Analysis of the thermal conductivity reduction in grey medium using a two-flux model for radiation heat transfer

• Autorzy: Kaniorczyk P. , Zmywaczyk J.
• Języki publikacji: EN

Abstrakty

EN

This paper is a continuation of considerations concerning the analytical and numerical analysis of the problem of "thickness effect curve" in interactive optical media mentioned in papers [3,4]. A 1-D conduction-radiation heat transfer model in an absorbing, emitting and scattering grey medium has been considered in this paper. To find the thermal conductivity thickness dependence k(l) (for a sample thickness l) and dependence of the radiative heat flux density q[r](l) upon the sample thickness /, a finite difference method together with the two-flux method (TFM) based on the Schuster-Schwarzschild approximation has been used iteratively [1,2]. The modified two-flux approximation assumes anisotropic scattering. The scattering albedo [omega], extinction coefficient [kappa] and backscattering coefficient b are used in the modified TFM [1,2]. Likewise to our earlier papers the initial data for performing numerical calculations represent a group of semi-transparent material (e.g. cellular concretes) with extinction coefficient [kappa] = 1000 m[^-1] and with the conductive component of thermal conductivity k[c] = 0,1 Wm[^-1]K[^-1] [3,4].

Słowa kluczowe

EN

anisotropic scattering media; radiative-conductive heat transfer; reduction of thermal conductivity

PL

przepływ ciepła radiacyjno-przewodnościowego; środki anizotropowe; zmniejszenie przewodnictwa

• Wydawca: Wydawnictwo Instytutu Maszyn Przepływowych PAN ; Komitet Termodynamiki i Spalania PAN
• Czasopismo: Archives of Thermodynamics
• Rocznik: 2007
• Tom: Vol. 28, no. 3
• Strony: 41--56
• Opis fizyczny: Bibliogr. 8 poz.,Tab., wz., wykr.,

Twórcy

autor

Kaniorczyk P.

autor

Zmywaczyk J.

• Military University of Technology, S. Kaliskiego 2, 00-908 Warszawa 49, Poland,

Bibliografia

• [1] HOTTEL H.C., SAROFIM A.F.: Radiative transfer, McGraw-Hill Book Company, 1967, 427-437.
• [2] REISS H.: Radiative Transfer in Nontransparent, Dispersed Media, Springer-Verlag, 1988.
• [3] KONIORCZYK P., ZMYWACZYK J.: Approximate analysis of influence of surface emissivity on combined heat radiation and conduction in aspect of the flat sample thickness effect on heat conduction of semitransparent media, Archives of Thermodynamics, Vol. 26(2005), No. 4, 3-16.
• [4] KONIORCZYK P., ZMYWACZYK J.: Reduction of an effective thermal conductivity in the aspect of two flux model for absorbing, emitting and scattering media, Archives of Thermodynamics, Vol. 25(2004), No. 4, 19-29.
• [5] ZMYWACZYK J.: Simultaneous estimation of the emissivity and the temperature-dependent thermal conductivity and specific heat in a semitransparent plane layer by an inverse method, Archives of Thermodynamics, Vol. 27(2006), No. 3, 39-62.
• [6] VISKANTA R., GROSH R.J.: Heat transfer by simultaneous conduction and radiation in an absorbing medium, J. of Heat Transfer, Transaction of the ASME, February 1962, 63.
• [7] FURMANSKI P., WISNIEWSKI T.S.: Influence of radiation scattering on heat transfer and determination of properties of thermal insulations, Thermal Conductivity, Vol. 26 (2004) ,400-411.
• [8] WISNIEWSKI T.S., FURMANSKI P., LUBINSKI R.: Theoretical analysis and experimental study of solar radiation conversion in porous materials in presence of forced convection, Proc. 19th Nat. Cong, of Thermodynamicists, Sopot, 5-8.09.2005 (in Polish).