Accession Number : ADA317980

Title :   Catalytic Combustion in Internal Combustion Engines: A Possible Explanation for the Woschni Effect in Thermally-Insulated Diesel Engines.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC SURFACE CHEMISTRY BRANCH

Personal Author(s) : Jones, Robert L.

PDF Url : ADA317980

Report Date : 15 NOV 1996

Pagination or Media Count : 29

Abstract : This report describes research undertaken to determine if catalytic combustion effects occur with the use of zirconia (ZrOsub2) thermal barrier coatings (TBCs), or other coatings, in diesel engines, and if so, whether these effects have significant impact upon engine combustion, fuel economy, or pollutant emissions. A simple furnace system was used to identify catalytic combustion effects in the ignition and combustion of propane/air mixtures over catalyst-doped m-ZrOsub2 spheres. Three classes of catalysts were examined: zirconia-stabilizing oxides (CeOsub2, Ysub2Osub3, MgO), transition metal oxides (Cosub3Osub4, Crsub2Osub3, Fesub2O3), and noble metals (Pt). Each class exhibited characteristic combustion effects, with the ignition temperature increasing, e.g., from approximately 2000 deg C for Pt to 5500 deg C for the stabilizing oxides. The results suggest that the Woschni effect, a controversial phenomenon wherein thermal-insulating measures are postulated to actually increase heat transfer from the diesel combustion chamber, may be only a manifestation of catalytic combustion. Previous research on catalytic combustion in internal combustion engines is briefly reviewed and discussed. An earlier version of this report is to be published in J. Surface and Coatings Technology as 'Catalytic Combustion Effects on m-ZrOsub2 Doped with Various Metal Nitrates.'

Descriptors :   *DIESEL ENGINES, *COMBUSTION, *INTERNAL COMBUSTION ENGINES, *THERMAL INSULATION, STABILIZATION, HEAT TRANSFER, EMISSION, METALS, TEMPERATURE, COATINGS, OXIDES, COMBUSTION CHAMBERS, CATALYSTS, CATALYSIS, POLLUTANTS, IGNITION, TRANSITION METAL COMPOUNDS, DIESEL FUELS, FURNACES, ZIRCONIUM OXIDES, NITRATES, PRECIOUS METALS.

Subject Categories : Thermodynamics
      Combustion and Ignition
      Reciprocating and Rotating Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE