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Introduction of a full-range model for liquid and vapor transport properties of autoclaved aerated concrete

Scheffler G. A.

Cement Wapno Beton

2011

nr spec.

53-59

The hygric performance of autoclaved aerated concrete is a key determinant for many other material properties as e.g. thermal conduction, carbonation or shrinkage behavior. Laboratory determination of hygric material properties, i.e. moisture storage and moisture transport, is hence a prerequisite and a standard in production and process supervision. In this context, prediction and simulation of the hygric material performance based on numerical calculation models has become a widely used research and design tool. However, for assessment of the material behavior under variable climatic conditions, the hygric material properties have to be determined in a first step. In a second step, these properties have to be transformed into the non-linear coefficients required by these numerical calculation models. This paper is the second of two focusing on the second step. It introduces a full-range hygric material model bridging the gap between measured material properties and the non-linear storage and transport coefficients in the transfer equation. The model is based on the conductivity approach and relies on a bundle of tubes approach to derive the transport function from the pore structure of the material. By extending this approach with a mechanistic treatment of serial and parallel structured transport, a semi-empirical material model is developed providing a high flexibility and adjustability. The model is applied for an aerated autoclaved concrete. Input data are basic material properties obtained by the methods introduced in the first paper [26]. The approximation procedure is described and the achieved accuracy is discussed. In conclusion, the model is very suitable for sophisticated research as well as for a broad application to autoclaved aerated concrete in particular, and to porous materials in general.

Analysis of coupled heat and water vapour transfer in textile laminates with a membrane

Sybilska W., Korycki R.

Fibres & Textiles in Eastern Europe

2010

Vol. 18, no. 3 (80)

65--69

Clothing materials coated with semi-permeable membranes were analysed as products protecting the organism against heat loss as well as ensuring the drainage of sweat. Both physical and mathematical models of the coupled heat and water vapour transfer within the multilayer structures were discussed. Material parameters should be determined for different numbers of layers, compositions of the raw material and thicknesses of the laminate with a membrane. The heat transfer resistance and resistance of the water vapour transfer were determined, which helped to design material for clothing that fulfils the user’s expectations and ensures thermal comfort.

Scharakteryzowano materiały odzieżowe, powleczone membranami półprzepuszczalnymi, pod kątem ich zdolności do ochrony organizmu przed utratą ciepła oraz zdolnością do odprowadzania potu wydzielonego przez człowieka. Wytypowane do badań materiały były zróżnicowane pod względem liczby warstw, składu surowcowego i grubości. Wyznaczono wartości oporu cieplnego i oporu pary wodnej, które stanowią podstawową wiedzę dla projektantów odzieży. Znajomość ta pozwala na świadome projektowanie materiałowe wyrobów odzieżowych, tak aby uzyskać wyrób, który pozwoli z jednej strony na optymalne wypełnianie funkcji określonych charakterem odzieży, z drugiej zaś zapewni użytkownikowi odzieży odpowiedni komfort w warunkach przyszłego użytkowania.