• Journal of Korean Society for Atmospheric Environment
• /
• v.7 no.1
• /
• pp.31-40
• /
• 1991

This study shows the correlation between $NO_x$ emission in the exhaust gas and various operation factors of dual fuel engine for Co-generation system. General tendency was shown that the thermal efficiency was lowered by the change of operation factors. However these were not confirmed on this experiment. Increasing T4 temperature (exhaust gas temperature at turbo-charger inlet) reduces $NO_x$ emission rate. The higher T4 temperature requires lower excess air as the excess air ratio is controlled by T4 temperature on gas mode operation. Another tendency was that $NO_x$ emission rate is reduced in case of increasing boost air temperature, quantity of pilot oil or bypassing flue gas through the exhaust gas boiler. The diameter of the fuel injection nozzle was changed smaller than design value and the injection timing was readjusted. Thus $NO_x$ emission rate could be reduced as retarding injection timing and changing hole diameter of fuel injection nozzle, however maxium engine out-put was decreased by changing fuel nozzle on the diesel mode operation.

• Journal of the korean Society of Automotive Engineers
• /
• v.10 no.5
• /
• pp.54-60
• /
• 1988

This study is a theoretical analysis and experimental effect of oxygen concentration, exhaust velocity and trap inlet temperature on particulate ignition temperature with installation of ceramic filter trap in diesel engine. So the following results are obtained. 1, Based on the fundamental experiments of the regeneration process, the analytical model was developed and the results from the analytical model agreed with the experiments, then the validity of the model was proved. 2, The ignition temperature for accumulated particulate was proportional to the exhaust velocity and it was known that the optimum exhaust velocity was about 15m/sec. 3, The ignition temperature for accumulated particulate was inversely proportional to the oxygen concentration and the trap inlet temperature, and a minimum oxygen concentration of 5% was required to sustain regeneration. 4, This experimental filter trap(EX-66) is found about 30% of smoke reduction efficiency in comparison with existing muffler.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.29-36
• /
• 2003

Exhaust manifolds suffer from serious temperature variation during the thermal fatigue test. The spatial distribution of temperature changes at each moment. Because transient flow can not be simulated during the long period of temperature change, the simulation can not be performed by conjugate heat transfer analysis. In this study, a new procedure for transient thermal analysis is established by decoupling fluid-solid analysis. The procedure consists of (1) transient CFD calculation (2 cycles), (2) mapping heat transfer coefficient to the inner surface of solid mesh as a boundary condition of heat conduction analysis and (3) transient heat conduction analysis in the long period (30 min). The realistic temperature change can be predicted by this procedure.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.12
• /
• pp.3553-3558
• /
• 2009

This study has been conducted to improve coolant flow pattern in the gasoline engine. Flow field has been calculated for the coolant passage mainly around the exhaust ports and valves. For the original model, a flow stagnant region has existed between exhaust valves of the second cylinder. To improve coolant flow characteristics, coolant passage area has been re-modeled and optimized. Furthermore, for the improved coolant core model, coolant passage under the exhaust manifold has been added to reduce exhaust-gas temperature. It was found that the flow through a gasket plays a critical role for the flow in the cylinder head and around exhaust valves. Finally, coolant flow around exhaust valves and in the cylinder head has been improved in terms of flow rate distribution.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.1
• /
• pp.72-79
• /
• 2009

Recently, the internal combustion engines have focused on reducing the $CO_2$ gas in order to cope with severe regulations for fuel economy. Therefore, various new technologies have been developed. Among them, cooling system is spotlighted because it has great effect on fuel economy. In this study, we measured the friction losses of engine parts according to engine speed and oil temperature. We also obtained optimized oil temperature which has the minimum friction losses. Then, we selected optimized oil temperature range and gave informations of friction losses for each engine parts. In addition, we analyzed relationship between coolant temperature and oil temperature by using engine performance test system. From this experiment, we obtained the database for relationship between coolant temperature and oil temperature. Then, we found the optimal temperature about engine oil. We analyzed BSFC and exhaust emissions by controlling the high coolant temperture. If we controlled coolant temperature more higher, BSFC has a little difference but exhaust emissions such as THC and CO have reduced. By using these experimental results, we predicted that IC engine have more low fuel consumption and exhaust emissions by optimized cooling control strategy.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.3
• /
• pp.115-125
• /
• 2008

Recently, Exhaust Gas Recirculation (EGR) system which re-flow a cooled exhaust gas from vehicles burning diesel as fuel to a combustion chamber of engine has been used to solve the serious air pollution. For the design and mass production of EGR system, it is essential to ensure structural integrity evaluation. The EGR system consisted of ten dimpled oval core rectangular tubes, two fix-plates, two coolant pipes, shell body and two flanges in this study. To confirm the safety of the designed system, finite element modeling about each component such as the dimpled oval core tube with the dimpled shape and others was carried out. The reliability of EGR system against exhaust gas flow with high temperature was investigated by flow and pressure analysis in the system. Also, thermal and strength analysis were verified the safety of EGR system against temperature change in the shell and tubes. Furthermore, modal analysis using ANSYS was also performed. From the results of FE analysis, there were confirmed that EGR system was safe against the flow of exhaust gas, temperature change in EGR system and vibration on operation condition, respectively.

• Journal of Power System Engineering
• /
• v.15 no.6
• /
• pp.11-15
• /
• 2011

This study investigated the symptoms of the a reduction in output while driving on the road, or increasing of fumer out exhaust gas on inclined road while working air-conditioner in summer. Notice how the experiment in 2010, the Ministry of Environment(Chapter No. 2010-46), and how the vehicle emissions inspection was carried out. 2500cc Diesel cars used in the study were used and compare to output of engine, exhaust gas, inhalation temperature measurement Inhalation of cold air has not been supplied to all agencies when comparing the results when cold air intake temperature of the supply air-conditioning switch range control from 1 to 4, the temperature drops $98^{\circ}C$ to $78^{\circ}C$. At the momentum of switch level 4, output from 63ps to 66ps after the connection has increased 9.6 percent, the highest concentration of exhaust emissions were reduced by 42.8%. This research can contribute in part to the reduction of exhaust directly supply into the cooling air intake line, doing the output of diesel cars in the summer. In addition, construction equipment and machinery that are currently being used excluding the engine's intercooler cooling of the supply line via a separate output in the summer and help reduce exhaust emissions is expected.

• Journal of Welding and Joining
• /
• v.27 no.1
• /
• pp.79-84
• /
• 2009

Ferritic stainless steel, which has been used as material for decoration parts in automobile, is recently used as material for the exhaust system due to its good performance at high temperature. To improve the fuel efficiency and purify automotive exhaust gas, it is needed to increase the temperature of exhaust gas. However, it is frequently reported that the rising of the temperature of exhaust gas increases thermal stress at exhaust manifold, which results in thermal fatigue failure in welded joints. Therefore, in this study, effects of chemical composition of steel and welding parameters on thermal fatigue properties of synthetic heat affected zone in ferritic stainless steel have been investigated. It has been found that thermal fatigue life in heat affected zone is affected by bead shape of welded joint and amount of soluble Nb in steel. Especially, Nb-Ti added steel has higher thermal fatigue life in comparison to Nb added steel, which is attributed to difference of precipitation behavior in both steels.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.3
• /
• pp.106-112
• /
• 2011

This study is to investigate the effect of an aromatic content in high cetane number (CN) fuels on exhaust emissions under low temperature diesel combustion, which expands the previous research about an aromatic content in low CN fuels. A 1.9L common rail direct injection diesel engine was run at 1500 rpm 2.6 bar BMEP with four fuel sets: an aromatic content of 20% (A20) or 45% (A45) with CN30, i.e. low CN fuels, and CN55, i.e. high CN fuels. Given experimental conditions, the trend of exhaust emissions in high CN fuels was inconsistent with that of low CN fuels which all produced nearly zero smoke but higher NOx for the high aromatic fuel (CN30-A45). For high CN fuels, however, the low aromatic fuel (CN55-A20) produced lower smoke than the high one (CN55-A45) while NOx was similar to each other. The cause of this discrepancy between high CN and low CN fuels is unclear whether it comes from that CN may be a dominant factor to govern exhaust emissions rather than an aromatic content or that the actual CN value of CN55-A45 is lower than CN55-A20. More decent fuel matrix should be prepared and further experiments are needed to confirm it.

• Corrosion Science and Technology
• /
• v.22 no.5
• /
• pp.351-358
• /
• 2023

Although many thermal power plants use heat recovery systems, high exhaust gas temperatures are maintained due to corrosion at dew points and ash deposits caused by condensate formation. The dew point of exhaust gas is primarily determined by the concentration of SO₃ and steam, and various experiments and calculation equations have been employed to estimate it. However, these methods are known to be less suitable for exhaust gases with low SO₃ concentrations. Therefore, in this study, since the temperature of the exhaust gas is expected to decrease due to the low-load operation of the coal-fired power plant, sulfuric acid condensation and low-temperature corrosion are anticipated. We aimed to conduct a quantitative evaluation to propose ways to prevent damage by limiting operating conditions and improving facilities. The experimental results showed that the corrosion rate increased linearly with rising temperatures at a certain sulfuric acid concentration. Furthermore, variations in sulfuric acid concentrations generated during the current power plant operation process did not significantly affect the dew point, and the dew point of sulfuric acid under these conditions was observed to be between 120 - 130 ℃.