To prevent CO₂ leakage and ensure the safety of long-term CO₂ storage, it is essential to investigate the flow mechanism of CO₂ in complex pore structures at the pore scale. This study focused on reviewing the experimental, theoretical, and numerical simulation studies on the microscopic flow of CO₂ in complex pore structures during the last decade. For example, advanced imaging techniques, such as X-ray computed tomography (CT) and nuclear magnetic resonance (NMR), have been used to reconstruct the complex pore structures of rocks. Mathematical methods, such as Darcy’s law, the Young–Laplace law, and the Navier-Stokes equation, have been used to describe the microscopic flow of CO₂. Numerical methods, such as the lattice Boltzmann method (LBM) and pore network (PN) model, have been used for numerical simulations. The application of these experimental and theoretical models and numerical simulation studies is discussed, considering the effect of complex pore structures. Finally, future research is suggested to focus on the following. (1) Conducting real-time CT scanning experiments of CO₂ displacement combined with the developed real-time CT scanning clamping device to achieve real-time visualization and provide a quantitative description of the flow behavior of CO₂ in complex pore structures. (2) The effect of pore structures changes on the CO₂ flow mechanism caused by the chemical reaction between CO₂ and the pore surface, i.e., the flow theory of CO₂ considering wettability and damage theory in a complex pore structures. (3) The flow mechanism of multi-phase CO₂ in complex pore structures. (4) The flow mechanism of CO₂ in pore structures at multiscale and the scale upgrade from microscopic to mesoscopic to macroscopic. Generally, this study focused on reviewing the research progress of CO₂ flow mechanisms in complex pore structures at the pore scale and provides an overview of the potential advanced developments for enhancing the current understanding of CO₂ microscopic flow mechanisms.

To prevent CO2 leakage and ensure the safety of long-term CO2 storage, it is essential to investigate the flow mechanism of CO2 in complex pore structures at the pore scale. This study focuses on reviewing the experimental, theoretical, and numerical simulation studies on the microscopic flow of CO2 in complex pore structures during the last decade. For example, advanced imaging techniques, such as X-ray computed tomography (CT) and nuclear magnetic resonance (NMR), are used to reconstruct the complex pore structures of rocks. Mathematical methods, such as Darcy's law, Young–Laplace’s law, and the Navier-Stokes equation, are used to describe the microscopic flow of CO2. Numerical methods, such as the lattice Boltzmann method (LBM) and pore network (PN) model, are used for numerical simulation. The application of these experimental and theoretical models and numerical simulation studies is discussed, considering the effect of complex pore structures. Finally, future research is suggested to focus on: (1) Conducting real-time CT scanning experiments of CO2 displacement combined with the developed real-time CT scanning clamping device to realize real-time visualization and provide quantitative description of the flow behavior of CO2 in complex pore structures; (2) The effect of pore structures change on the CO2 flow mechanism caused by the chemical reaction between CO2 and the pore surface, the flow theory of CO2 considering wettability and damage theory in a complex pore structures; (3) The flow mechanism of multi-phase CO2 in complex pore structures; (4) The flow mechanism of CO2 in the pore structures at multiscale and the scale upgrade from microscopic to mesoscopic to macroscopic. Generally, this study focuses on reviewing the research progress of CO2 flow mechanisms in complex pore structures at the pore scale and affords an overview of potential advanced developments to enhance the current understanding of CO2 microscopic flow mechanisms.

Zhao, Z. and Lei, Y., 2020. Mechanism analysis of uncovering coal in crosscut and gas outburst based on Flac3D. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 333–338. Coconut Creek (Florida), ISSN 0749-0208.Gas outbursts occur frequently in the process of uncovering coal in crosscut, so it is of great significance to study the outburst conditions of coal and gas in the process of tunneling. By establishing the model of these gas outbursts, we can obtain the function of the thickness of stone gate, gas pressure and gas outburst. With or without high pressure gas, the impact of high pressure gas during gas bursts is analyzed through the numerical simulation method. Based on the velocity, displacement, maximum principal stress and time curve of coal and rock interface in the center of roadway under two kinds of working conditions, the main conditions of gas bursts have been successfully verified. According to the results, in coal and gas outbursts, necessary conditions include the plastic zone penetration caused by high pressure gas storage and excavation disturbance, while sufficient conditions include the mutation of velocity field, displacement field and stress field in plastic zones.

The highly inefficient simultaneous extraction of coal and gas from low-permeability and high-gas coal seams in deep mines is a major problem often restricting the sustainable development of coal industry. A possible way to solve this problem under deep and complex geological conditions is represented by the technology based on the phase-change induced explosion of liquid carbon dioxide. In this work, the mechanism of formation of the coal mass fracture circle resulting from the gas cracking process is theoretically analyzed. Numerical simulations show that a blasting crushing zone with a radius of 1.0 m is formed around the blasting hole. The radius of the secondary expansion zone caused by the exploding gas is 2.0 m, and the extension limit of the explosion fracture is 2.3 m. The gas phase change explosion is influenced by the coal roadway driving face, the gas content index and the analytical index of coal shavings. Experiments conducted for comparison also lead to the conclusion that the initial gas emission is increased by 3.7 times from the 100-meter borehole in the original coal mass after coalbed gas explosion anti-reflection.

Diesel-powered equipment is widely used in underground coal mines for auxiliary transportation, material handling, and equipment relocation because of its long operating endurance, convenient refueling, and strong adaptability to complex operating conditions. However, carbon monoxide (CO) emissions from such equipment can accumulate locally under restricted ventilation, idling, and frequent start–stop operation, thereby threatening occupational health and mine safety. This review focuses on CO purification technologies for diesel-powered mining equipment. The operating characteristics and influencing factors are analyzed, and different technical routes are compared, including in-cylinder control, wet scrubbing, adsorption, non-thermal plasma (NTP), and catalytic oxidation. Recent advances in noble-metal catalysts, transition-metal and CeO₂-based reducible oxide catalysts, and single-atom catalyst (SAC) design strategies are summarized. Research progress in exhaust aftertreatment systems is also discussed. Overall, CO purification for diesel-powered mining equipment requires coordinated optimization of low-temperature activity, safety-oriented thermal management, flow resistance, and long-term operational stability. Future research should focus on structured catalytic units, durability under coupled exhaust conditions, online monitoring, and field validation to improve the compatibility of CO purification systems with underground mining conditions.