Fluid displacement in porous media is often associated with liquid-vapor phase change, and it plays a significant role in oil recovery, agriculture, hydrology, etc. Although numerous studies have been conducted on isothermal multiphase flow in porous media, the effects of pore distribution and conjugate heat transfer on non-isothermal multiphase flow in porous media are less understood. In this work, the lattice Boltzmann method is used for pore scale modeling of gravity-driven non-isothermal fluid displacement in disordered porous media. To characterize the pore distribution, a disorder parameter is introduced in our simulations to reflect the degree of fluctuation in the solid grain radius. After validating the numerical method, we focus on investigating how porosity, disorder parameter, and wettability affect gravity-driven non-isothermal fluid displacement in disordered porous structures. The results indicate that lower porosity leads to increased vapor capillary fingering, which affects the displacement pattern. We also identify two distinct modes of interface movement, the evaporative-diffusion invasion mode and the rapid invasion mode, through pressure analysis of liquid island disappearance. Additionally, an increased disorder parameter enhances the instability of vapor fronts and leads to the formation of more liquid islands. This increase also enhances heat transfer, which results in higher average system and solid temperatures. For uniform porous structures, we find that several localized peaks in the evaporation rate are associated with a `coalescence' mode of the Haines jump. Finally, to gain deeper insights into the mechanisms driving variations in vapor temperature, we analyze the time evolution of the two-phase interfacial length for different wettability conditions.

 

Pore scale study,phase change,disordered porous media,conjugate heat transfer,lattice boltzmann method