Soot Concentration Research Articles

Investigation of carbon-black emissions of a tractor biofuel diesel

BACKGROUND: On the one hand, a petroleum-based liquid fuel diesel engine is a reliable basis for tractors and self-propelled agricultural machines, and on the other hand, the current trends make us to think about the environmental component of these diesel engines and besides to remember about reasonable use of non-renewable petroleum motor fuel. In order to reduce the anthropogenic impact on natural ecosystems and to assess the smokiness of exhaust gases from a tractor diesel running on ethanol and rapeseed oil, the paper considers the relevant model of the carbon-black formation inside it. AIM: Development of the relevant model of carbon-black emission in a tractor diesel running on ethanol and rapeseed oil to assess the smokiness of exhaust gases and to reduce anthropogenic impact on natural ecosystems. METHODS: To simulate the processes of formation and burnout of carbon-black particles in a tractor diesel engine, the volume of the combustion chamber was conditionally divided into several areas (soot content indicators in different areas were added up), and the cycle of calculating the exhaust gas smokiness level included several stages (determination of pressure, integral and differential characteristics of heat dissipation, average temperature of the working fluid, fuel supply indicators and fuel evaporation rate, local coefficients of excess air, composition of gases, concentration of decomposition and oxidation products of rapeseed oil and ethanol, the number of carbon-black particles, the mass of dispersed carbon, the rate of transition of particles to the burnout zone). RESULTS: The developed mathematical model is capable of calculating the carbon-black concentration and the main components of the gas mixture in the reaction zone of the combustion chamber, the content of carbon-black in the exhaust gases at various speed and load modes of operation of a tractor diesel engine. It is capable of obtaining valuable information about the dynamics of the main stages of carbon-black formation and burnout in the cylinder of a tractor diesel engine running on ethanol and rapeseed oil. The results of numerical simulation of carbon-black formation and burnout in a tractor diesel cylinder when running on diesel fuel, ethanol and rapeseed oil are obtained and presented. CONCLUSION: Based on the developed relevant model of carbon-black emission in a tractor diesel engine running on ethanol and rapeseed oil, an assessment of its exhaust gas smokiness was carried out, clearly showing a decrease by 3.4–3.8 times in comparison with diesel fuel operation. The presented method for calculating the carbon-black emission of tractor diesel can be used in the multi-area modeling and researches of such in-cylinder processes as heat generation, heat transfer, etc. The accuracy of calculations based on the proposed model is characterized by the perfection of mathematical algorithms describing the rate of fuel evaporation, the development of a fuel flare, the determination of local temperatures, the rate of flame propagation, the local composition of gases in the cylinder, etc.

Properties of foam glass produced with the use of soot from a cement factory as a foaming agent: A Study Based on Taguchi Design of Experiments

Cellular glass is a lightweight, porous medium with excellent heat transfer resistance that can be used in a variety of industries. This study investigated the use of soot from cement plants as a new foaming agent for producing foam glass. The experiments were designed using the Taguchi Design of Experiments (DOE) method. By applying this approach, instead of creating and testing 27 different groups of samples, only 9 groups were produced. The properties of the remaining 18 sample groups were then predicted based on Taguchi analysis. Soot and silicon carbide were used simultaneously (at weight ratios of 2% and 3%) as foaming agents in the samples. Alumina was also used as a modifier with weight ratios of 4%, and 8%. Mechanical strength, water absorption, density, and thermal resistance were evaluated. The findings indicated a direct correlation between elevated soot content and increased water absorption (open porosity), coupled with a reduction in compressive strength and overall density of the foam glass. Electron microscopy observations revealed a wide range of crystallite morphologies in the resulting foam glass, which results in diverse properties in the material. The developed glass foams exhibit a density spanning from 125 to 700 kg/m3, with compressive strength varying between 1.2 and 6.7 MPa, and thermal conductivity in the range of 0.08–0.5 W/m·K. The samples with 3% soot, 0% alumina, and 3% SiC exhibited exceptional thermal insulation properties. In contrast, the samples containing 1% soot, 8% alumina, and 1% SiC demonstrated the highest compressive strength. Overall, this study found that soot from cement plants is a viable foaming agent for producing foam glass with desirable properties. The use of soot from cement plants can not only reduce the dispersion of pollution in the environment but also produce a wide range of foam glass with different properties at a lower cost.

Comparative analysis of the combustion and emission characteristics of biojet and conventional Jet A‐1 fuel: a review

AbstractConventional jet fuels derived from fossil sources contribute to greenhouse gas emissions and air pollution, leading to climate change. Recent studies have shown that biobased jet fuels from different feedstocks offer a more sustainable alternative to conventional fuels as they are derived from renewable biomass, reducing greenhouse gas emissions. The major feedstocks reviewed are jatropha curcas, camelina, karanja oil, waste cooking oil, and municipal solid waste. They offer diverse benefits for sustainable aviation fuel development. As a comparative analysis, this review examined jet fuel characteristics based on their physicochemical properties, namely energy content, viscosity, calorific value, cetane number, and freezing and flash points. The objective was to understand the influence of the properties on performance evaluation, environmental impact, and combustion characteristics. The properties of biojet fuels are compared with their fossil counterparts to validate their suitability as renewable alternatives and their benefits in terms of emissions reduction and engine performance. Biojet fuels perform better in terms of lower sulfur content, lower soot content, and a lower freezing point, their aromatic content, and their high cetane number. This study enhances the understanding of biojet fuels and their quality, and supports the development of sustainable fuel options. Overall, adherence to the American Society for Testing and Materials (ASTM) D7566‐18 standard is crucial for the acceptance and integration of biojet fuels into the aviation sector. Future research should explore feedstocks such as wood biomass, wastepaper, and agricultural residues for biojet fuels. It should also investigate the combustion and emission characteristics of biosourced aviation fuel at higher blending ratios (>50% by volume) with fossil Jet A‐1.

Soot volume fraction measurements in aero-engine model combustor outlet using two-color laser-induced incandescence

Quantitative measurement of Soot Volume Fraction (SVF) is an essential prerequisite for controlling soot particle emissions from aero-engine combustors. As an in-situ and non-intrusive optical diagnostic technique, Laser-Induced Incandescence (LII) has been increasingly applied for soot concentration quantification in various combustion environments such as laminar flame, vehicle exhaust, internal combustion chamber as well as aero-engine combustor. In this work, we experimentally measured the spatial and temporal distribution of SVF using two-color LII technique at the outlet of a single-sector dual-swirl aero-engine model combustor. The effect of inlet pressure and air preheat temperature on the SVF distribution was separately investigated within a pressure range of 241–425 kPa and a temperature range of 292–500 K. The results show that soot production increases with the inlet pressure but generally decreases with the air preheat temperature. Qualitative analysis was provided to explain the above results of parametric studies. The LII experiments were also conducted under 3 designed conditions to evaluate soot emission under practical operations. Particularly, weak soot emission was detected at the outlet under the idle condition. Our experimental results provide a valuable benchmark for evaluating soot emission in the exhaust plume of this aero-engine combustor during practical operations.

Optimized Mosaic Method for Accurate Measurement of Soot Concentration Indirect Method

Global air pollution poses health risks. Soot is a major contributor to warming and pollution. Measuring soot is key to mitigating emissions. This study proposes an empirical method using markers to indirectly gauge soot levels. The Mosaic method was tested against conventional techniques with over 50 samples. This method utilizes markers to collect impurities in the air, employing the µ/m³, m(g), and the newly devised Mosaic method. All results underwent standard statistical processing, enabling a comparison between the new method (Mosaic) and conventional techniques used.

Influence of spray-to-spray interaction after wall impingement of spray flames on diesel combustion characteristics

The influence of spray-to-spray interaction after wall impingement of spray flames on the combustion characteristics in high pressure and high temperature ambient gas like in combustion chambers of diesel engines was examined with a constant volume vessel. Fuel was injected onto a flat wall from two nozzles to form two parallel, adjacent sprays in the vessel, causing the spray-to-spray interaction after the wall impingement. The combustion was analyzed with the rate of heat release calculated from the pressure transition in the vessel and the spray flame was visualized by high-speed video. The 310 nm UV light images of the chemiluminescence from OH radicals are recorded to demonstrate the reaction activity in the spray flame. The images of transmitted light throughout the constant volume vessel were recorded to visualize the soot formation and oxidation processes as well as to quantify the soot concentrations as the KL factors. The results showed that the rate of heat release from the main combustion decreases and the afterburning increases with the spray-to-spray interaction after the wall impingement of the spray flame. Combustion suppression with the spray-to-spray interaction occurred in all the conditions of the experiments here when changing the distance from the nozzle to the impinging wall between 25 and 40 mm and the fuel injection pressures between 100 and 200 MPa. Inside the spray-to-spray interaction zone, the chemiluminescence from OH radicals is weaker, supporting the inactive combustion due to difficulties of the air entrainment, and the lower transmitted light intensities with larger KL factors, indicating higher soot concentrations. The spray-to-spray interaction zone on the impingement wall advances toward the inside of the vessel between the sprays and it moves away from the wall, entraining the unutilized air and causing a relatively active combustion as well as rapid soot oxidation during the late afterburning stage.

Following fuel conversion during biomass gasification using tunable diode laser absorption spectroscopy diagnostics

The efficiency of the gasification process and product quality largely depend on the degree of fuel conversion. We present the real-time in-situ tunable diode laser measurements of main carbon and oxygen-containing species in the hot reactor core of a pilot-scale entrained flow biomass gasifier (EFG). The concentrations of CO, CO2, CH4, C2H2, H2O, soot, and gas temperature were measured during the air and oxygen-enriched gasification of stem wood at varying equivalence ratios. The experiments were made at the upper and lower optical ports inside a 4 m long, ceramic-lined, atmospheric EFG, allowing to access the degree of the fuel conversion inside the reactor. The exhaust composition was measured by micro-GC, FTIR, and low-pressure impactor. There was a good agreement between the data measured inside the reactor and at the exhaust for oxygen-enriched gasification implying that the chemical reactions are practically frozen downstream the optical ports. For air, the data indicated that the gasification reactions are still active at the measurement locations. Significant concentrations of C2H2, up to 5000 ppm, were found inside the reactor.

Coupling effect of electric field and corona discharge on combustion and soot formation of ethylene jet flame

The coupling of electric field (E-field) and corona discharge is designed to adjust the appearance and soot formation of the ethylene jet flame. The temperature and content of soot are measured by the improved two-color pyrometry (TCP). Experiments indicate that the flame is stretched and deflected laterally under the coupling field. The maximum temperature of soot and the proportion of high temperature zone in the flame increase, and oxidation rate of soot increases. The flame is more stable under the coupling of reverse E-field and corona discharge. From the non-coupled field to the coupling field of 100 kV/m and −100 kV/m, the temperature proportion of the flame in the range of 1700 K–1800 K increases from 0 to 44.2 % and 54.8 % respectively, and the peak oxidation rates of soot also increase by 204 % and 219 % respectively. The E-field in the coupling field accounts for the main influence. The high voltage side of the flame is affected by the ionic wind generated by corona discharge, and the amount of soot generated under the high coupling field is less than that on the left side.

Badanie efektu dławienia w pożarze tunelu

As per the emergency ventilation strategy, air velocity of 3 m/s in case of the longitudinal ventilation is sufficient for smoke control in all fire conditions. Numerical experiments were carried out with FDS software to estimate the numerical value of the critical velocity. Numerical models were realized in 0-6% slope tunnels with a 1% step for 5, 10, 20, 30 and 50 MW fires for four types of fuel: gasoline, diesel fuel, oil and firewood. The paper notes that the dynamic pressure induced by a strong fire is much higher than the static pressure of tunnel jet fans. As a result, following the algebraic summation of positively-directed ventilation flows and the negatively-directed flows induced by fire, an intense back layering occurs, which casts doubt on the suitability of the specified emergency ventilation strategy when designing the fire ventilation. The critical ventilation speed of 3 m/s cannot cope with the traction caused by fire, expressed by the ascending movement of the high-temperature and low-density combustion products. The paper discusses the numerical modelling results with an adiabatic underground heat exchange model and presents typical tunnel fire modelling plans, which correspond to an inclined tunnel for ascending and descending ventilation flows as well as a horizontal tunnel. The article gives the regularities obtained by the numerical models of changes in the variables of average air temperature and density, average carbon monoxide, average carbon dioxide and soot concentrations. According to the emergency ventilation strategy, critical velocity is an important value and a major determinant of back layering prevention in sloping tunnels. Although many papers have been devoted to this problem, the obtained results differ much. The present paper shows that strong fires induce much greater dynamic pressures than the static pressures of the tunnel jet fans are. Consequently, the flows caused by these forces, as they move in different directions, following their algebraic summation, cause a strong back-layering in case of positive ventilation flows, i.e., when the ventilation flow is descending and the fire seat is found at a lower point compared to the air supply portal. The new results can be used to develop fire ventilation plans as well as life-saving and emergency control solutions in the operating tunnels for personnel and rescuers.

A Probabilistic Evaluation of Surface Loading and Concentration as Metrics for Post Structural Fire Assessment Soot Sampling Data

Surface sampling and laboratory analysis for soot/combustion particulates was conducted following a fire at an education/research facility in the southwest United States. This provided a bank of data by which to probabilistically evaluate the behavior of soot loading (counts/mm2) and relative soot concentration (percent ratio; %R) as useful metrics for quantifying differences in soot impact across a building. Surface tape sampling and analysis via light microscopy were conducted via industry standard protocols, and resulting data from various building zones were selected to construct various comparisons. The performance of counts/mm2 and %R as metrics to identify differences in soot impact for each comparison was assessed by comparing inference generated by traditional Student’s t test, Mann Whitney U rank comparison (MW), and the directly calculated axiomatic probability associated with difference in detection (pΔfd). The fourteen (14) comparisons in which a significant difference was inferred via pΔfd was similarly indicated via Student’s t and/or MW in only four (4) instances. Further, approximately one half of the comparisons generated different inference via pΔfd for counts/mm2 and %R, with the former demonstrating better discriminatory ability. In broad view, the heuristic concept of comparing numerical “soot levels” (e.g., average) by either metric was not generally suitable for the distribution of the data. In contrast, pΔfd avoids the statistical bias imposed by traditional statistical inference, and ultimately the efficacy of post fire comparative surface sampling is as dependent upon the metric and inference model utilized as it is on the sampling and laboratory analytical protocols.

Spray combustion characteristics and soot formation potential of Nano-Al2O3 diesel at low ambient temperatures

Nanoparticle additives have the potential to enhance combustion efficiency and reduce emissions in liquid combustion processes. This study thoroughly investigates the spray evaporation, ignition, and combustion characteristics of nanoparticle/fuel blends, especially under challenging environmental conditions, to improve combustion efficiency and reduce emissions. Employing diffused background illumination, shadowgraph, Mie scattering, high-speed natural luminosity, and two-color method, the spray combustion dynamics of thermally stable nano-Al2O3/diesel (NAD) blends were examined within a constant volume combustion chamber. Diesel, a prevalent primary or auxiliary fuel, represents other highly volatile renewable fuels, while Al2O3, a significant component in combustion fly ash, is noted for its specific catalytic properties and ability to re-burn, eliminating organic toxic elements. The results indicated that NAD blends exhibit a faster evolution rate for both liquid and vapor sprays compared to pure diesel, attributed to the increased kinetic energy of breakup droplets. Under most experimental conditions, incorporation of nano-Al2O3 slightly reduced the ignition delay time due to enhanced heat transfer. Notably, nano-Al2O3 altered the ignition mechanism of the diesel spray, transitioning it from partially premixed to diffusion combustion and relocating the ignition point nearer to the injector. The combustion flame of NAD blends demonstrated increased luminosity, a shorter flame lift-off length, and variations in start-of-injection and total-injection-nozzle-lift-off. However, due to a high equivalence ratio mixture between the liquid phase spray and combustion region, the soot concentration in NAD blends was higher than that in diesel. Additionally, the elevated flame temperature in NAD blends significantly increased the soot concentration. Overall, nano-Al2O3 markedly enhances diesel combustion, especially in low ambient temperatures, suggesting its impressive potential for the high-efficiency and low-emission utilization of renewable fuels or the combustion of recycled waste solvents.

Soot formation and its hazards in battery thermal runaway

As an increasingly important solution for the energy industry, batteries are widely used in electric vehicles and energy storage systems. However, thermal runaway of batteries is a serious safety hazard. In this process, the materials in the battery undergo thermal decomposition and combustion, resulting in the formation of soot and other harmful byproducts and posing a significant threat to the environment and human health. In this work, LiFePO4 and ternary lithium batteries are selected as experimental subjects to comprehensively evaluate the soot hazard in the thermal runaway process. The LiFePO4 and ternary lithium battery soot samples exhibited a typical "core-shell" structure, with lattice spacings ranging between 0.36-0.46 and 0.35–0.46 nm, respectively. The surfaces of these materials are covered with functional groups, including C–C, C–O, and O–H bonds. Soot samples taken from the thermal runaway of ternary lithium batteries also contain O–CO and π bonds, consistent with the functional groups in wood soot. Through EDS and XPS characterization, it is evident that the LiFePO4 battery soot contains C, O, Li, F, P, and Fe, while the ternary lithium battery soot, in addition to these elements, also contains Ni, Co, and Mn. The battery soot samples exhibited significant cytotoxicity to human cells, such as lung cells (MRC-5) and neural cells (SH-SY5Y). With high concentrations of soot, the survival rate of lung cells and nerve cells is low. Compared to wood soot, battery soot causes greater damage to human lungs and neural cells. The research in this work contributes to a better understanding of the hazardous characteristics of soot in battery thermal runaway and its potential threats to human health, offering a crucial reference for enhancing battery safety and emergency responses.

Trend in indices of public health risk caused by air pollution in an industrial center

Introduction. In industrialized regions and cities, atmospheric air pollution greatly contributes to the hazard for public health. The study aim was to assess the state of the atmospheric air in the city of Novokuznetsk over 2017–2022 and determine the levels of risks to public health. Materials and methods. Data on gross atmospheric emissions and average annual concentrations of the substances was taken from the reports on the state of the environment of the Kemerovo region and Novokuznetsk. Maximum permissible concentrations of atmospheric pollutants were determined according to SanPiN 1.2.3685–21. Calculations of the risks to public health were carried out in accordance with Guideline P 2.1.10.1920–04. The classification of risk levels was carried out on the basis of MR 2.1.10.0156–19. 2.1.10. Results. Decrease in total atmospheric emissions from 2017 to 2022 amounted to 50.1 thousand tons (about 16%). At the same time, there was revealed an excess of the average annual maximum permissible concentrations of benzo(a)pyrene (3.5-11.2 times); formaldehyde (1.7 and 3.4 times over 2021 and 2022, respectively); suspended substances (1.6 and 2.0 times in 2021 and 2022, respectively); hydrogen fluoride (1.2 times in 2021); nitrogen dioxide (1.6 times in 2022). The hazard coefficients of benzo(a)pyrene were 3.5–11.2 (high level of non-carcinogenic risk); formaldehyde and suspended substances – 1.1–3.0 (alarming level). In 2022, the hazard coefficient for formaldehyde was 3.4 (high risk level), suspended substances – 2.0, nitrogen dioxide – 1.6 (alarming risk level). Hazard indices of pollutants were detected in the range from 7.0 to 20.1 (high level of risk). The main critical organs and systems were the immune system (hazard indices were 4.0–14.6), development during childhood (hazard indices – 3.5–11.2), respiratory organs (hazard indices – 3.0–8.6). These risk levels range from alarming to high. The highest total individual carcinogenic risk (1.6•10–4) was determined in 2021 (alarming level), the main contribution is made by formaldehyde. Limitations. In 2022, there were no data on carbon (soot) concentrations, so the level of total carcinogenic risk this year cannot be considered to be correct. Conclusion. Reducing the total volume of atmospheric emissions does not provide a significant effect on improving the environmental situation and public health, since high concentrations of pollutants remain in the city’s atmosphere. When implementing air protection measures, it is necessary to take into account risk criteria.

Electrostatic vehicle exhaust particle sensor for the evaluation of the diesel particulate filter (DPF)

A real-time electrostatic particle sensor has been developed to measure the concentration of soot in diesel exhaust. Based on the Venturi effect, the self-priming sampling probe of the sensor was designed to generate a pressure difference to drive particles into the detection region of the electrostatic trap. A detection module was developed for real-time measurement of the nanoamp current generated by charged soot within the probe. The microcurrent was amplified by the signal processing system of the sensor. To guarantee the precision of particles, it was essential to test the performance. The sensor was able to measure currents from −100 nA to −30 nA with a relative error of −0.01%. In addition, experiments comparing the sensor with a commercial instrument have shown that they correlate well. Furthermore, the standard deviation of the sensor was 0.001049 during a 36 h long-term test, which is lower than a commercial instrument with better stability. The sensor was investigated to demonstrate the detection of diesel particulate filter (DPF) failure. The results showed that the consistency between the sensor and the regulatory measurement equipment was good. The data ratios of the sensors installed at the front and rear of the DPF differed by many fold, which indicated that the sensor was able to determine the status of the exhaust system.

Improving environmental indicators of the wheeled tractor diesel engine by using biofuels

The object of this study is the process of operation of a diesel engine in a wheeled tractor on methyl ether of spent frying sunflower oil. The task being solved is to improve the environmental performance of a diesel engine in a wheeled tractor during the operation of its diesel on such biodiesel fuel and its mixtures with mineral diesel fuel. The characteristics of the diesel D-243 were determined by the experimental method with the measurement of the toxicity of the waste gases during its operation on the methyl ether of the spent sunflower oil, mineral fuel, and their mixtures. A decrease in the content of soot in diesel exhaust gases and a slight increase in the types of nitrogen oxides was registered. The theoretical method using a mathematical model determined the indicators of a wheeled tractor during its movement with a trailer for the accepted driving cycle and the operation of its diesel on different fuels. To that end, the characteristics of a specific diesel engine were described by polynomial models. The adequacy of the mathematical model of the movement of a tractor with a trailer over a driving cycle was tested. By means of a mathematical model, the total road emissions of harmful substances of a diesel engine were calculated when the tractor is running with a trailer over the accepted driving cycle. Calculations were performed for two types of fuel: mineral diesel fuel and biodiesel fuel. Biofuel consumption increases by almost 10 % compared to diesel fuel. The total emissions of harmful substances are 1.1 times lower in a diesel engine running on biofuel than when using mineral fuel. The results could be used in the operation of technological transport in the industry and agriculture provided there is a sufficient volume of raw materials for the production of biofuel

Virtual cleaning of sooty murals in ancient temples using twice colour attenuation prior

Murals are artworks painted on walls that represent various cultures, traditions, historical periods, spiritual narratives and civilisations. Unfortunately, before modern preventive measures were implemented, murals suffered considerable degradation from accumulating substances, such as incense oil and carbon, leading to a darkening or blackening phenomenon called soot. The soot severely and extensively damaged the murals’ colour and motifs. However, no highly effective remedy is available to restore them to their original state. A novel approach for virtual cleaning of this degradation uses hyperspectral and image enhancement technologies. Existing techniques for sooty mural image restoration primarily use dark channel prior and Retinex bilateral filtering. During this process, the dark channel prior estimates the concentration of soot and removes it, restoring the mural’s colour with Retinex bilateral filtering. However, this restoration method has issues, such as neglecting the difference between soot and haze, resulting in a generally darker mural image. This result requires brightness adjustment, and the method presents further challenges, such as texture loss, colour distortion in some areas and a reduction in clarity. Therefore, we propose a new technique that integrates an inverse operation and twice colour attenuation prior to cleaning sooty murals. This technique involves normalised cross-correlation to match and stitch images to the different synthesised bands to reconstruct the mural image to be processed, which removes black marks from areas of mural loss. The sooty mural then undergoes an inverse operation, and the colour attenuation prior is used on the inverse image. The processed mural is then inverted again, transforming the colour of soot to white. Finally, the colour attenuation prior is again applied to the colour-changing mural, enabling virtual cleaning of the sooty murals. The results confirm the enhanced adaptability of our novel approach for the virtual cleaning of sooty murals. Moreover, the proposed method exhibits superior performance for various performance parameters.

Characterizing sedimentary black carbon in the Pearl River Estuary, Southern China

Sedimentary black carbon in coastal regions plays an important role in global carbon cycles due to its refractory nature in sediments. In this study, we conducted the first comprehensive investigation on black carbon (BC) in surface sediments of the Pearl River Estuary (PRE), a large tropical estuary system in China. We used two different analytical methods: IMPROVE-A thermal optical reflectance (TOR) and chemothermal oxidation (CTO-375) to constrain the distribution, and TOR can further constrain the composition (i.e., char and soot). The BC concentration determined by the TOR method (BCTOR) ranged from 0.07 to 7.13 mg/g, with char and soot contents ranging from 0.04 to 6.98 mg/g and 0.03–0.43 mg/g, respectively. The BC concentrations measured by the CTO-375 method (BCCTO) ranged from 0.27 to 1.88 mg/g. Char was the predominant constituent (87%) of sedimentary BCTOR in the PRE. Both char and soot had higher concentrations locating near the outlets and on the Shenzhen coast, indicating that they were sourced through direct fluvial transport and surface runoff. Soot particles were transported farther from fluvial sources than char particles. We estimated that the burial flux of BCTOR in the PRE sediments was 2.97 ± 1.61 mg/cm2/yr, acting as an important sink of BC. This study implies that large river estuaries are hotspots for BC burial, sinking a large amount of organic carbon from terrestrial reservoirs.

Particles influence on the direct absorption spectroscopy of TDLAS

Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology is widely used for monitoring the gas pollutants. But in actual measurement environments, there are usually particles, which will affect the TDLAS direct absorption spectroscopy. In this paper, the influence of particles on the direct absorption spectroscopy of TDLAS was analyzed by using TDLAS-DAS technology combined with particle extinction method. According to analysis, it was found that the presence of particles does not affect the gas characteristic absorption spectral line strength and the gas absorption spectroscopy broadening, but it does affect the output laser intensity and absorbance received by the detector. The transmittance of particles can be obtained through the slope of the output laser intensity, which can be used to correct the absorbance to achieve accurate measurement of gas concentration. This paper analyzed the effects of particle size, incident wavelength, and composition on particle extinction coefficient and obtained the extinction coefficient of soot. If the laser wavelength is 1.53 μm and the particle size of soot is 45 μm, the extinction coefficient of soot is 2.1016. The magnitude of laser intensity attenuation at different particle concentrations can be obtained based on the extinction coefficient of particulate matter. When the concentration of soot is greater than 26290 mg/m3 and the optical path is 100 cm, the transmittance is less than 0.1 and the laser intensity attenuation reach over 90 %, which may affect the detection of gas absorption spectroscopy information and the accuracy of measurement. On this basis, this paper established the relationship between gas concentration and corrected absorbance to invert the gas concentration in the presence of particulate matter when the concentration of soot is less than 26290 mg/m3. The inversion gas concentration error obtained by the absorbance peak calibration method is within 3 %, and the inversion gas concentration error obtained by the absorbance integration method is within 1 %. From the inversion results, it can be seen that the accurate measurement of gas concentration in the presence of particulate matter can be achieved by extracting the slope of the output laser intensity to correct absorbance.

Engine Oil Degradation in the Real-World Bus Fleet Test Based on Two Consecutive Operational Intervals

The literature on the subject and the results of numerous research experiments indicate that single replacement cycles do not reflect the actual state of oil quality in the context of its degradation. Monitoring the operational quality of the oil in several successive stages allows for a more accurate diagnosis of the optimal oil change time. Therefore, it was decided to investigate the relationship between two consecutive periods of changing the operating oil in an engine. Comparative tests of seven buses included in the fleet were carried out. An important division criterion was taken into account—the operation of city and intercity buses. The HDXRF instrumental chemical analysis method was used to determine changes in the content of abrasive metals, and additives in engine oils. Additionally, the oxidation, nitration, sulfonation, and soot content were assessed using infrared spectroscopy (FTIR) based on the ASTM E2414-10 standard and kinematic viscosity at 40 °C and 100 °C using a Stabinger viscometer according to ASTM D7042. The course of these changes was analyzed in terms of their dynamics. The comparative study aimed to identify trends and sources of differences between the tested oils, as well as to demonstrate the number of exceedances of limit values for the selected parameters.

Measurement of Soot Concentration in Burner Diffusion Flames through Emission Spectroscopy with Particle Swarm Optimization.

Measuring soot concentration in a burner flame is essential for an in-depth understanding of the formation mechanism and to abate its generation. This paper presents an improved emission spectroscopy (ES) method that uses an adaptive particle swarm optimization (APSO) algorithm for measuring the concentration of soot in methane burner flames. Experimental tests were conducted on a laboratory-scale facility under a methane flowrate ranging between 0.6 and 0.9 L/min. A comparison analysis of the soot concentration measured by the ES method, the improved emission spectroscopy (IES) method, and the thermocouple particle density (TPD) method (as a reference) was conducted. The ES method obtained a maximum absolute deviation of 0.84 ppm from the average soot concentration at the three measurement points compared to the TPD method, while that of the IES was only 0.09 ppm. The experimental results demonstrate that the proposed IES method can obtain a more accurate soot concentration of diffusion flames.