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THERMAL CONDUCTIVITY OF POROUS MATERIALS. 2. THEORETICAL TREATMENT OF RADIATIVE HEAT TRANSFER.

Author(s) : SIMPSON A., STUCKES A. D.

Type of article: Article

Summary

A THEORETICAL BACKGROUND RELATING TO RADIATIVE HEAT TRANSFER IN POROUS MATERIALS, AND THE EFFECT ON THERMAL CONDUCTIVITY, IS PRESENTED. SIMPLIFIED MODELS ARE CONSIDERED AS WELL AS A MORE RIGOROUS ANALYSIS PROVIDED BY THE HAMAKER TWO-FLUX MODEL. CONVENTIONAL EQUATIONS DERIVED FROM HAMAKER ASSUME RADIATION SCATTERING ONLY, AND PREDICT THAT THE RADIATIVE CONDUCTIVITY INCREASES WITH THICKNESS TO A LIMITING VALUE THE < THICKNESS EFFECT >. A MODIFIED EXPRESSION FOR RADIATIVE CONDUCTIVITY, WHICH INCLUDES ABSORPTION, HAS BEEN DERIVED FROM THE HAMAKER MODEL. THIS MIGHT BE EXPECTED TO APPLY TO INSULANTS WHERE ABSORPTION EFFECTS ARE SMALL COMPARED WITH THOSE OF SCATTERING AND WHICH ARE SUBJECT TO TEMPERATURE CONDITIONS NORMALLY FOUND IN THE BUILT ENVIRONMENT.

Details

  • Original title: THERMAL CONDUCTIVITY OF POROUS MATERIALS. 2. THEORETICAL TREATMENT OF RADIATIVE HEAT TRANSFER.
  • Record ID : 1991-0587
  • Languages: English
  • Source: Build. Serv. Eng. Res. Technol. - vol. 11 - n. 1
  • Publication date: 1990
  • Document available for consultation in the library of the IIR headquarters only.

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