Search Results (34)

This investigation focuses on synthesizing ZSM-5 zeolite from kaolin clay and its application as a catalytic converter to reduce NOx emissions in CRDI diesel engines. By doping the synthesized zeolite with CuCl₂ and AgNO₃ and coating it on a ceramic monolith, this study demonstrated superior catalytic activity for NO_x reduction compared to conventional converters. A set of experimental trials conducted by using a diesel engine with an AVL DI-gas analyzer showed that CuCl₂-ZSM5 and AgNO₃-ZSM5 catalysts reduced the NO_x conversion efficiencies to 72% and 66%. Additionally, these catalysts effectively reduced CO and HC emissions. The results highlight the potential of kaolin-derived zeolites with copper and cobalt dopants as efficient catalysts for emission control in internal combustion engines, offering a promising, sustainable solution for improving air quality and environmental sustainability. Full article

Air pollution poses a serious threat to human health and the environment. Emissions from motor vehicles, especially in large cities, contribute significantly to this problem. This study analyzes the results of emission inspections in the Slovak Republic to identify factors influencing emissions and their impact on air quality. The research analyzed data from emission inspections and their relationship to vehicle age, fuel type, and type of failure. The results show that older vehicles, especially those aged 10 to 20 years, have a higher probability of failing to meet emission standards. Specifically, up to 42.75% of diesel vehicles aged 15 to 20 years were rated as unfit, compared to 33.07% of gasoline vehicles in the same age category. An increased proportion of unfit vehicles was recorded for diesel engines, which indicates their negative impact on air quality. The most common failures were related to direct emission measurements. These findings have implications for environmental policy and the regulation of vehicle imports to improve air quality and reduce pollution. Data on emission inspections were drawn from the national system and show knowledge about the observation of emission inspections carried out during one calendar year. The study recommends the introduction of stricter control mechanisms for older vehicles, supporting the renewal of the vehicle fleet, and the implementation of modern technologies to reduce emissions. Rigorous emission inspections are essential for the protection of public health. Regular inspections and modern technologies reduce emissions of harmful substances, thus contributing to the improvement of air quality and public health. Full article

This study develops an integrated methodological approach for interpreting used oil analysis results in diesel engines, focusing on optimizing maintenance strategies. The methodology combines a literature review with a quantitative assessment of 156 lubricant analysis reports from a fleet of diesel waste collection trucks operating in Cuenca, Ecuador, a high-altitude city. The framework includes critical limits for key lubricant parameters, correlation analysis, and Principal Component Analysis (PCA) to identify dominant degradation mechanisms. The Binary Segmentation (BS) algorithm is also used for Change-Point Detection. The findings indicate four primary degradation pathways: thermal–chemical degradation influenced by sulfur, oxidation, and soot; metallic wear and base depletion, involving iron, chromium, and copper; external contamination linked to silica and copper; and viscosity alteration due to lubricant aging. Significant degradation shifts were identified at approximately 346 and 444 service hours, suggesting critical points for condition-based maintenance interventions. This study highlights the effectiveness of multivariate statistical tools in enhancing the interpretation of used oil analysis and optimizing predictive maintenance strategies. The integration of Change-Point Detection and multivariate analysis provides a robust framework for defining oil change intervals based on lubricant condition rather than fixed time- or mileage-based criteria. This approach offers practical benefits for fleet operations, enabling the reduction in operational costs, enhancing engine reliability, and minimizing the environmental impact of unnecessary lubricant changes. Full article

The research described in this paper aimed to verify the impact of road vehicle aging on air pollutant emissions. The problem of vehicle aging and the resulting changing air pollutant emissions was identified with the operational mileage of passenger cars. The validity of such an approach to research on air pollutant emissions changing over time was confirmed by a preliminary review of publications in scientific databases such as Scopus and Web of Science. The research problem presented in this paper was to assess the impact of vehicle aging on essential air pollutant emissions (CO, CO₂, NO_X). The research method included measuring the actual RDE air pollutant emissions using research equipment, i.e., the SEMTECH DS gaseous exhaust gas component analyzer. This study was conducted on vehicles with diesel engines, different operating ages, different mileages, and engines with similar displacement, mostly 1.9–2.0 dm³, and equipped with manual transmissions. The tests were conducted in the Poznań agglomeration. The results of measured air pollutant emissions in the RDE mode allowed for mapping the changes in air pollutant emissions for diesel engine vehicles with similar displacement as a function of operating age (mileage) and also for collecting preliminary data for analyses in the field of modeling road air pollutant emissions within the vehicle aging phenomenon. Full article

Common rail systems are a key component of modern diesel engines and highly increase their performance. During their working lifetime, there could be critical damages or failures related to aging, like backlash or friction, or out-of-spec operating conditions, like low-quality fuel with, e.g., the presence of water or particles or a high percentage of biodiesel. In this work, suitable data-driven methods are adopted to develop an automatic procedure to monitor, diagnose, and estimate some types of faults in common rail systems. In particular, the pressure control loop operating within the engine control unit is investigated; the system is described using a Hammerstein model composed of a nonlinear model for the control valve behavior and an extended linear model for the process dynamics, which also accounts for the presence of external disturbances. Three different sources of oscillations can be successfully detected and quantified: valve stiction, aggressive controller tuning, and external disturbance. Selected case studies are used to demonstrate the effectiveness of the developed methodology. Full article

In this study, we examine and assess the potential impact of diesel engine age on the levels of fine particulate matter (PM_2.5) in school buses. The concentration of air pollutants is influenced by several factors, including the technical characteristics of the bus and its engine, the type of fuel used, the length of the commute, the weather conditions, and the ambient air pollution. The behavior of the bus on the road, during the commute to and from school, is also important. This includes its position in traffic, the number of bus stops, boarding procedures, as well as the opening of doors and windows. Data were collected by accompanying a student during their commute to and from school, with bus commutes serving as the sampling unit. A semi-parametric regression was applied to assess the link between the PM_2.5 concentration and the bus engine age. It was demonstrated that the bus engine age has a statistically significant positive correlation with the PM_2.5 concentration inside the bus. The fine particulate matter concentrations during boarding at the school also depend on the engine age, indicating that bus idling affects the PM_2.5 concentration. In the first two minutes before boarding in front of the school and the first two minutes inside the bus, the PM_2.5 concentrations were 26.3 and 40.3 μg/m³, respectively. The findings of this study highlight the impact of bus engine age on the PM_2.5 concentration, showing that the PM_2.5 concentration increases with the engine age. However, the effect becomes less visible as the duration of the bus ride increases. Full article

Energy supply on high mountains remains an open issue since grid connection is not feasible. In the past, diesel generators with lead–acid battery energy storage systems (ESSs) were applied in most cases. Recently, photovoltaic (PV) systems with lithium-ion (Li-ion) battery ESSs have become suitable for solving this problem in a greener way. In 2016, an off-grid PV system with a Li-ion battery ESS was installed in Paiyun Lodge on Mt. Jade (the highest lodge in Taiwan). After operating for more than 7 years, the aging of the whole electric power system became a critical issue for its long-term usage. In this work, a method is established for analyzing the massive energy data (over 7 million rows), such as daily operation patterns, as well as the C-rate, temperature, and accumulated energy distributions, and estimating the health of the Li-ion battery system. A completed electric power improvement project dealing with power system aging is reported. Based on the long-term usage experience, a simple cost analysis model comparing lead–acid and Li-ion battery systems is built, revealing that expensive Li-ion batteries can compete with cheap lead–acid batteries for long-term usage on high mountains. This case study can provide engineers and researchers with a fundamental understanding of the long-term usage of off-grid PV ESSs and engineering on high mountains. Full article

Experience shows that dilution of lubricating oil with diesel oil is unfavorable to the engine, causing issues including deterioration of engine performance, shortening of oil life, and reduction in engine reliability and safety. This paper presents the verification of the hypothesis that the changes in lubricity, friction coefficient, and decreasing oil film thickness (using a relative approach, given as a percentage) are similar for lubricating oil and diesel mixtures prepared from fresh lubricating oil and used lubricating oil. To validate this hypothesis, an experiment is conducted using a high-frequency reciprocating rig (HFFR), in which the lubricity is determined by the corrected average wear scar WS_1.4, the coefficient of friction μ, and the percentage relative decrease in oil film thickness r. A qualitative visual assessment of the wear scars on the test specimens is also performed after the HFFR tests. The testing covers mixtures of SAE 30 grade Marinol CB-30 RG1230 lubricating oil with Orlen Efecta Diesel Biodiesel. The used lubricating oil is extracted from the circulating lubrication system of a supercharged, trunk-piston, four-stroke ZUT Zgoda Sulzer 5 BAH 22 engine installed in the laboratory of ship power plants of the Maritime University of Szczecin. Mixtures for the experiment are prepared for fresh lubricating oil with diesel oil and used lubricating oil with diesel oil. Mixtures of these lubricating oils with diesel oil are examined for diesel oil concentrations in the mixture equal to 1, 2, 5, 10, 15, and 20% m/m. The results of the experiment confirm the hypothesis, proving that, for up to 20% m/m diesel oil concentration in lubricating oil, the changes in the lubricity of used lubricating oil diluted with diesel oil can be evaluated based on reference data prepared for mixtures of diesel oil with fresh lubricating oil. The linear approximation of μ and r trends is made with a certain margin of error we estimated. The experiment also confirms the results of previous studies which state that oil aging products in small quantities contribute to improved lubricity. Full article

In recent years, increased attention to air pollutants such as NO_x has led the scientific community to focus meaningfully on developing strategies for NO_x reduction. Selective catalytic reduction of NO_x by ammonia (NO SCR by NH₃) is currently the main method to remove NO_x from diesel engine exhaust emissions. The catalysts with typical V₂O₅-WO₃/TiO₂ (VWTi) composition are widely used in NH₃-SCR for their high NO_x conversion activity, low cost, and robustness, especially concerning sulfur poisoning. However, in real diesel engine working conditions, the thermal and hydrothermal aging of catalysts can occur after several hours of operation at high temperature, affecting the catalytic performance. In this study, the stability of a commercial VWTi monolith, self-supported and containing glass fibers and bentonite in its matrix, was investigated as a case study. In laboratory conditions, NO SCR tests were performed for 50 h in the range of 150 to 350 °C. Subsequently, the VWTi monolith was thermally and hydrothermally aged at 600 °C for 6 h. The thermal aging increased the NO_x conversion, especially at low temperature (<250 °C), while the hydrothermal aging did not affect the SCR. The differences in NO_x conversion before and after aging were associated with the change in vanadium and tungsten oxide surface coverage and with the reduction in the surface area of catalysts. In order to correlate the change in SCR activity with the modifications occurring after aging processes, the monolithic samples were characterized by several techniques, namely XRD, SSA and pore analysis, TPR, XPS, Raman, TGA and SEM/EDX. Full article

Replacing alkaline for alkaline-earth metal hydroxide in the synthesis gel during the synthesis of siliceous SSZ-13 zeolite (Si/Al~10) yields SSZ-13 with novel, advantageous properties. Its NH₄-form ion-exchanges higher amount of isolated divalent M(II) ions than the conventional one: this is the consequence of an increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO₄⁻ motives to reside closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and X-ray absorption spectroscopy measurements and show their utility for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more isolated cobalt(II) and, thus, perform better as ambient-air NOx adsorbers. Notably, Co(II)/SSZ-13 with an increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading Pd(II) into Co-SSZ-13(Sr) produces an active NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in the presence of Sr(OH)₂ does not lose its PNA capacity after extremely harsh aging at 850 and 900 °C (10 h in 10% H₂O/air flow) and loses only ~55% capacity after hydrothermal aging at 930 °C. This can be extended to other divalent metals for catalytic applications, such as copper: we show that Cu/SSZ-13 catalyst can survive hydrothermal aging at 920 °C without losing its catalytic properties, metal dispersion and crystalline structure. Thus, we provide a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications. Full article

International trade is continuously rising, leading to an increase in the flow of goods passing through transportation hubs, including air and sea. In addition, the aging fleet of inland vessels necessitates renewal through the construction of new vessels, presenting opportunities for the adoption of modern transport technologies. Autonomous barges can transport bulk and containerized cargo between the central port of a specific region and smaller satellite ports, enabling the dispersal of goods over a wider area. Equipping autonomous barges with advanced sensors, such as LIDAR, computer vision systems that operate in visible light and thermal infrared, and incorporating advanced path finding and cooperation algorithms may enable them to operate autonomously, subject only to remote supervision. The purpose of this study is to explore the potential of autonomous electric propulsion barges in inland waterway transport. Given the increasing demand for efficient and sustainable transport solutions as a result of various new policies, which have set new ambitious goals in clean transportation, this study aims to develop a proposition of an electric propulsion hybrid drive inland waterway barge, and compare it to a conventional diesel-powered barge. The methodology involves the creation of a simulation model of an inland waterway class IV electric barge, equipped with advanced sensors and autonomous control systems. The barge’s navigation is managed through a multi-agent system, with evolutionary algorithms determining a safe passage route. This research also utilizes a proprietary networked ship traffic simulator, based on real inland vessel recorded routes, to conduct the autonomous navigation study. The energy consumption of the barge on a route resulting from the ship traffic simulation is then examined using the mathematical model using the OpenModelica package. As a result of the study, the proposed hybrid propulsion system achieved a 16% reduction in fuel consumption and CO₂ emissions, while cutting engine operation time by more than 71%. The findings could provide valuable insights into the feasibility and efficiency of autonomous electric propulsion barges, potentially helping future developments in inland waterway transport. Full article

The skin is the outermost layer of the body and, therefore, is exposed to a variety of stressors, such as environmental pollutants, known to cause oxinflammatory reactions involved in the exacerbation of several skin conditions. Today, inflammasomes are recognized as important modulators of the cutaneous inflammatory status in response to air pollutants and ultraviolet (UV) light exposure. In this study, human skin explants were exposed to the best-recognized air pollutants, such as microplastics (MP), cigarette smoke (CS), diesel engine exhaust (DEE), ozone (O₃), and UV, for 1 or 4 days, to explore how each pollutant can differently modulate markers of cutaneous oxinflammation. Exposure to environmental pollutants caused an altered oxidative stress response, accompanied by increased DNA damage and signs of premature skin aging. The effect of specific pollutants being able to exert different inflammasomes pathways (NLRP1, NLRP3, NLRP6, and NLRC4) was also investigated in terms of scaffold formation and cell pyroptosis. Among all environmental pollutants, O₃, MP, and UV represented the main pollutants affecting cutaneous redox homeostasis; of note, the NLRP1 and NLRP6 inflammasomes were the main ones modulated by these outdoor stressors, suggesting their role as possible molecular targets in preventing skin disorders and the inflammaging events associated with environmental pollutant exposure. Full article

Aging diesel engines on the road require the development of an after-treatment system to meet current emission regulations, and a reduction in NOx (Nitrogen Oxide) is significant. The SCR (Selective Catalytic Reduction) system is the after-treatment system for removing NOx from exhaust gas in diesel engines using NH₃ (Ammonia) gas. However, the mixing and conversion process between NH₃ and NOx in SCR has not been entirely clarified. That process produces NH₃ slip in the catalyst surface; the NH₃ slip will make the after-treatment performance worse. This study informs how the UWS (Urea Water Solution) injection controlling method can minimize the NH₃ slip in the after-treatment system. For this, the NH₃ adsorption and desorption rates are important factors for determining the quantity of UWS injection in the system. The NH₃ adsorption rate and desorption rate in the SCR are not significantly affected by engine speed, i.e., the exhaust gas flow rate. However, as the exhaust gas temperature increased, the adsorption rate and desorption rate of NH₃ in the SCR increased. Through this, the exhaust gas temperature dramatically affects the NH₃ adsorption rate and desorption rate in the SCR. Therefore, if the urea water is injected based on this knowledge that the NH₃ adsorption amount in the SCR decreases as the exhaust gas flow rate increases, NH₃ slip can be suppressed and a high NOx reduction rate can be achieved. Therefore, if the SCR adsorption and desorption mechanisms are analyzed according to the exhaust temperature and the exhaust flow rate in this paper, it can be used as a reference for selecting an appropriate SCR when retrofitting an old diesel engine car. Full article

At present, passive NO_x adsorbers (PNAs) represent one of the most effective technologies for addressing NO_x emissions from diesel engines during cold-start periods. Conventional PNAs, which primarily consist of noble metals (such as Pt, Pd, and Ag) loaded on metal oxides or zeolites, share the common drawback of high production costs. Consequently, developing low-cost PNAs with outstanding NO_x storage performance remains a significant challenge. In this study, a series of CuxBa5Ce adsorbents were synthesized using the impregnation method, and a monolithic adsorbent was employed to evaluate NO_x storage and release performance. Techniques such as XRD, UV-Vis DRs, H₂-TPR, XPS, and in situ DRIFTs confirmed the crucial roles of Cu and Ba in NO_x storage and release. Specifically, the incorporation of Cu into CeO₂ enhanced NO_x storage performance. Moreover, in the Cu3Ba5Ce adsorbent, the addition of Ba not only introduced new storage sites and altered the stability of NO_x adsorption species but also helped prevent the aggregation of CuO, thereby prolonging the complete NO_x storage duration and satisfying desorption temperature requirements. The Cu3Ba5Ce adsorbent exhibited the most favorable NO_x storage performance, including a complete NO_x storage time of 135 s and a NO_x storage efficiency exceeding 50% at 80 °C over a 10 min period. While PNAs loaded with noble metals, such as Pd/CeO₂ and Pt/CeO₂, exhibited NO_x storage efficiencies below 50% after adsorbing for 5 min at 80 °C. Therefore, this research offered a crucial strategy for developing non-noble-metal-loaded, Ce-based PNAs. Full article

To meet more and more stringent emission standards, the combined technologies must be used to purify the emission pollutants of vehicle exhaust. Among them, the aftertreatment devices, including DOC, SCR, DPF, and so on, are the most efficient methods. However, after long-term running, the performance of the aftertreatment devices will inevitably degrade. There are several mechanisms that can be used to explain the aging phenomena. For the catalytic devices, such as DOC and SCR, thermal aging and poisoning aging are the most important reasons for their performance deterioration. As for DPF, ash clogging is a key problem for its stable working. To develop and test aftertreatment devices better and faster, the accelerated aging methods must be researched and applied. The small-sample aging method enables accelerated aging of catalyst samples at a very low cost, but its aging accuracy may not be good enough. Although the results of the whole-vehicle aging method and bench engine aging method are more in accord with the real using course, they take too much time and are too expensive to be used widely. Burner aging is a promising way to simulate the long-term running of the catalysts. Full article