Search Results (231)

In the context of increasingly stringent vehicle emission regulations, computer-aided engineering has been indispensable for optimizing the design and the operational strategies of emission control systems. This paper proposes a new filtration model for particulate filters that enables the accurate estimation of solid particle number emissions above 10 and 23 nm in diameter (SPN10 and SPN23, respectively). The model incorporates a persistent slip factor and a linear filtration efficiency of cake layers into the unit collector model proposed by Konstandopoulos and Johnson. This enhancement captures PM escape phenomena, such as a passage through interconnected large pores in filter walls. Simulations using a 1D + 1D two-channel framework with the proposed model successfully reproduced experimental results of SPN10 and SPN23 emissions downstream of a miniature gasoline particulate filter (GPF) tested with a synthetic particle generator. The model was also able to represent the observed continuous emissions during a cake filtration mode. Additional simulations using the same model parameters showed good agreement with experimental data of SPN10 and SPN23 emissions downstream of a full-size GPF tested with a gasoline direct injection (G-DI) engine under 5 steady-state operating conditions. The simulations revealed that particles in the 10–100 nm size range dominated the downstream SPN emissions despite their high filtration efficiency, whereas particles in the 100–200 nm size range were less significant. The proposed model is expected to contribute to the GPF developments to comply with the stringent emission regulations of the upcoming Euro 7. Full article

This study evaluates the impact of a Closed Crankcase Ventilation (CCV) system on Caterpillar G3516J NG engine performance and emissions, focusing on engine performance, methane (CH₄) emissions, oil consumption, and oil particle size distribution. Three configurations were analyzed: Indirect Open Crankcase Ventilation (OCV), OCV-Direct, and CCV. The results show that the CCV system significantly reduced CH₄ slip, with reductions ranging from 12% to 23% compared to the Indirect OCV configuration, and 10% to 17% compared to the OCV-Direct configuration. The CCV system also lowered oil concentration in the crankcase ventilation gas and demonstrated high filtration efficiency, achieving values between 99.22% and 99.89%. The oil particle size distribution revealed a substantial reduction in the concentration of smaller particles, with filtration efficiencies ranging from 88.77% for the smallest particles (0.032 µm–0.018 µm) to 99.89% for particles between 1 µm and 0.560 µm. These results suggest that the CCV system not only enhances engine thermal efficiency by reducing CH₄ slip but also contributes to lower oil consumption and reduced particulate matter (PM) emissions. Additionally, the study demonstrates the effects of the CCV system on engine operational parameters like crankcase pressure and performance metrics like Brake Specific Fuel Consumption (BSFC). Full article

This study investigates the impact of teacher decisions and other contextual factors on indoor air quality (IAQ) in mechanically ventilated elementary school classrooms using low-cost air quality sensors. Four classrooms at a K–8 school in San Jose, California, were monitored for airborne particulate matter (PM), carbon dioxide (CO₂), temperature, and humidity over seven weeks. Each classroom was equipped with an HVAC system and a portable air cleaner (PAC), with teachers having full autonomy over PAC usage and ventilation practices. Results revealed that teacher behaviors, such as the frequency of door/window opening and PAC operation, significantly influenced both PM and CO₂ levels. Classrooms with more active ventilation had lower CO₂ but occasionally higher PM_2.5 due to outdoor air exchange, while classrooms with minimal ventilation showed the opposite pattern. An analysis of PAC filter material and PM morphology indicated distinct differences between indoor and outdoor particle sources, with indoor air showing higher fiber content from clothing and carpets. This study highlights the critical role of teacher behavior in shaping IAQ, even in mechanically ventilated environments, and underscores the potential of low-cost sensors to support informed decision-making for healthier classroom environments. Full article

Compression–ignition engines emit particulate matter (PM) (soot), prompting the widespread use of diesel particulate filters (DPFs) in the automotive sector. An alternative method for PM reduction involves the use of ultrasonic waves to disperse and modify the structure of exhaust particles. This article presents experimental results of the effects of ultrasonic emitter parameters, including the number, arrangement, and power, along with the engine speed, on the exhaust smoke density. Tests were conducted on a laboratory prototype equipped with six ultrasonic emitters spaced 0.17 m apart. The exhaust source was a diesel engine from a construction excavator, based on the MTZ-80 tractor design, delivering 80 HP and a displacement of 4750 cm³. A regression model was developed to describe the relationship between the engine speed, emitter power and spacing, and smoke density. The optimal configuration was found to involve an emitter power of 319.35 W and a spacing of 1.361 m for a given engine speed. Under the most effective conditions—an engine speed of 1500 rpm, six active emitters, and a total power of 600 W—smoke emissions were reduced by 18%. These findings support the feasibility of using ultrasonic methods as complementary or alternative exhaust gas filtration techniques for non-road diesel engines. Full article

Sugar production generates wastewater rich in dissolved solids and organic matter, and improper disposal poses severe environmental risks, exacerbates water scarcity, and creates regulatory challenges. Conventional treatment methods, such as evaporation and chemical precipitation, are energy-intensive and often ineffective at removing fine particulates and dissolved impurities. This study evaluates membrane-based separation as a sustainable alternative for water reclamation and sugar recovery from sugar industry effluents, focusing on replacing evaporation with membrane processes, ensuring high permeate quality, and mitigating membrane fouling. Cross-flow filtration experiments were conducted on a lab-scale membrane system at 70 °C to suppress microbial growth, comparing direct reverse osmosis (RO) of the raw effluent to an integrated ultrafiltration (UF)–RO process. Direct RO resulted in rapid membrane fouling. A tight UF (5 kDa) pre-treatment before RO significantly mitigated fouling and improved performance, enabling 28% water recovery and 79% sugar recovery, maintaining permeate conductivity below 0.5 mS/cm, sustaining stable flux, and reducing membrane blocking. Additionally, the UF and RO membranes were tested via SEM, EDS, and FTIR to elucidate the fouling mechanisms. Full article

Particulate matter (PM) and volatile organic compounds (VOCs) are major air pollutants that can cause significant risks to public health. To mitigate exposure, fibrous filters have been widely utilized for air purification. In this study, we developed electrospun silk fibroin/poly (ethylene oxide)/cyclodextrin (SF/PEO/CD) nanofibers as multifunctional air filters capable of efficiently reducing PM_2.5 and degrading VOCs. The resulting SF/PEO/10CD demonstrated the best multifunctional filtration performance, achieving PM_2.5 capture efficiencies of 91.3% with a minimal pressure drop of 4 Pa and VOC removal efficiency of 50%. These characteristics highlight the potential of the SF/PEO/10CD nanofiber with effective, multifunctional properties and environmental benefits for sustainable air filtration application. Full article

The advancement of high-tech industries, notably in semiconductor manufacturing, pharmaceuticals, and precision instrumentation, has imposed stringent requirements on cleanroom environments, where strict control of airborne particulates, microbial presence, temperature, and humidity is essential. However, these controlled environments incur significant energy consumption, with air conditioning systems accounting for 40–60% of total usage due to high air circulation rates, intensive treatment demands, and system resistance. In light of global carbon reduction goals and escalating energy costs, improving the energy efficiency of cleanroom heating, ventilation, and air conditioning (HVAC) systems has become a critical research priority. Recent efforts have focused on optimizing airflow distribution, integrating heat recovery technologies, and adopting low-resistance filtration to reduce energy demand while maintaining stringent environmental standards. Concurrently, artificial intelligence (AI) methods, such as machine learning, deep learning, and adaptive control, are being employed to enable intelligent, energy-efficient system operations. This review systematically examines current energy-saving technologies and strategies in cleanroom HVAC systems, assesses their real-world performance, and highlights emerging trends. The objective is to provide a scientific basis for the green design, operation, and retrofit of cleanrooms, thereby supporting the industry’s transition toward low-carbon, sustainable development. Full article

Developing resource-efficient technologies for producing ceramic materials with specific properties and performance characteristics is one of the most important tasks in modern materials science. As natural resources face depletion, the use of anthropogenic wastes, including fly ash from coal combustion, for the development of new compositions and the production of ceramics with an improved microstructure is of particular significance. The use of PM₁₀ fly ash microspheres in ceramic production will help to reduce particulate matter emissions. In this study, fine narrow fractions of PM₁₀ microspheres were successfully separated from coal fly ash using aerodynamic and magnetic separation. Glass–ceramic materials with a homogeneous microstructure, an open porosity of 0.4–37%, a compressive strength of 5–159 MPa, and acid resistance of up to 99.9% were obtained using narrow fractions. The materials obtained are promising for application as highly porous ceramics, effective microfiltration membranes, and fine-structured technical ceramics, which can be used in installations operating in aggressive media and/or at high temperatures. The ceramic membranes were characterised by high liquid permeability values up to 1194 L·m⁻²·h⁻¹·bar⁻¹. Filtration tests showed that the retention coefficient for dispersed microsilica particles with d_av = 1.9 μm is 0.99. Full article

Stormwater runoff is a significant source of microplastics to surface water. This study addresses challenges in the sampling, treatment, and characterization of microplastics in existing stormwater control measures across various regions in the United States. Stormwater sediment samples were collected via traditional stormwater sampling approaches for particulate and inorganic contamination with portable automatic samplers, analyzed using visible and fluorescence microscopy with Nile red as a selective stain, and subsequently confirmed through Raman spectroscopy. The inclusion of laboratory and field blanks enabled the identification of contamination at key steps during sample handling. The results reveal that the filtration process is a significant source of laboratory contamination, while the sampling process itself could be a primary contributor to overall sample contamination. Additionally, it was found that using green fluorescence as the sole emission wavelength may underestimate MP quantities, as some particles emit fluorescence exclusively in the red spectrum. Raman analysis revealed interferences caused by pigments and additives in plastics, along with challenges evaluating particles in the low micron range (≤10 microns), which complicates a comprehensive analysis. The findings of this study emphasize the importance of implementing strong quality assurance and control measures when assessing the levels of microplastics in the environment, including sample collection, processing, and analysis. Full article

The escalating industrial emissions have dramatically increased airborne particulate matter (PM), particularly submicron particles (PM0.3), creating substantial health risks through respiratory system penetration. Current fiber-based filtration systems predominantly relying on electrostatic adsorption mechanisms suffer from critical limitations, including insufficient efficiency, potential secondary contamination, and performance degradation in humid environments. We develop a flexible silica composite aerogel to overcome these challenges with customizable and exceptional superamphiphobicity. This composite aerogel exhibits high porosity of ~95% and robust compression Young’s modulus that reaches ~220 kPa at 50% strain even after 1000 cycles. These features enable it to maintain a high filtration efficiency of ~98.52% for PM0.3, even after 50 cycles under traditional artificial simulation conditions. Significantly, a competitive filtration efficiency of ~97.9% is still performed in our composite aerogel at high humidity (water mist), high temperatures (50–250 °C), and corrosive solutions or atmospheres environments, revealing potential industrial applications. This work is expected to replace conventional air filtration materials and pave the way for various human protection and industrial production applications. Full article

This study investigated the potential of Tillandsia plants, which can be arranged as a soil-free living green panel, and Banksia flower spikes, which could be arranged as a non-living natural panel, to filter particulate matter (PM) and airborne microorganisms. The Tillandsia panels demonstrated superior PM filtration, achieving up to 74% efficiency for large particles (>10 μm) at air velocities of 1.0 and 1.5 m/s without increasing pressure drop substantially. Conversely, Banksia performed better at 0.5 m/s, filtering up to 53% of PM compared to Tillandsia’s 13%. Notably, both panel types demonstrated significant fungal filtration, removing over 50% of airborne spores at 1.5 m/s. These findings suggest that incorporating plant-based panels into urban environments can enhance air quality and public health especially for allergenic particles and microorganisms. Full article

A novel cost-effective, rapid, and eco-friendly method was described for the removal of carbon dioxide (CO₂) from the gaseous emissions of gasoline engines. This involved the use of a sandwich filter (~10 cm diameter) made of a nonwoven poly (m-phenylene isophthalamide) (Nomex) fabric loaded with a thin layer of activated carbon. The optimized filter, with an activated carbon mass of 2.89 mg/cm², a thickness of 4.8 mm, and an air permeability of 0.5 cm³/cm²/s, was tested. A simple homemade sampling device equipped with solid-state electrochemical sensors to monitor the concentration levels of CO₂ before and after filtration of the emissions was utilized. The data were transmitted via a General Packet Radio Service (GPRS) link to an Internet of Things (IoT)-based gas monitoring system for remote management, and real-time data visualization. The proposed device achieved a 70 ± 3.4% CO₂-removal efficiency within 7 min of operation. Characterization of the filter was conducted using a high-resolution scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Brunauer–Emmett–Teller (BET) analysis. The effects of loaded activated carbon mass, fabric type, filter porosity, gaseous removal time, and adsorption kinetics were also examined. The proposed filter displayed several advantages, including simplicity, compactness, dry design, ease of regeneration, scalability, durability, low cost, and good efficiency. Heat resistance, fire retardancy, mechanical stability, and the ability to remove other gasoline combustion products such as CO, SO_x, NO_x, VOCs, and particulates were also offered. The filtration system enabled both in situ and on-line CO₂ real-time continuous emission monitoring. Full article

The spleen, the largest secondary lymphoid organ, plays several vital roles in the body, including blood filtration, hematopoiesis, and immune regulation. Despite its importance, the spleen has not received substantial attention as a target organ for drug delivery. Most systemically administered colloidal and particulate drug carriers are cleared from the blood by the liver and spleen, making these two organs potential targets for drug accumulation. While various systems have been developed to target the liver, there is an urgent need to design spleen-targeted drug delivery systems that can evade clearance and degradation while delivering drugs efficiently to their target cells in the spleen. Targeting the spleen holds great potential for the treatment of a range of diseases, including blood disorders, immune and inflammatory diseases, infectious diseases, and cancer. It is also crucial for the development of effective vaccines. In this review, we explore different approaches used to target the spleen after systemic administration, and we discuss the factors that shift the biodistribution of drug carriers from the liver to the spleen. We focus on cell-specific delivery within the spleen, strategies to avoid degradation, and methods to achieve the efficient intracellular delivery of various drugs and genes. We also highlight the therapeutic implications of spleen-targeted drug delivery systems, particularly for the prevention and treatment of cancer. Full article

Air pollutants, such as particulate matter (PM) and ammonia (NH₃), generated by intensive animal farming pose considerable threats to human health, animal welfare, and ecological balance. Conventional materials are often ineffective at simultaneously removing multiple pollutants, maintaining a low pressure drop, and ensuring durability in heavily polluted environments. Inspired by the dust-retention properties of Pinus sylvestris var. mongolica (PS) needles, this study developed a biomimetic grooved ribbon fiber using electrospinning technology. These fibers were further assembled into a three-dimensional bioinspired aerogel structure through freeze-forming technology to achieve efficient dust capture. Additionally, the introduction of UiO-66-NH₂ nanoparticles significantly enhanced the properties of the aerogels for NH₃ adsorption. Among the various prepared aerogels (PG, UPG-5, UPG-10, UPG-15, and UPG-20), UPG-10 demonstrated the best performance, achieving a filtration efficiency of 99.24% with a pressure drop of 95 Pa. Notably, it exhibited a remarkable dust-holding capacity of 147 g/m², and its NH₃ adsorption capacity reached 99.89 cm³/g, surpassing PG aerogel by 31.46 cm³/g. Additionally, UPG-10 exhibited outstanding elasticity, maintaining over 80% of its original shape after 30 compression cycles. This biomimetic aerogel presents a promising solution for air purification, contributing to improved agricultural efficiency and environmental sustainability. Full article

The transportation sector mainly relied on fossil fuel and is one of the major causes of climate change and environmental pollution. Advances in smart sensing technology are paving the way for the development of clean and intelligent vehicles that lead to a more sustainable transportation system. In response, the automotive industry is actively engaging in new sensor technologies and innovative control and diagnostic algorithms that improve energy sustainability and reduce vehicle emissions. In particular, recent regulations for diesel vehicles require the integration of smart soot sensors to deal with particulate filter on-board diagnostic (OBD) challenges. Meeting the recent, more stringent OBD requirements will be difficult using traditional diagnostic approaches. This study investigates an advanced diagnostic strategy to assess particulate filter health based on resistive soot sensors and available engine variables. The sensor data are projected to generate a 2D signature that reflects the changes in filtration efficiency. A relevant feature (character) is then extracted from the generated signature that can be transformed into an analytical expression used as an indicator of DPF malfunction. The diagnostic strategy uses an adaptive approach that dynamically adjusts the signature’s characters according to the engine’s operating conditions. A correction factor is calculated using an optimization algorithm based on the integral of engine speed measurements and IMEP set points during each sensor loading period. Different cost functions have been tested and evaluated to improve the diagnostic performance. The proposed adaptive approach is model-free and eliminates the need for subsystem models, iterative algorithms, and extensive calibration procedures. Furthermore, the time-consuming and inaccurate estimation of soot emissions upstream of the DPF is avoided. It was evaluated on a validated numerical platform under NEDC driving conditions with simultaneous dispersions on engine-out soot concentration and soot sensor measurements. The promising results highlight the robustness and superior performance of this approach compared to a diagnostic strategy solely reliant on sensor data. Full article