Technical Briefs

Note on a New Blackbody Fraction Function Used for Surfaces With a Linear Emissivity in a Wavelength Interval

[+] Author and Article Information
Tiegang Fang

e-mail: tfang2@ncsu.edu
Department of Mechanical and Aerospace Engineering,
North Carolina State University,
911 Oval Drive,
Campus Box 7910,
Raleigh, NC 27695

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received August 7, 2012; final manuscript received January 7, 2013; published online April 11, 2013. Assoc. Editor: He-Ping Tan.

J. Heat Transfer 135(5), 054506 (Apr 11, 2013) (4 pages) Paper No: HT-12-1424; doi: 10.1115/1.4023393 History: Received August 07, 2012; Revised January 07, 2013

In this note, a new blackbody radiation fraction function is proposed for calculating the emissive power or total emissivity of a surface that has an emissivity depending linearly on wavelength in a wavelength interval. This new fraction function is expressed as a function of the product of wavelength and temperature and the numerical values are tabulated. Based on the new defined fraction function, the emissive power in a given wavelength interval can be calculated very conveniently combined with the traditional blackbody radiation fraction function. This new function can be used in many practical applications with good accuracy without numerical integration.

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Siegel, R., and Howell, J. R., 1992, Thermal Radiation Heat Transfer, 3rd ed., Hemisphere Publishing Corporation, Washington, DC, pp. 22, 34, 62–63.
Harrison, W. N., Richmond, J. C., Shorten, F. J., and Joseph, H. M., 1963, “Standardization of Thermal Emittance Measurements,” Technical Report No. WADC-TR-59-510, Part 4.


Grahic Jump Location
Fig. 1

Relationship of the fraction functions with λT

Grahic Jump Location
Fig. 2

Spectral emissivity for example 3.5 in Ref. [1]

Grahic Jump Location
Fig. 3

Emissivity profile as a function of wavelength for a real surface from Ref. [2]



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