QUALITATIVE ANALYSIS OF THE PERMEABILITY OF A RIVERBED USING 3D PRINTED MODELS SIMILAR TO CHARCOAL GEOMETRIES

Abstract

This study evaluated the porosity and permeability of beds formed by geometric models with some similarity to industrial-use charcoal, aiming to understand how dimensions and geometries influence permeability. The pieces were printed in PLA and filled with mortar to increase density, with dimensions corresponding to cylinders of 9 mm in diameter and heights of 11, 21, and 31 mm, in addition to models with reduced sections (½ and ¾ of the original cross-sectional area for the predominant 9 x 21 mm model in the mixtures). Experimental tests were performed to determine total porosity, oil flow rate under gravity, and air pressure drop at flow rates of 5, 7, 9, 11, and 13 L/min at 2 bar pressure. It was observed that permeability is influenced not only by overall porosity but also by connectivity and the size of the voids formed by the combination of particles. Mixtures containing a higher proportion of long particles (9 x 31 mm) showed lower pressure losses and higher flow rates, indicating greater permeability. In contrast, the addition of smaller particles reduced pore connectivity, increasing resistance to flow. The results confirm that bed permeability does not depend solely on total porosity and dimensional homogeneity, but also on the distribution and geometric interaction of the particles, indicating that it would be an important parameter for controlling and/or evaluating the quality of charcoal received in pig iron production plants.