Mach-Zehnder interferometry investigations in drying of water-saturated porous materials

Abstract

An experimental study of the drying behavior of water-saturated porous materials has been conducted. Two measurement techniques, namely, gravimetry and interferometry, have been utilized simultaneously. A white-light Mach-Zehnder interferometer has been used to measure the concentration gradients in the test cell, which occur as a result of the drying process. The interferograms, as well as the weight of the materials, have been measured and recorded, as they dry and reach equilibrium with the ambient air. The weight-loss data, which are obtained by gravimetry, are then used as a boundary condition to solve Crank's surface evaporation equation. Upon solving Crank's equation for surface evaporation, the concentration gradient above the drying substrate has been obtained. The concentration gradients in the test cell obtained by both measurement techniques have been compared.