ARTICLE:

• CORRELATION OF RADIANT TRANSFER COEFFICIENT WITH PACKED BED MICROSTRUCTURE IN THE ABSORBING SYSTEMS  download article

Sh.-K. Lee
Hong Kong University of Science and Technology, Kowloon, Hong Kong

S. K. Chu
Hong Kong University of Science and Technology, Kowloon, Hong Kong

S. C.-H. Ip
Hong Kong University of Science and Technology, Kowloon, Hong Kong

ABSTRACT

In some high temperature applications of a sphere packing system, radiation would be the dominant mode of heat transfer. Radiant energy transmits through the bed voids, and is more effective than the sphere-to-sphere contact conduction. The practical applications include the powder sintering, the chemical reactors as well as porous medium heat generators. To model and study the radiant energy exchange, the two main approaches are the Radiant Transfer Equation (RTE) and the Ray-tracing Technique, where each has its own advantages and also limitations. Recently, a Radiation Transfer Coefficient (RTC) scheme has been developed to compute the exchange factor between packing spheres. Through the RTC, the distribution of a packed bed can be computed. Energy balancing equation can be formulated to obtain the temperature of each sphere, which is very encouraging. This paper linked with the work, and published a correlated equation relating with the packed bed microscopic properties as coordinate number (CN) and the contact surface ratio (AC). The correlated equations were compared with the distribution data from ray-tracing method. Also, transmittances were computed from this correlated equation to validate against the ray-tracing results and also the Two-Flux Model analytical solution. In summary, this paper has built up a RTC correlated equation, which could later allow for intensity, temperature computation among spheres in a packed bed.

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