Aiming to achieve the highest combustion efficiency and less pollutant emission, a catalytic coating for cylinder walls in internal combustion engines was developed and tested under several conditions. The coating consists of a La0.8Sr0.2CoO3 (LSCO) catalyst on an aluminum-based ceramic support. Atomic force microscopy was applied to investigate the surface roughness of the LSCO coating, while in situ diffuse infrared Fourier transform spectroscopy was used to obtain the molecular understanding of adsorption and conversion. In addition, the influence of LSCO-coated substrates on the flame quenching distance was studied in a constant-volume combustion chamber. Investigations conclude that an LSCO coating leads to a reduction of flame quenching at low wall temperatures but a negligible effect at high temperatures. Finally, the influence of LSCO coatings on the in-cylinder wall-near gas composition was investigated using a fast gas sampling methodology with sample durations below 1 ms. Ion molecule reaction mass spectrometry and Fourier transform infrared spectroscopy revealed a significant reduction of hydrocarbons and carbon monoxide when LSCO coating was applied.
Future vehicle powertrain systems with internal combustion engines must achieve higher efficiencies and further reduced pollutant emissions. This will require the application of new advanced technologies. Against this background, this paper presents a holistic approach to reduce temporally the wall heat losses, and hydrocarbon and carbon monoxide emissions with thermal coatings on the combustion chamber walls. For this purpose, an yttria-stabilized zirconia (YSZ) coating is applied and evaluated by different methods. The thin layer in combination with the low thermal effusivity of the material allows the wall temperature to follow the gas temperature and perform a so-called thermal swing. The interaction between an uncoated and a YSZ-coated wall with the flame front as well as partially burned gas was investigated. First, in terms of the coating’s potential to reduce the flame quenching distance using an optical method in a constant volume combustion chamber. Second, regarding its influence on the near-wall gas composition, which was analyzed with in-situ diffuse reflectance infrared Fourier transform spectroscopy measurements and a fast gas sampling technique on a single-cylinder engine. From this, it could be derived that the quenching distance can be reduced by 10% at ambient conditions and by 5% at an elevated temperature of 200 °C by using the coating. These findings also support the results that have been obtained by the near-wall gas composition measurements, where a reduced total hydrocarbon emission was found with the applied coating.
in: BIBLIOTHEKSDIENST 28 (1994), H, 5. 654 -674In diesem Aufsatz nimmt \N. Gödert in sachlicher und bekannt kompetenter Weise erneut Stellung zu Fragen der RSWK-basierten Sacherschließung in Online-Systemen. Dabei wiederholt er schon früher und an anderen Stellen gemachte Aussagen zur Behandlung von RSWK-Ketten in der Online-Recherche -völlig zu Recht und sachlich geboten, da auf diese, m. E. höchst richtigen und wichtigen, Sachverhalte nicht oft genug hingewiesen werden kann. Zu seinen berechtigten Forderungen gehören u. a. die Behandlung der SW-Kette in Gänze als Informationseinheit (also kein Zerschlagen in Einzelglieder beim RetrievaO oder die Nichtzulässigkeit der Recherche-Verknüpfung einzelner Bestandteile unterschiedlicher Ketten bei einem Dokument.
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