Pore‐scale determination of parameters for macroscale modeling of evaporation processes in porous media

Abstract

[1] Evaporation is an important process in many natural and technical systems, such as the unsaturated zone of the subsurface or microchannel evaporators. For the understanding and prediction of the involved processes, numerical simulations of multiphase flow and transport processes are an important tool. In order to achieve an accurate, physically based description of kinetic interphase mass and heat transfer occurring during evaporation, the numerical model has to account for the interfacial areas between phases. A recently developed model for two-phase flow in porous media is able to account for the involved processes by using interfacial areas explicitly as parameters in the model. The crucial issue, however, is the determination of the relationships between specific interfacial areas, capillary pressure, and saturation in this paper, we present a multiphase lattice Boltzmann model, which allows us to determine these relationships. On the basis of the scanned geometry of a natural porous medium, the relationships between specific interfacial areas, capillary pressure, and saturation are determined. To the best of our knowledge, this is the first time that fluid-solid specific interfacial area relationships have been obtained from pore-scale data. Using these functions, we present the results of macroscale simulations of an evaporator device and of drying in a porous medium.Citation: Ahrenholz, B., J. Niessner, R. Helmig, and M. Krafczyk (2011), Pore-scale determination of parameters for macroscale modeling of evaporation processes in porous media, Water Resour. Res., 47, W07543,

Modeling two-phase flow in a micro-model with local thermal non-equilibrium on the Darcy scale

“…Each of these terms has to be given for each component in each phase, leading to four balance equations for the case of a two-phase two-component system. This approach builds on the work presented in Ahrenholz et al [2] with a refined mass exchange term and results in the following set of balance equations for a two phase, two component system: In general, the index w stands for the wetting phase and the index n stands for the non-wetting phase. The exponents w; n stand for the main components of the respective phases.…”

“…The macro-scale balance equations used in this work build on Ahrenholz et al [2], extended in Nuske et al [17]. In that work, local chemical and thermal non-equilibrium are allowed between the fluid phases and the solid and fluid phases respectively.…”

Development of a numerical workflow based on <i>μ</i>-CT imaging for the determination of capillary pressure–saturation-specific interfacial area relationship in 2-phase flow pore-scale porous-media systems: a case study on Heletz sandstone

“…The quantity of the (typically unknown parameter) interfacial area between two phases restricts kinetic interphase mass and energy transfer (Ahrenholz et al, 2011). In numerical modelling with classical macro-scale flow models, these processes are not properly taken into account (Muccino et al, 1998;Ahrenholz et al, 2011). Here, averaged quantities neglecting the interfacial area are often used (Tatomir et al, 2015), which are described to lead to negligence of kinetics of mass transfer, assuming local equilibrium (Niessner and Hassanizadeh, 2009).…”

“…carbon capture and storage (CCS), nuclear waste repository, oil recovery; Hassanizadeh and Gray, 1990;Joekar-Niasar et al, 2008;Niessner and Hassanizadeh, 2008;Reeves and Celia, 1996). The quantity of the (typically unknown parameter) interfacial area between two phases restricts kinetic interphase mass and energy transfer (Ahrenholz et al, 2011). In numerical modelling with classical macro-scale flow models, these processes are not properly taken into account (Muccino et al, 1998;Ahrenholz et al, 2011).…”

“…in the form of micromodels as described amongst others in Karadimitriou et al (2013Karadimitriou et al ( , 2014, Karadimitriou and Hassanizadeh (2012) and Lenormand and Touboul (1988). Corresponding numerical models are given, amongst others, in Ahrenholz et al (2011) and Porter et al (2009). These specific approaches succeed in deriving the p c -S w -a wn relationship, but are based on Lattice-Boltzmann simulations, which are considered to be elegant but are limited by computational resources (White et al, 2006).…”