Search Results (120)

Permeable pavement is an alternative to conventional impermeable pavement for various applications. However, a common issue with permeable pavement is clogging over time. Permeability is a parameter that reflects the capacity of the pavement to reduce surface runoff; a decline in permeability implies the occurrence of clogging. In this study, permeability data collected on pervious concrete (PC) and JW Eco-Technology (JW) revealed that JW maintained consistent permeability over time. However, PC displayed reduced values, and several locations along the edges had zero permeability, despite no regular vehicular and pedestrian use. Therefore, a portable pressure washer was used to clean the pavements. The cleaning procedure was able to recover the permeability of the areas that showed signs of clogging (0 to 2.69 cm/s) and restore the permeability of PC up to 4.60–5.58 cm/s for corner and center areas, respectively. Moreover, visual inspection using a borescope further revealed the full function of the JW pores (aqueducts), regardless of cleaning. Regardless, it is recommended that periodic cleaning maintenance be performed for both PC and JW using a pressure washer due to its convenience and efficacy, which will be discussed. Full article

Underground hydrogen storage (UHS) in carbonate and siliceous formations presents a promising solution for managing intermittent renewable energy. However, experimental data on hydrogen–rock interactions under representative subsurface conditions remain limited. This study systematically investigates mineralogical and petrophysical alterations in dolomite, calcite-rich limestone, and quartz-dominant siliceous cores subjected to high-pressure hydrogen (100 bar, 70 °C, 100 days). Distinct from prior research focused on diffraction peak shifts, our analysis prioritizes quantitative changes in mineral concentration (%) as a direct metric of reactivity and structural integrity, offering more robust insights into long-term storage viability. Hydrogen exposure induced significant dolomite dissolution, evidenced by reduced crystalline content (from 12.20% to 10.53%) and accessory phase loss, indicative of partial decarbonation and ankerite-like formation via cation exchange. Conversely, limestone exhibited more pronounced carbonate reduction (vaterite from 6.05% to 4.82% and calcite from 2.35% to 0%), signaling high reactivity, mineral instability, and potential pore clogging from secondary precipitation. In contrast, quartz-rich cores demonstrated exceptional chemical inertness, maintaining consistent mineral concentrations. Furthermore, Brunauer–Emmett–Teller (BET) surface area and Barrett–Joyner–Halenda (BJH) pore distribution analyses revealed enhanced porosity and permeability in dolomite (pore volume increased >10×), while calcite showed declining properties and quartz showed negligible changes. SEM-EDS supported these trends, detailing Fe migration and textural evolution in dolomite, microfissuring in calcite, and structural preservation in quartz. This research establishes a unique experimental framework for understanding hydrogen–rock interactions under reservoir-relevant conditions. It provides crucial insights into mineralogical compatibility and structural resilience for UHS, identifying dolomite as a highly promising host and highlighting calcitic rocks’ limitations for long-term hydrogen containment. Full article

Lithium-ion batteries (LIBs), crucial in modern advanced energy storage systems, inherently experience several side reactions during operation, with the formation of a solid electrolyte interface (SEI) and lithium plating being the most significant. These side reactions, which deplete lithium ions and lead to the clogging of negative electrode pores, considerably impair the battery’s cycle life and overall performance. This study introduces a numerical model for the battery aging process, grounded in existing research on SEI formation and its temperature-dependent aging kinetics. The model aims to elucidate how variations in the porosity of the negative electrode impact the battery’s cycle life. The study initially focuses on analyzing the principal mechanisms behind pore clogging in LIBs’ negative electrodes following extensive charge/discharge cycles. Subsequently, the study conducts numerical simulations to thoroughly investigate the effects of various non-uniform porosity structures in the negative electrode, encompassing both linear and gradient configurations, on the battery’s cycle life. Additionally, the investigation conducts a comparative analysis to determine how different gradients in porosity structures influence pore clogging. It also delves into a detailed exploration of heat generation associated with the linear porosity structure of the negative electrode. The results indicate that the accumulation of the SEI layer significantly reduces porosity. This reduction, in turn, affects the conductivity and alters the current density during the SEI reaction. Notably, the linear porosity structure exhibits a significant advantage over traditional structures, especially in terms of reducing pore clogging and minimizing irreversible heat generation. In summary, this study presents a multi-physics and detailed numerical model to evaluate the impact of variations in negative electrode porosity on the cycle life of LIBs. Furthermore, it provides essential theoretical support for battery design and performance optimization, particularly in the determination of pore structures and material selection. Full article

In this study, a conceptual turbine blade model with internal cooling channels was designed and fabricated using the selective laser melting (SLM) process. The optimal manufacturing orientation was evaluated through simulations, and the results indicated that vertical orientation yielded the best outcomes, minimizing support material usage and distortion despite increased manufacturing time. Two configurations were produced, namely, an entire-turbine blade model and a cross-sectional model. Non-destructive analyses, including 3D laser scanning for dimensional accuracy, surface roughness measurements, and liquid penetrant testing, were conducted. Visual inspection revealed manufacturing limitations, particularly in the cooling channels at the leading and trailing edges. The trailing edge was too thin to accommodate the 0.5 mm channel diameter, and the channels in the leading edge were undersized and potentially clogged with unmelted powder. The dimensional deviations were within the acceptable limits for the SLM-fabricated metal parts. The surface roughness measurements were aligned with the literature values for metal additive manufacturing. Liquid penetrant testing confirmed the absence of cracks, pores, and lack-of-fusion defects. The SLM is a viable manufacturing process for turbine blades with internal cooling channels; however, significant attention should be paid to the design of additive manufacturing conditions to obtain the best results after manufacturing. Full article

In this study, a statistical analysis of results reported in the literature was conducted through a 2ⁿ experimental design on the synthesis of bifunctional catalysts used in the production of lighter fuels, aiming for optimization while considering factors such as support (bentonite and vermiculite), acidity modifier (zirconium and cerium), metal (tungsten and molybdenum), metal content (5% and 10%), promoter (nickel and cobalt), and heteropolyacids (tungstophosphoric acid and molybdophosphoric acid), identifying their influence on textural properties and catalytic performance. Regarding the textural properties, vermiculite proved to be the most favorable support due to its high porosity. It was also established that the implemented metals impart positive characteristics to the catalysts due to their various properties; however, incorporating large amounts led to an adverse effect by clogging the pores. Catalytic performance was analyzed in isomerization and cracking reactions, which were enhanced by the use of cerium due to the presence of Brønsted acid sites and molybdenum for its stability. In this way, the statistical analysis conducted in this study was crucial for identifying the influence of key factors on the textural properties and catalytic performance of bifunctional catalysts. Using a 2ⁿ experimental design allowed for a systematic evaluation of variables reported in the literature, such as support, acidity modifiers, metals, metal content, promoters, and heteropolyacids. Full article

This study posits that soil particles in the filter layer are ellipsoidal. The effective pore radius of the filter material was calculated for various particle-shape parameters and distributions. The relationship between the porosity of the filter material and the ratio of the long axis to the short axis of ellipsoidal particles in a loose arrangement was also examined. The results indicate that the porosity of the filter material initially decreases and subsequently increases with increases in the ratio of the long axis to the short axis; however, the rate of increase progressively slows. A method for transforming irregularly shaped particles into ellipsoidal forms is proposed. The particle-shape parameter, S, is introduced to characterize the shape of irregular particles. The relationship between particle-shape parameters and the ratio of the long axis to the short axis was investigated specifically for ellipsoidal particles. It was found that the particle-shape parameters exhibit an approximately linear relationship with the ratio of the long axis to the short axis within a specific range. The discrete element method was employed to investigate the impact of particle shape on the filtration characteristics of the filter layer and was complemented by comparative experimental analysis. By analyzing the pore structures of spherical and ellipsoidal particles, this study predicts the relationship between pore structure and particle-shape parameters for any irregularly shaped natural-particle filter layer. Full article

This study investigates the influence of various reinforcing fibers, including coconut, basalt, glass, merino wool, and polypropylene, on the properties and processability of cementitious mixtures, with a particular emphasis on their application in 3D printing. The incorporation of fibers at a concentration of 1 wt.% was found to significantly hinder the printing process. Specifically, certain fibers, such as polypropylene, rendered extrusion impractical due to nozzle clogging. However, reducing the fiber content to 0.5 wt.% improved material flowability and minimized structural defects during printing. Fiber selection, in addition to its impact on mechanical properties, plays a crucial role in determining overall process efficiency. Mixtures incorporating coal slag as a dense filler, combined with stiff fibers such as basalt or glass, exhibited the highest flexural strength. Moreover, the inclusion of merino wool fibers enhanced the flexural performance of fly ash-based mixtures, achieving strength levels comparable to or exceeding those of stiffer fibers. These findings contribute to the advancement of sustainable construction practices. Notably, samples produced via 3D printing consistently demonstrated higher flexural strength than those fabricated using traditional molding techniques. This enhancement is attributed to microstructural modifications induced by the layer-by-layer deposition process. Depending on the sample composition and the type of reinforcing fiber, water absorption behavior varied significantly. Merino wool and coconut fibers exhibited the highest water absorption due to their hydrophilic nature and capillary action, particularly in 3D-printed samples with open-pore structures. In contrast, glass and basalt fibers, characterized by their higher density and hydrophobicity, exhibited lower water absorption levels. These results underscore the importance of optimizing fiber type, concentration, and processing methodologies to achieve tailored performance in fiber-reinforced cementitious mixtures. Such optimizations align with the principles of sustainable development and hold significant potential for advancing 3D-printed construction applications Full article

Sandy soils are prone to engineering issues due to their high permeability and low cohesion in the natural environment. Therefore, eco-friendly reinforcement techniques are required for projects such as subgrade filling and soft soil foundation reinforcement to enhance their performance. This study proposes a synergistic reinforcement method that combines Enzyme-Induced Calcium Carbonate Precipitation with Glutinous rice slurry (G-EICP). The macroscopic mechanical properties and pore structure evolution of reinforced sand were systematically investigated through triaxial permeability tests, unconfined compressive strength (UCS) tests, and microstructural characterization based on Scanning Electron Microscope (SEM) and Micro- Computed Tomography (CT) tests. The results indicate that when the glutinous rice slurry volume ratio (V_G) reaches 10%, the UCS of G-EICP-reinforced soil peaks at 449.2 kPa. The permeability coefficient decreases significantly with increasing relative density (D_r), V_G, confining pressure (σ₃), and seepage pressure (p). Microstructural analysis reveals that glutinous rice slurry may promote calcium carbonate crystal growth, potentially by providing nucleation sites, establishing a dual mechanism of skeleton enhancement and pore-throat clogging. The increased incorporation of glutinous rice slurry reduces the number of connected pores, lowers the coordination number, and elevates tortuosity, thereby inducing marked enhancements in both the strength and permeability of the treated soil compared to plain soil. Full article

To examine the effect of flocculation treatment on slurry clogging during vacuum preloading, this study conducted vacuum preloading model tests using lime, anionic polyacrylamide (APAM), and the dual use of polyaluminum chloride (PAC) and APAM in conjunction with particle image velocimetry (PIV) analysis. The results demonstrated that flocculation treatment enhanced the efficiency of vacuum preloading and mitigated the clogging of slurry. Compared to untreated slurry, the lime-flocculated slurry exhibited an approximately 248% increase in pore water pressure dissipation, a 462% increase in clogging zone width, and an 80% improvement in slurry strength near the PVD. The dual use of PAC and APAM significantly improved the slurry’s filtration performance by approximately 77 s, resulting in the highest water discharge rate (47% higher than untreated slurry) under vacuum pressure. In contrast, APAM alone enhanced the water discharge rate primarily in the early stages of vacuum preloading but had a limited effect on the final water discharge volume and horizontal strain. Furthermore, this study investigated the evolution of the clogging zone in flocculated slurry and elucidated the underlying mechanism of flocculation in mitigating the clogging of slurry. The findings can provide a theoretical basis for the selection of flocculants and the arrangement of PVDs in large-scale land reclamation and dredged slurry treatment projects. Full article

The increasing demand for freshwater resources, coupled with industrial pollution, necessitates improved water treatment technologies. This study investigates the potential of quartz-based filtration systems enhanced with hydrophilic nanoparticles for efficient oil-water separation. The quartz material, abundant and cost-effective, was processed and modified through sequential coatings to enhance its hydrophilicity and separation efficiency. Comprehensive characterization techniques, including SEM, XRD, and Raman spectroscopy, were employed to evaluate surface morphology, chemical composition, and structural integrity at different stages of coating. The findings demonstrated that the first coating achieved the most uniform nanoparticle distribution, significantly improving hydrophilicity and separation efficiency, reducing oil content in filtrates to 17.3 mg/L. Subsequent coatings resulted in agglomeration and pore clogging, leading to diminished performance. Validation through mathematical models corroborated experimental observations, confirming the first coating’s superior balance of nanoparticle integration, permeability, and separation efficiency. This research highlights the potential of surface-engineered quartz as a scalable, cost-effective solution for sustainable water reuse. Future work will focus on optimizing coating techniques, scaling up, and integrating the system with complementary technologies to enhance water treatment processes. Full article

Among the technologies for carbon neutral, CO₂ geological sequestration is one of the most promising. The mechanisms of CO₂ behavior within pore space are complex and influenced by multiple factors, with the geometric structure of porous formations being particularly critical to the technology’s efficiency. Among several important and challenging problems in geological sequestration, this work addresses the issue of selecting lithologies based on their geometrical structure. This study proposes a mathematical approach to characterize the geometric structure of porous rock and fluid flow using a random walk (RW) method. Our approach simulates the time evolution of particle flow through highly disordered and heterogeneous digital rock models under a pressure gradient imposed between inlet and outlet surfaces. Through RW simulations, a probabilistic model for mineralization via a clogging (pore-filling) model is introduced, to examine the accumulation of particles within porous structures over time: single-phase clogging and multiple-phase clogging. In single-phase clogging, the porosity decrease can be described as a monotonically non-increasing function of the deposition probability. However, this is no longer true in the multiple-phase strategy because large deposition probability blocks the capillaries near the inlet surface, preventing the fluid from easily invading easily the outlet. In this study, numerical studies conducted on four types of natural rocks—Bentheimer, Doddington, Estaillades, and Ketton—revealed that Ketton exhibits the highest permeability. Our results suggest that Bentheimer, Doddington, and Ketton formations are suitable candidates for CO₂ sequestration, while Estaillades is less favorable from a geometric standpoint. The methods presented in this work contribute to effectively identifying natural rocks with geometric structures advantageous for CO₂ storage. Full article

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). Previous studies have presented a challenge in upscaling fluid dynamics from a small scale to a large scale, thereby constraining our understanding of the spatiotemporal variations in flow paths as porous media evolve. To address this limitation, this study simulated subsurface mixing by injecting Fe(II)-rich freshwater into a DO-rich saltwater flow within a custom-designed syringe packed with glass beads. Micro-computed tomography imaging at the representative elementary volume scale was utilized to track the development of Fe precipitates over time and space. Experimental observations revealed three distinct stages of Fe hydroxides and their effects on the flow dynamics. Initially, hydrous Fe precipitates were characterized by a low density and exhibited mobility, allowing temporarily clogged pathways to intermittently reopen. As precipitation progressed, the Fe precipitates accumulated, forming interparticle bonding structures that redirected the flow to bypass clogged pores and facilitated precipitate flushing near the syringe wall. In the final stage, a notable reduction in the macroscopic capillary number from 3.0 to 0.05 indicated a transition from a viscous- to capillary-dominated flow, which led to the construction of ramified, tortuous flow channels. This study highlights the critical role of high-resolution imaging techniques in bridging the gap between pore-scale and continuum-scale analyses of multiphase flows in hydrogeochemical processes, offering valuable insights into the complex groundwater–seawater mixing. Full article

Engineers, geomorphologists, and ecologists acknowledge the need for temporally and spatially resolved measurements of sediment clogging (also known as colmation) in permeable gravel-bed rivers due to its adverse impacts on water and habitat quality. In this paper, we present a novel method for non-destructive, real-time measurements of pore-scale sediment deposition and monitoring of clogging by using wire-mesh sensors (WMSs) embedded in spheres, forming a smart gravel bed (GravelSens). The measuring principle is based on one-by-one voltage excitation of transmitter electrodes, followed by simultaneous measurements of the resulting current by receiver electrodes at each crossing measuring pores. The currents are then linked to the conductive component of fluid impedance. The measurement performance of the developed sensor is validated by applying the Maxwell Garnett and parallel models to sensor data and comparing the results to data obtained by gamma ray computed tomography (CT). GravelSens is tested and validated under varying filling conditions of different particle sizes ranging from sand to fine gravel. The close agreement between GravelSens and CT measurements indicates the technology’s applicability in sediment–water research while also suggesting its potential for other solid–liquid two-phase flows. This pore-scale measurement and visualization system offers the capability to monitor clogging and de-clogging dynamics within pore spaces up to 10,000 Hz, making it the first laboratory equipment capable of performing such in situ measurements without radiation. Thus, GravelSens is a major improvement over existing methods and holds promise for advancing the understanding of flow–sediment–ecology interactions. Full article

Hydrogeochemical processes contribute to long-term alterations in key physical properties of a porous medium, including porosity, tortuosity, and permeability, making it essential to understand their evolution and address clogging-dominated problems in hydrogeological systems such as acid rock drainage treatment and aquifer storage and recovery. However, accurately simulating extreme cases of evolving pore space presents challenges due to the inherent heterogeneity and nonlinear reactions in a porous medium. In response, this study introduces a comprehensive model that integrates the effects of tortuosity on permeability and surface area on reactivity during oxidative precipitation of Fe(II) in a porous medium. Benchmark simulations include an innovative permeability–tortuosity–porosity model accounting for Fe precipitation, as well as the occurrence of complete clogging from localized precipitation, which leads to a reduction of permeability and outflow. The outcomes demonstrate complete pore clogging when Fe(II) concentration reaches 10 mmol/L and a significant decrease in outflow at a Fe(II) concentration of 100 mmol/L. The model’s predictions provide detailed insights into the evolution of the pore matrix during hydrogeochemical reactions and support the development of regional engineering-scale models for applications in mining, agriculture, and environmental management. Full article

For the removal of waterborne pathogens in remote areas and disaster emergency situations, point-source water treatment methods are more suitable. Photothermal sterilization is ideal for point-of-use (POU) systems, as it effectively eliminates pathogens without secondary pollution or bacterial resistance issues. By combining photothermal with membrane treatment, these membranes rapidly heat up under near-infrared (NIR) light, enabling both bacterial retention and sterilization. However, the decrease in membrane flux due to pore clogging during water treatment can significantly impact membrane efficiency. And adjusting the membrane pore size can significantly enhance flux recovery during cleaning, thereby restoring membrane efficiency. By synthesis multifunctional membranes that combine bacteria retention, sterilization, and flux recovery, it can meet the requirements of point-source water treatment: compact size, high efficiency, good safety, and easy maintenance. In this study, we developed an intelligent thermally responsive membrane (NIPAN@CNTs/PAN) by incorporating carbon nanotubes (CNTs) and forming a copolymer of N-isopropylacrylamide and polyacrylonitrile (NIPAN) coating into polyacrylonitrile membranes, offering dual functions of photothermal sterilization and self-cleaning. With 3% CNTs, the membrane achieves 100% sterilization within 6 min of NIR exposure, while the NIPAN layer’s added roughness boosts photothermal efficiency, achieving 100% sterilization within 4 min. Rinsing at 50 °C improved flux recovery from 50% to 87% and reduced irreversible fouling from 49.7% to 12.9%, demonstrating stable performance over multiple cycles and highlighting its potential for long-term use in practical POU applications. Full article