Cheolwoong Park

Effects of Multiple Injections in a HSDI Diesel Engine Equipped with Common Rail Injection System

The authors would like to appreciate the support of the National Research Laboratory scheme of Korea.

Effects of the ignition timing retard and the compression ratio on the full-load performance and the emissions characteristics of a heavy-duty engine fuelled by hydrogen–natural-gas blends

Heavy-duty natural-gas vehicles contribute towards environmental improvement in the air quality of downtown areas because the particulate matter emissions are quite low and lean combustion facilitates improvement in the efficiency and reduction in the harmful emissions. However, because stronger emission regulations such as Euro VI cannot be satisfied using the current technology, new technology is required. Hydrogen–natural-gas blend engines have been investigated as an alternative in preparation for the hydrogen era. Such engines make further emission reductions and efficiency improvements possible by extending the lean-combustion limit. However, they do have some disadvantages such as the degradation in the full-load performance, which can limit the reduction in the nitrogen oxide emissions or the operation range because the extension of the lean-burn limit requires a larger amount of intake air even under a wide-open throttle operating condition. In the present study, the full-load performance and emissions characteristics of a hydrogen–compressed-natural-gas engine were evaluated using hydrogen–compressed-natural-gas fuel with a hydrogen content of 30 vol %. In order to achieve performance improvement, a spark timing retard strategy was employed, together with a change in the compression ratio. After examining the full-load performance for each parameter change, the emission characteristics were assessed to analyse the commercialization potential and feasibility of this hydrogen–compressed-natural-gas engine. For a higher compression ratio, the specified torque value could be achieved with spark timing retard; an excess air ratio of 1.8 was found to be preferable, and the nitrogen oxide emissions standard of Euro VI was satisfied.

A Study on the Lean Combustion Characteristics with Variation of Combustion Parameter in a Gasoline Direct Injection Engine

Today gasoline engines for vehicular application are not only faced with stringent emission regulation but also with increasing requirements to better fuel economy, while guaranteeing power density. The spray-guided type gasoline direct injection (GDI) engine has an advantage of improved thermal efficiency and lower harmful emissions. Centrally mounted high pressure injector and adjacent spark plug allow stable lean combustion due to the flexible mixture stratification. In the present study, the performance and emissions characteristics of developed spray-guided type GDI combustion system were evaluated at various excess air ratio conditions. The specific fuel consumption and nitrogen oxides (NO x) emissions were reduced due to the achievement of stable lean combustion under flammability limit. Multiple injection strategy was not helpful to improve fuel consumption while further reduction of NOx emissions was possible.

Effect of Low Calorific Natural Gas on Performance and Emission Characteristics of Engine

Key Words: Low Calorific Natural Gas(저발열량천연가스), Compressed Natural Gas(천연가스), ThermalEfficiency(열효율), Emission(배기가스), Full-Load Performance, World Harmonized Steady StateCycle(정상상태표준모드), World Harmonized Transient Cycle(과도응답상태표준모드)초록:본연구에서는저발열량천연가스가현재상용되고있는대형천연가스엔진에미치는영향을살펴보기위하여3종류의연료를적용하였다. 전부하운전조건과WHSC 및WHTC 모드테스트를수행하여엔진성능및배기특성을분석하였다. 실험결과전부하실험에서토크성능이9,800kcal/Nm3의발열량을갖는저발열량가스의경우현행천연가스(10,400kcal/Nm3)를사용한결과에비해4.4% 감소하였다. 저발열량연료를사용하였을때일산화탄소, 이산화탄소및질소산화물의배출량은감소하였지만,탄화수소의배출량은증가하였다. WHSC 및WHTC 실험결과저발열량연료에서열효율이증가하였으며배기특성은전부하실험결과와유사한경향을보였다. 저발열량천연가스를사용할경우제원상의출력을만족하기어렵고, 탄화수소의배출이증가하는문제점을확인하였다.Abstract: In this, three types of natural gas were employed to investigate the effect of low-calorific naturalgas on the performance of and emissions from a heavy-duty CNG engine. The performance and emissioncharacteristics were analyzed by conducting a full-load test, WHSC mode test, and WHTC mode test. Theresults showed that the torque of low-calorific natural gas with 9,800 kcal/Nm

The Effect of Multi-ignition Strategy on the Combustion and Emission Characteristics in a Ultra Lean Burn GDI Engine

Since air pollution problem by emissions from automotive vehicles has become social issues, lean-burn gasoline direct injection (GDI) engine is focused as an alternative to meet the requirement of reinforced emission regulation and improved fuel consumption. Spray-guided type DI combustion is promising technology, which characterized by the centrally mounted injector and closely positioned spark plug, since stable lean combustion can be realized even at ultra-lean mixture condition. In the present study, the effect of multi-ignition with developed charge coil on combustion and emission characteristics was investigated in optical accessible single cylinder engine. In order to fully understand the in-cylinder phenomena and the mechanisms of emission production, optical diagnostics, such as flame visualization was also carried out at frequently using operating condition. Multi-ignition is effective to improve fuel economy but increase NOx emission at flammability limit.

A Study on Performance Characteristics According to the Fuel Conditions for a Fuel Pump in LPG Engine

Abstract The need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as Liquefied Petroleum Gas(LPG) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a high vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to apply it for the conventional gasoline or diesel fuel pump directly. In this study, experiments are performed to get performance and efficiency of the fuel pump at different condition as temperature, rotating speeds, composition of fuel. The characteristics of fuel pump is affected by cavitation due to the variation of temperature and composition.기호설명  : 토출압력 [kgf/cm 2 ]  : 흡입압력 [kgf/cm 2 ]  : 토출유속 [m/sec]  : 흡입유속 [m/sec] : 중력가속도 [m/sec 2 ] : 토출 및 흡입압력 측정공의 수직높이 [m]  : 펌프 효율  : 모터 효율WHP : 수동력 [W]BHP : 축동력 [W] †책임저자, 회원, 한국기계연구원 E-mail : cwpark@kimm.re.kr TEL : (042)868-7928 FAX : (042)868-7305 * 회원, 한국기계연구원

Combustion Characteristics of Stratified Mixture in Lean-Burn LPG Direct-Injection Engine With Spray-Guided Combustion System

Today, we are faced with the problems of global warming and fossil fuel depletion, and they have led to the enforcement of new emissions regulations. Direct-injection spark-ignition engines are a very promising technology that can comply with the new regulations. These engines offer the advantages of better fuel economy and lower emissions than conventional port-injection engines. The use of LPG as the fuel reduces carbon emissions because of its vaporization characteristics and the fact that it has lower carbon content than gasoline. An experimental study was carried out to investigate the combustion process and emission characteristics of a 2-liter spray-guided LPG direct-injection engine under lean operating conditions. The engine was operated at a constant speed of 2000 rpm under 0.2-MPa brake mean effective pressure, which corresponds to a common operation point of a passenger vehicle. Combustion stability, which is the most important component of engine performance, is closely related to the operation strategy and it significantly influences the degree of fuel consumption reduction. In order to achieve stable combustion with a stratified LPG mixture, an inter-injection spark ignition (ISI) strategy, which is an alternative control strategy to two-stage injection, was employed. The effects of the compression ratio on fuel economy were also assessed; due to the characteristics of the stratified LPG mixture, the fuel consumption did not reduce when the compression ratio was increased.© 2014 ASME

Comparison of Combustion Characteristics with Combustion Strategy and Excess Air Ratio Change in a Lean-burn LPG Direct Injection Engine

Abstract : Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investi-gate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a func-tion of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion. Key words : LPG direct injection(LPG 직접분사), Ultra lean combustion(초희박연소), Spray-guided type combustion system(분무유도방식 연소기구), Brake specific fuel consumption(연료소비율), Combustion stability(연소안정성)

A Study on the Combustion Characteristics of a Generator Engine Running on a Mixture of Syngas and Hydrogen

Key Words: Syngas(합성가스), Hydrogen(수소), LHV(저위발열량), Generator(발전기), Combustion stability(연소안정성)초록: 바이오매스나기타유기성폐기물로부터가스화공정을거쳐얻을수있는합성가스는환경보호와화석연료고갈방지측면에서유망한대체연료중하나로여겨지고있다. 그러나가스화로부터얻어지는합성가스는일반적인천연가스와같은가스연료에비해발열량이낮고연료조성이불균일하여내연기관에적용시안정적이고지속적인운전이어렵다는단점이있다. 따라서본연구에서는이러한저발열량과불균일한가스조성의특징을가진합성가스가연소에미치는영향을파악하여고효율의엔진을개발하고자연구를수행하였다. 저발열량의합성가스를모사하기위하여천연가스에질소를희석한연료를사용하였다. 또한체적당발열량을유지하면서동일유량조건으로합성가스에수소혼합비율을10 ~30%로변화시키면서연소특성변화를살펴보았다.Abstract: Internal combustion engines running on syngas, which can be obtained from biomass or organicwastes, are expected to be one of the suitable alternatives for power generation, because they areenvironment-friendly and do not contribute to the depletion of fossil fuels. However, syngas has variablecompositions and a lower heating value than pure natural gas, owing to which the combustion conditions needto be adjusted in order to achieve stable combustion. In this study, a gas that has the same characteristics assyngas, such as low heating value (LHV), was produced by mixing N

PM Reduction Characteristics of Gasoline Direct Injection Engines with Different Types of GPFs

In the recent times, the use of gasoline direct injection (GDI) engines has been regarded as a means of enhancing conformance to emission regulations and improving fuel efficiency. GDI engines have been widely adopted in the recent years for their better engine performance and fuel economy compared to those of conventional MPI gasoline engines. However, they present some disadvantages related to the mass and quantity of particulate matter generated during their use. This study investigated the nanoparticle characteristics of the particulate matter exhausted from a GDI engine vehicle installed with different types of gasoline particulate filters, after subjecting it to ultra-lean burn driving conditions. Three metal foam and metal fiber filters were used for each experimental condition. The number concentrations of particles were analyzed for understanding their behavior, and the reduction characteristics were obtained for each type of filter.