Seokjoo Kwon

Combustion and emission characteristics of a gasoline–dimethyl ether dual-fuel engine

An experimental investigation was performed to investigate the effect of a split-injection strategy on the combustion and exhaust emission characteristics as well as on the particle number distribution for a single-cylinder compression ignition engine with gasoline–dimethyl ether dual fuelling. The gasoline–dimethyl ether dual-fuel injection system utilized port injection for gasoline and direct injection for dimethyl ether. In the present system, premixed fuel (i.e. gasoline) was injected into the premixing chamber at an injection pressure of 3 MPa using gasoline direct injection to mix the air–gasoline mixture sufficiently. However, dimethyl ether fuel was injected at an injection pressure of 50 MPa directly into a combustion chamber in order to control the combustion phase, resulting in a change in the direct-injection timing from −20° to +2° crank angle. The experimental results show that the gasoline–dimethyl ether dual-fuel engine exhibited benefits in the indicated mean effective pressure for early-injection cases (i.e. near −10° crank angle after top dead centre). However, the indicated mean effective pressure of the gasoline–dimethyl ether dual-fuel engine deteriorated for delayed-injection cases owing to incomplete combustion. In addition, a significant reduction in the nitrogen oxide emissions was observed using gasoline–dimethyl ether dual fuel compared with those obtained using conventional dimethyl ether combustion. In particular, soot emissions are almost at zero level for all the cases. On the other hand, hydrocarbon and carbon dioxide emissions increase with an increasing portion of premixed injection fuel (i.e. gasoline) in conventional injection timing, which is near top dead centre.

Numerical and experimental study of combustion and emission characteristics in gasoline direct-injection compression ignition engines using intake preheating

This paper presents a numerical and experimental study of the combustion and emission characteristics of a gasoline direct-injection compression ignition engine using intake preheating. The gasoline direct-injection compression ignition engine was predicted to reduce emissions compared with the emissions from a conventional diesel engine. To compare the combustion and emission characteristics of the gasoline direct-injection compression ignition and diesel engines, numerical modelling was conducted using the KIVA-3V release 2 code, which is integrated with the Chemkin chemistry solver II. Numerical simulations were performed under a variety of conditions to determine the optimal conditions for gasoline direct-injection compression ignition engine operation. In order to achieve the gas pressure in the cylinder and the emission characteristics, experiments were performed using a single-cylinder engine. The simulation results agreed well with the experimental data. The gasoline autoignition was in the parcels with a lower equivalence ratio of 0.6–0.8 as opposed to the diesel autoignition parcels with a high equivalence ratio of greater than 1. The ignition delay of gasoline was longer than that of diesel; therefore, the gasoline direct-injection compression ignition engine could reduce the soot emissions. The nitrogen oxide emission levels for gasoline direct-injection compression ignition were increased because of the intake preheating.

Effects of DME Additives on Combustion Characteristics and Nano-particle Distributions in a Single Cylinder Compression Ignition Engine

This study describes effects of DME additives on combustion and exhaust emissions characteristics including nano-particle in a single cylinder compression ignition engine. Considered additives include bio-diesel, n-butanol, and MTBE for increasing kinematic viscosity. Among three additives, n-butanol showed the greatest kinematic viscosity. In addition MTBE showed the highest vapor pressure. In the present study mixing ratios of additives were kept constant at 1 and 10% by volume. Experiments were performed at 1200rpm engine speed and nano-particles were measured by SMPS (Scanning mobility particle sizer) devices. Results of combustion characteristics showed that considered additives had little effects on combustion pressure. However, patterns of heat release rate were dependent on properties of additives. Nano-particles of MTBE were the lowest among considered additives.This study describes effects of DME additives on combustion and exhaust emissions characteristics including nano-particle in a single cylinder compression ignition engine. Considered additives include bio-diesel, n-butanol, and MTBE for increasing kinematic viscosity. Among three additives, n-butanol showed the greatest kinematic viscosity. In addition MTBE showed the highest vapor pressure. In the present study mixing ratios of additives were kept constant at 1 and 10% by volume. Experiments were performed at 1200rpm engine speed and nano-particles were measured by SMPS (Scanning mobility particle sizer) devices. Results of combustion characteristics showed that considered additives had little effects on combustion pressure. However, patterns of heat release rate were dependent on properties of additives. Nano-particles of MTBE were the lowest among considered additives.

Exhaust Emissions Characteristics on Driving Cycle Mode and Ignition Advance Condition Change of CNG/LPLI Bi-Fuel Vehicle

Recently rise in oil prices feet the burden on not only diesel vehicle driver but also LPG vehicle driver, and get interested in various way to reduce fuel costs. In this study discuss on exhaust emissions characteristics on driving cycle mode and ignition advance condition change of CNG/LPLI Bi-Fuel vehicle. Experimental test was performed by changing the conditions of fuel (LPG/CNG), spark advance (Base, 10oCA, 15oCA), and driving mode (FTP-75, HWFET, and NEDC). In case of CO emission, in the order of CNG Base, CNG S/A10, S/A15 condition are average reduced -21%, -35%, -29% respectively compared to LPG fuel. The active emission reduction from the initial engine start, spark retard is likely to be beneficial in catalyst warm-up and improve combustion stability rather than spark advance.