Diesel Exhaust Particles Research Articles

Evaluating the performance of particle oxidation catalyst for construction equipment

The regeneration ability of diesel particulate filter (DPF) may not meet the immense power demand of construction equipment. Furthermore, few research addresses the emission control technologies for construction equipment. Therefore, this study aims to provide the potential application of diesel oxidation catalyst (DOC) and particle oxidation catalyst (POC) in terms of reducing PM, gaseous pollutants, and polycyclic aromatic hydrocarbons (PAHs) emitted from the exhaust of diesel engines without losing power. The results showed an absence of reaction on engine power when DOC + POC was installed due to the open-flow channel of the POC. Moreover, POC reduced the PM emissions by 92.4%–93.1% and for gaseous pollutants, CO was reduced by 87.2%–93.3% while HC showed 80.7%–100%. Against DPF, the PM filtration of the POC is lower however, the two Euro III diesel engines still met the Euro V standards for PM, CO, and HC. For new POC condition, a minimum of 80.9% PAH removal efficiency was shown by both engines, while lower percentages were displayed for the remaining conditions. Although, the data suggest that the POC utilized did not wane, but rather an incomplete combustion occurred which lowered the PAH removal efficiency of the other conditions. Nevertheless, the DOC + POC still managed a 33.0%–57.0% PAH mass reduction. Lastly, following the high-performance results of the engines, the same was seen on the excavator as 86.5–96.7% of PM were removed from the raw exhaust while testing its idle and action mode.

Research on dynamic modeling and carbon load estimation of diesel particulate filter

ABSTRACT Accurate estimation of carbon load in diesel particulate filters is an important basis for efficient and safe operation of active regeneration. Currently, model-based carbon load prediction has the advantages of high accuracy and low influence by working conditions. In this paper, a dynamic model of diesel particulate filters was developed based on the deep bed and cake layer trapping mechanism and regeneration mechanism. The trapping process was described using the spherical trapping mechanism, while the regeneration process was based on the non-catalytic oxidation process of the trapped particles. A pressure drop correction based on the extended Kalman filter was developed to correct the errors accumulated in the carbon load prediction during the integration. The maximum error of carbon load prediction was 0.3 g/L, and the average error was less than 0.17 g/L, the maximum error of pressure drop was 0.7 kPa, and the average error was less than 0.33 kPa. The carbon load prediction algorithm was proved to have good accuracy and can be used for start-stop judgment of DPF active regeneration, and the pressure drop and temperature calculated by the DPF model can be used for DPF status monitoring during regeneration to ensure safety and reliability.

Study on Selection of Diesel Engine Exhaust After-Treatment System Materials and Emission Performance for Genset Applications

The use of diesel engines for the transportation sector is ubiquitous and covers a broad continuum, like buses, trucks, agriculture, construction equipment, generators, and industrial applications. However, because of their increased use of off-road engines, they contribute more emissions in various sectors than on-road. As a result, worldwide, regardless of ongoing emission control efforts, these off-road, stationary engines also continue to be a substantial source of air pollutant emissions in the United States, European Union and Asian markets. Accordingly, while improving emissions performance, the selection of after-treatment system materials and the use of compatible after-treatment specification selections are also critical. This is only possible by effectively combining clean diesel technologies such as Fuel Injection Equipment (FIE), Turbocharger with Intercooler (TCIC), Cooled Exhaust Gas Recirculation (C-EGR), and after-treatment systems like Diesel Oxidation Catalyst (DOC), Selective Catalytic Reduction (SCR), and Diesel Particulate Filter (DPF). Overall, in this study, the influence of after-treatment system configurations and their effect on emission reduction performance are studied for three different DOC specifications based on emission testing for catalyst and size optimization. With the selected DOC catalyst specification, suitable combinations of DPF and SCR specifications are optimized further using GT-SUIT software simulation. This study was carried out during the conversion of a 15 kW NA engine to a 27 kW TCIC engine to meet diesel engine emission norms.

Diesel soot combustion in air-NO environment: Evolution of soot physical properties and fragmentation characteristics

Since the oxidation activity of nitrogen oxides on soot is obviously higher than that of O2, it is one of the most effective means to improve soot combustion in diesel particulate filter (DPF) by fully utilizing the oxidation activity of nitrogen oxides in diesel exhaust. This paper investigated the physical properties (i.e. morphology, primary particle diameter, fractal dimension and nanostructure) and oxidation-induced fragmentation characteristics of diesel exhaust soot particles during oxidation degrees (0 %, 20 %, 50 % and 80 %) in different atmospheres (air, air-1000 ppm NO and air-2000 ppm NO). The results showed that during the oxidation process the variation trends of soot morphology in air and air-NO environments were similar, while the number and size of primary particles in an aggregate decreased and the fractal dimension of the aggregate increased with the presence of NO in air atmosphere. With the progress of oxidation, the nanostructure of soot particles became more ordered, while this variation trend was slowed down when NO was added to the air atmosphere. This is because soot particles oxidized in air-NO atmospheres showed less probability of internal oxidation but more external oxidation than those in air atmosphere. Over the oxidation process, the soot aggregate fragmentation rate presented a decreasing variation trend under each oxidizing atmosphere, with a higher aggregate fragmentation rate and more apparent variations in air-NO atmospheres. Moreover, in the air atmosphere, the probability of primary soot particle fragmentation showed a consistent upward trend, while the addition of NO slowed down this trend and showed an upward trend in stages 1(0 % ∼ 20 %) and 2(20 % ∼ 50 %), but a downward trend in stage 3(50 % ∼ 80 %). This suggests that the addition of NO reduces the probability of oxidants (especially O2) entering the particles, which would lead to a decrease in the probability of primary soot fragmentation caused by internal oxidation.

PGM-free metal oxide nanoarray forests for water-promoted low-temperature soot oxidation

In this study, PGM free metal oxide based nanorod array (nanoarray) forests have been conformally integrated onto the millimeter-sized channel walls and microscale pores of SiC diesel particulate filter (DPF) substrates using scalable microwave-assisted hydrothermal and dip-coating methods. High-efficiency and robust low temperature soot oxidation is successfully achieved using such a new type of cDPFs as a result of i) promoted tight soot-catalyst contact through spontaneous soot deposits in-between nanorods, ii) highly dispersed loading of LaSrCoO3 perovskite oxidation catalysts onto ZnO nanorod arrays, effectively mitigating active site blockage by soot deposition. The light-off temperature of soot oxidation was lowered to 250 °C in oxygen, a 250 °C decrease compared to that of the commercial Pt based catalyst, due to the abundant oxygen vacancies enabled by the LaSrCoO3/ZnO (LSCO/ZnO) nanorod array catalysts. The performance of the catalyst was further enhanced to initiate the soot oxidation at ∼150 °C with co-fed gas of NO, due to the LSCO catalyzed NO2 formation and its favorable oxidation with soot at low temperature. Furthermore, the nanoarray supported perovskite catalyst shows excellent stability and activity after 120 h of hydrothermal aging at 650 °C. Soot oxidation Tmax is lowered from 542 °C to 510 °C under 6 % water steam condition due to the formation and promotion effect of oxidative -OH species. In situ DRIFTS study reveals that such -OH species form at various catalyst surfaces and interfaces, pointing to a potentially generic water promotion effect for solid/solid interfacial catalytic oxidation under humidity condition. Finally, the mechanistic soot oxidation pathways under O2, NO2, and H2O feeds are proposed for understanding the low-temperature soot oxidation behaviors over the nanoarray supported perovskite catalysts.

Siraitia grosvenorii Extract Attenuates Airway Inflammation in a Mouse Model of Respiratory Disease Induced by Particulate Matter 10 Plus Diesel Exhaust Particles.

Exposure to particulate matter (PM) causes considerable breathing-related health risks. Siraitia grosvenorii fruit is a traditional remedial plant used in Korea and China to treat respiratory diseases. Our recently published study showed that S. grosvenorii extract (SGE) ameliorated airway inflammation in lipopolysaccharide- and cigarette-smoke-induced chronic obstructive pulmonary disease in mice. Thus, we aimed to assess the inhibitory effects of SGE on airway inflammation in mice exposed to a fine dust mixture of PM10 (PM diameter < 10 mm) and diesel exhaust particles (DEPs) known as PM10D. The mice (BALB/c) were treated with PM10D via intranasal injection three times over a period of 12 days, and SGE 70% ethanolic extract (50 or 100 mg/kg) was orally administered daily for 12 days. SGE attenuated neutrophil accumulation and the number of immune B and T cells from the lung tissue and bronchoalveolar lavage fluid (BALF) of the PM10D-exposed mice. SGE reduced the secretion of cytokines and chemokines, including interleukin (IL)-1α, tumor necrosis factor (TNF)-α, IL-17, C-X-C motif chemokine ligand (CXCL)1, and macrophage inflammatory protein (MIP)-2 in the BALF. Airway inflammation, infiltration of inflammatory cells, and collagen fibrosis in the lung after PM10D exposure were investigated via histopathological analysis, and SGE treatment ameliorated these symptoms. SGE decreased the mRNA expression of mucin 5AC (MUC5AC), CXCL1, TNF-α, MIP-2, and transient receptor potential ion channels in the lung tissues. Furthermore, SGE ameliorated the activation of mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF-κB) signaling by PM10D in the lungs. We conclude that SGE attenuated PM10D-induced neutrophilic airway inflammation by inhibiting MAPK/NF-κB activation. These results show that SGE may be a candidate for the treatment of inflammatory respiratory diseases.

Effect of ash on temperature and particulate emission characteristics of diesel particulate filter during active regeneration

As one of the most effective devices to reduce particulate emission from diesel engines, the diesel particulate filter (DPF) has been widely used. However, long-term use of the DPF can cause a large amount of ash to deposit in it, which can significantly affect its performance. In this study, a burner was utilized to deposit ash, derived from four different lubricating oil additives (zinc dialkyl dithiophosphate (Zn-based), calcium sulfonate (Ca-based), magnesium sulfonate (Mg-based), and composite), into four DPFs with the same specification. The four ash-loaded DPFs and a fresh ashless DPF were subsequently tested for active regeneration on an engine bench at the same soot load. The temperature and particulate emission characteristics of the DPFs were measured using thermocouples and a particulate analyzer. The peak regeneration temperature of ash-loaded DPFs moved forward when compared to the fresh DPF, and the peak regeneration temperature of Mg-based DPF reached 694 °C and moved forward to the axial position of 71.5 mm. A low temperature zone appeared at the rear end of edge channels, forming a large temperature gradient up to 75.5 °C/cm. The emission of nucleation-mode particulates at each DPF outlet increased to different degrees during active regeneration, especially for the Zn-based DPF, whose particulate concentration even approached 108 #/cm3. The X-ray computed tomography (X-CT) images of ash-loaded DPFs showed that the distribution of ash in each DPF was quite different, and ash plugs or bridges appeared in the middle and front of some channels, forming a strong blocking effect. It is due to the presence of ash that the soot deposition position moved forward and the wall-flow velocity rose, which increased the local soot density, causing the peak regeneration temperature to rise and move forward. The increase in wall-flow velocity reduced the diffusion filtration efficiency of ash-loaded DPFs, so escaped particulates that were broken up from soot agglomerate burning increased.

Impact of diesel exhaust particles on infections with Mycobacterium bovis BCG in in vitro human macrophages and an in vivo Galleria mellonella model

There are strong suggestions for a link between pulmonary tuberculosis (TB) and air quality. Diesel exhaust is one of the main contributors to pollution and it is reported to be able to modify susceptibility to lung infections. In this study we exposed THP-1 human macrophages and Mycobacterium bovis BCG to diesel exhaust particles (DEPs). High cytotoxicity and activation of apoptosis was found in THP-1 cells at 3 and 6 days, but no effect was found on the growth of M. bovis BCG. Infection of THP-1 cells exposed to a non-cytotoxic DEP concentration showed a limited capacity to engulf latex beads. However, M. bovis BCG infection of macrophages did not result in an increase in the bacterial burden, but it did result in an increase in the bacteria recovered from the extracellular media, suggesting a poor contention of M. bovis BCG. We also observed that DEP exposure limited the production of cytokines. Using the Galleria mellonella model of infection, we observed that larvae exposed to low levels of DEPs were less able to survive after infection with M. bovis BCG and had a higher internal bacterial load after 4 days of infection. Unraveling the links between air pollution and impairment of human antimycobacterial immunity is vital, because pollution is rapidly increasing in areas where TB incidence is extremely high.

Emission Characteristics of Particulate and Gaseous Pollutants from a Light-Duty Diesel Engine with SDPF.

Due to the inherent combustion characteristics of diesel engines, particulate matter (PM) and nitrogen oxides (NOx) are the main pollutants of diesel engines. NOx emissions under low load and low temperature are the focus of future regulation. Selective catalytic reduction coated on diesel particulate filter (SDPF) can reduce NOx and PM emissions of diesel engines at the same time, especially improving the emission characteristics of NOx under low load and low temperature. In this paper, a light-duty diesel engine with diesel oxidation catalyst (DOC) and SDPF was studied, and emission of particulate and gaseous pollutants of the engine before DOC, after DOC, and after SDPF was measured under 10 steady-state operating conditions. The effects of SDPF on particulate size distribution, the filtration efficiency of particulate, and the conversion efficiency of gaseous pollutants were analyzed. The results show that DOC + SDPF can trap PM with particle sizes between 10 and 23 nm by 1-2 orders of magnitude, and the conversion and filtration efficiency of DOC + SDPF for both gaseous pollutants and PM exceeds 90% under low-temperature and low-load conditions. The filtration efficiency of SDPF is 94.37% for PM and 90.36% for PN, and the conversion efficiency is 91.43% for NOx.

Formation, conversion, and elimination of intermediate spinel phase in MgO/kaolin mixture firing for cordierite

AbstractCordierite ceramic is usually used for diesel particulate filter owing to its excellent low thermal expansion coefficient and high thermal shock resistance properties. However, the co‐exited intermediate spinel phase can deteriorate the thermal and mechanical performances of cordierite ceramic product, because the spinel phase has much higher thermal expansion coefficient comparing to that of cordierite. In this study, two methods are utilized to reduce the spinel impurity in the cordierite ceramic. On the one hand, rational reaction resources were introduced to decrease spinel production. The formation of intermediate spinel phase is systematically researched by X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman characterizations and the results clarified the preference of path “Enstatite + Mullite → Cordierite” for less spinel production in comparison to path “Enstatite + Al2O3 → Cordierite + Spinel.” Additionally, MgO was introduced as fluxing agent to promote liquid‐phase sintering, thus facilitating the conversion of spinel. On the other hand, the sintering schedule was improved by introducing a holding temperature gradient to promote the diffusion of Si4+ and further promote the conversion of spinel into cordierite. With these methods, the residual spinel phase is minimized, the resulting high‐purity cordierite has a 47% reduction in the thermal expansion coefficient from 3.07 × 10−6/K to 1.63 × 10−6/K compared to the original cordierite sample.

{In vitro} DNA methylome and transcriptome analysis in human alveolar epithelial cells after long-term exposure of diesel exhaust particles

{In vitro} DNA methylome and transcriptome analysis in human alveolar epithelial cells after long-term exposure of diesel exhaust particles

Effect of filter material and porosity on the energy storage capacity characteristics of diesel particulate filter thermoelectric conversion mobile energy storage system

The thermal energy generated by the diesel particulate filter (DPF) is converted into electrical energy through the thermoelectric generator (TEG) and stored in a mobile battery power energy storage (MBPE) system. The filter material and porosity directly affect the regeneration temperature of the DPF, which in turn affects the thermoelectric conversion capability of the thermoelectric module (TEM). This study explores the energy storage capacity characteristics for the DPF-TEG of the MBPES system at a regeneration temperature of 923 K. The filter materials considered are cordierite, mullite and SiC with porosities of 0.4, 0.45, 0.5, 0.55, 0.6, 0.65 and 0.7. The maximum output power and thermoelectric conversion efficiency are analyzed. The thermal input power for the SiC filter is approximately 2.4 times and 1.8 times than that of the cordierite filter and the mullite filter. As the porosity increases from 0.4 to 0.7, the output current for the DPF-TEG of the MBPES system with the 3 filter materials ranges from 0.66 A to 2.11 A. The output voltage changes from 50.62 V to 161.98 V. The maximum output power varies from 33.36 W to 341.59 W and the conversion efficiency rises from 0.88% to 2.72%.

Integration and optimization of the after-treatments systems to reduce the acoustic footprint of the ships

Exhaust Gas Cleaning Systems (EGCS) such as scrubbers are mandatory and extensively used to abate SOx in exhaust gases when high sulphur content fuel oil is employed in the marine engine in order to comply with international ship emission regulations, both in new and existing ships. Currently, about 13% of bulker, container, and tanker ships have a scrubber installed, despite the fact that their installation on board is challenging due to their large dimensions to be fitted into the funnel and the complexity of the system, since the exhaust line must control both the chemical and acoustic emissions. In the presented work a combined FEM, CFD simulations and GA optimization methodology aimed at the integration of the abatement system, while optimizing the acoustic properties, is developed. The methodology is first assessed on an industrially-relevant scenario that involves the use of a Genset mock-up equipped with a reference Diesel Oxidation Catalyst (DOC) and a scrubber for the abatement of both NOx and SOx, showing that acoustic performances of the DOC are reliably modelled by the FEM-CFD methodology, which has a significantly reduced computational cost as compared to conventional CFD modelling of acoustic properties. The GA optimization is carried out to improve the DOC acoustic properties showing that it is possible to confer the silencing effect to the after-treatment systems, thus eliminating the traditional silencers from the exhaust line. This leads to a compact exhaust line that integrates the EGCS while maintaining efficient both the chemical pollution abatement capability, and silencing effects to guarantee full compliance (i.e., acoustic and chemical) with the international regulations.

P09-40: Complex effects of urban dust and diesel exhaust particles on estrogen-like responses in human cells

P09-40: Complex effects of urban dust and diesel exhaust particles on estrogen-like responses in human cells

Multi-objective optimization study of hydrothermal aging on NOx-assisted soot catalytic combustion and secondary pollution emission in regeneration of CeO2 catalytic diesel particulate filter

The present study aimed to explore the effect of hydrothermal aging on the heterogeneous catalytic combustion process of soot in CeO2 catalytic diesel particular filter and the formation of secondary pollutants (N2O and CO).The present study was based on a fixed-bed experimental bench for NOx-assisted soot catalytic oxidation in CeO2-CDPF with different soot loading and catalyst coating amounts. A non-linear regression surrogate model and a multi-objective optimization decision approach were used to analyze the trade-off relationship between the design variables and the optimization objectives. The results showed that lower levels of soot loading (2.5 g/L), CeO2 catalyst coating amount (2.5 g/L) and higher NOx concentration (1000 ppm) in fresh catalysts were favorable for improving the performance of soot-assisted catalytic combustion and minimizing the formation of N2O and CO. However, it was observed that higher levels of catalyst coating amount (10 g/L) resulted in better soot catalytic combustion performance with lower N2O and CO emissions. Global sensitivity analysis showed a positive correlation between N2O and CO peak concentrations and peak temperatures with soot loading, but a negative correlation with catalyst loading. Over time, hydrothermal aging of CDPF caused the inhibitory effect of CeO2 catalyst on N2O to shift from negative to positive correlation, while also decreasing the synergistic performance of NOx in soot catalytic combustion.

P10-16: Toxicological effects of diesel exhaust particles observed on human airway cell models using air-liquid interface systems

P10-16: Toxicological effects of diesel exhaust particles observed on human airway cell models using air-liquid interface systems

P21-17: The Impact of Diesel Exhaust Particles on Neurodegeneration: Differential Effects on Glutamatergic and Dopaminergic Neurons in C. elegans

P21-17: The Impact of Diesel Exhaust Particles on Neurodegeneration: Differential Effects on Glutamatergic and Dopaminergic Neurons in C. elegans

Prediction of Strap Joint Design Margin in After Treatment System

The automotive vehicle has an exhaust system, also known as the after treatment System. It consists of different components such as Diesel Oxidation catalysts (DOC), Diesel Particulate Filters (DPF), Selective Catalytic Reduction Systems (SCR), etc. These components are mounted in the chassis with the help of strap joints. The strap joints provide flexible and serviceable connections between ATS bodies and chassis. The strap joint assembly consists of a T bolt, trunnion, and nut with strap. As the nut tightened, the tension induced in the strap, which results in clamping the body. If the tension in the strap is not sufficient, it may cause the failure of the joint. The failure can be yielding of material, slipping, and separation of the body. The strap joint should be designed so that these kinds of failures can be avoided. This paper presents the work on the calculation of the design margin using analytical and FEA methods. The failure modes addressed in this paper are yielding of the strap joint due to applied preload on the T bolt, slipping, and separation of the ATS body from the strap due to the application of dynamic loads such as acceleration G loads in multiple directions. The acceleration load is calculated from the PSD profile. For calculating design margins from the FEA method, nonlinear analysis is performed, followed by PSD analysis to estimate the bracket reaction forces. These reaction forces are used to calculate slip and separation margins. The tests were performed under similar conditions on a shaker table, and the results from both analytical and FEA methods were correlated with test observations to validate the proposed method of calculation of strap join design margin.

CO oxidation under lean and stoichiometric conditions over ceria-zirconia with very low metal contents (Cu, Co, Ag and Pt)

In this work, several ceria-zirconia based catalysts with very low (and equimolar) metal contents were prepared, characterised and tested for the CO oxidation reaction (under lean and stoichiometric conditions), trying to emulate those conditions found in a diesel oxidation catalyst (DOC) system from a diesel engine and those encountered under gasoline exhaust (λ = 1). The metals chosen are Cu, Co, Ag and Pt (as a reliable benchmark). The results reveal enormous differences among reducibility and catalytic activity despite quite similar structural and textural properties of the catalysts, showing differences among dispersion (Ag-catalyst seems to present a low level of dispersion). This catalyst seems to be characterised, as well, by a strong electronic interaction between Ce and Ag centres which is suggested to yield an improved reducibility under H2-TPR conditions. Nevertheless, the order in catalytic activity (Cu > Ag > Co ≈ Pt >> support) seems not to follow the order found in reducibility and the Cu-catalyst seems to be the most active independently on the reaction conditions, yielding nearly overlapped CO oxidation catalytic curves. Interestingly, a strong correlation between the catalytic activity under the two conditions tested and the OSC values of the Ce0.8Zr0.2O2-supported metal catalysts is found. Therefore, OSC parameter measured at 150 °C can be used as a relevant descriptor to evaluate the CO oxidation activity at low and medium conversions for the investigated catalysts, much better than the H2-TPR measurements.

Effects of lubricant components on ash-bridge deposition characteristics in the diesel particulate filter

Diesel particulate filter (DPF), an important after-treatment system, is widely used to trap particulates from diesel engines. After many active regenerations of the DPF, non-volatile ash may form an ash bridge phenomenon in the DPF channel. This paper studies the effects of lubricant components on ash-bridge deposition characteristics in the DPF. Four test lubricants were prepared based on the CK-4 standard lubricant with four different additives (Ca-based, Mg-based, compound, and Zinc dialkyl dithiophosphate (ZDDP) additives), which were separately and proportionately blended into diesel fuel to form four different fuels. A particulate loading and active regeneration cycle of the DPF with those fuels were performed on a burner. The results show that mid-channel ash deposits (MCD) and the ash-bridge phenomenon were observed in the DPF with all four fuels, and the ash-bridge was mainly located in the middle region of the DPF channel. Mg-based or ZDDP additives can improve the ash-channel ratio (A: C) of the MCD. Ca- or Mg-based additives can reduce the distribution density of ash bridges and avoid sintering of DPF. Different shapes of ash bridges will cause different blockage rates in the DPF channel. When the blockage rate of the DPF channel is greater than about 70 %, DPF channels near the ash bridge are destroyed.