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In diesel engine development, the new technology is coming out to meet the stringent exhaust emission regulation. The regulation demands more eco-friendly vehicles. Euro6c demands to meet not only WLTP mode, but also RDE(Real Driving Emission). In order to satisfy RDE mode, the new technology to reduce emissions should cover all operating areas including High Load & High Speed. It is a big challenge to reduce NOx on the RDE mode and a lot of DeNOx technologies are being developed. So the new DeNOx technology is needed to cover widened operating area and strict acceleration / deacceleration. The existing LNT(Lean NOx Trap) and Urea SCR(Selective Catalytic Reduction) is necessary to meet the typical NEDC or WLTP, but the RDE mode demands the powerful DeNOx technology. Therefore, the LNT & Urea SCR on DPF was developed through this study.

To meet Euro6 regulation particulate matter MEMS sensor is suggested. This sensor detects induced charges by PM. To increase sensitivity of the sensor, surface area of the sensor is increased by MEMS process. Sensor is made by low resistive silicon. Total size is 4.3 mm x 59.4 mm x 1 mm and size of sensor part is 4.3 mm x 13 mm. On the backside of the sensor, Pt heater is fabricated to remove piled PM on sensor part. After sensor part, charge amplifier is used to measure the induced charge of the sensor. From FFT of sensor signal, it can sense 5.46 mg/m₃ of PM. In this paper, MEMS devices for exhaust system monitoring of automobiles are investigated. PM emitted from diesel engine is charged particle. Charge-induced-type PM sensor we designed can measure by real time and it doesn't need particle collection apparatus

Future emission limits of diesel engines require additional effort to develop advanced after-treatment devices. The Urea-SCR system is a promising device to reduce NOx emissions. The purpose of this work is to reduce NOx emissions from a Light Duty Vehicle (LDV) with a Urea-SCR (Selective Catalytic Reduction) system, a Catalytic Particulate Filter (CPF), and a Diesel Oxidation Catalyst (DOC). The purpose of the development is to analyze the atomization characteristics of the urea solution and to optimize the flow path shape in front of the SCR catalyst for uniform reductant (NH3) distribution. Additionally, the development purpose is to determine the strategy for urea solution injection quantity and to verify the performance of the Urea-SCR system on the vehicle. The NO2/NOx ratio plays a pivotal role in reducing NOx with Urea-SCR system. Although NO is converted into NO2 through the DOC, the NO2/NOx ratio is reduced due to the CRT (continuous regenerating trap) effect in the CPF.

As the use of diesel engines increases in the transportation industry and emission regulations tighten, the implementation of diesel particulate filter systems has expanded. There are many challenges associated with the design and development of these systems. Some of the key robustness parameters include regeneration, efficiency, fuel penalty, engine performance, and durability. One component of durability in a diesel particulate filter (DPF) system is the filter's ability to resist ring-off-cracking (ROC). ROC is described as a crack caused primarily by thermal gradients, differentials, and the resulting stresses within the DPF that exceed its internal strength. These cracks usually run perpendicular to the substrate flow axis and typically result in the breaking of the substrate into separate halves.

An external injection system was introduced to control the lean Nox trap(LNT). LNT absorbs Nox in lean condition of exhaust gas and discharges N2 by reducing Nox in rich condition. To make exhaust gas lean or rich, fuel injection into the exhaust gas is used with the engine control. There are two ways to add a reducing agent into exhaust gas. One is post injection using common rail system and the other is external injection. The external injection has prior benefit; can be controlled independently without disturbing engine control, can be adapted to various layout of exhaust system, has no oil dilution problem, and etc. In this study the effect of an external fuel injection on the control of LNT system was investigated. At first, the injection characteristic of the external injection was analyzed: flow rate and atomization characteristic was controlled by the PWM signal and the fuel pressure. Then the external injection system was introduced into NPRS(Nox PM Reduction System).

A NOx absorber and a fuel cracking catalyst were combined to investigate whether this could increase the low temperature activity of a NOx absorber system. Before engine exhausted gas tests, the activity and properties of the NOx absorbing catalyst were examined by simulated gas and temperature programmed desorption. Diesel fuel cracking catalysts were designed to maximize the hydrogen productivity. From the hexadecane reaction experiments for these catalysts, it was found that the hydrogen generation amount was significant even at 200°C. Engine bench test results with the diesel fuel cracking catalysts confirmed the improvement of NOx removal efficiency. In case of high NOx capacity with prolonged regeneration interval condition showed the best results. It reflects the importance of optimization of the NOx absorber and the pre-oxidation catalyst, the regeneration strategy.

Environmental standards concerning Suspended Particulate Matter (SPM) are continuously becoming stricter. The light-duty diesel passenger car market is rapidly increasing due to performance improvements and the economic advantages of the diesel engine. To meet EURO 4 diesel passenger car emission regulations, regeneration experiments of a catalyzed particulate filter (CPF) system have been performed with 2.0L common-rail diesel engine. For effective regeneration of the CPF system, we investigated the effects of various regeneration conditions on the system. Conditions such as exhaust gas temperature, oxygen/hydrocarbon concentrations, gas compositions, etc. were investigated. We found that the regeneration efficiency was improved when the exhaust gas temperature increased to more than 700°C during CPF regeneration using engine post injection. An additional amount of post injection increased the exhaust gas temperature and residual hydrocarbon content.

To meet EURO 4 diesel passenger car emission regulations, various experiments of a catalyzed particulate filter (CPF) system have been performed with 2.0L common-rail diesel engine. The main components of a CPF system are a filter and a catalyst, thus we performed the optimization of these two components accordingly. First, we constructed a system with a high porosity silicon carbide (SiC) filter coated with a catalyst washcoat and precious metal loading optimized for performance, cost, etc. We primarily investigated the effects of the catalyst on the DOC and CPF on the diesel emissions. We performed various catalytic activity experiments in order to verify the effects of filter shape, catalyst washcoat loading amount, precious metal loading amount, aging effects through regeneration, etc. Finally we evaluated the catalytic activities through the European vehicle emission driving cycle (NEDC) mode.