Temperature field inversion and break-down at the interface of semi-transparent two-layer system in radiative heat transfer

• Published in: International journal of thermal sciences 2001, Vol.40 (10), p.865-876
• Main Authors: Aronov, Boris I, Zvirin, Yoram
• Format: Article
• Language: English
• Subjects: diffuse interface; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Heat transfer; participating media; Physics; radiative heat transfer; semi-transparent layer; Thermal radiation
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/S1290-0729(01)01273-X

The paper describes analysis of radiation heat transfer in a system of semi-transparent two layers, with a diffuse or partially diffuse interface. Two cases are considered, of “optically closed” and “optically open” systems. In the former case, heater and cooler surfaces with angular-dependent emissivities enclose the two layers. In the latter case, the system is irradiated by a collimated heat flux on one side and the two boundary surfaces radiate to space. Two interesting phenomena have been found from the results obtained by the mathematical–numerical methods developed here: inversion and break-up of the temperature field. In some cases, depending on the radiation properties of the heater and cooler surfaces and on the refraction indices of the layers and the specular–diffuse shares of the interface: the temperature decreases from the side facing the heater to the interface, exhibits a sharp jump increase across it, and then decreases, again, in the second layer (facing the cooler). The whole temperature curve is sometimes higher in the second layer than in the first one. These phenomena occur due to collimation of the radiative heat flux at the boundary surface facing the heater and “de-focusing” the flux at the diffuse (or partially diffuse) interface. The strength of these effects depends on the radiative properties mentioned above and on the optical thickness. Another phenomenon is that of “heat trap” in the case of “optically open” one- or two-layer system, caused by total internal reflection.