Experimental Investigation of Drying in a Model Porous Medium: Influence of Thermal Gradients

Abstract

In this study, isothermal and non-isothermal drying experiments with imposed constant temperature gradients have been conducted in a two-dimensional square pore network of borosilicate glass (SiO 2 ) with interconnected etched channels. In experiments with temperature decreasing from the open surface of the pore network, a travelling stabilized gas-liquid region could be established, while in isothermal experiments with uniform temperature faster breakthrough and an extended two-phase zone were observed. Both findings are in good agreement with pore network simulations. However, numerical underestimation of drying rates (especially in the second period of drying) indicates that liquid films might play a major role in the experimental pore networks, even in the presence of thermal gradients.

Transport of a water-soluble polymer during drying of a model porous media

“…Some 2D model porous systems consisting of glass beads exist, allowing imaging the drying process using a camera. [13][14][15] To measure fluid distributions inside 3D porous materials, techniques like synchrotron X-ray tomography [16] and nuclear magnetic resonance (NMR) imaging [17][18][19] allow noninvasive probing of moisture with a sufficiently high spatial and time resolution. For this study, NMR imaging was used to monitor the moisture distribution during drying process.…”

Drying with Formation of Capillary Rings in a Model Porous Medium

“…Thus, the temperature field from experiment (with 62. Vorhauer et al 2013 for more details). Since temperature affects surface tension of liquid and therewith the capillary pressure, order of emptying of liquid menisci can be different when the variations are high enough (see also Vorhauer et al 2014).…”

“…The drying experiment was performed under quasi-isothermal conditions (T ≈ 63 • C). See Vorhauer et al (2013Vorhauer et al ( , 2014 for more details. As expected from previous works and illustrated in Fig.…”

“…As specified in detail in Vorhauer et al (2013), temperatures vary slightly in space during experiments. Thus, the temperature field from experiment (with 62.…”

“…Prat (2002) and Metzger et al (2007), the details are not repeated here. We simply recall the main features of this model with the assumptions corresponding to the version used in Vorhauer et al (2013).…”