Seokwon Cho

Southwest Research Institute

div class="section abstract"> Catalyst heating operation in compression-ignition engines is critical to ensure rapid light-off of exhaust catalysts during cold-start. This is typically achieved by using late post injections for increased exhaust enthalpy, which retardability is constrained by acceptable CO and unburned hydrocarbons emissions, since...

div class="section abstract"> To cope with regulatory standards, minimizing tailpipe emissions with rapid catalyst light-off during cold-start is critical. This requires catalyst-heating operation with increased exhaust enthalpy, typically by using late post injections for retarded combustion and, therefore, increased exhaust temperature. However,...

In this study, a skeletal chemical kinetic mechanism for gasoline surrogates is developed from a detailed mechanism by applying several reduction techniques. Directed relation graph (DRG) routines and DRG-aided sensitivity analysis methods are applied with worst-case error tolerances equal to 30% and 40%, respectively. Issues with reaction dead-end...

In this study, the effects of doping a regular E10 gasoline with 2-ethlyhexyl nitrate (EHN) are investigated under homogeneous charge compression ignition conditions. Experiments are performed in a 1-liter single-cylinder engine fueled with both straight and EHN-doped E10 gasoline. Numerical studies are performed with an internal combustion engine...

A numerical and experimental investigation about the chemical kinetic interactions between 2-ethylhexylnitrate (EHN) and PRF91 was performed in this study. Rapid compression machine experiments were conducted to investigate the effect of EHN on the autoignition reactivity of the fuel, and a reduced chemical kinetic mechanism was developed including...

Pretreating natural gas using catalytic oxidative coupling of methane (OCM) produces ethylene and ethane, both species that increase fuel reactivity, thus increasing the potential to expand the operability range of highly efficient compression ignition combustion in natural gas engines. This paper presents the first experimental results on the impa...

Diesel piston-bowl shape is a key design parameter that affects spray-wall interactions and turbulent flow development, and in turn affects the engine’s thermal efficiency and emissions. It is hypothesized that thermal efficiency can be improved by enhancing squish-region vortices as they are hypothesized to promote fuel-air mixing, leading to fast...

div class="section abstract"> To comply with increasingly stringent pollutant emissions regulations, diesel engine operation in a catalyst-heating mode is critical to achieve rapid light-off of exhaust aftertreatment catalysts during the first minutes of cold starting. Current approaches to catalyst-heating operation typically involve one or more l...

Renewable liquid fuels have potential to greatly reduce the carbon footprint of the transportation sector while leveraging existing powertrain technologies and infrastructure. Prior studies identified a mixture of 2-methyl furan and 2, 5 dimethyl furan as one of the most promising components for formulating renewable gasoline fuel blends. Within th...

To comply with stringent CO2 regulations, enhanced thermal efficiency has been prioritized in internal combustion engine development; however, this has strongly driven the development of engines with operating conditions more prone to knock. Current knock sensors have its limitations to decompose knock signal by degradation so that it required a cr...

Clean and stable operation during the catalyst heating mode in a direct-injection spark-ignition engine is crucial to meet increasingly stringent emission regulations. Although the injection strategy has a profound effect on both emission and combustion characteristics, the relative importance of various injection parameters is not well understood...

Direct injection system is widely adopted in spark-ignition engines to achieve higher thermal efficiency, but it accompanies a penalty in particulate emission, especially when engine is not fully warmed-up. Split injection strategy is known to be an effective measure to reduce engine-out particulate emissions. To better understand the role of split...

div class="section abstract"> Compliance with future ultra-low nitrogen oxide regulations with diesel engines requires the fastest possible heating of the exhaust aftertreatment system to its proper operating temperature upon cold starting. Late post injections are commonly integrated into catalyst-heating operating strategies. This experimental st...

Reducing wall temperatures is a promising method to suppress knocking behavior in spark-ignited engine. However, this may increase undesirable heat loss which acts as countereffect, so a strategic cooling approach is required. In this study, a multidisciplinary investigation of the wall temperature effect was demonstrated using experiments and simu...

Turbulence is one of the most important aspects in spark-ignition engines as it can significantly affect burn rates, heat transfer rates, and combustion stability, and thus the performance. Turbulence originates from a large-scale mean motion that occurs during the induction process, which mainly consists of tumble motion in modern spark-ignition e...

Abstract : In this study, knock phenomena occurred in each individual cycle was comprehensively investigated, with varying the main engine geometry – stroke-to-bore ratio (S/B ratio). For the experiment, the single-cylinder, with direct injection system, spark ignition engine was used, with various conditions of S/B ratio – 1.0, 1.2, 1.47. In order...

As global regulations on fuel economy and CO2 emission are getting stringent, development of high-efficiency SI engine is now more urgent than ever before. Along with advanced techniques on friction reduction, automakers endeavor to decrease bore-to-stroke ratio (B/S) to reduce the heat loss and enhance the fuel conversion efficiency. In this study...

The knock phenomenon is one of the major hindrances for enhancing the thermal efficiency in spark-ignited engines. Due to the stochastic behavior of knocking combustion, analytical cycle studies are required. However, there are many problems to be addressed with regard to the individual cycle analysis of in-cylinder pressure data. This study thus p...

Because of the combustion principle of a gasoline HCCI (homogeneous charge compression ignition) engine, the operating range is limited within a narrow area. The objectives of this study were to extend the operating range of gasoline HCCI combustion and to develop control logic. To extend the high load operating range, several strategies including...

Ethanol has the potential to improve engine efficiency and reduce harmful emissions when used as fuel in a spark-ignited engine. Ethanol is mostly supplied in a splash-blended form with gasoline or in a pure form; however, this is not an optimal way of using ethanol because the use of ethanol leads to increased brake specific fuel consumption. To f...

Ethanol is becoming more popular as a fuel component for spark-ignited engines. Ethanol can be used either as an octane enhancer of low RON gasoline or splash-blended with gasoline if a single injector is used for fuel injection. If two separate injectors are used, it is possible to inject gasoline and ethanol separately and the addition of ethanol...

Ethanol, one of the most widely used biofuels, has the potential to increase the knock resistance of gasoline and decrease harmful emissions when blended with gasoline. However, due to the characteristics of ethanol, a trade-off relationship between knock tolerance and BSFC exists which is balanced by the blending ratio of gasoline and ethanol. Fur...