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Mode transition between low temperature combustion (LTC) and conventional combustion was performed by changing the exhaust gas recirculation (EGR) rate from 60% to 0% or vice versa in a light duty diesel engine. The indicated mean effective pressure (IMEP) before mode transition was set at 0.45 MPa, representing the maximum load of LTC in this research engine. Various engine operating parameters (rate of EGR change, EGR path length, and residual gas) were considered in order to investigate their influence on the combustion mode transition. The characteristics of combustion mode transition were analyzed based on the in-cylinder pressure and hydrocarbon (HC) emission of each cycle. The general results showed that drastic changes of power output, combustion noise, and HC emission occurred during the combustion mode transition due to the improper injection conditions for each combustion mode.

Polyamide 6(PA6)/hexagonal boron nitride(h-BN) and polyphenylene sulfide(PPS)/graphite composites have been prepared to investigate the possible usage as battery housing materials. The addition of the highly conductive filler improved thermal conductivity of polymer matrix more than 2 times. On the basis of the experimental results and intrinsic material parameters, thermal behavior in a battery pack has been monitored by computational simulation. The heat generated within a cell was readily dissipated as a highly thermal conductive aluminum(Al) was used and thus the temperature was evenly distributed over a whole package. In the case of a battery pack made of polymer or polymer composites, on the other hand, the temperature inside cell is much higher due to the accumulation of heat. The predicted heat flow behavior may be useful in selecting proper housing materials.

We used a one-dimensional monolithic catalyst model to predict the transient thermal and conversion characteristics of a dual monolithic catalytic converter with a Palladium only (Pd-only) catalyst and a Palladium/Rhodium (Pd/Rh) catalyst. Prior to the numerical investigation of the dual-catalyst converter, we modified the pre-exponential factor and activation energy of each reaction for both catalysts to achieve acceptable agreement with experimental data under typical operating conditions of automobile applications. We validated the conversion behavior of the lumped parameter model for each catalyst against different engine operating conditions. Two higher cell density substrates, Pd-only catalyst (600cpsi/3.9mil) and Pd/Rh catalyst (600cpsi/4mil), for faster light-off and improved warm-up performance are used in this study and the two monoliths has been connected without the space between monoliths.

To reduce diesel engine emissions, a split injection strategy with PHCCI combustion in a diesel engine was investigated with simulation. A multidimensional CFD application, Star-CD coupled with a modified 2-D flamelet was used to simulate multiple injection combustion. Several mass ratios of the first injection and second injection conditions compared to the conventional pilot and main injection strategy were evaluated. The injection angle and the injection timing of the first injection were fixed to 150° and 55° BTDC, respectively. Because of the early injection, the in-cylinder pressure and temperature were much lower than those of normal injection conditions, and the fuel could not fully evaporate. As a result, wall impingement can be occurred, and THC and CO would be increased. To eliminate the wall impingement, the injection timing of the first injection was then retarded to 35-30° BTDC, and the piston bowl geometry was modified to capture droplets in the piston bowl.

An on-board monitoring system for an automobile emission gas has developed using porous ceramic sensor to apply in automotive. We have performed model experiment using similarity and engine dynamometer experiment. By the model experiment, output signal of HC sensor is followed with amount of hydrocarbon in the mixed gas under high temperature range. A single hydrocarbon sensor exposed to the exhaust gas in the chamber to render a signal responsive to the hydrocarbon. The HC sensor in test chamber checked the conductive ions in emission gas. A preferred application includes hydrocarbons in an automotive exhaust gas stream by exposing a porous alumina (Al2O3) ceramic based sensor to the same exhaust gas stream. By combining the electrical signal, a measure of hydrocarbons can be provided. By the developed temperature mode test and the load mode test for engine dynamometer experiment, we have confirmed a possibility of catalyst monitoring used HC sensor in the engine dynamometer.

On-board diagnostics (OBD) of diesel vehicles require various sensors to detect system malfunctions. The Particulate Matter (PM) sensor is one of OBD devices which gather information which could be critical in determining a crack in the diesel particulate filters (DPFs). The PM sensor detects PM which penetrates cracked DPFs and converts the amount of PM into electrical values. The PM sensor control unit (SCU) receives those analog signals and converts them to digital values through hardware and software solutions. A capacitive sensing method would be a stable solution because it detects not raw analog signals but electrical charges or a time constant going through the capacitive load. Therefore, amount of PM would be converted reasonable value of capacitance even though there is a little amount of PM.

While the request of diesel engine is recently increased due to its excellent fuel economy benefit, the regulation of emission becomes reinforced. The variety of method such as engine technologies and aftertreatment systems have been developed and applied to meet the criteria of regulation so far. One of recognizable technologies utilized in a heavy commercial vehicle is SCR system using urea solution as a reductant, which eliminates NOx. This paper includes the experiment of a diesel engine equipped with Urea SCR system, and its emission characteristic including particle is analyzed and evaluated against its regulation. This evaluation is performed for the diesel engine using ELPI(Electric Low Pressure Impactor) under the condition of constant engine RPM and load, and injecting urea solution to SCR system, particle number distribution of particle range from 7nm to 10μm was estimated.