Yuxing Li

With the growing use of methanol as a chemical feedstock, low-carbon fuel, and energy carrier, leaks from overhead pipelines pose risks of toxic exposure and fire or explosion. This study develops an integrated model for methanol leakage dispersion by coupling an orifice discharge equation, dynamic liquid-pool spreading, two-film vaporization, and Gaussian atmospheric dispersion. Controlled experiments in a closed chamber examined the effects of wind speed, leak diameter, leakage flow rate, and ambient temperature on methanol concentration distributions and exposure-warning distances. The model dynamically links leakage-source evolution, liquid-pool spreading, vapor generation, and atmospheric transport, enabling rapid prediction of the post-leak process. Wind speed dominated vapor-cloud transport: increasing it from 0.2 to 1.5 m/s shifted dispersion from near-source vertical accumulation to downwind horizontal transport and increased the dispersion distance by approximately 60%-80%. Increasing the leak diameter from 3 to 12 mm reduced the near-field high-concentration region by 40%-50% but enhanced long-range low-concentration dispersion. Increasing the leakage flow rate from 5 to 20 kg/h expanded the dispersion range by 40%-60%, while higher temperatures intensified vaporization and local accumulation under low-wind conditions. At 200 ppm, the maximum warning distance ranged from 0.24 to 16.19 m, supporting hazard prediction, detector placement and warning-zone delineation.

Wall adhesion in low-temperature, high-water-cut oil–water pipe flow is a dynamic multiphase interfacial process jointly governed by oil-phase retention, interfacial deformation, and hydrodynamic removal by the continuous water phase. However, the relationship between local morphological evolution and the global hydraulic response remains unclear. In this study, pressure-drop, temperature, and flow rate measurements were combined with end point weighing and wall visualization to investigate wall adhesion at water cuts of 90%, 93%, and 97% and mixture superficial velocities of 0.16, 0.32, and 0.48 m s−1. The global hydraulic response exhibited three stages: rapid growth, decelerated development, and quasi-steady fluctuation. Even after the equivalent adhesion thickness entered the quasi-steady stage, the wall-adhered oil phase continued to undergo streamwise elongation, necking, edge recession, and local rearrangement. This finding indicates that hydraulic quasi-steadiness does not correspond to a static local morphology, but instead reflects an approximate balance between continued oil-phase retention and hydrodynamic removal. Based on these observations, a retention–removal kinetic model was developed, in which wall adhesion was described as the dynamic outcome of competition between continued oil-phase retention and hydrodynamic removal. The model achieved a coefficient of determination of 0.971, a root mean square error of 0.193 mm, and a mean absolute error of 0.148 mm. Within the investigated parameter range, the model satisfactorily described the dynamic evolution of wall adhesion.

Ensuring the integrity of hydrogen‐blended natural gas (HBNG) infrastructure is pivotal for the sustainable hydrogen energy landscape, yet the surface interactions governing hydrogen embrittlement remain a critical challenge. This study presents a multiscale quantitative characterization of the film structure and hydrogen permeation kinetics of corrosion product films (CPFs), primarily composed of FeCO ₃ , by integrating X‐ray micro‐computed tomography (micro‐CT), in situ high‐pressure gaseous hydrogen permeation testing, and molecular dynamics (MD) simulations. Our findings elucidate that hydrogen traverses the CPFs predominantly in molecular form, with interconnected pores functioning as low‐impedance “short‐circuit” diffusion pathways. Kinetic evaluations indicate that the CPF densification over an extended duration drives the pressure exponent n from 0.783 to 0.901, marking a fundamental mechanistic shift from mixed molecular/atomic control to a dominant molecular barrier‐controlled regime. Furthermore, a structural influence factor α and a quantitative correlation model are developed to accurately describe the attenuation of hydrogen flux induced by film densification. This work uncovers the potential of CPFs as natural hydrogen barriers, and also provides a robust theoretical framework for material compatibility evaluation and hydrogen embrittlement mitigation in HBNG infrastructure.

Slow strain rate tensile (SSRT), fatigue crack growth rate (FCGR), and fracture toughness tests were conducted to evaluate the hydrogen embrittlement behavior of L245 pipeline steel base metal (BM) and weld metal (WM) in inert gas and high-pressure hydrogen environments. Hydrogen significantly degraded the mechanical performance of both BM and WM, as evidenced by reduced ductility, accelerated fatigue crack growth, and lower fracture toughness. Comparatively, the BM showed greater susceptibility in tensile ductility loss and toughness degradation, whereas the WM exhibited a more pronounced acceleration of hydrogen-assisted fatigue crack growth. These results indicate that hydrogen-assisted damage in L245 pipeline steel cannot be assessed using a single parameter; instead, plasticity loss, crack-growth behavior, and toughness degradation should be considered together. The findings provide an experimental basis for defect-tolerance analysis and fitness-for-service assessment of L245 pipeline steel for hydrogen transportation pipelines.

Methanol is increasingly relevant to low-carbon energy systems and product-pipeline transportation, but accidental releases from buried pipelines can create toxic-exposure, flammable-vapor and soil-contamination risks before emergency boundaries are known. Early liquid-phase migration in unsaturated backfill remains poorly quantified, especially for short-duration, high-flux releases and methanol/diesel mixtures. We conducted two-dimensional visualization sand-box experiments to examine how leakage rate, grain size, porosity and methanol/diesel ratio govern plume evolution. Time-series image processing was used to extract plume-front contours and vertical and horizontal migration distances. Higher leakage rates substantially enlarged the affected zone and promoted vertical penetration more strongly than lateral spreading. Coarser media reduced capillary retardation and produced gravity-dominated elongated or fingered plumes. At a fixed leakage mass, higher porosity shortened the visible plume-front distance because larger pore storage and residual retention delayed continuous advance. Methanol/diesel mixtures showed nonlinear migration and spatial segregation, with methanol-rich regions concentrated inside the wetted zone and diesel preferentially distributed near the plume periphery. A constrained semi-empirical model incorporating time, leakage rate, grain size, porosity and methanol volume fraction predicted most migration distances with average relative errors below 10%. These results provide experimental evidence and a screening model for buried pipeline leakage assessment, emergency excavation planning and pipeline risk management.

With the global advancement of carbon peaking and carbon neutrality goals, the importance of carbon capture, utilization, and storage (CCUS) technologies has become increasingly prominent. As a critical component of CCUS systems, gaseous CO₂ pipeline transportation has emerged as a research hotspot due to its efficiency and cost effectiveness. However, there are invariably corrosion problems when it comes to gaseous CO₂ pipeline transportation. These issues pose a significant threat to both the safety and economic viability of pipeline operations. Therefore, it is of importance to investigate gaseous CO₂ corrosion during pipeline transportation. In this work, based on recent domestic and international research achievements, research progress in the field of gaseous CO₂ corrosion during pipeline transportation is systematically reviewed. First, the corrosion mechanisms and corrosion characteristics during gaseous CO₂ pipeline transportation are studied, and the synergistic mechanisms by which key parameters such as impurities, temperature, pressure, flow velocity, and water content jointly influence pipeline wall corrosion behavior are elucidated. Then, corrosion products in CO₂ transportation pipelines are analyzed, and protective measures applicable to gaseous CO₂ pipeline systems are synthesized. Finally, future research goals are proposed to promote research on gaseous CO₂ corrosion during pipeline transportation: the impact of interactions among multiple impurities on corrosion behavior should be clarified; the inhibitory effects of the dynamic evolution of product films on mass transfer processes should be considered in corrosion rate calculation models; and more economical and efficient anti-corrosion technologies should be developed to meet diverse operational requirements. This work can provide guidance for the corrosion protection of gaseous CO₂ pipeline transportation.

Blending hydrogen into natural gas pipelines is a key pathway for hydrogen transportation, but hydrogen embrittlement (HE) at corrosion defects threatens operational safety. This study investigates the effect of corrosion defects on hydrogen compatibility of X42 steel via high-pressure in-situ gaseous slow strain rate tensile (SSRT) tests, hydrogen permeation tests, and microstructural characterization. Results show that the corrosion product layer (FeOOH, Fe2O3, FeCl2) hinders hydrogen permeation, reducing steady-state hydrogen flux. However, local corrosion pits induce severe stress concentration, which drives hydrogen enrichment and exacerbates HE. A competitive mechanism between “permeation inhibition” (corrosion products) and “embrittlement enhancement” (stress concentration) is revealed, with stress concentration identified as the dominant factor controlling material failure. This work provides a theoretical basis for safety assessment of hydrogen-blended pipelines with corrosion defects.

A standardized full-chain evaluation framework is established to bridge material science with engineering requirements for industrial hydrogen pipeline coatings.