Incomplete Combustion Research Articles

Analysis of the impact of misfiring on the throttle body in ayla vehicles using the fast fourier transform method

An essential component of an automobile's air intake system, the throttle body controls airflow during combustion by acting as an idle speed control mechanism. Making ensuring the throttle body is operating properly is crucial to keeping the engine running at its best. The Fast Fourier Transform vibration analysis is one technique used for this (FFT). A an LCGC Ayla 1000 cc vehicle's throttle body and engine underwent vibration testing with rotational rates set to 750 rpm, 1000 rpm, 1500 rpm, and 2000 rpm. Vibration responses were measured using an accelerometer sensor coupled to an FFT analyzer, and Matlab was used for analysis. The throttle body had anomalous frequency readings at 1977 Hz with an amplitude of 0.03171 m/s2, according to the test results. On the other hand, the frequency value at 1410 Hz with an amplitude of 0.03435 m/s2 was observed under normal circumstances. Similar to this, abnormal frequency values with an amplitude of 0.02378 m/s2 were found on the engine at 1493 Hz, whereas normal frequency values with the same amplitude were found at 1712 Hz. These results point to incomplete combustion as the cause of the increased vibration

Biocatalytic Potential of Pseudomonas Species in the Degradation of Polycyclic Aromatic Hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs), one of the major environmental pollutants, produced from incomplete combustion of materials like coal, oil, gas, wood, and charbroiled meat, that contaminate the air, soil, and water, necessitating urgent remediation. Understanding the metabolic pathways for PAHs degradation is crucial to preventing environmental damage and health issues. Biological methods are gaining increasing interest due to their cost-effectiveness and environmental friendliness. These methods are particularly suitable for remediating PAHs contamination and mitigating associated risks. The paper also outlines the processes for biodegrading PAHs, emphasizing the function of Pseudomonas spp., a kind of bacterium recognized for its capacity to degrade PAHs. To eliminate PAHs from the environment and reduce threats to human health and the environment, Pseudomonas spp. is essential. Understanding the mechanism of PAH breakdown by means of microbes could lead to effective clean-up strategies. The review highlights the enzymatic capabilities, adaptability, and genetic versatility of the genes like nah and phn of Pseudomonas spp., which are involved in PAHs degradation pathways. Scientific evidence supports using Pseudomonas spp. as biocatalysts for PAHs clean-up, offering cost-effective and eco-friendly solutions.

Boron nitride: Novel ceramic reductant for low‐activity waste vitrification

AbstractDuring vitrification of radioactive wastes, excessive foaming reduces processing rates within melters by hindering heat transfer from the molten glass pool to the reacting melter feed. Formulations of low‐activity waste (LAW) melter feeds, for vitrification at the Waste Treatment and Immobilization Plant at the Hanford Site, conventionally include the addition of sucrose to mitigate excessive foaming by hastening the denitration process. However, incomplete combustion of sucrose produces organics such as acetonitrile (C2H3N) that may exceed bounding limits of downstream effluent treatment facilities. Using boron nitride (BN) as an alternate reductant to sucrose, in a representative LAW melter feed reduced C2H3N production by 90% by preventing the low‐temperature sucrose–nitrate reactions. Furthermore, foaming was suppressed due to the higher decomposition temperature of BN than H3BO3 meaning a delayed reaction of a large fraction of boron with the transient glass‐forming melt until above the foam onset temperature, thus reducing the quantity and viscosity of the connected melt and trapping less gas in the foam layer.

A fundamental analysis on PAHs in food products to detect the toxicity index using fuzzy logic system

Polycyclic Aromatic Hydrocarbons (PAHs) are complex chemical compounds that occur naturally in unprocessed food when it is exposed to contaminated air during transportation, natural emission such as volcano, forest fire and through pesticides spray. It is reported by different agencies that there are 16 types of PAHs in which BaP (Benzo[a] pyrene), BaA (Benz[a]anthracene), BbF(Benzo [b] fluoranthene), Chr (Chrysene) are considered to be carcinogenic and it can occur due to different processes. In processed food it occurs due to various processing methods like overheating, incomplete burning, drying etc. The presence of PAH in food is conventionally found through analytical, traditional, and semi-automatic methods. These methods are found to be valuable but expensive and time-consuming. Further, these methods are used only for the detection of PAHs and the toxicity level is measured or identified based on expert knowledge of researchers and the Standards. Therefore, in this research, a simple harmfulness index system has been developed using Fuzzy Logic System(FLS). The proposed system has been designed based on the PAH values of different food and food products. Hence to initiate the study and to determine the significance of the results, PAH data have been collected from different articles that have investigated food products experimentally. These PAH data were analyzed using statistical measures such as Min, Mean, Max, Standard Deviation, Variance and Kurtosis method. Based on the observations from the results, the fuzzy sets were designed with four membership functions for each PAH and the rules were framed. The strength output from the inference engine has been associated with harmfulness index such as normal, low risk, medium risk, and high risk. From the evaluation, it can be observed that 89.72% of the food samples were recognized along with their degree of harmfulness. Also it can be inferred that 11% of the misclassified samples showed clear metrics of their harmfulness with PAH variations.

Distribution of polycyclic aromatic hydrocarbons and carcinogenic risk assessment in street-barbecued foods in China

Street-barbecued foods, despite their popularity, produce carcinogenic polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]anthracene (BaA), chrysene (Chr), benzo[b]fluoranthene (BbF), benzo[a]pyrene (BaP) due to incomplete charcoal combustion, direct food-fuel contact, and excessive heating. This study analyzed barbecued foods from high-traffic street vendors using high-performance liquid chromatography. Among five food categories (meat, vegetable, aquatic, starch, and soy products), eight foods exceeded China’s BaP limit (5 µg/kg) and twelve exceeded the EU limit (2 µg/kg). The highest BaP and PAH4 levels were found in barbecued beef and pork belly, respectively. Chr levels were notably high due to open flame exposure. Health risk assessments indicated fourteen foods posed elevated carcinogenic risks. This study highlights the necessity of consumption control to mitigate these risks and provides evidence for improving street food safety and dietary security.

Coupling Effect of Elemental Carbon and Organic Carbon on the Changes of Optical Properties and Oxidative Potential of Soot Particles under Visible Light.

Soot particles, coming from the incomplete combustion of fossil or biomass fuels, feature a core-shell structure with inner elemental carbon (EC) and outer organic carbon (OC). Both EC and OC are known to be photoactive under solar radiation. However, research on their coupling effect during photochemical aging remains limited. This study examines how the optical properties and oxidative potential (OP) of wood, coal, and diesel soot particles with varying EC and OC levels are affected by exposure to visible light. Wood soot, which has the highest OC content, showed the most significant changes in both optical properties and OP, indicating its highest sensitivity to visible light aging. Molecular composition analysis revealed that the reduction of polycyclic aromatic hydrocarbons (PAHs) and methyl-PAHs primarily affects the optical properties, while oxygenated PAHs play a major role in OP. Combined with the results from reactive oxygen species detection, it is suggested that EC initiates photoreactions by generating superoxide anions, while OC undergoes compositional changes that result in subsequent atmospheric effects. These findings enhance our understanding of the photochemical aging process of soot particles and their implications for climate and health.

Formation Mechanism and Biotransformation of Halogenated polycyclic aromatic hydrocarbons (HPAHs) from Ecological sources to Food chain sink

Halogenated polyaromatic hydrocarbons (HPAHs, H = F, Cl, Br) are a new class of PAHs derivatives that mainly originate from the incomplete combustion of halogen-laden materials and via metallurgical operations. These compounds circulate extensively in various environmental matrices. This survey provides a comprehensive review on governing synthesis routes of HPAHs, their environmental occurrence, and their health and ecological effects. The review comprehensively enlists and presents emission sources of these emerging organic pollutants into the air that serves as their main reservoir. The formation of HPAHs ensues through successive addition reactions of smally compounds accompanied by ring cyclization steps; in addition to direct unimolecular fragmentation of parents halogenated. Halogenation of parent PAHs rapidly occurs in saline ecosystems thus multiplying the availability of these notorious compounds in the environment. Certain HPAHs appear to be more carcinogenic than dioxins. Transmission routes of HPAHs from their emission sources to water bodies, soil, aquatic life, plants, terrestrial animals, and humans are well-documented. Later, the direct and indirect diffusion of HPAHs from air to the biotic (plants, animals, humans) and abiotic components (soil, water, sediments) are described in detail. The study concludes that HPAHs are permeable to the carbon matrices resulting in the alleviation of the source-to-to-sink interface. As a potential future perspective, understanding the transmission interfaces lays a foundation to intervene in the introduction of these toxicants into the food chain.

Strategies to improve ammonia combustion in a dual fuel marine engine by using CFD

Maritime transportation is currently responsible for delivering most of the world trade, and it still plays a major role in the global economy and pollutant emissions. Due to their heavy loads and long distances, full electrification is generally assumed as an unsuitable pathway, leaving combustion engines as the dominant technology in the marine sector. For a long time, these engines have benefited from the low costs of heavy oils produced from oil refining, but these fuels present a difficult combustion and are associated with significant pollutant emissions and greenhouse gases. Today, carbon-free fuels such as hydrogen and ammonia are gradually getting a foothold in the shipping market.In the present paper, an investigation on several strategies to improve the oxidation of ammonia is carried out for a dual fuel (DF) medium speed marine engine. A CFD analysis using ANSYS FORTE® code is performed on an improved and more realistic bowl geometry by varying the premixed fuel according to methods validated in previous studies and introducing adequate kinetic mechanisms from the literature. Results show that the sole use of ammonia to replace natural gas, as premixed fuel, leads to incomplete combustion; the increase of diesel fuel can only mitigate this condition, but it cannot be considered as viable solution. Therefore, several blends of ammonia/hydrogen are tested to examine combustion development and pollutant emissions. The addition of hydrogen above 10% to the premixed charge composition demonstrates to promote the oxidation of ammonia and to effectively reduce CO2 emissions of 84% without a dramatic increase in nitrogen oxides. On the contrary, hydrogen percentages lower than 10% feature a worsening of the combustion of the premixed charge. Finally, the use of a fuel containing nitrogen promote a slight formation of NOx emissions.

Satellite derived air pollution climatology over India and its neighboring regions: Spatio-temporal trends and insights

This study examines the spatial and temporal variations of key air pollutants, including Nitrogen Dioxide (NO₂), Carbon Monoxide (CO), Tropospheric Ozone (O₃), Sulfur Dioxide (SO₂), Aerosol Optical Depth (AOD), and Formaldehyde (HCHO) over India and neighboring regions, using satellite data from 2005 to 2022. Peak NO₂ (∼11–13 × 101⁵molecules/cm2) occurs in pre-monsoon and winter, mainly over urban centers, thermal plants, and crop-burning areas, emphasizing anthropogenic emissions. High CO levels (2.0–2.3 × 101⁸molecules/cm2) during summer dominate in Indo-Gangetic Plains (IGP), Eastern India, and Northeastern region, linked to the incomplete combustion of organic matter (e.g., natural forest fires and biofuel-based household cooking). Stable CO trends reflect effective government policies promoting cleaner fuels. Tropospheric O₃ shows a spatial gradient, with higher values in northern and coastal regions influenced by sunlight, humidity, and precursor emissions. Seasonal peaks in summer are governed by solar intensity, while the December peak over the northern region is likely due to dynamical transport from O₃-rich areas. SO₂ hotspots in IGP, central and eastern India, especially during winter (∼1.3–1.9 × 101⁵molecules/cm2), are attributed to local anthropogenic emissions and fossil fuel combustion such as coal. Long-term trends reveal rising SO₂ levels. AOD hotspots occur over IGP, Central and Southern India, with particularly high values during the pre-monsoon (0.5–0.6) and winter seasons. HCHO shows hotspots in the IGP, west coast, eastern, and northeastern regions, peaking in summer (7.5–8.5 × 101⁵molecules/cm2) due to biogenic VOC emissions. This study underscores the need for integrated policies to mitigate emissions, improve air quality, and protect public health.

From flames to lab: A robust non-destructive sampling method for evaluating PAH exposure in firefighters’ personal protection equipment

Polycyclic aromatic hydrocarbons (PAHs) are compounds with high carcinogenic potential, produced during incomplete combustion. Certain professions, such as firefighting, expose workers to significant levels of PAHs during their operations, making it essential to investigate sampling protocols to evaluate their exposure in the work environment.This study presents a non-destructive and cost-effective sampling method for monitoring PAHs in firefighters’ personal protective equipment (PPE) and intervention vehicles. Sampling was conducted using three isopropanol wipes per collection zone, with comprehensive validation trials ensuring the method’s effectivenes. The method was tested under both natural contamination and spiking scenarios, showing similar results in both protocols.Analysis of contaminated PPE revealed significant PAH contamination in specific zones, such as gloves, lower back sleeves, and knees, due to direct exposure to flames and smoke during firefighting, with the highest concentrations in the outer and moisture layers. The cleaning efficacy of PPE was also evaluated employing specific washing machines, showing substantial reductions in PAH levels of approximately 76%. Additionally, non-targeted analysis detected organophosphate flame retardants (OPFRs) and furans, suggesting broader utility for environmental monitoring. This comprehensive approach improves the accessibility of chemical exposure studies in high-risk professions, contributing to better protective measures and occupational health and safety.

The development of rapid immunoassays for the urinary analysis of 1-hydroxypyrene glucuronide facilitate both laboratory and on-site polycyclic aromatic hydrocarbon biomonitoring

Polycylic Aromatic Hydrocarbons (PAHs) are produced during the incomplete burning of organic materials. PAH sources include vehicle exhaust, tobacco smoke and waste incineration. Environmental and occupational exposures to PAHs are known to occur. Cancer is a significant endpoint of PAH exposure and several occupations associated with high PAH exposure have been classified by IARC as carcinogenic to humans (Group 1).Pyrene is a common component of PAH mixtures and metabolism of pyrene leads to the excretion of 1-hydroxypyrene glucuronide (1-OHPyrG) in urine. Laboratory measurement of urinary 1-OHPyrG is employed in occupational and environmental biomonitoring programmes. The production of an anti-1-OHPyrG monoclonal antibody would allow the development of a PAH biomonitoring ELISA facilitating large scale laboratory screening and routine testing.The development of a lateral flow immunoassay and the production of a field test (point of use test) would greatly increase the value of biomonitoring. A novel Lateral Flow has been developed which employs an anti-1-OHPyrG sheep monoclonal antibody (Mab) to capture the PAH metabolite. The captured metabolite is visualised through a second Mab raised against the Mab-1-OHPyrG immune complex. This sandwich assay provides a positive correlation between the assay signal and biomarker concentration.A Smartphone camera allows signal measurement and a carefully considered ‘app’ provides result interpretation and data analysis. Results are provided in an exposed/not-exposed format. Performance of the lateral flow was confirmed through a comparative study and field trial. The development of a lateral flow test provides "real-time" analysis to occupational health professionals. On-site screening allows the immediate confirmation of safe working practice, provides immediate reassurance to those involved in potentially hazardous activities and greatly increases the efficacy of biomonitoring.

An in situ combustion carbon deposit diagnostic instrument based on Raman microscopy.

Carbon deposit of the aero-engine combustor, resulting from incomplete combustion and fuel pyrolysis, can cause nozzle blockage, fuel consumption increase, power decrease, and even flight unsafety. In this work, an in situ combustion carbon deposit diagnostic instrument is developed to reveal the crystalline structure and the changes under real combustion conditions. The instrument integrates the in situ microscopic Raman technique and the combustion system. The burner is characterized by a sloping tip, making it possible to observe the coke from the side view. The burner is installed to the optical positioning stage by a specially made adapter so that the relative location is fixed and it is possible to observe the carbon deposit from the ignition. The carbon deposit of acetylene/air diffusion jet flame was studied. A 50× objective lens was used to collect the Raman scattering signal of carbon deposits continuously 30s after ignition. A five-band model was used to fit the Raman spectra. The time-resolved information was calculated, including the normalized total area, area proportion, peak ratio, and crystalline size. The results show that the carbon deposit of acetylene flames with different velocities presents different tendencies of formation and degree of graphitization, which is attributed to the influence of temperature and flow. The performance of this system is evaluated quantitatively. The signal-to-noise ratio of Raman spectra of carbon deposits ranges from 6.4 to 28.9. This work provides an in situ method to analyze the dynamic change of carbon deposit on the burner, and further work is needed to reveal the mechanism.

Greenhouse gas column observations from a portable spectrometer in Uganda

Abstract. The extensive terrestrial ecosystems of tropical Africa are a significant store of carbon and play a key but uncertain role in the atmospheric budgets of carbon dioxide and methane. As ground-based observations in the tropics are scarce compared with other parts of the world, recent studies have instead made use of satellite observations assimilated into atmospheric chemistry and transport models to conclude that methane emissions from this geographical region have increased since 2010 as a result of increased wetland extent, accounting for up to a third of global methane growth, and that the tropical Africa region dominates net carbon emission across the tropics. These studies critically rely on the accuracy of satellite datasets, such as those from the Orbiting Carbon Observatory-2 (OCO-2), the Greenhouse gases Observing SATellite (GOSAT), and the Sentinel-5 Precursor TROPOspheric Monitoring Instrument (TROPOMI), along with results from atmospheric transport models, over a geographical region where there are little independent data to test the robustness of published results. In this paper we present the first ground-based observations of greenhouse gas column concentrations over East Africa, obtained using a portable Bruker EM27/SUN Fourier transform infrared (FTIR) spectrometer during a deployment covering the first few months of 2020 in Jinja, Uganda. We operated the instrument near autonomously by way of an automated weatherproof enclosure and observed total atmospheric column concentrations of the greenhouse gases carbon dioxide and methane, as well as carbon monoxide, a useful proxy for emissions from incomplete combustion processes in the region. We discuss the performance of the combined enclosure and spectrometer system that we deployed in Jinja to obtain these data and show comparisons of our ground-based observations with satellite datasets from OCO-2 and Orbiting Carbon Observatory-3 (OCO-3) for carbon dioxide and TROPOMI for methane and carbon monoxide, whilst also comparing our results with concentration data from the GEOS-Chem and Copernicus Atmosphere Monitoring Service (CAMS) atmospheric inversions that provide a means of increasing spatial and temporal coverage where satellite data are not available. For our measurement period, we find mean differences in XCO2 between OCO-2 and the EM27/SUN of −0.29 % and between OCO-3 and the EM27/SUN of −0.28 %. In the case of TROPOMI, the mean difference in XCH4 that we find between TROPOMI and the EM27/SUN is −0.44 %, whilst for XCO the mean difference is −5.65 %. In each of these cases, the mean difference observed between the satellite and ground-based column concentrations is either close to or within the precision and accuracy requirements for the respective missions. With regard to the model and reanalysis comparisons with the EM27/SUN column concentrations, we see mean differences from the EM27/SUN of a global GEOS-Chem inversion for XCO2 of −0.08 %, a regional high-resolution GEOS-Chem inversion for XCH4 of −0.22 %, and the CAMS global reanalysis for XCO of −9.79 %. Our results demonstrate the value of ground-based observations of total column concentrations and show that the combined EM27/SUN and enclosure system employed would be suitable for acquisition of the longer-term observations needed to rigorously evaluate satellite observations and model and reanalysis calculations over tropical Africa.

Benzo[a]pyrene: A carcinogen, its sources, adverse effects, and preventive measures

A polycyclic aromatic hydrocarbon called benzo[a]pyrene (B[a]P) is produced during incomplete burning of fuels. The most common way humans consume B[a]P is through food products, particularly grilled or smoked foods. B[a]P is also frequently detected in the sediments, soil, surface water, and air. Once bioactivated, it produces a highly reactive epoxide monomer that can create adducts by chemically reacting with biological molecules, such as DNA. B[a]P is implicated in various cancers due to its interaction with the aromatic hydrocarbon receptor (AhR). Apart from its detrimental impacts on development and reproduction, this substance also suppresses the immune system. Microbes, however, are critical to cleaning up the B[a]P-contaminated environment. This review focuses on forming B[a]P in different compartments of the environment and human surroundings, and the mechanisms responsible for its harmful effects and carcinogenic risk. This review also discusses the strategies for the deterioration of B[a]P.

Comparative assessment of acute neurotoxicity of real-world ultra-fine black carbon emitted from residential solid fuel combustion

Incomplete combustion of residential solid fuel is one of the main anthropogenic sources for black carbon (BC). Fresh BC, mainly enriched in ultra-fine fraction of particles, can directly cross blood-brain barrier and are reported to be associated with neurodegenerative diseases. Because of the difficulties in collection and purification of BC from ambient particles, there are still significant knowledge gaps in understanding neurotoxicity caused by real-world BC. The purpose of this study is to compare the neurotoxic effects caused by BCs emitted from combustion of six residential solid fuels, and try to reveal associated biological mechanisms in SH-SY5Y cells. Two straw BC (Wheat-BC and Corn-BC) showed highest neurotoxic effects followed by wood BC (Pine-BC and Aspen-BC) and coal BC (Xvzhou and Longkou Coal), as indicated by viability, lactic dehydrogenase, malondialdehyde, adenosine triphosphate and acetylcholine levels. Coal BC caused nearly no toxicity in human neuroblastoma (SH-SY5Y) cells within highest dose of 200 μg/mL. RNA sequence and bioinformatics analysis were applied to effectively identify differential genes and signaling pathways. Based on Gene Ontology (GO) annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, Protein Protein Interaction network (PPI network) construction, we found biomass BC affected mitochondrial function, interfered with cellular metabolic processes, disturbed redox homeostasis, and finally resulted in cellular damages. Coal-BC mainly caused cytokine/chemokine related inflammatory responses. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting methods were further applied to find out related signaling pathways. Biomass BC activated IL6R/JAK3/STAT3 and JAK3/STAT6 pathways leading to oxidative stress and inflammatory responses. Coal BC activated JAK3/STAT3 pathway leading to chemokine related responses. This study revealed the heterogeneity in neurotoxicity of BCs from different combustion sources and provided important data for health risk assessment. BC-related neurotoxicity should be considered when making air pollution emission control strategies, with residential biomass receiving more policy attention.

Potential impact of the 2023 Lahaina wildfire on the marine environment: Modeling the transport of ash-laden benzo[a]pyrene and pentachlorophenol

The Lahaina urban/wildland fire event is considered the deadliest wildfire in the past century of U.S. history. This fire resulted in over 2200 building structures destroyed or damaged, approximately 4000 automobiles were incinerated and between 450 and 878 ha of grassland burned in areas adjoining the town of Lahaina, Maui County, State of Hawaii, U.S.A. One of the most abundant contaminants of both wildland and urban fires is the incomplete combustion product, benzo[a]pyrene. Pentachlorophenol from burned and unburned utility poles/residential burn sites enter into navigable waters, thus posing a serious risk to the water quality of coastal waters. The Risk Quotient Plumes for benzo[a]pyrene and pentachlorophenol, mobilized from Lahaina into coastal waters were calculated based on a hydrodynamic analysis and an integrated ecological risk assessment. This plume was simulated using rainfall events in November 2022 as a proxy for the first major rainfall event expected in Lahaina in 2024. The models indicated that the estimated levels of benzo[a]pyrene and pentachlorophenol posed a risk to near shore habitants within 2 km of Lahaina. The levels of pentachlorophenol were more widespread than benzo[a]pyrene and were predicted to pose a hazard to marine life as far away as Molokini Shoal Marine Life Conservation District and ʻĀhihi-Kīnaʻu Natural Area Reserve. Fisheries species captured near these areas should be tested for consumption safety.

Combination of high cetane diesel fuel and post injection mode in a diesel engine: A path towards lower exhaust emissions

The major objective of the presented work is to explore the effect of post injection (PI) strategy using neat diesel fuel (D100) blended with cetane number enhancer (CNE). The motive behind adding CNE in diesel fuel was to lower its self-ignition temperature and hence delay period subsequently. This can lead to more efficient combustion of post injected fuel which leads to lower incomplete combustion losses. The CNE used was Di-Tert-Butyl Peroxide (DTBP) which was blended with D100 in proportion of 1 % by volume. Initially experiments were conducted with D100 under various PI modes where variation of post injection timing (PIT) as well as post quantity (PQ) was considered. The experimental results showed that implementing PI resulted in lower smoke, unburned hydrocarbon (UHC), carbon monoxide (CO) and nitrogen oxides (NOx) emissions compared to single injection while affecting fuel consumption negatively. Then after similar experiments under various PI modes were repeated using blends of D100 and DTBP (D/DTBP) and results were compared with D100 case. It was found that addition of CNE in D100 resulted in more complete combustion of post fuel which further reduced CO and UHC emissions. The shorter delay period in case of D/DTBP blend compared to D100 case led to lower NOx emissions as well as higher smoke emissions. The obtained results revealed that PI mode with 3 mg PQ and 20° after top dead center (ATDC) PIT with D/DTBP blend offered 41.18 %, 17.55 %, 64 % and 62.5 % reduction in smoke, NOx, UHC and CO emissions respectively compared to single injection mode using D100 fuel.

Study on Oxygen-Enriched Combustion Characteristics of Blast Furnace Gas Boiler

ABSTRACT To study the dynamic characteristics of OEC (oxygen-enriched combustion) in a BFG (blast furnace gas) boiler, the BFG boiler of an iron and steel enterprise is taken as the research object, and a thermal test bed for OEC of BFG is set up, and a thermodynamic simulation model of the BFG boiler is constructed based on the heat loss of chemical incomplete combustion obtained from thermal test, using MSP (Multi-Subject Simulation Platform). The effects of OC (oxygen concentration) and the position of oxygen entering the furnace chamber on the key parameters of the OEC process of the BFG boiler under different working conditions were analyzed. The results showed that the excess air coefficient of 1.2 and exhaust temperature of 120°C was kept constant during the thermal test. With a fuel volume of 2.4 Nm3/h, for example, after the OC was increased from 21% to 40%, the combustion flame temperature in the furnace was increased by about 34°C, the heat loss due to unburned gas was reduced by 0.21%, and the boiler efficiency was increased by 1.38%. In the dynamic model, at the instant when the OC is changed, the disturbance of the whole system is relatively large, and the FAT (furnace average temperature) outlet, the pressure of the steam ladle, and the MST (main steam temperature) will have a step change, and then gradually level off again. With the increase of OC, the combustion reaction is more and more intense, the steam side of the heat transfer process is strengthened, the boiler efficiency is improved, and the FAT chamber outlet, the steam ladle pressure and the MST after OEC in different ways of oxygen entry into the furnace chamber will be longer and longer to reach a stable value. The results of the study can provide a reference for the OEC operation of BFG boilers.

Transcriptomic analysis-based study on the response mechanism of juvenile golden cuttlefish (Sepia esculenta) to benzo[a]pyrene exposure

Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon from incomplete combustion, builds up in coastal regions through river runoff, atmospheric deposition, and coastal activities. BaP's lipophilicity and stability lead to persistent environmental impacts due to its resistance to degradation. The economically valuable golden cuttlefish, Sepia esculenta, often spawns and hatches in shallow waters, making it prone to BaP exposure. This study employs transcriptomic analysis to initially investigate juvenile golden cuttlefish's response to BaP. The results indicate that BaP exposure significantly affects various physiological and molecular functions of the juveniles, particularly affecting pathways related to immune and inflammatory responses, metabolic regulation, and nervous system functions. Functional enrichment and PPI network analyses identified key genes such as HSGALT-like, ASAH1-like, and GTL-like in the BaP response. These genes exhibited a suppressive trend during short-term exposure, indicating that BaP exposure may influence lipid metabolism, energy conversion, and digestive functions at the genetic level, which could further disrupt the overall physiological state and developmental processes of juvenile golden cuttlefish. The study offers novel insights into BaP's effects on juvenile golden cuttlefish and marine life, aiding marine ecosystem and biodiversity conservation.

Exploration of altered reaction pathways in aging pyrotechnic compositions under seasonal cycles

Since pyrotechnic delays are utilized to control the initiation timing of the metal-rich chemical reactions, precise control of these reactions is desired even when the combustion mixture is subjected to extended storage conditions. However, alterations in physicochemical and geometrical properties, accompanied by changes in thermal behavior, significantly influence the reaction pathways. This study explores the reactions of tungsten (W)-based pyrotechnic compositions subjected to aging. In particular, the work identifies the altered reaction pathways and fundamental causes leading to deterioration in both thermodynamic and physicochemical characteristics due to aging under seasonal cycles. Surface analyses revealed the major aging products as KClO3, WO3, BaO, and Cr2O3, along with three distinct effects of aging: pre-oxidation of metals, a priori decomposition of oxidizers, and surface cracking. Thermal analyses using peak deconvolution techniques described the sub-reactions of the major exothermic reaction, such as chemical reactions #1: (W and KClO4) and #2: (W, KClO4, and BaCrO4) and (WO3 and BaO). Notably, samples aged longer than 2 weeks underwent an additional side reaction, #3: (KClO3 decomposition). The multi-step reaction kinetics obtained from the Friedman method disclosed notably distinct trends in both pristine and aged samples. Among the aging products, KClO3 played a decisive role in altering the Eα-α relationship from a monotonic increase to a convex pattern. The measured decrease in Eα due to the involvement of KClO3 was approximately 30 % (from 464.7 kJ/mol to 272.4 kJ/mol). This demonstrates that KClO3 is critical to performance degradation, as it can release excess oxygen at initiation and decompose at a later stage. This results in incomplete combustion and a decline in thermodynamic performance due to the resulting ad-hoc O/F ratio. Thus, these findings may help in designing the time delay margins and estimating the shelf-life of these compositions.