Search Results

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.

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.