Cha Lee Myung

Effect of the mixture preparation on the nanoparticle characteristics of gasoline direct-injection vehicles

Time-resolved nanoparticle number concentrations and size distribution characteristics were investigated in gasoline direct-injection vehicles, according to fuel preparation methods. Particle number emissions were measured using the golden particle measurement system recommended by the Particle Measurement Programme, and the particle size spectrum was determined using a DMS500 spectrometer installed at the tailpipe of the vehicles. The wall-guided gasoline direct-injection vehicle exhibited the most temperature-dependent nanoparticulate matter exhaust characteristics, owing to direct accumulation of fuel on the piston head and cylinder liner and a high concentration of accumulation mode particles. The air-guided gasoline direct-injection vehicle emitted particle emissions mostly during cold transient driving conditions and high acceleration, which had a weak trimodal characteristic with evenly distributed nucleation and accumulation mode particles. The spray-guided gasoline direct-injection vehicle continuously discharged 105 particles/cm3 during constant-speed driving segments, because of the ultra-lean-burn operation and bulk quenching; particulate matter from the spray-guided gasoline direct-injection vehicle demonstrated a strong bimodal characteristic, spreading over 10–100 nm. The particle number emissions for the gasoline direct-injection vehicles for the New European Driving Cycle test mode were 1.48 × 1012 particles/km, 6.03 × 1011 particles/km and 3.17 × 1012 particles/km for the wall-guided type, the air-guided type and the spray-guided type respectively, and none of these were able to satisfy the proposed particle number regulations for the Euro 6 standard. For gasoline direct-injection vehicles, it should be considered that engine hardware modifications, as well as energy management system calibrations and even the application of the particle filter, may be needed to meet the upcoming particulate matter number regulation.

Experimental study of particle emission characteristics of a heavy-duty diesel engine and effects of after-treatment systems: Selective catalytic reduction, diesel particulate filter, and diesel particulate and NOx reduction

This investigation focused on the particle emission characteristics of a heavy-duty diesel engine and the effects of after-treatment systems such as diesel particulate filter and selective catalytic reduction. The test engine was operated on the worldwide harmonized transient cycle mode, which is a new transient cycle for Euro 6, and the conventional European transient cycle mode. Four combinations of after-treatment systems, engine-out, selective catalytic reduction, diesel particulate filter, and diesel particulate and nitrogen oxide reduction, were evaluated for the transient cycles, respectively. The whole test procedure, as part of the Korea particulate measurement programme and the inter laboratory correlation exercise for domestic heavy-duty diesel engines, complied with the recommended method of particulate measurement programme. The particles that were extracted through the golden particle measurement system the constant volume sampler tunnel consisted of solid particles like carbonaceous fraction, metal ash, etc. The particles emitted from the tail-pipe, as analyzed by the differential mobility spectrometer, included volatile or soluble particles like sulphate fraction, nitrate fraction, and organic fraction. The test results showed that the particle number and size distribution depended on the catalytic activity or filtration efficiency of the after-treatment system. Compared to the accumulation mode, the nucleation mode was easily caught or oxidized by the after-treatment system. Additionally, the nucleation mode was sharply increased by excessive ammonia injection because nitrogen dioxide-assisted diesel particulate filter regeneration resulted in reduced conversion efficiency of the selective catalytic reduction.

Study of regulated emissions and nanoparticle characteristics of light-duty direct-injection vehicles fuelled with gasoline and liquefied petroleum gas in the New European Driving Cycle and the Federal Test Procedure 75 driving cycle

This study evaluated the pollutants and nanoparticles, the fuel economy and the levels of carbon dioxide emissions of vehicles equipped with a 1.6 l direct-injection spark ignition engine fuelled by gasoline or by liquefied petroleum gas. The nanoparticles were analysed using a particle measurement system that is used in Europe for regulatory purposes. A fast-response particle size and number spectrometer (model DMS500) were used to characterize the size-resolved particle distributions. The vehicle was tested on a chassis dynamometer for the New European Driving Cycle and Federal Test Procedure 75 in its factory default state (gasoline version) and modified state (for liquefied petroleum gas fuel), and the results were compared. The liquefied-petroleum-gas direct-injection vehicle emitted significantly lower levels of total hydrocarbons than did the gasoline direct-injection vehicle. However, the levels of nitrogen oxide emissions from the liquefied-petroleum-gas direct-injection vehicle were equivalent to those from the gasoline direct-injection vehicle. Because of the higher combustion and exhaust temperatures and relatively higher loads imposed during the driving cycles, the liquefied-petroleum-gas direct-injection vehicle showed a slightly higher level of nitrogen oxide emissions. The particle emissions from the vehicles were mainly affected by the vehicle driving conditions of the test driving cycles. In particular, the particle emissions from the vehicle were pronounced in the cold-start and accelerating phases of the emission certification standards. The nanoparticles from the liquefied-petroleum-gas direct-injection vehicle were significantly fewer in number, exhibiting a reduction of over 99%.

Experimental investigation of the effect of thin-wall substrates and spark timing retard on total hydrocarbon emissions during cold start for super-ultra-low-emission vehicle application

As the basic approach to improve the emission performance under cold start engine operation to meet stringent emission regulations, the effects of thin wall catalysts and spark timing retard on total hydrocarbon (THC) emission characteristics were investigated by engine performance and vehicle emissions tests. From this study, the effects of cell density on back pressure and engine performance were studied for thin-wall catalysts. The light-offtime reduction of the thin-wall catalysts was also demonstrated through vehicle emission tests. The effect of spark timing retard from minimum spark advance for best torque on THC emission reduction under the cold-start condition was also studied quantitatively using a fast flame ionization detector and a flame visualization technique. As the spark timing is retarded, THC emission at the exhaust manifold is effectively reduced regardless of the air-fuel ratio. From flame visualization, as the spark timing is retarded, the flame propagation speed becomes slower and the duration of the main flame is longer. It was also found that the reduction in THC emission at the beginning of the engine start is essential to meet the more stringent emission regulations. As a result, the adoption of a high-cell-density catalyst (900 cells/2.0 mil) and the spark timing retard technique (spark advance retard case, after top dead centre 8 ° crank angle) makes it possible to meet the super-ultra-low-emission vehicle emission regulation if effectively combined along with a metallic catalyst and exhaust gas-flow-optimized exhaust manifold.

Dependence of nanoparticle and combustion characteristics of gasoline direct injection engines on coolant temperature

이에 현재 시중에 판매되고 있는 GDI 차량 Key Words: GDI(가솔린직접분사), DMS(고속 PM 분석기), HFR-400(고속 THC 분석기), CLD-400(고속 NOx 분석기), THC(미연탄화수소), NOx(질소 산화물), PM(입자상 물질) 초록: 본 논문에서는 GDI 엔진의 냉각수 온도에 따른 연소 및 배출가스 특성을 연구하였다. 엔진에서 나오는 입자상 물질의 수와 크기 분포는 DMS-500 장비로 측정하였다. 배기포트 에 장착된 CLD-400 과 HFR-400 을 통해 NOx 및 THC 의 배출 특성을 연소주기 별로 측정하였다. 결과적으로 낮은 냉각수온에서 5~10 nm 의 입자상 물질이 크게 증가하는 특성을 보였다. THC 또한 낮은 냉각수온에서 증가하는 특성을 보였는데 이는 연소실 내 연료의 액막현상 때문이다. 그리고 NOx 는 높은 냉각수온에서 감소하는 특성을 보였는데 이는 내부 EGR 이 증가하기 때문이다. 결론적으로 THC 와 NOx 그리고 입자상 물질의 배출을 줄이기 위해서는 냉각수온을 빠르게 올리는 EMS 변수 설정 필요하다. Abstract: This paper investigated the combustion and exhaust gas characteristics of gasoline direct injection engines for various cooling water temperature. The engine-out nanoparticle emission number and size distribution were measured by a DMS-500 equipped upstream of the catalyst. A CLD-400 and an HFR-400 were equipped at the exhaust port to analyze the cyclic NOx and total hydrocarbon emission characteristics. The results showed that the nanoparticle emission number greatly increased at low coolant temperatures and that the exhaust mainly contained particulate matter of 5–10 nm. THC also increased under low temperature conditions because of fuel film on the combustion chamber. NOx emissions decreased under high temperature conditions because of the increase in internal exhaust gas recirculation. In conclusion, an engine management system control strategy for driving coolant temperature up rapidly is needed to reduce not only THC and NOx but also nanoparticle emissions.

Evaluation of the Time-Resolved Nanoparticle Emissions and the Vehicle Performance Characteristics for a Turbocharged Gasoline Direct-Injection Vehicle with a Metal-Foam Gasoline Particulate Filter

The nanoparticle emissions from gasoline direct-injection engines are of concern because of the high particle number concentrations compared with those from a gasoline port fuel injection engine. A gasoline particulate filter is a potential solution for reducing the particulate matter emissions. In this study, a 2.0 l turbocharged gasoline direct-injection vehicle with a metal-foam-type gasoline particulate filter was tested using the New European Driving Cycle and steady vehicle operating conditions. The particle number concentration, the particle-size distribution and the filtration efficiency were determined using a condensation particle counter and a fast response differential mobility spectrometer (DMS500). The particle number emissions (particle numbers per vehicle travelling distance (particles/km)) over the New European Driving Cycle were 1.95 × 1012 particles/km for a base vehicle equipped with a three-way catalytic converter and 5.68 × 1011 particles/km for the additional installation of a gasoline particulate filter on the base gasoline direct-injection vehicle. The filtration efficiency of the particle number and the particulate matter mass reached approximately 71% and 67% respectively. The nucleation-mode particles in the size range less than 23 nm for the gasoline direct-injection vehicle equipped with a three-way catalytic converter were further reduced on installation of a gasoline particulate filter at the downstream position of the three-way catalytic converter. A sharp pressure drop between the gasoline particulate filter of 21.0 mbar was obtained at a vehicle speed of 120 km/h in the New European Driving Cycle. The exhaust gas temperature before the gasoline particulate filter reached around 380–610 °C at steady vehicle speeds of 60–120 km/h. The installation of the gasoline particulate filter has the potential to satisfy the Euro 6c particle number emissions regulations for light-duty gasoline direct-injection vehicles.

Study of Particle Emission Contour Construction & Characteristics and Reduction Efficiency of Exhaust-Treatment System of Diesel Engine

Key Words: PM(입자상물질), DPF(매연여과장치), EGR(배기재순환), DMS(고속입자상물질측정장치),NucleationMode(핵화모드),AccumulationMode(축적모드)초록: 본연구는승용디젤엔진의입자상물질배출특성에관한것으로써, 엔진에서배출된입자상물질이배기관및후처리장치인디젤산화촉매와매연여과장치를통과할때의특성변화를파악하기위하여후처리장치각각전 후단및배기관에서직접측정하였다.또한다양한엔진회전속도및부하조건에서측정함으로써입자상물질배출맵을구축하였으며,디젤산화촉매및매연여과장치의입자상물질저감효과에대해평가하였다.뿐만아니라배기재순환율과연료분사시기를변경시켜입자상물질의배출특성변화를파악하였다.모든시험에서입자상물질을5~1000nm크기까지측정할수있는DMS500을이용하였다.Abstract: Inthisstudy,wemainlyfocusedonthePM(ParticulateMatter)emissioncharacteristicsofadieselengine.To analyze particle behavior in the tail-pipe, particle emission was measured on the engine-out (downstream ofturbocharger), each upstream and downstream both of DOC (Diesel Oxidation Catalyst) and DPF (Diesel ParticulateFilter). Moreover, particle emission contours on each sampling point were constructed. The reduction efficiency ofparticlenumberconcentrationandmassthroughtheDOCandDPFwasstudied.ParameterssuchasEGR(ExhaustGasRecirculation) and the main injection timing were varied in part load conditions and evaluated using the engine-outemissions. TheDMS500(Differential MobilitySpectrometer) wasusedasaparticlemeasurement instrument that canmeasure particle concentrations from5 nmto 1000 nm. Nano-particles of sizes less than 30 nmwere reduced byoxidationorcoagulatedwithsolidparticlesinthetail-pipeandDOC.TheDPFhasaveryhighfiltrationefficiencyoveralloperatingconditionsexceptduringnaturalregenerationofDPF.

Investigation on the DeNOx Efficiency in Urea-SCR System at Various Operating Conditions and Injection Characteristics for a Passenger Diesel Engine

Selective Catalytic Reduction (SCR) system is a high-effective NOx reduction technology in diesel engines. As the emission standard of diesel engines is more stringent, vehicle manufactures makes efforts on emission technologies. This paper discusses the performance of Urea-SCR system according to the engine operating conditions in a passenger diesel engine. Engine test results in this paper show that it is important to consider the catalyst temperature and space velocity to obtain high NOx conversion efficiency. In condition of high catalyst temperature, over 90% NOx conversion efficiency is indicated. However, when catalyst temperature is low, NOx conversion efficiency was decreased. Also, it was shown that space velocity mainly effects on the DeNOx performance under 220 degree celsius of SCR catalyst temperature. As the urea injection pressure was decreased, NOx conversion efficiency was declined. It is concerned about urea droplet atomization. This work shown in this paper can lead to improved overall NOx conversion efficiency.

LPi Engine Combustion and Emission Characteristics Depending on LPG Properties from Various Fuel Supply Types by Using DC Motor Type Fuel Pump

Abstract This study is mainly focused on the assessment of return, semi return, and returnless fuel supply system for an LPi engine. In order to compare the return type with returnless one with various LPG blends, combustion analysis and cyclic THC emission characteristic were tested at the part load operating condition of the LPi engine. Considering heat balance of each fuel supply systems, pressure and temperature increment of return type showed lower at the fuel rail during idle warm up operation. However, those of returnless type at LPG tank maintained stable and slow increment because the heat transfer from the LPi engine was minimized. Finally, hot restartability of each fuel supply systems were evaluated with the various LPG blends and fuel temperatures. As a result, semi return type has equivalent performance to return type considering combustion and emission characteristic, hot restartability performance for LPi engine. 1. 서 론 기존 믹서방식 연료공급시스템의 단점을 개선한 LPi(Liquid phase injection) 시스템은 LPG 탱크 내부에 장착된 연료펌프를 이용하여 LPG 연료를 가압 후 연료탱크의 토출부에서부터 인젝터까지 액체 상태를 유지한 다음 이를 전자식 인젝

An experimental study on individual HC emission characteristics and startability for various composition ratio of LPG fuel on LPLi engine

The regulations for hydrocarbon emission from vehicles have become much more stringent in recent years. These more stringent regulations request vehicle manufacturers to develop the advanced exhaust system for reducing exhaust emissions. The exhaust emissions has many sources in vehicle. In order to investigate the characteristics of hydrocarbon(HC) in the exhaust manifold, concentrations of individual HC species were measured in exhaust process. Using sampling valve, the light hydrocarbon emissions were captured in the exhaust manifold(catalyst before and after) and analyzed from LPLi engine exhaust manifold(catalyst before and after) using different fuel properties. Then exhaust samples were measured by gas chromatography(GC) and exhaust gas analyzer. Catalyst conversion efficiency for fuel properties of Butane 100% was better than Propane 100%. Start delay of LPLi engine was observed as increment of propane contents in LPG fuels.