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The effective thermal conductivity of unsaturated fibrous media is simulated by Fractal-Monte Carlo simulations in this work. Based on the probability model and thermal-electrical analogy method, the proposed model of the effective thermal conductivity can be expressed as an explicit function of fractal dimensions, D t , D f , intrinsic thermal conductivities, k s , k w , k g , the straight capillary length of a unit cell L 0 , liquid saturation S , pore size λ i as well as porosity ϕ. Each parameter of the proposed model has physical meaning and the function has no empirical constant. The results calculated by Fractal-Monte Carlo simulations have been compared with the experimental data available, and an excellent agreement has been shown for an appropriate range of porosity except for the condition at a lower liquid saturation. It is found that, when k s / k g > 1 and k w / k g > 1 , the dimensionless effective thermal conductivity of unsaturated fibrous media decreases with increment in fractal tortuosity dimension and porosity and decrement in liquid saturation. On the other hand, when k s / k g < 1 and k w / k g < 1 , the correlations are opposite. The present Fractal-Monte Carlo technique may have its own advantages in predicting other transports in unsaturated fibrous media. [ABSTRACT FROM AUTHOR]

The Kozeny–Carman (KC) equation is a well-known semi-empirical formula, which is used to calculate the permeability of porous media in the seepage field. The KC constant is an empirical constant in the KC equation. In this paper, based on the fractal theory, the Fractal-Monte Carlo technique is used to simulate the KC constant of the roughened fibrous porous media (RFPM) with micro-scale effects. There is no empirical constants in the proposed model, and each parameter has its physical meaning. The KC constant model of RFPM can be expressed as a function of structural parameters, including relative roughness (), porosity (ϕ), pore area fractal dimension ( D f ), tortuosity fractal dimension ( D T ), capillary diameter (λ) and Knudsen number (Kn). The result shows that the KC constant increases with increases in ϕ , , D f and D T . On the contrary, with increases in λ and Kn , the KC constant decreases. In addition, the KC constant model constructed in the paper agrees well with the existing experimental data and the model. According to the proposed Fractal-Monte Carlo technique, it is possible to better clarify the transmission physical mechanism in RFPM with micro-scale effects. [ABSTRACT FROM AUTHOR]

As a result of advancements in gas reservoir development technologies and a deeper understanding of seepage theory, numerous nonlinear seepage problems have emerged. Consequently, conventional analytical solution models are no longer applicable. Moreover, existing semi-analytical and numerical solution models suffer from issues like high computational complexity and limited flexibility, significantly constraining their practical utility. For this purpose, a gas reservoir transient seepage model is established based on the dual-reciprocity boundary element method (DRBEM). This model couples the wellbore storage coefficients with skin factor and introduces a novel dual-porosity transient interporosity seepage algorithm, enabling the resolution of transient seepage problems in dual-porosity gas reservoirs with nonlinear point source distributions. Additionally, it investigates the dynamic behavior of bottomhole pressure during the early production stage of gas wells, while capturing the dynamic pressure distribution within the seepage field. This approach offers the advantages of semi-analyticity, meshless, and eliminates the need for Laplace transforms, resulting in a significant reduction in computational complexity. Ultimately, the application of our model to well-pattern production with the production system transition issues, in conjunction with the log-log type curves of bottomhole pressure, and the dynamics of gas reservoir pressure, enables the analysis of interference characteristics between injection-production wells. This showcases the practical advantages of the model's application. The findings of this study provide valuable assistance for modeling and solving transient seepage problems in dual-porosity oil and gas reservoirs production. The application of DRBEM in unsteady-state diffusion, heat conduction, stress fields, and other potential field problems is relevant for reference. • Established a new pressure transient analysis model based on dual reciprocity boundary element method (DRBEM). • A grid-free, semi-analytical approach for solving the wellbore-reservoir transient pressure field. • Realized a time-domain, dual-porosity, transient seepage coupling method without the need for Laplace transforms. • Introduced a time-domain, meshless model coupling method for well models. [ABSTRACT FROM AUTHOR]

Herein, dodecahedron, concave cube with a cavity and leaf-like ZIF were prepared through water hydrogen bond induced coordination structure engineering. MOF-derived C materials, with feature of generally maintained ZIF morphology, adjustable mesoporous structure and in situ N doping, were constructed with simple pyrolysis under N 2 and phosphoric acid etching strategies. Ru loaded ZIF template-assisted mesoporous carbon materials were utilized for the ammonia borane hydrolysis and p -nitrophenol reduction. Up to 1031 min−1 TOF in ammonia borane hydrolysis and as high as 1.602 min−1 p -nitrophenol reduction efficiency could be achieved over Ru loaded dodecahedron ZIF-67 template-assisted mesoporous carbon. Above excellent catalytic performance should be ascribed to the partial retained coordination structure engineering based catalytic active center optimization, the phosphoric acid etching assisted mesoporous structure construction for hydrophilicity and mass transfer promotion, as well as the Ru–Co synergistic structure induced charge transfer improvement. MOF-derived C materials, with features of generally maintained ZIF morphology, adjustable mesoporous structure and in situ N doping, were constructed through simple pyrolysis under N 2 and phosphoric acid etching strategies. Up to 1031 min−1 TOF in ammonia borane hydrolysis and as high as 1.602min−1 p -nitrophenol reduction efficiency could be achieved over Ru@CoNC-67-M. Above excellent catalytic performance should be ascribed to the retained partial coordination structure engineering based catalytic active center optimization, the phosphoric acid etching assisted mesoporous structure construction for hydrophilicity along with mass transfer promotion, and the Ru–Co synergistic structure induced charge transfer improvement. [Display omitted] • Dodecahedron, concave cube with cavity & leaf-like ZIFs for C materials preparation. • Unprecedented 1031 min−1 AB hydrolysis TOF & 1.602 min−1 4-NP reduction efficiency. • Retained coordination structure in C materials for catalytic center optimization. • H 3 PO 4 etched mesoporous structure for hydrophilicity and mass transfer promotion. • Metal synergistic effect in MOF-derived catalyst for catalytic performance promotion. [ABSTRACT FROM AUTHOR]

Water vapor sorption in nanoporous media with complex pore structures, like shale, is not well understood. To address this, a pseudopotential lattice Boltzmann method (LBM) is developed to investigate water sorption behavior. The LBM model incorporates long-range molecular forces using a modified Shan-Chen model based on the Carnahan-Starling equation of state. The simulation results show that the presence of water films in nanopores can create a liquid pressure difference of up to 100 MPa between confined and free states. The adsorption theories based on simple pore shapes are not applicable to nanoporous systems with complex pore geometries. Additionally, when the relative humidity exceeds 1, water vapor condenses inside hydrophobic nanostructures while being attracted by neighboring liquid, leading to cluster formation. In water-wet nanoporous media, capillary condensation occurs progressively from small throats to large pores, and the sorption curves vary smoothly with pressure variation. In mixed-wet nanoporous media, the sorption curves exhibit no hysteresis in the early desorption stage, where the adsorption and desorption processes occur in the region around the hydrophobic particles and are reversible. Overall, this study provides valuable insights into water sorption behavior in nanopore systems of shale and sets the foundation for modelling liquid-vapor distribution in nanoporous media at the pore scale. • A pseudopotential-based LBM was developed to model water vapor sorption at nanoscale. • The LBM-simulated vapor-liquid curves can match theoretical models in literature. • Sorption theories based on simple pore shape are not applicable to nanoporous system in shale. • The sorption curves in mixed-wet nanoporous shale showed no hysteresis in early desorption. [ABSTRACT FROM AUTHOR]