Engine Exhaust Particle Research Articles

Controllable generation of engine exhaust similar soot particles using an inverted nitrogen-diluted flame burner for calibration purpose

The calibration of vehicle engine exhaust PN analyzers has been a challenge due to the significant difference in properties between calibration particles and measured particles. In this study, an inverted nitrogen-diluted flame burner was designed to generate engine exhaust similar soot particles and evaluated for calibration use. The burner can produce reference-unimodal soot particles at 61–311 nm and total number concentration up to 108 #/cm3 by adjusting the flow rate of ethylene, nitrogen and air. Excellent stability of 0.91 % enables it to generate a fairly stable calibration particle flow. Mixing nitrogen in ethylene makes burner have a high degree of variability in generating smaller particles. The properties of size distribution, morphology, effective density indicate that the generated soot particles can simulate well with engine exhaust particles. TOA results indicate that the soot have high TC mass concentration of over 559.26 mg/m3 and EC/TC fraction of over 90 %.

Mechanism underlying the role of integrin α3β1 in adhesive dysfunction between thyroid cells induced by diesel engine exhaust particles

The role and mechanisms of DEP exposure on thyroid injury are not yet clear. This study explores thyroid damage induced by in vivo DEP exposure using a mouse model. This study has observed alterations in thyroid follicular architecture, including rupture, colloid overflow, and the formation of voids. Additionally, there was a significant decrease in the expression levels of proteins involved in thyroid hormone synthesis, such as thyroid peroxidase and thyroglobulin, their trend of change is consistent with the damage to the thyroid structure. Serum levels of triiodothyronine and tetraiodothyronine were raise. However, the decrease in TSH expression suggests that the function of the HPT axis is unaffected. To delve deeper into the intrinsic mechanisms of thyroid injury, we performed KEGG pathway enrichment analysis, which revealed notable alterations in the cell adhesion signaling pathway. Our immunofluorescence results show that DEP exposure impairs thyroid adhesion, and integrin α3β1 plays an important role. CD151 binds to α3β1, promoting multimolecular complex formation and activating adhesion-dependent small GTPases. Our in vitro model has confirmed the pivotal role of integrin α3β1 in thyroid cell adhesion, which may be mediated by the CD151/α3β1/Rac1 pathway. In summary, exposure to DEP disrupts the structure and function of the thyroid, a process that likely involves the regulation of cell adhesion through the CD151/α3β1/Rac1 pathway, leading to glandular damage.

Water extraction in aero gas turbines for contrail mitigation

Abstract Water vapour and particles in aero engine exhaust can give rise to condensation trails (contrails) in the wake of aircrafts, and recent studies suggest that persistent contrails and contrail cirrus account for circa 50% of the total aviation-derived radiative forcing (RF). The Schmidt-Appleman criterion is widely used to qualitatively predict the formation of contrails. The criterion indicates that the formation of contrails is affected by both aero engine exhaust and ambient air conditions and can therefore provide the theoretical basis to devise contrail mitigation strategies and further allows quantitative assessment of these strategies. This work focuses on water extraction from the aircraft engine exhaust for contrail mitigation. The fuel water emission index ( ${\rm{E}}{{\rm{I}}_{{{\rm{H}}_2}{\rm{O}}}}$ ) is one of the key factors that determines whether persistent contrails form or not. It indicates the amount of water produced for every kg of fuel burnt. Research has indicated that water extraction from the exhaust of the aero engine has been considered for Nitrogen oxides (NOx) reduction, but not for contrail mitigation. Assuming that water extraction is indeed possible, the emphasis of this work will therefore be on understanding how much water is needed to be extracted for contrail mitigation depending on the altitude and the relative humidity (RH), with the aim to carry out a meaningful study on the mitigation of persistent contrails and contrail cirrus to enable a fast and considerable reduction in aviation-derived RF.

Unlocking the nanoparticle emission potential: a study of varied filaments in 3D printing.

This study investigates nanoparticle emission during 3D printing processes, assessing various filament materials' impact on air quality. Commonly used 3D printers, including both filament and resin-based types, were examined. The study's scope encompasses diverse filament materials like ABS (acrylonitrile butadiene styrene), PLA (polylactic acid), PETG (polyethylene terephthalate glycol), ASA (acrylonitrile styrene acrylate), TPU (thermoplastic polyurethane), PP (polypropylene), nylon, and wood-based variants, alongside three types of resins. The research delves into the relationship between the type of material and nanoparticle emissions, emphasizing temperature's pivotal role. Measurement instruments were employed for nanoparticle quantification, including an engine exhaust particle sizer spectrometer, condensation particle counter, and nanozen dust counters. Notably, results reveal substantial variations in nanoparticle emissions among different filament materials, with ASA, TPU, PP, and ABS showing considerably elevated emission levels and characteristic particle size distribution patterns. The findings prompt practical recommendations for reducing nanoparticle exposure, emphasizing printer confinement, material selection, and adequate ventilation. This study offers insights into potential health risks associated with 3D printing emissions and provides a basis for adopting preventive measures.

Analysis of the correlation between mechanical and physicochemical properties of particles based on a diesel oxidation catalytic system

The mechanical and physicochemical properties of diesel engine exhaust particles before and after diesel oxidation catalyst (DOC) treatment are analyzed. It is considered important to explore the interrelationships between these attributes in order to understand their relevance. Understanding of these properties provides insights into the deposition characteristics of particles within the system and the evolution of the particles after the DOC treatment, which may help the selection of appropriate aftertreatment strategies. In this paper, particle samples were collected before and after the DOC to explore the variations in the mechanical and physicochemical properties of the particles under different operating conditions. Atomic force microscopy, thermogravimetric analysis, transmission electron microscopy, and Raman spectroscopy were employed to investigate the attraction force, adhesion force, adhesion energy, oxidative reactivity, primary particle size, nanostructure, and graphitization degree of the particles. The results indicated that under post-injection conditions, the attraction force, adhesion force, and adhesion energy of the particles increased significantly. However, when the particles passed through the DOC, these properties decreased to varying degrees. By analyzing the combination of physicochemical properties, it was determined that the attraction force of the particles was primarily influenced by the primary particle size and the particle's graphite structure. The adhesion force was found to be closely related to the content of soluble organic matter. Additionally, the soluble organic matter affected the degree of particle agglomeration by altering the adhesion energy of the particles.

Estimation Method of Charged Particle Concentration in Aircraft Engine Exhaust Based on Electric Field Detection

Aircraft engines, serving as the power core of aircraft, also constitute a significant source of potential malfunctions. The charge level of exhaust particles from aircraft engines serves as a crucial indicator of engine malfunction severity. This paper introduces a method for estimating the charge of exhaust particles based on electric field detection to monitor charged particles in the exhaust of aircraft engines. Initially, a mathematical model for estimating the charge of exhaust particles based on Gauss’s theorem is presented. Subsequently, an exhaust electric field induction device is designed, and the distribution of electric field sensors is studied, providing an overall design for the exhaust particle charge measurement system. Finally, the proposed method for estimating the charge of exhaust particles is analyzed through finite element simulation. The results indicate that the introduced aircraft engine exhaust particle charge estimation method based on electric field detection exhibits high accuracy and effectiveness. It offers a novel means for monitoring engine operation faults in aviation, with the potential for application in engine ground testing to further investigate engine state characterization technologies based on exhaust particle monitoring.

Marine Fuel Regulations and Engine Emissions: Impacts on Physicochemical Properties, Cloud Activity and Emission Factors

AbstractMarine regulations aim to reduce sulfur and nitrogen exhaust emissions from maritime shipping. Here, two compliance pathways for reducing sulfur dioxide emissions, fuel sulfur content reduction and exhaust wet scrubbing, are studied for their effects on physicochemical properties and cloud forming abilities of engine exhaust particles. A test‐bed diesel engine was utilized to study fresh exhaust emissions from combustion of non‐compliant, high sulfur content fuel with (WS) and without (HiS) the usage of a wet scrubber as well as a regulatory compliant, low sulfur content fuel (LoS). Particle number emissions are decreased by ≈99% when switching to LoS due to absence of 20–30 nm sulfate rich particles. While number emissions for WS are also decreased, a shift in the sulfate mode toward larger sizes was found to increase particle mass emission factors by at least 31%. Changes in the mixing state induced by the compliance measures are reflected in the hygroscopicity of the exhaust particles. Fuel sulfur reduction decreased cloud condensation nuclei emissions by at least 97% due to emissions of primarily hydrophobic soot particles. Wet scrubbing increased those emissions, mainly driven by changes in particle size distributions. Our results indicate that both compliance alternatives have no obvious impact on the ice forming abilities of 200 nm exhaust particles. These detailed results are relevant for atmospheric processes and might be useful input parameters for cloud‐resolving models to investigate ship aerosol‐cloud interactions and to quantify the impact of shipping on radiative budgets from local to global scales.

Effects of different national standards and driving conditions on pollutants and persistent free radicals in diesel engine exhaust particles

Exhaust pollutants from diesel vehicles constitute an important portion of air pollution. In addition to conventional pollutants such as carbon and nitrogen oxides, persistent free radicals (PFRs) exist on exhaust particles could also pose a health risk by inducing oxidative stress. However, recently there is a dearth of comprehensive studies addressing this concern. In this study, the exhaust particles emitted by tractors adhering to two prominent emission standards, namely GB III and GB I, that currently hold the largest tractor stocks, were collected under various working conditions. For the first time, this study dynamically monitored the characteristics of PFRs in exhaust particles emitted by internal combustion engines using biodiesel as fuel during driving on rural actual roads. Due to the stricter emission standard of GB III, which resulted in lower particle emissions, the concentration of PFRs emitted under the same fuel consumption was ultimately reduced. Noteworthily, while advancements like fuel atomization under engine electronic control unit (ECU) and the utilization of oxidation catalysts with low ignition temperature successfully decreased polycyclic aromatic hydrocarbons (PAHs) emission by altering combustion in the engine, they also resulted in heightened carbon structure defects, leading to a higher concentration of PFRs emitted per unit mass of particles. Additionally, compared to non-plowing driving conditions, localized hypoxia during plowing that could cause excessive fuel injection and uneven formation of fuel-air mixture resulted in the emission of a significant amount of carbon-containing substances with unstable structures. Consequently, this scenario led to an increased concentration of PFRs during plowing conditions. The results of this study demonstrated that the stricter emission standards and optimized technology could better reduce the concentration and types of PFRs in exhaust particles, reducing the environmental risk of exhaust particle, which is also of great significance for the realization of pollution reduction and carbon reduction goals.

Characterization of in-cylinder spatiotemporal flame and solid particle emissions for ethanol-gasoline blended in gasoline direct injection engines

Stricter regulations for internal combustion engines have necessitated the inclusion of eco-friendly fuels with conventional ones to reduce gas and solid emissions. Gasoline direct injection (GDI) engines, however, have been found to produce more particle number and mass emissions than port fuel injection engines. To address this, bioethanol fuel has been selected as an additive eco-friendly fuel for gasoline, with the aim of reducing particle emissions. In this study, we quantitatively characterize in-cylinder spatiotemporal flame to feature combustion performance and particle emissions for ethanol fuel in the GDI combustion chamber. We examined three engine combustion modes differed in equivalence ratio and injection strategy to produce various combustion results to quantify combustion performance and particle emission characteristics. Using an eight-channel non-intrusive flame luminosity sensor in one cylinder, we measured the flame front and its propagation direction. At the tailpipe, we measured particulate emissions using an engine exhaust particle sizer and a micro soot sensor coupled with a catalytic stripper that removed semi-volatile compounds. Our study found that increasing ethanol fuel content for different combustion modes resulted in distinct combustion and flame development. The particle size distribution also showed different patterns at each combustion mode, depending on the ethanol content. Lean combustion modes yielded high diffusion flame intensity compared to stoichiometric combustion mode, which resulted in a larger amount of particle formation. The physical properties of ethanol fuel were found to predominantly determine the fuel-air mixture quality, combustion process, and flame development at each combustion mode. An increase in ethanol fuel content at lean-homogeneous mode resulted in higher diffusion flame intensity and larger particle emissions. Our comparative study of flame and solid particles for ethanol fuel content improves the understanding of in-cylinder combustion processes and their correlations.

Study on the Catalytic Characteristics of Precious Metal Catalysts with Different Pt/Pd Ratios for Soot Combustion.

Soot particles in engine exhaust seriously pollute the atmosphere and endanger human health. For soot oxidation, Pt and Pd precious metal catalysts are widely used and are effective. In this paper, the catalytic characteristics of catalysts with different Pt/Pd mass ratios for soot combustion were studied through X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis, scanning electron microscopy, transmission electron microscopy, the temperature-programmed oxidation reaction, and thermogravimetry. Besides, the adsorption characteristics of soot and O2 on the catalyst surface were explored by density functional theory (DFT) calculations. The research results showed that the activity of catalysts for soot oxidation from strong to weak is Pt/Pd = 10:1, Pt/Pd = 5:1, Pt/Pd = 1:0, and Pt/Pd = 1:1. XPS results showed that the concentration of oxygen vacancies in the catalyst is the highest when the Pt/Pd ratio is 10:1. The specific surface area of the catalyst increases first and then decreases with the increase of Pd content. When the Pt/Pd ratio is 10:1, the specific surface area and pore volume of the catalyst reach the maximum. The following are the DFT calculation results. With the increase of Pd content, the adsorption energy of particles on the catalyst surface decreases first and then increases. When the Pt/Pd ratio is 10:1, the adsorption of C on the catalyst surface is the strongest, and the adsorption of O2 is also strong. In addition, this surface has a strong ability to donate electrons. The theoretical simulation results are consistent with the activity test results. The research results have a guiding significance for optimizing the Pt/Pd ratio and improving the soot oxidation performance of the catalyst.

Placental-fetal distribution of carbon particles in a pregnant rabbit model after repeated exposure to diluted diesel engine exhaust

BackgroundAirborne pollution particles have been shown to translocate from the mother’s lung to the fetal circulation, but their distribution and internal placental-fetal tissue load remain poorly explored. Here, we investigated the placental-fetal load and distribution of diesel engine exhaust particles during gestation under controlled exposure conditions using a pregnant rabbit model. Pregnant dams were exposed by nose-only inhalation to either clean air (controls) or diluted and filtered diesel engine exhaust (1 mg/m3) for 2 h/day, 5 days/week, from gestational day (GD) 3 to GD27. At GD28, placental and fetal tissues (i.e., heart, kidney, liver, lung and gonads) were collected for biometry and to study the presence of carbon particles (CPs) using white light generation by carbonaceous particles under femtosecond pulsed laser illumination.ResultsCPs were detected in the placenta, fetal heart, kidney, liver, lung and gonads in significantly higher amounts in exposed rabbits compared with controls. Through multiple factor analysis, we were able to discriminate the diesel engine exposed pregnant rabbits from the control group taking all variables related to fetoplacental biometry and CP load into consideration. Our findings did not reveal a sex effect, yet a potential interaction effect might be present between exposure and fetal sex.ConclusionsThe results confirmed the translocation of maternally inhaled CPs from diesel engine exhaust to the placenta which could be detected in fetal organs during late-stage pregnancy. The exposed can be clearly discriminated from the control group with respect to fetoplacental biometry and CP load. The differential particle load in the fetal organs may contribute to the effects on fetoplacental biometry and to the malprogramming of the fetal phenotype with long-term effects later in life.

34 Placental-Fetal Distribution of Carbon Particles in a Pregnant Rabbit Model After Repeated Exposure to Diluted Diesel Engine Exhaust

Abstract Airborne pollution particles have been shown to translocate from the mother’s lung to the fetal circulation but their placental-fetal distribution and internal tissue load remain poorly explored. Here, we investigated the placental-fetal distribution of diesel engine exhaust particles during gestation under controlled exposure conditions using a pregnant rabbit model. Pregnant dams were exposed by nose-only inhalation to either clean air (controls) or diluted and filtered diesel engine exhaust (1 mg/m3) for 2h/day, 5 days/week, from gestational day (GD) 3 to GD27. At GD28, placental and fetal tissues (i.e., heart, kidney, liver, lung and gonads) were collected for biometry and to study the accumulation of carbon particles (CPs) using white light generation by carbon particles under femtosecond pulsed laser illumination. CPs were detected in the placenta, fetal heart, kidney, liver, lung and gonads in significantly higher amounts compared with controls. By using multiple factor analysis, we were able to discriminate the diesel engine-exposed pregnant rabbits from the control group taking all variables related to fetoplacental biometry and CP load into consideration. Although our findings did not reveal a sex effect, a potential interaction effect might be present between exposure and fetal sex. The results confirm the translocation of maternally inhaled CPs from diesel engine exhaust to the placenta and the ability to reach fetal organs during late-stage pregnancy. The differential particle load in the fetal organs may contribute to the disruption of blood flow in the placenta with possible effects on fetoplacental biometry and placental function.

Comprehensive analysis on the effect of lube oil on particle emissions through gas exhaust measurement and chemical characterization of condensed exhaust from a DI SI engine fueled with hydrogen

This research study aims to investigate the causes of the particles emitted by a spark ignition engine fueled with hydrogen. The experiments were carried out on a single cylinder 250 cm3 direct injection spark ignition engine. Two operating conditions at 2000 rpm both full and low load, representative of typical urban conditions, were investigated. A physical characterization of the particles, size and number, was performed through an Engine Exhaust Particle Sizer coupled to a single diluter. Chemical characterization was carried out on the condensed exhaust. The simultaneous analysis of the physical properties and their chemical characterization allows to point out not only the role of the oil on the particle emissions but also to give an important information on its state/composition, if it was unburned and oxidized. Particles were detected with conventional spectrometer at low load while at high load the noise signal ratio is too high to distinguish the presence of particles. More detailed chemical techniques highlighted the presence of PAH, alkyl-PAHs, oxy-PAHs and unburned hydrocarbon in the exhaust due to the mineral oil.

Comparison of Particle Sizers and Counters with Soot-like, Salt, and Silver Particles

Vehicle emission regulations in Europe and many Asian countries include a particle number limit. The number concentration is measured, typically, with condensation particle counters (CPCs). For research purposes, the size distributions provide useful information. Scanning mobility particle sizers (SMPSs) accurately provide the size distribution but are not suitable for transient aerosol. Engine (fast) exhaust particle sizers (EEPSs) cover this gap, but with less accuracy. Fast size distribution instruments are commonly used in the research and development of engines. In the last few years, instrument algorithms have been improved, but studies assessing the improvements are limited, in particular in their lower size range, around 10–20 nm, and for soot-like aerosol. In this paper, we compared the three instruments using salt, silver, diffusion flame soot (CAST), and spark discharge graphite particles. Moreover, vehicle exhaust number concentration measurements with EEPSs over a seven-year period were presented. In terms of particle concentration, EEPS overestimated, on average, 25% compared to CPC, in agreement with previous studies. Its accuracy for mean particle size determination was better than 5 nm compared to SMPS. The agreement between the instruments was satisfactory but the uncertainty increased at low concentrations and larger particle sizes, showing that there is still room for further improvements. Experimental challenges, such as low concentration levels of modern vehicles, losses in the diluters, use of photometric mode by the CPCs, and the material impact, are also discussed.

Volatility of aircraft exhaust ultrafine particles inferred from field measurements at Narita International Airport

We conducted field measurements of aerosols near a runway at Narita International Airport (NRT) in February 2018 to characterize the physical and chemical properties of aircraft exhaust ultrafine particles (UFPs; diameter <100 nm). An ultrafine condensation particle counter (UCPC; d50 = 2.5 nm), a condensation particle counter (CPC; d50 = 10 nm), and an engine exhaust particle sizer (EEPS; 6.0–523 nm) were used to measure the particle number concentrations and size distributions in ambient air. The sample flow for the UCPC and CPC was passed through an evaporation tube for heated measurements (150 °C, 250 °C, or 350 °C) or through a bypass tube for unheated measurements. The evaporation tube temperature (Ttube) of 350 °C was used as a threshold point for the separation of volatile and non-volatile particles. The removal efficiency of the volatile particles at intermediate temperatures (<350 °C) was evaluated in the laboratory using triacontane (C30) and tetracontane (C40) as test compounds. The critical temperature at which the laboratory-generated 30-nm C30 and C40 particles were almost entirely removed was ∼130 °C and ∼250 °C, respectively. The particle number concentrations measured by the UCPC, CPC, and EEPS at NRT were used to investigate the volatility of aircraft exhaust UFPs under real-world operating conditions. The number fraction of the non-volatile particles strongly depended on the geometric mean diameter (GMD) of the unheated particle number size distributions, whereas the vaporization temperature of the volatile particles did not exhibit significant dependency on GMD. The particle number fraction remaining, calculated for the selected evaporation tube temperature (Ttube), indicates that ∼50% and ≳ 90% of the volatile particles were removed at Ttube = 150 °C and 250 °C, respectively, on a number basis. These results suggest that a large fraction (more than half by number) of the volatile UFPs emitted from aircraft was equally or less volatile than the 30 nm pure C30 particles and only a small fraction of the volatile UFPs was equally or less volatile than the 30 nm pure C40 particles.

Effect of ethanol blends, E10, E25 and E85 on sub-23 nm particle emissions and their volatile fraction at exhaust of a high-performance GDI engine over the WLTC

This study was aimed to characterize the effect of ethanol blends on sub-23 nm particles and on their volatile organic fraction from a turbocharged 1.8 L direct injection spark ignition engine. Tests were performed on the Worldwide Harmonized Light Vehicles Test Cycle. Engine was fueled with three different blends: 10, 25 and 85 %v/v of ethanol content, gasoline was used as reference fuel. An Engine Exhaust Particle Sizer was used to measure the particle number and size in the range 5.6–560 nm. Particle measure was carried out by diluting the sample gas through both a single diluter and the Dekati Engine Exhaust Diluter. The number and diameter of particles emitted from ethanol blends as well as the presence of volatiles are affected from both the specific phase of the cycle and the fuel properties. A large fraction of volatiles in the sub-23 nm range, especially in the low and extra-high phases of the test cycle, was observed whatever the fuel. Anyway, the percentage of sub-23 m particles increases as the ethanol content in the blends increases except for E85. For this blend, the greater decrease of temperature due to the stronger charge cooling effect ascribable to the larger ethanol content, deteriorates the combustion evolution contributing to the formation of large soot particles. The addition of ethanol to gasoline fuel increases the volatile organic fraction whatever the blend ratio.

Influence of Global Operating Parameters on the Reactivity of Soot Particles from Direct Injection Gasoline Engines

The aim of this study is to investigate the impact of global operating parameters, e.g., engine speed, brake mean effective pressure, and air–fuel ratio, of a turbocharged 4-cylinder GDI engine on the reactivity of soot particles against oxidation. The knowledge of soot reactivity is crucial for optimizing gasoline particulate filter regeneration strategies and is, consequently, a key parameter for reducing fuel consumption and CO2 emissions. In this work, time-resolved in-cylinder soot concentrations and exhaust particle size distributions are measured by using two-color pyrometry, engine exhaust particle sizer and smoke meter, respectively. Reactivity against oxidation by molecular oxygen is determined by temperature programmed oxidation analysis. To derive a physicochemical explanation for varying soot reactivity, the morphological and nanostructural primary particle structure of collected samples is analyzed using high-resolution electron microscopy and image analysis algorithms. The results reveal that engine operating parameters affect soot reactivity differently. While engine speed has only a slight effect, a reduction of air/fuel ratio (λ < 1.0) or an increase of BMEP > 10 bar significantly reduces the soot oxidation reactivity. These findings give evidence, that the quality of the fuel/air mixture is a significant parameter influencing soot reactivity. Measured soot concentrations substantiate the hypothesis that low-sooty homogeneous premixed combustion of a homogeneous fuel/air mixture favors formation of high-reactive soot particle fractions. Reactive soot particle aggregates are composed of multiple soot fractions of different reactivity. Reactive primary particles are composed of short graphene-like layers and vice versa, providing a physicochemical explanation for varying soot reactivity depending on engine operating conditions.

A controlled chamber study of effects of exposure to diesel exhaust particles and noise on heart rate variability and endothelial function

Background Adverse cardiovascular effects are associated with both diesel exhaust and road traffic noise, but these exposures are hard to disentangle epidemiologically. We used an experimental setup to evaluate the impact of diesel exhaust particles and traffic noise, alone and combined, on intermediary outcomes related to the autonomic nervous system and increased cardiovascular risk. Methods In a controlled chamber 18 healthy adults were exposed to four scenarios in a randomized cross-over fashion. Each exposure scenario consisted of either filtered (clean) air or diesel engine exhaust (particle mass concentrations around 300 µg/m3), and either low (46 dB(A)) or high (75 dB(A)) levels of traffic noise for 3 h at rest. ECG was recorded for 10-min periods before and during each exposure type, and frequency-domain heart rate variability (HRV) computed. Endothelial dysfunction and arterial stiffness were assessed after each exposure using EndoPAT 2000. Results Compared to control exposure, HRV in the high frequency band decreased during exposure to diesel exhaust, both alone and combined with noise, but not during noise exposure only. These differences were more pronounced in women. We observed no synergistic effects of combined exposure, and no significant differences between exposure scenarios for other HRV indices, endothelial function or arterial stiffness. Conclusion Three-hour exposure to diesel exhaust, but not noise, was associated with decreased HRV in the high frequency band. This indicates activation of irritant receptor-mediated autonomic reflexes, a possible mechanism for the cardiovascular risks of diesel exposure. There was no effect on endothelial dysfunction or arterial stiffness after exposure.

Correlation analysis of mechanical and state characteristics of diesel engine exhaust particles

AbstractAiming at the influence of diesel engine exhaust particle mechanical characteristics on the state characteristics, studies were carried out using atomic force microscopy, high‐resolution transmission electron microscopy, and x‐ray small‐angle scattering. The variation rules of cluster‐particle interaction force and state characteristic parameters such as particle morphology and spatial structure were discussed. According to the principle of normalization, the relationship between the mechanical and state characteristics of the particles is analyzed. The results show that as the particle size increases in the exhaust process, the attractive force Fat, adhesion Fad, and adhesion energy Wad increase between the particles, Fat from 1.27 to 1.58 nN, Fad from 3.75 to 4.38 nN, Wad from 2.17 × 10−16 to 2.44 × 10−16 J. The particles are gradually agglomerated, and the cluster size is increased, indicating a certain relationship between the mechanical characteristics of the particles and the morphology. Along the exhaust direction, the particle equivalent diameter increases, and the mechanical characteristics are enhanced, while the organic matter and moisture in the exhaust are continuously adsorbed, aggravating the aggregation and shrinkage between the particles. The scattering characteristic parameters qminand qTdecrease, qminfrom 0.34 to 0.28 and qTfrom 0.72 to 0.63, the pore structure parameters decrease, the pore number concentration decreases, the peak pore size changes from 7–9 nm to 5–6 nm, the agglomerate particle structure defects decrease and the density is increased, indicating that there is a certain relationship between the mechanical characteristics of the particles and the spatial structure.

Measurement of transient nanoparticle emissions of pulse-jet cleaned filters applying an engine exhaust particle sizer

Baghouse filters are used in a variety of gas cleaning applications in order to lower dust emissions and protect the environment and human health. Regarding health aspects, nanoparticle emissions of pulse-jet cleaned filters are of great interest. Due to the transient emission behavior of the filters, conventional SMPS measurement is not suitable (high sample times). A potential method for the detection of transient particle emission peaks after filter regeneration in the nanometer region is the application of an engine exhaust particle sizer (EEPS). In this study, the size resolved particle emission of pulse jet-cleaned surface filters in a test rig according to DIN ISO 11057 (different filter media) and a small scale baghouse filter measured with an optical spectrometer/particle counter (OPC) (Palas® Promo®2000 with Welas®2100 sensor - measurement range: 200 nm − 10,000 nm) is compared to that measured with an EEPS (TSI® EEPS 3090 - measurement range: 5.6 − 560 nm). Significant nanoparticle emissions could be measured after filter regeneration, which are outside of the OPC measurement range. The size fraction with the highest emission detected by both devices differs greatly and is lower than previously shown by optical detection methods (approx. 200 nm for the EEPS and 300 nm for the OPC measurement). In the overlap region between the two devices above 200 nm, the particle size distributions are in good agreement.Copyright © 2021 American Association for Aerosol Research