Effect of translucence of engineering ceramics on heat transfer in diesel engines

Technical Report · Wed Apr 01 00:00:00 EST 1992

DOI:https://doi.org/10.2172/7267573· OSTI ID:7267573

Wahiduzzaman, S; Morel, T ^[1]

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1. Integral Technologies, Inc., Westmont, IL (United States)

This report describes the experimental portion of a broader study undertaken to assess the effects of translucence of ceramic materials used as thermal barrier coatings in diesel engines. In an earlier analytical work a parametric study was performed, varying several radiative properties over ranges typical of engineering ceramics, thereby identifying the most important radiative properties and their impact on in-cylinder heat transfer. In the current study these properties were experimentally determined for several specific zirconia coatings considered for thermal barrier applications in diesel engines. The methodology of this study involved formulation of a model capable of describing radiative transfer through a semitransparent medium as a function of three independent model parameters, ie, absorption coefficient, scattering coefficient and refractive index. For the zirconia-based ceramics investigated in this study, it was concluded that for usual coating thicknesses (1.5--2.5 mm) these ceramics are optically thick and hence, are effective as radiative heat transfer barriers. These ceramics possess high scattering coefficients and low absorption coefficients causing them to be highly reflective (60-80%) in the spectral region where thermal radiation is important. The performance of the investigated ceramics and the mechanism of heat transfer were found to depend on surface condition, specifically on soot deposition. Thus, to insure the optimum thermal barrier operation for either clean or heavily sooted surfaces, a ceramic material with high scattering coefficient provides the best choice.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Integral Technologies, Inc., Westmont, IL (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7267573
• Report Number(s): ORNL/Sub-88-22042/2; ON: DE92041384
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
DIESEL ENGINES
MATERIALS
ZIRCONIUM OXIDES
HEAT TRANSFER
CERAMICS
COATINGS
ENERGY ABSORPTION
PROGRESS REPORT
REFRACTION
SCATTERING
ABSORPTION
CHALCOGENIDES
DOCUMENT TYPES
ENERGY TRANSFER
ENGINES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
OXIDES
OXYGEN COMPOUNDS
SORPTION
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
330102* - Internal Combustion Engines- Diesel
360204 - Ceramics
Cermets
& Refractories- Physical Properties