Heat Transfer in a Parallel-Plate Enclosure with Graded-Index Coatings on its Walls

A numerical study on the heat transfer in the thermal barrier coatings and the substrates of a parallel-plate enclosure is carried out. Some of the thermal barrier coatings, such as ceramics, are semitransparent and are of interest for high-temperature applications where radiation effects are significant. The radiative transfer equations and the energy equations are solved by using the discrete ordinates method and the finite difference method. Illustrative results are presented for temperature distributions in the coatings and the opaque walls under various heating conditions. The results show that the temperature distribution is more uniform in the interior portion of each coating away from its boundary for the case with a larger average of varying refractive index and a positive gradient of refractive index enhances radiative transfer to the substrates.

Authors:

• Jiun-Wei Chen
• Chih-Yang Wu
• Ming-Feng Hou

Keywords:

• Radiative transfer
• parallel-plate enclosure
• coatings
• varying refractive index

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