ISBN 9783843939492

978-3-8439-3949-2, Reihe Thermodynamik

Anuradha Ashok Bhatia
Moisture Sorption in Porous Media: Experimental and Numerical Enquiries Applicable to the Automotive Passenger Compartment

156 Seiten, Dissertation Universität Stuttgart (2019), Softcover, A5

Zusammenfassung / Abstract

An oft-stated fact about our planet's surface is that it is mostly water. Our planet's position in the solar system affords it unique conditions that allow water to exist in all three physical states, viz. solid, liquid and gas. It is thus of little wonder then, that studying the effects of water on various materials, man-made or otherwise, is necessary.

The research discussed in this thesis includes experimental as well as numerical investigations of the interaction between moisture and porous media. There are several different physical processes through which water can interact with other materials. Two different processes have been studied here. Moisture sorption from humid air and drying of water-saturated materials. The materials considered here are non-perforated leather, perforated leather and a poly-blend textile material.

The experimental investigations include the use of interferometry and gravimetry. The dynamic vapour sorption measurement instrument was used to ascertain the affinity of each material for moisture. The sorption isotherms for each material indicate that the behaviour can be mathematically described by the Brunauer, Emmett, Teller multi-layer sorption model. The instrument was also utilised to conduct sorption experiments at humidity levels of 50%, 70% and 90%.

The Mach-Zehnder interferometer was used to conduct further experiments. Drying experiments were conducted by placing a water-saturated material in the test cell. Absorption experiments were conducted by placing a material which had reached equilibrium with the ambient humidity in the test cell, then introducing water-vapour into it. The changes in the interference pattern for both experiments were observed and recorded.

The dynamics between humid air and the materials considered here can be described as a diffusion-sorption process. The sorption process was defined using first-order chemical kinetics. The partial differential equations that describe the moisture sorption process in porous materials have been solved using the method of lines. The results obtained by the numerical simulations were validated with experimental data.