• Journal of Power System Engineering
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• v.12 no.5
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• pp.27-33
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• 2008

Natural gas has been considered one of the most promising alternative fuels for transportation because of its abundance as well as its ability to reduce regulated pollutants. We measured emission characteristics of nanoparticles from lean burn H/D(Heavy-Duty) CNG (Compressed Natural Gas) engine equipped with oxidation catalysts. The experiments were carried out to measure the emission and engine performance according to the ESC test cycle. The CO and THC conversion efficiencies on the best catalyst in the ESC test cycle achieved about 91 % and 83 %, respectively. From the measurement by the SMPS, the number of nanoparticles emitted from H/D CNG engine is reduced by about 99 % which is more than that of 2.5 L diesel engine. The particle number concentrations of H/D CNG engine were almost nanoparticles. Nanoparticles smaller than 30 nm emitted from the H/D CNG engine and diesel engine equipped with a CDPF(Catalyzed Diesel Particulate Filter) were quite similar. However, the particles bigger than 30nm from the CNG engine were smaller than the particles from diesel engine equipped with a CDPF. The higher the CNG engine load, the lower the particle number from engine-out, but it increased slightly at full load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.37-42
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• 2010

The objective of this study is to find heat emission characteristics on the natural convection radiator in a heating system when the aspect ratio of radiator is changed. In addition the computer simulation method is used in order to find the characteristics of heat transfer. When the width of the radiator is long and the height of radiator is short, the temperature difference from the floor level 0.5m to about 2.7m above the floor is small. It shows that thermal environment in heating space is good than the other case. For the future, I hope to compare the results between the computer simulation and experimental method for reliability.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.245-253
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• 2019

BACKGROUND: Weathering of bottom ash (BA) might induce change of its surface texture and pH and affect physical and chemical properties of soil associated with greenhouse gas emission, when it is applied to the arable soil. This study was conducted to determine effect of weathering of BA in mitigating emission of greenhouse gases from upland soil. METHODS AND RESULTS: In a field experiment, methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) emitted from the soil was periodically monitored using closed chamber. Three month-weathered BA and non-weathered BA were applied to an upland soil at the rates of 0, 200 Mg ha^-1. Maize (Zea mays L.) was grown from July 1_st to Oct 8_th in 2018. Both BAs did not affect cumulative CH₄ emission. Cumulative CO₂ emission were 23.1, 19.8, and 18.8 Mg/ha/100days and cumulative N₂O emission were 35.8, 20.9, and 17.7 kg/ha/100days for the control, non-weathered BA, and weathered BA, respectively. Weathering of BA did not decrease emission of greenhouse gases significantly, compared to the weathered BA in this study. In addition, both BAs did not decrease biomass yields of maize. CONCLUSION: BA might be a good soil amendment to mitigate emissions of CO₂ and N₂O from arable soil without adverse effect on crop productivity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.473-479
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• 2013

This study focused on a heavy-duty natural gas engine fuelled with HCNG (CNG: 70 vol%, hydrogen: 30 vol%) and CNG. To study the emission characteristics of an HCNG engine with high compression ratio, the exhaust gas of CNG and HCNG fuel were analyzed in relation to the change in the compression ratio at the half load condition. The results showed that the thermal efficiency improved with an increase in the compression ratio. Consequently, $CO_2$ emission decreased. CO emission increased with inefficient oxidation due to the low exhaust gas temperature. $NO_x$ emission with high compression ratio was increased at the same excess air ratio condition. However, $NO_x$ emission was not affected by a compression ratio exceeding ${\lambda}$ = 1.9 because of the same MBT timing.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.25-34
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• 2022

Recently, as a study to air cooled slag, which is an industrial by-product, research is being proceed to use it as a material for concrete. In this study, the workability, air content, compressive strength, CO₂ emission and economic feasibility of concrete were analyzed when air cooled slag, an industrial by-product, was applied as aggregate for rural road pavement concrete. As a result of the analysis, both the slump and air contents test results of concrete using the air cooled slag aggregate satisfied the target values, and the compressive strength was increased when the air cooled slag aggregate was used compared to when the natural aggregate was applied. On the other hand, the largest amount of CO₂ emission by raw material was found in aggregate. The carbon emission of rural road pavement concrete using air cooled slag aggregate increased when the Korean LCI DB was applied compared to when natural and crushed aggregates were applied, and the emission decreased when the German LCI DB was applied. This results are due to differences in the viewpoints of industrial by-products. However, considering the recycling of waste from the environmental aspect, it is necessary to simultaneously review the CO₂ emission and recycling aspects in the future. Also, the application of air cooled slag aggregate had the effect of improving the economic efficiency of rural road pavement concrete about 18.75%.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.6
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• pp.451-461
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• 1997

The soil NO flux measurements in Korea were made from 17 May 1997 to 16 June 1997 on grass land at Kunsan National University in southwestern Korea by using flow-through chamber technique. The experiment was conducted in an effort to determine the role of natural emissions of NO on rural atmospheric photochemistry, and to understand the soil NO emission mechanism with respect to soil parameters. Soil NO fluxes were measured every minutes and averaged in every 15 minutes as well as soil temperature. Soil samples were analyzed for $NO_3^-, NH_4^+$, and moisture in soil. Soil nitrate was not detected in most times, and total N-containing was limited in site soils. There was a optimum range of soil moisture and temperature for soil NO flux. The overall average of soil NO emission rates were found to be 1.30 $\pm 0.92 ngNm^{-2}s^{-1}$ (n=1219), and ranged from 0.01 ngNm^{-2}s^{-1}$ to 5.62 ngNm^{-2}s^{-1}$. Diurnal variation of soil NO emission was typical, which was in higher level during daytime, and was in lower level over the night. NO flux showed a strong soil temperature dependence $(r^2=0.78)$, but not with soil moisture and soil N-containing during this experimental period; NO fluxes increased exponentially as soil temperature increased. In order to assure the relevant relationship between soil NO flux and the soil parameters, long-term soil flux measurement on different types of land use should be planned and conducted continuously.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.13-18
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• 2012

This research is about the exhaust gas and driving performance test which are for CNG-Diesel dual fuel engine. The CNG-Diesel dual fuel engine converted from 2500cc diesel has two steps of injection systems; small amount of diesel is injected to mixture CNG in cylinder to ignite before CNG is injected into each intake manifold to form mixture. The amounts of output power and emission in duel fuel consumption were measured by engine dynamometer and exhaust gas analyzer. Over 90% of diesel consumption reduction, similar driving performance to current diesel engine and reduced emission on $CO_2$ and PM, respectively, were indicated through the measurements. The two steps of system were applied to vehicle to investigate exhaust gas characteristics and driving performance via NEDC mode and real driving test. Additional oxidation catalyst was applied to reduce emission on the test vehicle and the NEDC mode test showed the reduction of Co, $CO_2$, Pm and THC.

• Journal of Energy Engineering
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• v.9 no.2
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• pp.83-88
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• 2000

In this study, the performance and pollutant emission of CNG engine using diesel oil as a source of ignition, so called CNG dual fuel diesel engine is considered by experiment. One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of total hydrocarbon (THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrogen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. and when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the knocking limit decrease and the produce of NOx increases.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.57-63
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• 2000

This paper deals with a study on combustion and emission characteristics of a direct injection diesel engine dual fueled with natural gas. Dual fuelling systems tend to emit high unburned fuel especially at low load, resulting in a decreased thermal efficiency. This is because natural gas-air mixtures are too lean for flame to propagate under low load conditions. Suction air quantity and injection timing controls are very useful to improve emissions and thermal efficiency at low load.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.78-83
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• 2011

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its high thermal efficiency and lower harmful emissions, including $CO_2$. Although the high octane value of natural gas increases engine output and efficiency due to the high compression ratio, this fuel is prone to such difficulties as a narrow limit of inflammability and a slow combustion speed in the lean burn operation domain, leading to unstable combustion and higher emissions of harmful exhaust gases. Hydrogen blended with natural gas can extend the lean burn limit while maintaining stable, efficient combustion and achieving lower NOx, hydrocarbon and green house gas emissions. In this study, the effect of hydrogen addition on an engine performance and NOx emission characteristics was investigated in a heavy duty natural gas engine. The results showed that thermal efficiency was increased and NOx emissions were reduced due to the expansion of lean operation range under stable operation. NOx emission can be significantly reduced with the retard of spark advance timing.