Formation Of Fine Particles Research Articles

Composition, Structure and Properties of Antifriction Alloys Based on the Charge Obtained by Electrodispersion of Bronze Waste BrO5C25 in Kerosene

Purpose. Study of the composition, structure and properties of antifriction alloys based on the electroerosion charge of bronze BrO5C25 obtained in a carbon–containing medium lighting kerosene.Methods. Dispersion of the waste of the BrO5S25 alloy was carried out at an installation for electrodispersing electrically conductive materials. The waste of the BrO5C25 alloy was used as metal waste. Lighting kerosene was used as the working fluid.As a result of exposure to short-term electrical discharges between the electrodes and the waste, their destruction occurred with the formation of fine particles. To obtain compacted materials, a Herzog TP 20 manual table press was used. Modern equipment and complementary methods of physical materials science were used to study the composition, structure and properties of the sintered products obtained.Results. Surface analysis showed that the alloys have a fine-grained structure, uniform phase distribution and a small number of pores. The analysis of the elemental composition found that carbon is contained on the surface of the new alloys, and all other elements Sn, Cu and Pb are distributed relatively evenly. The analysis of the studied alloys showed the presence of phases in them: Cu, CuSn, SnO, CuO, PbO, Pb. There are no carbide-forming elements in the alloy. It has been experimentally established that the composition, structure and properties of the charge dispersed by electroerosion of bronze BrO5C25 affect the tribological properties of the alloy blanks. In particular, the presence of free carbon in the alloy from the electroerosion charge obtained in kerosene, which acts as a solid lubricant, leads to a decrease in the coefficient of friction.Conclusion. It is shown that alloys obtained from an electroerosive charge have higher microhardness values in comparison with an alloy obtained from an industrially used charge. A significant increase in the microhardness of alloys is explained by the presence of highly hard particles formed during the quenching of metal vapors in the working fluid during dispersion. The presence of small fractions in electroerosive materials contributes to an increase in the density of compressions and a decrease in the porosity of workpieces.

Process mineralogy characteristics of a very fine disseminated refractory gold deposit

The grade, recovery rate, or leaching rate of gold concentrate obtained by the flotation process or cyanide leaching process of gold ore is low, which is typical refractory gold ore. In order to fully understand the properties of the gold ore and optimize the gold recovery process and indicators, the process mineralogy of the ore was systematically studied by means of chemical multi-element analysis, optical microscope, scanning electron microscope (SEM), X-ray energy spectrometer, automatic mineral parameter analysis system (BPMA), and other test methods. The results show that the average grade of valuable element gold in the ore is 2.98g/t, and the contents of harmful elements mercury and carbon are 0.50% and 0.32% respectively; The main gold ore is natural gold, with a small amount of silver gold and tellurium gold; The main metal minerals are pyrite, pyrrhotite, magnetite, hematite, etc; The main gangue minerals include quartz, feldspar, kaolinite, mica, calcite, etc. Under the condition that the grinding fineness is -0.074mm, accounting for 90%, the distribution rates of single gold and bare gold in the ore are 3.15% and 57.66% respectively, and the distribution rates of gold with pyrite and quartz crystals are 5.77%, and the total distribution rates of the three are 66.58%, that is, the maximum theoretical flotation recovery rate of gold under the grinding fineness, but the particle size and fineness of gold minerals are both 5 μ Below m, the particle size of some gold ores is less than 0.5 μ m. It exists in the form of fine particles, micro gold, or ultra-micro gold, and it is difficult to recover gold by the flotation process, so it is recommended to adopt the whole slime cyanidation leaching process.

Real-Time Automated Solubility Screening Method Using Deep Neural Networks with Handcrafted Features.

Solubility measurements are essential in various research and industrial fields. With the automation of processes, the importance of automatic and real-time solubility measurements has increased. Although end-to-end learning methods are commonly used for classification tasks, the use of handcrafted features is still important for specific tasks with the limited labeled images of solutions used in industrial settings. In this study, we propose a method that uses computer vision algorithms to extract nine handcrafted features from images and train a DNN-based classifier to automatically classify solutions based on their dissolution states. To validate the proposed method, a dataset was constructed using various solution images ranging from undissolved solutes in the form of fine particles to those completely covering the solution. Using the proposed method, the solubility status can be automatically screened in real time by using a display and camera on a tablet or mobile phone. Therefore, by combining an automatic solubility changing system with the proposed method, a fully automated process could be achieved without human intervention.

Significant contribution of carbonyls to atmospheric oxidation capacity (AOC) during the winter haze pollution over North China Plain

Atmospheric carbonyl compounds play significant roles in the cycling of radicals and have exhibited surprisingly high levels in winter that were well correlated to particulate matter, for which the reason have not been clearly elucidated. Here we measured carbonyl compounds and other trace gasses together with PM2.5 over urban Jinan in North China Plain during the winter. Markedly higher carbonyl concentrations (average: 14.63 ± 4.21 ppbv) were found during wintertime haze pollution, about one to three-times relative to those on non-haze days, with slight difference in chemical composition except formaldehyde (HCHO). HCHO (3.68 ppbv), acetone (3.17 ppbv), and acetaldehyde (CH3CHO) (2.83 ppbv) were the three most abundant species, accounting for ∼75% of the total carbonylson both haze and non-haze days. Results from observational-based model (OBM) with atmospheric oxidation capacity (AOC) indicated that AOC significantly increased with the increasing carbonyls during the winter haze events. Carbonyl photolysis have supplied key oxidants such as RO2 and HO2, and thereby enhancing the formation of fine particles and secondary organic aerosols, elucidating the observed haze-carbonyls inter-correlation. Diurnal variation with carbonyls exhibiting peak values at early-noon and night highlighted the combined contribution of both secondary formation and primary diesel-fuel sources. 1-butene was further confirmed to be the major precursor for HCHO. This study confirms the great contribution of carbonyls to AOC, and also suggests that reducing the emissions of carbonyls would be an effective way to mitigate haze pollution in urban area of the NCP region.

Ash deposition and fine particle formation when utilizing biomass and coal fly ash in lab-, pilot- and full-scale

Fine particles were sampled at the 800 MWth Avedøre Power Station Unit 2 (AVV2) as well as at the 900 MWth Studstrup Power Station Unit 3 (SSV3), both utilizing wood pellets together with coal fly ash (CFA), for alkali capturing. In parallel, fine particle formation was quantified in the BoCTeR pilot-scale pulverized-fuel biomass combustion test-rig, at the Technical University of Munich, using the same wood pellets and CFA-additive as was applied in full-scale, to compare the impact of the CFA-addition. A comparison between fine particle formation and concentration in the BoCTeR and in full-scale, revealed a higher quantity of submicron particles (PM1) at AVV2, compared to SSV3, i.e. differences between the two full-scale boilers, while the PM1-values at BoCTeR was found to be substantially higher than what was measured in full-scale, mainly due to differences in temperature–time history between these two combustor scales.Ash deposition during wood pellets firing with CFA-addition, was quantified by an advanced deposit probe at SSV3. The results showed that with a probe surface temperature of 550 °C, and 2 %wt or 3 %wt CFA-addition, no significant amount of deposit was formed. When increasing the probe surface temperature to 650 °C, at 3 %wt CFA-addition, deposit was formed on the upstream side of the probe. No Cl was detected in the deposit samples, indicating that Cl-related corrosion can be effectively suppressed by 2 %wt or 3 %wt coal fly ash addition.Finally, deposit formation when firing different pre-treated biomasses; K- and Cl-rich wheat straw, milled wood pellets, hydrothermally carbonized (HTC)-leaves and steam exploded (SE)-bark, with and without a K-capturing additives, was also investigated in the entrained flow reactor at Technical University of Denmark (DTU-EFR). In terms of deposit formation, the K- and Cl-rich wheat straw proved to be the most problematic fuel, while milled wood pellets, HTC-leaves and SE-bark, had significantly lower deposition propensities. When applying kaolin and two types of CFA (both rich in Al and Si), as K-capturing additive, the deposition propensity of wheat straw decreased significantly, when applying a molar ratio of fuel-K/additive-Al of 1.0.This paper was originally presented at the recent 28th International Conference on Impacts of Fuel Quality on Power Production, the, Aare, Sweden, September 19–23, 2022.

Photooxidation potential of fine particles from desulfurization flue gas aerosol

In China, desulfurization flue gas from coal-fired power plants (CFPPs) has been the focus of research for many years. In this study, for the first time, we simulated the emission process of flue gas and prepared photocatalysts by deposition. An innovative photocatalytic perspective was applied to study the composition, photocatalytic properties, hygroscopicity, and redox properties of the fine particles from flue gas aerosols. The characterization results of XRD, HRTEM, and XPS of freeze-dried desulfurized flue gas samples indicated that aerosol condensation occurred during the smoke plume transportation process, resulting in the formation of well-crystallized fine particles primarily consisting of soluble salts and metal oxides. The UV–vis and ESR results confirmed that desulfurized flue gas has UV light utilization and photocatalytic potential for producing oxidation groups such as hydroxyl radicals and superoxide radicals in light. The subsequent photocatalyst experiments revealed an 85.4 % reduction of 7 ppm isoprene in 30 min; ozone production (373 μg/m3) was observed under more complicated conditions (NO2 = 80 ppb, VOCs = 7 ppm). As a result of the study, a new research approach was proposed for exploring the photoactive potential of flue gas aerosol produced by CFPPs, as well as its impact on the concentration of VOCs and ozone. The finding provided a new possible pathway for desulfurization flue gas emissions and a reference for futureresearch on the observation and control of atmospheric pollution.

Effect of Rolling Reduction on Microstructures and Mechanical Properties of Sc-Containing Al-3.2Cu-1.5Li Alloy

The effects of various rolling reductions (64.7%, 72.1%, 81.4% and 88.2%) on the microstructures and mechanical behaviors of Sc-containing Al-3.2Cu-1.5Li-based alloys were experimentally investigated through XRD, SEM (equipped with EBSD), TEM and the tensile test. The results showed that the grains of hot-rolled and T6-treated alloys are mainly dominated by substructure features, and the addition of the trace Sc element can obviously impede the static and dynamic recrystallization due to the formation of fine and stable nano-Al3(Sc, Zr) particles. Additionally, the combined effects of fine grains, dispersion, substructure and precipitation strengthening make the alloys with a rolling reduction of 81.4% possess higher tensile properties. With an increase in the rolling reduction, the tensile strength of the alloys increases first and then decreases, while the elongation gradually increases and then reaches a plateau, which was ascribed to the variation in the grain size and substructure features.

Analysis of atmospheric deposition in the territory of the Republic of North Ossetia-Alania by biomonitoring data

Attention to the tourism potential of the Republic of North Ossetia-Alania is increasing with the attendant need to monitor and control atmospheric air pollution.Aim. The assessment of the possibility of using mosses as biomonitors for determining the content of heavy metals and other trace elements in the atmosphere of the territory of the Republic of North Ossetia-Alania.Material and Methods. The green mosses Hylocomium splendens and Pleurosium schreberi were used as bioindicators. Multi-element chemical analysis of mosses was carried out using X-ray fluorescence and the morphology and composition of dust fallouts on the moss surfaces was studied using a scanning electron microscope equipped with an X-ray energy-dispersive spectrometer.Results. The maximum concentration of Pb, Zn, Cr, As, Sn, Sb, Ba, Cd, Cu, Ti, Ce, As, Fe, Sr is observed in mosses in areas of the territory with a high aerotechnogenic load. The analysis of biomonitor moss in the area of the Fiagdonna tailing dump indicates that recultivation measures had been effective. Toxic elements fall on moss surface in form of fine particles as large as 1 micron and pose a danger to human health.Conclusions. The abnormally high content of Zn, Pb, Cd, Cu, Ce, As, Fe, Sr, Ti, Ba in the composition of biomonitor mosses was registered in the zone of influence of mining and processing enterprises (in the area of the Unal tailings dump) and metallurgical industries in Vladikavkaz (JSC Electrozinc and JSC Pobedit. The base source of toxic elements was determined to be fine aerotechnogenic particles that accumulate on the surface of mosses, thus confirming the high efficiency of their use for monitoring. The territory near the village of Dur Dur can be recommended as a background for ecological and geochemical research.

Effect of Ni and Fe elements on microstructure and high temperature oxidation behavior of laser cladding aluminum bronze coating

In this work, two kinds of aluminum-bronze coatings were successfully prepared on 316 stainless steel substrate by laser cladding technology. The changes of microstructure and high temperature oxidation behavior of pure aluminum bronze laser cladding layer before and after adding Ni and Fe elements were studied and compared. The results show that a certain amount of κ phase and Fe–Cr phase are constituted in the modified coating with the addition of Ni and Fe elements, which refines the structure and grains. The main components of the oxide layer of the two coatings are Al2O3. In the high temperature oxidation process, both two coatings experienced the formation, spallation, and recovery of an oxide film. The time to form a stable oxide film on the surface of the modified coating is significantly shorter than that of the original coating. As a result of the formation of fine and dense oxide particles on the modified coating's surface, the stability and internal stress resistance of the oxide film is superior. Under the condition of 1000 °C oxidation for 100 h, the oxidation film thickness and oxidation rate constant (kp) of the modified coating are about 0.88 and 0.79 times of that of the original coating. The addition of Ni and Fe can greatly enhance the laser cladding aluminum bronze coating's resistance to high-temperature oxidation.

Use of marble and granite dust waste as partial replacement of fine aggregates in concrete

The growth in Infrastructural development resulted in fast decline of available natural resources. In contrast the marble and granite production has generated a very huge amount of by-products in the form of fine particles which causes large scale environmental pollution. This has led to a major concern in the environmental as well as construction industry due to the disposal of these million tons of fine particles. The purpose of this study is to experimentally investigate the compatibility of marble and granite dust by-product for replacing of fine aggregates in concrete partly. In this work, a mixture of marble and granite dust in ratio 0.5:0.5 is used as a for replacing of sand in different percentages (10%,20%,30%,40%,50%) by weight and cement is partially replaced with slag (GGBS) by a by 40%. Influence of replacement of sand with marble and granite dust on the strength behaviour on concrete was studied at curing ages 7 and 28 days and the results are compared with conventional concrete blocks. A 20% replacement of fine aggregates with marble and granite dust mixture resulted in 23.34% and 14.4% increase in compressive strength was at 7 and 28 days of curing, as compared to controlled concrete. The results of the experimental study show that, mixture of marble and granite dust can partially be used in place of fine aggregate in concrete and saves considerable amount of sand there by preserving the valuable natural resource resulting in sustainable replacement for sand.

Influence of additive surface area degradation on fine particle formation during biomass pulverised-fuel combustion

This study examined the surface area degradation of kaolin, coal fly ash and the resulting impact on the alkali capture efficiency in a pilot-scale real flame combustion test rig using beech wood as fuel. Experiments in an electrically heated furnace revealed the thermal surface area evolution of kaolin with residence times between 30and 3600 s and temperatures between 790 and 1400 °C under calcination conditions. Subsequent measurements of the resulting specific BET (Brunauer-Emmet-Teller method) surface area of the kaolin samples were carried out. The temperature profile in the top-down fired biomass combustion test rig (BoCTeR) was measured with a suction pyrometer when combusting natural gas and beech wood powder. Additional experiments were performed by injecting kaolin and coal fly ash particles directly into a natural gas flame at different reactor heights. Those kaolin particles exposed to high temperatures in the natural gas flame were collected and subsequently analysed for the specific BET area to evaluate the corresponding degree of surface loss. The main test series comprises a setup combusting beech wood with kaolin or coal fly ash injected at different positions of the combustion chamber. The alkali sorption capacity of the kaolin and coal fly ash used is indirectly measured by the combustion aerosol reduction performance determined with an electrical low-pressure impactor (ELPI). The goal of this work is to show the impact of surface area degradation phenomena of additives and the resulting optimisation potential when using Al/Si-based in-furnace additive during the pulverised-fuel combustion of biomass. The surface area development of the additives at high temperatures affects the most suitable temperature window for the additive injection. The results show an optimum for the kaolin injection. The coal fly ash reduced PM best when injected as early possible into the combustion chamber.

Study on the characteristics of sulfate ion in condensable particulate matter from ultra-low emission coal-fired power plants

The sulfate ion (SO42−) in condensable particulate matters (CPM) discharged by ultra-low emission coal-fired power plants has caused a series of environmental problems. In this work, condensation temperature, H2O, NOx and NH3 were investigated to elucidate the characteristics of SO42− under fast condensation. The results demonstrated that SO3 was a crucial component for the formation of SO42− in CPM, and the SO42− concentration increased with the increase of proportion of deposited H2SO4. The SO42− produced by heterogeneous reaction of SO2 could be enhanced in low temperature, and SO2 and SO3 could jointly promote the formation of SO42−. Furthermore, H2O vapor could also strengthen the formation of SO42−, which was caused by the Stefan flow. NH3 acted as the core, and the formation of SO42− was promoted. NOx could provide an acidic environment, which would interfere with the state of SO42− and even suppress the aqueous-phase oxidation of SO2. Finally, the formation of fine particles would aggravate the capture difficulty of CPM, which might help to explain the decrease of SO42− concentration in real flue gas. The results could provide basic guidance for improving the control of SO42− in CPM emitted from coal-fired power plants.

Tellurium Treatment for the Modification of Sulfide Inclusions and Corresponding Industrial Applications in Special Steels: A Review

Tellurium treatment is used to control the morphology of manganese sulfide (MnS) inclusions, reduce the mechanical anisotropy, and improve the machinability of sulfur‐bearing steels, such as free‐cutting steels, super free‐cutting steels, medium‐carbon microalloyed steels, and die steels. The boiling point of tellurium is low, and it is mainly added to steel in the form of fine particles wrapped in a cored wire. In steels, tellurium mainly exists in the form of Mn(S, Te) inclusions or MnTe–MnS composite inclusions. The strength of MnS inclusions is increased through tellurium doping; thus, the aspect ratio of sulfide after hot working is significantly decreased through tellurium treatment. However, the tellurium content in steel should not be too high; otherwise, brittle compounds will form and cause embrittlement, particularly in high‐alloyed steels. The Te/S mass ratio is considered an important factor in tellurium treatment. When the Te/S mass ratio in steel is 0.2, the aspect ratio of the as‐cast sulfide could be controlled within the optimal range. During steelmaking, the yield of Te can be improved by reducing the basicity of the slag and decreasing the time of Te evaporation. Through data‐driven material design, Te treatment technology undergoes broader development.

Overall Water Splitting Under Visible Light Irradiation Over Ir and A‐Codoped KTaO3 (A=Ca, Sr, Ba, La) Photocatalysts

Metal oxides are an attractive material group as photocatalysts, while the number of visible‐light‐responsive metal oxide photocatalysts especially for overall water splitting is quite limited. Herein, overall water splitting under visible light irradiation over Ir and A‐codoped KTaO3 (A = Ca, Sr, Ba, La) photocatalysts is demonstrated. The Ir and A‐codoped KTaO3 works by the electron transition from impurity levels formed by Ir3+ to the conduction band formed by Ta5d orbitals. The codoping of Ca, Sr, Ba, and La contributes to the formation of fine photocatalyst particles and stabilization of doped Ir as trivalent. An Rh‐core/Cr2O3‐shell cocatalyst loaded by photodeposition is effective for overall water splitting over Ir and La‐codoped KTaO3 compared to a RhCrO3 cocatalyst loaded by impregnation and other metal‐core/Cr2O3‐shell cocatalysts. The Rh/Cr2O3‐loaded KTaO3 codoped with Ir and La is also active for solar water splitting.

Effects of heat treatment and Y addition on the microstructure and mechanical properties of as-cast Mg–Si alloys

In Mg–Si alloys, both primary and eutectic Mg2Si particles normally appear with sharp edges, which can lead to weak mechanical properties as the result of stress concentration at the sharp corners of these brittle particles. Thus, it would be of great importance to modify the morphology of these particles. In this study, microstructure modification mechanisms after 0.5 wt% Y addition and heat treatment (HT) at 420 °C for 24 h are comprehensively studied in hypo-eutectic Mg–1Si and hyper-eutectic Mg–2Si alloys. Microstructural observations were performed using optical and scanning electron microscopy equipped with electron disperse spectroscopy, while phase analysis was done by X-ray diffraction. Mechanical properties of the studied alloys were evaluated by shear punch testing technique. The obtained results indicate that 0.5% Y addition to the as-cast Mg–1Si and Mg–2Si alloys could modify morphology of the eutectic Mg2Si from coarse lamellar to very short rod-shaped. The poisoning effect of Y was the main mechanism for this modification. The ultimate shear strength (USS) increased after Y addition to the Mg–1Si and Mg–2Si alloys, due to the modified eutectic Mg2Si morphology and also formation of fine Y-containing particles. Moreover, it was observed that HT could modify the morphology of the eutectic Mg2Si phase to the punctiform or disconnected rod-shaped in the studied alloys. Another important effect of HT was observed to be rounding sharp corners of the primary Mg2Si particles and changing their morphology to some new shapes such as star-like, indicating unstable morphology of the primary Mg2Si particles in the Mg–2Si–0.5Y alloy at high temperature. The USS values were improved for the Mg–1Si and Mg–2Si alloys after HT due to the modified morphology of the Mg2Si particles.

Refinement of Al-containing particles and improvement in performance of W-Al-Y2O3 alloy fabricated by a two-step sintering process

The Al-containing particles in ODS alloys with Al addition usually exhibit relatively large size, and inevitably result in a limited improvement in mechanical properties. In this paper, W-Al-Y2O3 alloy was prepared by a two-step sintering process to refine the Al-containing particles. Microstructure evolution of dispersoid particles was characterized by scanning electron microscope (SEM), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM). During the first holding step at 1000 °C, the dissolved Al precipitated directly from W matrix, where the formed γ-Al2O3 particles were nano-sized and developed a coherent relationship with W matrix. This coherent relationship hindered transformation of γ-Al2O3 into submicron-sized α-Al2O3. Moreover, the nano-sized γ-Al2O3 contributed to formation of fine Y3Al5O12 dispersoid particles with the sintering temperature further increased to 1600 °C. 71% of the dispersoid particles were distributed within grains and most of them were nano-sized γ-Al2O3 and Y3Al5O12, giving a fine grain size of 0.49 μm. Due to the refined microstructure, the compressive strength and microhardness of W-Al-Y2O3 alloy reached 2545.9 MPa and 787.8 HV, respectively.

Influence of Cu and Ni on the Hot Ductility of Low C Steels with Respect to the Straightening Operation When Continuous Casting

Cu-containing steels can suffer from hot shortness unless Ni is added to protect them but whether this problem also influences the straightening operation is not clear. Previous work on hot ductility has found that only when the tensile samples from Cu-containing steels are oxidised can any deleterious influence of copper be found. However, this paper shows that oxidation is not essential. It is more complex than that and, as Cu has been suggested for TRIP steels at levels up to 2.5% Cu to increase their strength and ductility, a greater understanding is required, both of hot shortness and cracking during straightening. The present paper explores the hot ductility behaviour of steels alloyed with Cu and Ni in the straightening temperature range, 700–1000 °C, when tested in air and in an argon atmosphere. Segregation of Cu to the sulphides and grain boundaries occurred allowing the formation of fine Cu2S particles at the austenite grain boundaries favouring intergranular failure and this was more pronounced under oxidising conditions and required strain. It was concluded that a Cu addition, as well as causing hot shortness at higher temperatures will also cause cracking problems in the straightening temperature range in the more sensitive to cracking grades of steel and although the problems are different they are nevertheless interrelated and provided there is sufficient Ni, both may be avoided.

Grain refinement effect of ZrB2 in laser additive manufactured metastable β-titanium alloy with enhanced mechanical properties

Significant grain refinement of β grains in metastable β TB2 titanium alloy (Ti–8Cr–3Al–5Mo–5V) was achieved through the minor addition of zirconium diboride (ZrB2) during laser melting deposition (LMD). The size of β grains decreased from ∼150 μm in the as-deposited TB2 alloy to ∼70 μm in TB2+0.5ZrB2 (TB2 with 0.5 wt% ZrB2 addition) alloy. This study demonstrates that TB2+0.5ZrB2 exhibits good combination of ultimate tensile strength (UTS ≈ 896 MPa) and ductility (EL ≈ 15%) in comparison to the as-deposited TB2 (UTS ≈ 811 MPa and EL ≈ 18%). At similar strength (UTS≈ 900 MPa), TB2+0.5ZrB2 shows superior ductility than TB2+0.4Zr+0.1B and TB2+0.1B because of the formation of fine TiB particles (length of ∼0.6 μm) by uniformly introducing boron (B) into TB2 and lower diffusion rate of B. The excellent mechanical properties of TB2+0.5ZrB2 are attributed to the synergistic effect of strengthening from refined β grains and fine-scale TiB precipitation. The mechanism associated with refinement of β grains is elucidated and discussed in the context of relevant phase diagrams.

Road Traffic and Its Influence on Urban Ammonia Concentrations (France)

Ammonia (NH3) is an unregulated atmospheric gaseous pollutant in ambient air, involved in the formation of fine particles. Ammonia is therefore a major precursor of particulate matter (PM), the health effects of which have been widely demonstrated. NH3 emissions are clearly dominated by the agricultural sector (livestock and fertilizers), but other sources may also be important and less studied, such as road traffic with the increased use of catalytic converters in vehicles. This study is based on a long-term real-time measurements campaign (December 2019–September 2021) on two urban sites: a background site and a roadside site in the same agglomeration in France. The study of historical measurements at the background site clearly demonstrated the dominance of agriculture on the ammonia concentrations. This influence was also observed at both sites during the measurement campaign. The annual and monthly averages obtained in the study were similar to previous ones, with concentrations between 1–10 µg/m3 at both sites, indicating lower levels than previous studies for the roadside site. The ammonia levels measured during the campaign at the traffic site were significantly higher than those measured at the background site, highlighting the road traffic influence on ammonia in urban area. The biomass burning influence also seemed to be observed during this long measurement campaign at the agglomeration scale. The influences of road traffic and biomass burning on ammonia concentration remain small compared to agriculture.

Spatially-Resolved experimental investigations of combustion characteristics in a solid fuel doped methane swirl flame and the influence on the formation of ultrafine particulate matter

The formation of inhalable fine particles (dp≤10 µm) is an undesirable side effect of solid fuel combustion processes. These particles can accumulate in the human respiratory system and thus cause severe lung damage. Therefore, an understanding of the formation of these particles is of crucial importance to avoid or to reduce the amount of fine particulate matter (PM) released into the atmosphere. Until now, most of the studies have been carried out for laminar and early-stage solid fuel combustion under simplified conditions (e.g. flat flame burner with radial almost homogeneous conditions) and only a few studies have been carried out with more complex turbulent flame structures. As the majority of real applications on an industrial scale involves turbulent conditions, research in this area is highly important. For the investigation of particulate matter formation, a swirled methane-assisted pulverized solid fuel combustion test rig with full optical access which allows intrusive and non-intrusive measurements in different heights and radial positions was developed. In order to study the local influences of flame characteristics on the formation of ultrafine particulate matter, results from laser Doppler velocimetry (LDV), suction pyrometer, Fourier transform infrared (FTIR) spectroscopy, and scanning mobility particle sizer (SMPS) spectrometer measurements are presented and discussed. It is shown that the local differences - such as gas temperature, the velocity of the solid fuel particles, and concentrations species - have an influence on the formation of particulate matter. Especially in regions with high local velocities and shear zones, PM coagulates strongly due to the increased turbulence in this area. The data presented in this paper are an important foundation for further studies to validate CFD simulations using the measurements and to further develop existing PM formation models for turbulent cases.