Search Results (209)

High and variable moisture in wood logs limits their use in continuous carbonization reactors. Artificial drying emerges as a solution to homogenize the moisture of the raw material, optimizing the process, increasing yield, and improving the quality of charcoal. This study aimed to develop an experimental fixed-bed drying system for logs, evaluating the effects of cutting layout (40 cm, 20 cm, and split), diameter class (>12 cm, 12.1–14 cm, 14.1–16 cm, and 16.1–18 cm), and residence time (30, 60, and 90 min) at 300 °C. Split logs showed higher heating and drying rates, positively impacting efficiency. However, split and 20 cm logs subjected to 90 min of drying underwent combustion, indicating operational limits for these layouts under the tested conditions. The heartwood and sapwood regions of split logs heated more rapidly, resulting in higher drying rates and moisture loss, directly affecting drying efficiency. Split logs dried for 60 min showed the best drying efficiency and greatest moisture reduction, making this the most recommended treatment. This study not only demonstrates the technical feasibility of artificial drying of logs for continuous carbonization but also establishes fundamental guidelines for the development of more efficient, safe and sustainable industrial technologies in the charcoal production sector. Full article

This work proposes a coating approach for obtaining flame-retardant ethylene–vinyl acetate (EVA) and ethylene–butyl acrylate (EBA) copolymer-based materials. Nanocomposite films of EVA and EBA were first produced by cast extrusion, with two types of layered double hydroxides (LDHs) differing in the aspect ratio used as nanofillers. Subsequently, the films were applied as a coating to the corresponding neat copolymer substrate, and the combustion behavior of the so-obtained samples was evaluated through cone calorimeter tests. Despite the small amount of nanofillers (0.5 wt.% considering the whole specimen), the application of the coatings significantly improved the time to ignition compared to the pristine copolymers, while the shape of the heat release rate curves and the relative peak values remained relatively unchanged. The effect of the embedded nanofillers in delaying the ignition was more effective for the EVA-based systems than for the EBA ones (showing an increment of 30% and 12%, respectively, compared to the uncoated samples), likely due to the more homogeneous dispersion of the LDHs obtained in the first case. The obtained results demonstrate the effectiveness of the coating approach, since it allows the flame-retardant action to be concentrated on the surface of a polymer system, where combustion specifically takes place, while minimizing the required amount of flame retardant. Full article

Driven by the urgent reduction in industrial energy consumption and nitrogen oxide (NO_x) emissions, numerical simulation becomes a significant tool to understand the internal working process and optimize the structure of the combustion chamber in coke oven. However, conventional numerical simulation is computationally expensive and impractical for real-time monitoring or multi-parameter optimization. To address this challenge, this study proposes a novel parameter fusion convolutional network (PFCN) to rapidly reconstruct the spatial temperature distribution in the combustion chamber of a coke oven. The key innovation of PFCN is its dual-stream encoding mechanism, which processes structural parameters (1 × 5 vector) and spatial coordinates (25 × 200 matrix) separately via dedicated encoders, followed by a cross-modal fusion to effectively integrate these heterogeneous inputs. Furthermore, a support vector machine (SVM) is coupled downstream of the PFCN to estimate the exhaust NO_x emissions based on the predicted physical information. This coupled PFCN–SVM framework allows universal applicability across different combustion chamber configurations. Based on this framework, parametric influence analysis and co-optimization of five key structural parameters are conducted for a three-stage air-supply coke oven. The results reveal that both the air staging ratio and staging height significantly affect combustion performance. Compared to the basecase, the optimized design simultaneously improves temperature homogeneity by 15.2% and reduces NO_x emissions by 8%, with negligible computational cost. This integrated data-driven approach demonstrates considerable potential for combustion chamber optimization, transient process predictions, multi-physics coupling analyses, and online control implementations. Full article

The use of hydrogen in the diesel engine automotive can be a viable and sustainable solution through which to reduce carbon-based emissions for the same operating regimens, without major constructive modifications of the engine. The use of hydrogen in the automotive diesel engine constitutes an efficient solution for controlling its operation with low carbon-based emissions and with reduced energetic specific consumption. This way, the requirements of the EC’s Green Deal policy can be met without major costs. Substitution of fossils fuels with hydrogen ensures the reduction of the carbon content of the air–fuel mixture in the engine cylinder, with favourable influences on the processes of the air–fuel mixture formation and combustion, making it possible to reduce carbon-based emissions. The improvement of the combustion process due to hydrogen use leads to the reduction in carbon-based emissions. For the experimental investigations carried on an automotive diesel engine with 1.5 L by displacement, the authors highlighted the following results: a reduction in smoke emissions by over 22%, a reduction in unburned hydrocarbon emissions by over 25%, and a reduction in carbon dioxide by about 20%, even from the use of relatively low cyclic doses of hydrogen at a usual engine load compared with a standard engine. The authors also obtained an 18.5% increase in the level of nitrogen oxides in the partial load engine, even with the use of small amounts of hydrogen added to the intake air; this is a disadvantage, but by applying specific measures, this emission can be reduced. The increase in the homogeneous air–fuel mixture with the use of hydrogen and the combustion processes’ duration time were reduced due to the high combustion flame speed of hydrogen comparative to diesel fuel; this ensures a reduction in energetic specific consumption and an increase in thermal efficiency. Full article

A comprehensive understanding of the denitration kinetics of nitrocellulose-based propellants is crucial for optimizing combustion performance and achieving controllable fabrication. However, most existing studies rely on a single kinetic model, which is restricted by formulation composition and grain geometry, limiting their general applicability. In this work, the denitration rate was quantified using the change in explosion heat, introducing an energy-based characterization approach instead of traditional mass-loss measurements. Three kinetic models (the shrinking-core, pseudo-homogeneous, and Avrami models) were employed to identify the rate-controlling step. The shrinking-core model provided the most accurate description of the process. At moderate reagent concentrations (8 wt.% and 12 wt.%) and temperatures (65–75 °C), denitration was primarily reaction-controlled, while at higher temperatures (80 °C), internal diffusion resistance became significant. The apparent activation energy ranged from 69.8 to 73.7 kJ·mol⁻¹, confirming that chemical reaction is the dominant mechanism. This study refines the kinetic understanding of nitrocellulose denitration and provides theoretical guidance for the controlled fabrication of gradient nitrocellulose propellants with tunable progressive-burning behavior. Full article

This study develops and validates a weft knitted Mini-Jacquard in Peruvian Pima cotton as a print-free coloration strategy by integrating CAD-based pattern simulation with prototype manufacturing. A three-color design (red, blue, white) was programmed on a flat knitting machine using a 10 × 14 rapport. Color-wise yarn consumption was computed directly from the digital pattern, and the physical sample was characterized through combustion testing and optical micrographs. The prototype exhibited a yarn count of ~20/1 Ne, S-twist (~11.18 TPI), and 100% cellulosic composition. The blue yarn showed the highest consumption (≈73.81%), followed by white (≈19.65%) and red (≈6.55%), consistent with the digital rapport’s color distribution. The CAD stage ensured pattern fidelity and supported raw-material planning; the knitted sample showed a soft hand, dimensional stability, and sharp motif definition upon visual assessment. A sustainability and comparative analysis with chemical printing was conducted, revealing that the Mini-Jacquard achieved the highest design accuracy and tactile comfort, outperforming screen printing and heat transfer in geometric fidelity, chromatic homogeneity, and texture. The Mini-Jacquard optimized operational times (320 min/m²) compared to transfer printing (332 min/m²) and screen printing (740 min/m²), reducing process stages and complexity. Although Jacquard production involves higher energy costs ($34.8) and material expenses ($11.6), it provides greater structural value and durability, positioning it for high-end applications. Moreover, the Mini-Jacquard could reduce water consumption by approximately 90% and thermal energy use by 70%, eliminating chemical residues and extending fabric lifespan, thus offering high sustainability and circular potential. A transparent scenario-based analysis indicates substantial reductions in water and thermal-energy use when omitting printing/fixation/washing stages, along with the elimination of printing-stage effluents. Overall, design-integrated coloration via Mini-Jacquard is technically feasible and potentially eco-efficient for Pima-cotton value chains, with applications in apparel, accessories, and functional textiles. Full article

In order to study the differential characteristics of heavy metal contamination levels and their sources in soils under various land use types and anthropogenic activities at a regional scale, this study focused on the Beijing–Tianjin–Hebei (BTH) urban agglomeration in North China. We analyzed heavy metal content in three land use types (urban green spaces, croplands, and vegetable fields/orchards) through field sampling and laboratory analysis, with content determined by inductively coupled plasma mass spectrometry (ICP-MS). The sources of heavy metals were quantitatively apportioned their sources using the absolute principal component score–multiple linear regression (APCS-MLR) method. Results of this study are as follows: (1) Heavy metal content varied among different soil types, with vegetable fields/orchards soils showing relatively higher content. Urban green spaces and cropland soils exhibited comparable heavy metal levels, though urban green spaces displayed higher spatial heterogeneity, while cropland soils showed more homogeneous distributions. (2) The APCS-MLR model identified five pollution sources: mixed traffic–coal combustion sources, industrial sources, agricultural sources, natural sources, and unknown sources. Natural sources were consistently the dominant contributors of arsenic (As), chromium (Cr), and nickel (Ni) across all three land use types, with contribution rates of 32.62–70.26%. Traffic and coal combustion emissions were the primary sources of lead (Pb) and copper (Cu) in urban green spaces, accounting for 40.28–66.26%, while industrial activities showed the highest contributions to zinc (Zn) and cadmium (Cd) in urban green spaces, at 45.88–65.25%. Agricultural activities contributed similarly to Cd accumulation in both cropland and vegetable fields/orchards soils (41.68–51.32%), but their contributions to Cu and Zn in vegetable fields/orchards soils (46.62–55.58%) were significantly higher than those in cropland (9.21–13.40%). Notably, unexplained sources accounted for 18.64–42.59% of heavy metals in vegetable fields/orchards soils, suggesting particularly complex sources in these systems. This study provides a scientific basis for sustainable soil management strategies and promoting coordinated pollution control in urban agglomeration regions. Full article

Eco-friendly flame retardants are becoming a popular alternative to traditional fire retardants, many of which contain toxic halogens. These modern additives, which are based on phosphorus, nitrogen, or silicon compounds, minimize the emission of harmful gases during combustion, making them safer for the environment and human health. This study aimed to synthesize and analyze poly(vinyl chloride) (PVC) composites using a newly synthesized hybrid fire retardant, boehmite derivative (aluminium dibutyl phosphonate), as an environmentally friendly additive. The fire-retardant properties of chitosan, which is derived from the natural biopolymer chitin, have also been tested. The chemical structure of the synthesized compounds was confirmed using ATR/FTIR spectroscopy and SEM-EDX analysis. Next, PVC-based dry blends were prepared with the addition of a stabilizer, plasticiser, chalk, and selected flame retardants (aluminium dibutyl phosphonate or chitosan) at concentrations of 10 wt%, 30 wt%, and 50 wt%, resulting in homogeneous materials intended for evaluating fire performance, thermal stability (DSC, TGA), and mechanical resistance. Full article

Leveraging catalytic microreactors as compact yet powerful thermal sources represents a promising approach to enable rapid and reliable startup of small-scale solid oxide fuel cell (SOFC) systems. In the present study, the homogeneous–heterogeneous (HH) combustion behavior of a propane/air mixture in a Pt-catalyzed microreactor is investigated using two-dimensional computational fluid dynamic (CFD) simulations. The catalytic reaction kinetics model is integrated into the general module of ANSYSY Fluent via a user-defined function (UDF) interface. By varying the surface area factor, the ignition characteristics of the propane/air mixture under different catalyst activities are systematically explored. Numerical results reveal that the relative catalyst activity range of 0–2 represents a sensitive region for propane/air ignition characteristics, characterized by a 541 K decrease in ignition temperature and a 50% reduction in ignition delay time. Nevertheless, further increases in relative catalyst activity from 2 to 10, yield a much smaller reduction—64 K in ignition temperature and 6.7 s in ignition delay time—indicating a weakly responsive regime. The relative contribution of the heterogeneous reaction (HTR) to the total heat release decreases with higher feed temperatures but increases with enhanced catalyst activity. Regarding the temporal evolution of HTR contribution, the initiation of homogeneous ignition undermines the dominance of HTR contribution. Irrespective of catalytic activity levels, the relative contributions of the two reaction pathways subsequently undergo dynamic redistribution and ultimately stabilize, reaching an equilibrium state within approximately 10 s. These findings provide critical insights into the role of catalyst activity in propane/air mixture ignition and the interplay between homogeneous and heterogeneous reactions in microscale combustion systems. Full article

Utilization of waste tires via pyrolysis is a promising solution. The liquid hydrocarbons generated during this process could be used for enhancing low-reactivity coals for energy application. Current study investigates oxidation and combustion characteristics (including composition of gaseous combustion products) of low-reactivity coal mixed with liquid hydrocarbons from pyrolysis of waste tires with a concentration up to 20%wt at 700 °C. The oxidation tests via TG-analyzer revealed that at heating rates up to 10 °C/min, the process had one stage, associated with combined oxidation of coal-liquid hydrocarbons mixture. Starting from 10 °C/min the second stage occurred at temperature ~400 °C due to evaporation of light components of the mixture. Combustion tests at experimental setup at 700 °C revealed almost linear increase in fuel reactivity, expressed into decline in ignition delay time of mixtures (up to 71.6%) with increasing concentration of liquid hydrocarbons, while flame and diffusion combustion times were, in contrast, increasing (by up to 69.5%). Increasing concentration of additives from 2.5 to 20%wt resulted not only in change in the form of obtained mixture but also changed the combustion mechanism from predominantly heterogeneous smoldering to majorly homogeneous gas-phase ignition and combustion. Gas-phase combustion products concentration curves generally complimented previously observed peculiarities of combustion. Increased CO and NO_x concentrations in combustion products of coal mixed with liquid hydrocarbons revealed necessity in additional tailoring of burner characteristics for mitigating these effects. The compromise composition of mixture was found to include 10%wt of liquid hydrocarbons for enabling quick gas-phase ignition while maintaining moderate level of combustion products emissions. Full article

Ammonia–coal co-combustion has emerged as a promising strategy for reducing carbon emissions from coal utilization, although its underlying reaction mechanisms remain insufficiently understood. The Chemkin simulation of zero-dimensional homogeneous reaction model and entrained flow reaction model was employed here, and the ROP (rate of production) and sensitivity analysis was performed for analyzing in-depth reaction mechanisms. The nitrogen conversion pathways were revealed, and the mechanisms were simplified. Based on simplified mechanisms, molecular-level reaction pathways and thermochemical conversion networks of nitrogen-containing precursors were established. The results indicate that NO emissions peak at a 30% co-firing ratio, while N₂O formation increases steadily. The NH radical facilitates NO reduction to N₂O, with NH + NO → N₂O + H identified as the dominant pathway. Enhancing NNH formation and suppressing NCO intermediates are key to improving nitrogen conversion to N₂. This paper quantifies the correlation between NO_x precursors such as HCN and NH₃ and intermediates such as NCO and NNH during ammonia–coal co-firing and emphasizes the important role of N₂O. These insights offer a molecular-level foundation for designing advanced ammonia–coal co-combustion systems aimed at minimizing NO_x emissions. Full article

In this study, the decarburization behavior in basic oxygen furnace (BOF) steelmaking was investigated based on the multi-zone reaction mechanism. The contributions of the main reaction zones to decarburization were clarified, and the effects of key factors—including the effective reaction amount in the main reaction zones, the post combustion ratio (PCR) in auxiliary reaction zones, and the carbon content of scrap steel—on decarburization behavior were quantitatively analyzed. The results indicate that decarburization predominantly occurs in the jet impact reaction zone (approximately 76% of the total decarburization), followed by the emulsion and metal droplet reaction zone (approximately 14%) and the bulk metal and slag reaction zone (approximately 10%). Variations in the effective reaction amount for the main reaction zones significantly affect both the decarburization rate and the endpoint carbon content, with the direct oxidation decarburization reaction in the jet impact reaction zone being the dominant factor. In addition, the PCR in the gas homogenization zone of the auxiliary reaction zones determines the distribution ratio of effective reaction oxygen, while the melting behavior of scrap steel in the metal homogenization zone plays a critical role in the precise control of the endpoint carbon content. This study provides a quantitative elucidation of the effects of different reaction zones on decarburization behavior, offering a foundation for the precise control of endpoint carbon content in BOF steelmaking. Full article

This review article provides an overview of the use of hydrogen and tyre pyrolysis oil as fuels for homogeneous charge compression ignition (HCCI) engines. It discusses their properties, the ways they are produced and their sustainability, which is of particular importance in the present moment. Both fuels have certain advantages but also throw up many challenges, which complicate their application in HCCI engines. The paper scrutinises engine performance with hydrogen and tyre pyrolysis oil, respectively, and compares the fuels’ emissions, a crucial focus from an environmental perspective. It also surveys related technologies that have recently emerged, their effects and environmental impacts, and the rules and regulations that are starting to become established in these areas. Furthermore, it provides a comparative discussion of various engine performance data in terms of combustion behaviour, emission levels, fuel economy and potential costs or savings in real terms. The analysis reveals significant research gaps, and recommendations are provided as to areas for future study. The paper argues that hydrogen and tyre pyrolysis oil might sometimes be used together or in complementary ways to benefit HCCI engine performance. The importance of life-cycle assessment is noted, acknowledging also the requirements of the circular economy. The major findings are summarised with some comments on future perspectives for the use of sustainable fuels in HCCI engines. This review article provides a helpful reference for researchers working in this area and for policymakers concerned with establishing relevant legal frameworks, as well as for companies in the sustainable transport sector. Full article

This study presents a comparative investigation of 3Ni2Ce/Al catalysts synthesized via different methods dry impregnation (DI), capillary impregnation (CI), and solution combustion synthesis (SC) for the complete oxidation of methane. The aim was to elucidate the influence of the preparation method on the catalytic activity and reduction behavior of the catalysts. Among the samples tested, the catalyst prepared by the solution combustion method exhibited the highest activity: at 500 °C, the methane conversion reached 82%, compared to 43% and 41% for the 3Ni2Ce/Al (CI) and 3Ni2Ce/Al (DI) prepared catalysts, respectively. At 550 °C, the 3Ni2Ce/Al (SC) catalyst achieved 99% conversion, surpassing the 3Ni2Ce/Al (CI) (72.5%) and 3Ni2Ce/Al (DI) (95%) analogs. Hydrogen temperature-programmed reduction (H₂-TPR) analysis revealed that the 3Ni2Ce/Al (SC) catalyst exhibited enhanced hydrogen uptake in the range of 450–850 °C, indicating the presence of more easily reducible NiO species interacting with CeO₂ and the alumina support. Scanning electron microscopy (SEM) further confirmed a more uniform distribution of the active phase on the surface of the 3Ni2Ce/Al (SC) catalyst in comparison to the impregnated samples. Overall, the findings demonstrate that the preparation method has a significant impact on the development of a redox-active catalyst structure. The superior performance of the SC-derived catalyst in methane oxidation is attributed to its improved reducibility and homogenous morphology, making it a promising candidate for high-temperature catalytic applications. Full article

This study proposes an innovative Thermodynamic Activity Controlled Homogeneous Charge Compression Ignition (TAC-HCCI) strategy for diesel–natural gas dual-fuel engines, aiming to achieve high thermal efficiency while maintaining low emissions. By employing numerical simulation methods, the effects of the intake pressure, intake temperature, EGR rate, intake valve closing timing, diesel injection timing, diesel injection pressure, and diesel injection quantity on engine combustion, energy distribution, and emission characteristics were systematically investigated. Through a comprehensive analysis of optimized operating conditions, a high-efficiency and low-emission TAC-HCCI combustion technology for dual-fuel engines was developed. The core mechanism of TAC-HCCI combustion control was elucidated through an analysis of the equivalence ratio and temperature distribution of the in-cylinder mixture. The results indicate that under the constraints of PCP ≤ 30 ± 1 MPa and RI ≤ 5 ± 0.5 MW/m², the TAC-HCCI technology achieves a gross indicated mean effective pressure (IMEPg) of 24.0 bar, a gross indicated thermal efficiency (ITEg) of up to 52.0%, and indicated specific NOx emissions (ISNOx) as low as 1.0 g/kW∙h. To achieve low combustion loss, reduced heat transfer loss, and high thermal efficiency, it is essential to ensure the complete combustion of the mixture while maintaining low combustion temperatures. Moreover, a reduced diesel injection quantity combined with a high injection pressure can effectively suppress NOx emissions. Full article