Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Journal of Technical Physics

2 Koniorczyk P.

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: zjawisko redukcji

Sortuj według:

Ogranicz wyniki do:

The Rosseland theory of diffusion radiation as applied to the study of the phenomenon of reduction in thermal conductivity

Koniorczyk P.

Journal of Technical Physics

1999

Vol. 40, no 2

147-161

The present paper is devoted to an analysis of the problem of applicability of the Rosseland theory of diffusion radiation to the study of the phenomenon of reduction in thermal conductivity observed in small-thickness samples of some selected materials, namely the block polymerized methyl metacrylate (PMM) and polyamide 6 (PA6), two types of glass {with high and low Fe203 content), molten N03K and B203 salts, toluene and carbon tetrachloride (CC14) (5-14). The method of division of the radiation absorption spectrum into bands of different width has been used for the analysis of those materials additionally characterised by considerable optical thickness R = Er * z. The Rosseland extinction coefficient E[r] has been determined for each material and introduced, together with a function F(l) referred to as a microstructure function, into the theory of calculation of the radiation thermal conductivity [lambda]r of the selected materials. Another problem which has been discussed here is that of the criterion to be satisfied by the results of experimental investigation into the phenomenon of reduction in thermal conductivity in samples of small thickness lambda(l) and the related temperature slips on the cold and hot sides of the sample, [Delta]T[s](z -->ł 0) and [Delta]T[s](z --> l) , respectively.

Modeling and numerical analysis of the phenomenon of reduction in thermal conductivity in small thickness samples of some selected synthetic materials

Koniorczyk P.

Journal of Technical Physics

1998

Vol. 39, no 1

91-104

The phenomenon of reduction in thermal conductivity which is observed in thin samples (of some milimetres in thickness) of synthetic materials and the related temperature slip at the cold measurement surface of the sample have been studied. Various forms of depedence of the jump-like variation in essential thermal conductivity on the sample thickness have been simulated, their influence on the differential equation of steady-state heat transfer being studied for samples having the form of discs of different thickness. Our considerations were not concerned with particular synthetic materials, but the depedence of the essential thermal conductivity on the sample thickness and the temperature difference [delta]T = 65 degree C between the heater and the cooler of the plate apparatus assumed for the considerations were closely connected with earlier experimental investigations into the relations mentioned for polymethyl metacrylate and polyamide 6, pure and with soot addition [3, 7, 9]. It has been shown by numerical analysis that the phenomena of reduction in thermal conductivity of thin samples enables us to determine the depedence of the temperature slip on the plate thickness and explain the range and the character of that variation in the direction of sample thickness.