of about 18 million Won per year, if four heat exchangers are installed in a factory. 6) A further study is recommended to identify the relationship among the flow rate of the exhaust gas, the size of the heat exchanger and the capacity of the air preheater. For a maximum heat recovery from the exhaust gas an automatic control system is required to control the flow rate of the cold fluid depending on the boiler load.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.236-241
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• 2009

After analyzing the characteristics of the cooling dryer, the mixed cooling dryer was developed by adding the desiccant dryer which supplement the cooling dryer's demerits. Also, the hybrid desiccant cooling dryer was developed to use effectively the exhaust heat energy of the cooling dryer. It could make a more that 20 percent reduction in energy compared with the mixed desiccant cooling dryer. It has become essential to supply this equipment and search the suitable drying product.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.112-122
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• 1995

As an alternative fuel producing less exhaust emissions, natural gas is of interest for use both in SI and CI engines. The potential of natural gas fuelled dual-fuel engine is considered high enough. However, much effort has to be made so that gaseous fuel is used efficiently with simultaneous minimum use of pilot oil. Hence, a simplified three-dimensional model, using a finite volume method in cylindrical coordinates, has been developed to facilitate an understanding of the dual-fuel combustion phenomena and to predict the complex interactions between the pilot distillate and natural gas. The computer model was calibrated by comparing it with the experimental results obtained from diesel engine like combustion bomb tests. In the pre-mixed natural gas combustion, the fuel burning was highly reliant on the injection condition and subsequent burning nature of the pilot distillate.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.22-28
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• 2005

Exhaust gas emissions from internal combustion engines are one of the major sources of air pollution. And, it is extremely difficult to increase gasoline engine efficiency and to reduce $NO_X$ and PM(particulate matter) simultaneously in diesel combustion. This paper offers some basic concepts to overcome the above problems. To solve the problems, a recommended technique is CAI(controlled auto-ignition) combustion. In this paper, a flame trap was used to simulate internal EGR(exhaust gas recirculation) effect. An experimental study was carried out to find combustion characteristics using homogeneous premixed gas mixture in the constant volume combustion chamber(CVCC). Flame propagation photos and pressure signals were acquired to verify the flame trap effect. The flame trap creates high speed burned gas jet. It achieves higher flame propagation speed and more stable combustion due to the effect of geometry and burned gas jet.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.491-494
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• 2008

The hydrogen fuel and fuel cell which have high energy efficiency and low pollutant emission are getting interest as an alternative energies due to the fossil fuel exhaust, green house effect and atmospheric pollutant problems. The hydrogen gas is very effective as an alternative energy. But, if it is leaked into the air it forms the mixed gas with the air then the danger of the explosion is risen up. So, the secure the safety is mostly important. In this research, to detect the leakage of the hydrogen rapidly, added the odorant materials which don't include the sulfur component into the hydrogen gas and researched on the effect of each odorant on the performance of the fuel cell. As the results, setting the cumulation electric power on the basis and comparing the pure hydrogen, 2,3-Butanedione 5ppm mixed gas 86.1%, 5-Ethylidene-2-Norbornene 17ppm mixed gas 88.2%, Isovaleraldehyde 10ppm mixed gas 74.8%, Ethyl Isobutyrate 2.2ppm mixed gas 93.5% of performance was shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.84-92
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• 2002

On the cold start of LPG engine, as the engine temperature has not reached its equilibrium temperature, liquid LPG could not be changed perfectly gaseous LPG, although it was passed to the vaporizer. Liquid and gas mixed fuel could influence starting ability and exhaust emission characteristics of LPG engine. In this study, the vaporization characteristic of liquid LPG was investigated with a conventional vaporizer and the vaporizer with heat source(glow plug) installed at preheated chamber inlet, by using the visualization methods and engine test. According to visualization result, even if the engine coolant temperature was $14^{\circ}C$, liquid fuel was supplied to primary chamber over 25 seconds without vaporizing from preheated chamber in such a conventional vaporizer. However, the vaporizer with heat source do not correspond with that, scarcely had been trim on glow plug when LPG began to vaporize. The effectiveness of heat source could be verified by application to the conventional LPG engine.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.279-283
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• 2007

In this study, the potential possibility of oxygenates on di-ether group (DBE, dibutyl ether) was investigated as an additives for an agricultural direct injection diesel engine. It tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenates additives blending fuel which has four kinds of mixed ratio. The smoke emission of blending fuel (diesel fuel 80 vol-% + DBE 20 vol-%) was reduced in comparison with diesel fuel, that is, it was reduced approximately 26% at 2500 rpm, full load. And, power, torque and brake specific energy consumption didn't have large differences. But, NOx emission of blended fuel was increased compared with commercial diesel fuel.

• ETRI Journal
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• v.28 no.6
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• pp.777-786
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• 2006

Since the introduction of competition in the telecommunication market due to the growth of the interconnection between heterogeneous networks, particularly fixed and mobile networks, the interconnection charge based on traffic-sensitive (TS) and non-traffic-sensitive (NTS) costs has become more important. Although there have been many studies of the public switched telephone network (PSTN), previous studies of TS and NTS costs in mobile networks are very few. In this paper, as a pilot study, we propose three criteria and a procedure for the classification of TS and NTS costs based on mobile systems. The three criteria are the following: function type, investment requirement, and main exhaust driver. Moreover, for a CDMA mobile system, strongly TS, strongly NTS, and mixed components are classified by the proposed criteria and procedure. The proposed criteria, procedure, and classification can provide a systematic and useful guideline to decide the scope of mobile facilities and to determine the terminating cost on mobile networks from fixed networks.