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Dimethyl ether(DME) is easily reformed into H2, since the chemical structure of DME does not feature direct C-C bonds, in contrast to diesel fuel. We have researched reforming catalysts for effectively generating H2 from the exhaust gases of a DME engine. The objective of this study is to evaluate the de-NOx performance of a combined system of RC(Reforming Catalyst) and LNT(Lean NOx Trap) for a DME engine according to reforming catalysts. The H2 generation of the reforming catalyst was observed under various conditions. CAT-A, CAT-B and CAT-C were prepared as reforming catalysts, and OC(Oxidation Catalyst) and LNT (Lean NOx Trap) were examined as commercial catalysts. The CAT-A catalyst has a higher amount of acid sites compared to the CAT-B and CAT-C catalysts. The CAT-A which is a mixing of mordenite and γ-Al2O3, has the highest H2 yield. However, the H2 yield decreased in the reforming reaction when CO2, NO and O2 coexisted.

Particulate matter emissions can jeopardize good health. Diesel particulate matter (PM), of diameters less than 10,000nm, was measured from a high-speed direct injection (HSDI) diesel engine by using an electrical low pressure impactor (ELPI). Results were obtained for the smoke level and the PM level (masses and numbers) from this engine by using the ELPI and the Bosch smoke meter, and the results were compared. The effects of a diesel oxidation catalyst (DOC) were also investigated. Under a high speed and high load condition, HSDI diesel engine exhausts a considerable mass of particulate matter with diameter over 100nm, and considerable number of PM from 7 to 100nm at the same driving condition. DOC showed reduction in the total mass of PM, but showed increase in the number of ultra fine PM. At low temperature, before light-off temperature of the soot, the DOC adsorbs the PM, and oxidizes the PM after the light-off temperature. Finely-sized PM could be created during oxidation.

In this paper, the effects of the precious metals composition in the double-layer washcoat TWC were examined by the conversion efficiency and the catalytic reaction. The double-layer tri-metal three-way catalyst (TWC) was designed to achieve a high conversion performance and a high thermal durability. The catalytic performance on the PMs loading weight was impacted by the dispersion of the PMs in washcoats. In the results of the CO-pulse chemisorption experiment, the over amount of the optimum PMs loading weight decreases the PMs dispersion in washcoats and the catalytic performance. This was accelerated on the thermal aged catalyst. TPD (temperature-programmed desorption), TPR (temperature-programmed reduction), TEM (transmission electron microscope) and BET analysis were conducted to discuss the effect of the double-layer on both the catalytic reaction and thermal stability.

We analyzed the in-cylinder flow fields of an optical-access single cylinder diesel engine with the PIV and STAR-CD CFD code. The PIV analysis was carried out in the bottom and side view mode during a compression stroke (ATDC 220°-340°) at 600 rpm. The flow pattern traced by the streamlines, the location of vortex center, the generation and disappearance of tumble, and the squish effect agreed well, as visualized by the PIV and CFD. Vorticity and spatial fluctuation intensities abruptly increased from ATDC 310, reflecting more complicated flow pattern as approaching TDC. In a quantitative sense, the velocity magnitudes obtained from the PIV were, on an average, higher than those from the CFD by 1 m/s approximately and the difference in velocity magnitude between them was about 26 %. In the CFD analysis, the standard high Reynolds κ-ε and RNG k-ε model were adopted for calculation with tetra and hexa or their hybrid meshes, to determine the turbulence model dependencies.

In this study, experiments have been conducted to investigate parameters that effect the catalytic reaction of methane. Parameters considered were catalysts, catalyst additives, space velocity and exhaust gas components (NO, CO, H2O, O2, CO2). Catalysts used in the experiment were Pd and Pt metal loaded on γ-Al2O3 on a cordierite monolith. Methane conversion efficiency was improved for the Pd series catalyst with additive of La and Zr. With Pd/Pt catalyst, the presence of nitric oxide and water vapor showed an inhibitory effect on methane oxidation. Methane conversion efficiency decreased rapidly over 60000 h-1 space velocity.

Experiments have been conducted to investigate the inhibitory effect of the catalytic reaction of methane and the formation of formaldehyde in the presence of NO. With precious metal catalysts, the presence of NO showed an inhibitory effect on the methane oxidation and caused the formation of formaldehyde. In the absence of oxygen, however, formaldehyde was not produced in the catalytic reaction of methane and NO. Maximum formation of formaldehyde was about 0.6 % of NO with the Pt and Rh series catalysts. N2O formation is similar to the formaldehyde formation from the catalytic oxidation of methane in the presence of NO.

As alternative fuel, natural gas holds a dominant position with widely distributed resources in the world and a low CO2 emission rate compared with the other fuels for automobile. Natural gas should be used in liquid phase (LNG) especially in automobile use due to considerations of energy density. Research and development was conducted for a practical LNG vehicle equipped with a LNG engine and LNG supply and engine control systems. The LNG engine system was given a high compression ratio, manifold gas injection, and spark ignition for the effective use of natural gas. For the components of LNG supply system, LNG tank, vaporizer, LNG control valve and gas injector were developed. The LNG tank and the LNG control valves were given super insulation constructions to prevent gas boil off. LNG was vaporized using heat from the radiator. The gas injector is controlled by a solenoid coil for optimum fuel supply. A computer using fuzzy logic was developed in part for the engine control system.

The purification performances of catalytic converters (Pt, Rh, Pd, Pd/Rh, Pt/Pd, Pt/Rh/Pd, Pt̲Pd and Pd̲Cu) were investigated to select suitable one for newly developed liquified natural gas(LNG) fueled vehicle. Two types of the construction of the catalytic converter, single-bed type and dual-bed type using two different catalysts in series, were used. A natural gas engine that has been modified the 3 cylinder gasoline spark ignition engine of 0.55 liter displacement equipped with newly developed manifold injectors was used for the investigation. The conversion performance of the exhaust gas at different catalyst temperatures was discussed with main emphases on methane conversion. The durability of the catalyst and the optimum loading of Pd catalyst were also investigated. To understand the suitable operating condition for the developed LNG engine, the effect of air excess ratio and engine load were examined.