Volume Of Particulate Matter Research Articles

Simulation Study on Influence of Fuel Injection Strategy on Regeneration Performance of Catalytic Particle Filter

The influence rule of fuel injection strategy on regeneration performance of catalytic particle filter (CPF) will be studied in this paper, through using system dynamics, GT-POWER and AVL FIRE to build and match respectively the onedimensional complete machine model of D19 high pressure common rail diesel engine of variable geometry turbocharger (VGT) and the three-dimensional simulation model of CPF, which are based upon the 50% load working condition with 3000r/min. The study shows that with the delay of main injection timing, the regeneration rate of CPF gradually increase, simultaneously, residual volume of particulate matter (PM), pressure drop and NO2 of CPF at exit end decrease. At the earlier main injection timing, with increasing exhaust gas recirculation (EGR) rate, regeneration rate of CPF is decreasing and residual volume of PM is increasing dramatically. At the later main injection timing, with increasing EGR rate, PM residual volume shows trend of rise then descend. Adoption of post injection benefits for regeneration of CPF, with delay of post injection timing, pressure drop and PM residual volume of CPF both show trend of rise then descend, the post injection timing corresponding with the best efficiency of CPF regeneration will be forward lead with increasing of EGR rate. Appropriately enhancing amount of post injection will benefit for regeneration of CPF. And, the negative effect of CPF regeneration will be increased when using post injection and later timing to rise EGR rate.

Chemical and Morphological Characteristics of Particulate Matter Suspended in the Air of the Dhaka University Area of Bangladesh

Total suspended particulate matter (SPM) in the urban atmosphere of Dhaka city was collected using a high volume sampling technique for a period of one month (August 2017-September 2017). Chemical characterization of particulate matter (PM) was investigated, and characterized concerning the size distribution, morphological features such as count, total area, average size, perimeter, circularity, aspect ratio (AR), roundness; equivalent spherical diameter (ESD), surface area and volume of PM. The results of elemental analysis showed that the presence of heavy metal in PM was ten to hundred times higher than the standard value prescribed by WHO and USEPA. Several morphological analysis indicated that particles varying in shape from nearly spherical to various irregular shape, had higher surface energy, higher content of Cl and S bearing particles and had a large surface area which can cause greater damage to lungs. The presence of various organic compounds containing functional groups like alcohols, ketones aldehydes, carboxylic acids as well as unsaturated and saturated carbon bonds was observed by FT-IR analysis. Scanning Electron Microscopy (SEM) was used to characterize the morphology of the PM. Agglomerates and shoots type particles were mostly seen in SPM.

Source apportionment of ambient particle number concentrations in central Los Angeles using positive matrix factorization (PMF)

Abstract. In this study, the positive matrix factorization (PMF) receptor model (version 5.0) was used to identify and quantify major sources contributing to particulate matter (PM) number concentrations, using PM number size distributions in the range of 13 nm to 10 µm combined with several auxiliary variables, including black carbon (BC), elemental and organic carbon (EC/OC), PM mass concentrations, gaseous pollutants, meteorological, and traffic counts data, collected for about 9 months between August 2014 and 2015 in central Los Angeles, CA. Several parameters, including particle number and volume size distribution profiles, profiles of auxiliary variables, contributions of different factors in different seasons to the total number concentrations, diurnal variations of each of the resolved factors in the cold and warm phases, weekday/weekend analysis for each of the resolved factors, and correlation between auxiliary variables and the relative contribution of each of the resolved factors, were used to identify PM sources. A six-factor solution was identified as the optimum for the aforementioned input data. The resolved factors comprised nucleation, traffic 1, traffic 2 (with a larger mode diameter than traffic 1 factor), urban background aerosol, secondary aerosol, and soil/road dust. Traffic sources (1 and 2) were the major contributor to PM number concentrations, collectively making up to above 60 % (60.8–68.4 %) of the total number concentrations during the study period. Their contribution was also significantly higher in the cold phase compared to the warm phase. Nucleation was another major factor significantly contributing to the total number concentrations (an overall contribution of 17 %, ranging from 11.7 to 24 %), with a larger contribution during the warm phase than in the cold phase. The other identified factors were urban background aerosol, secondary aerosol, and soil/road dust, with relative contributions of approximately 12 % (7.4–17.1), 2.1 % (1.5–2.5 %), and 1.1 % (0.2–6.3 %), respectively, overall accounting for about 15 % (15.2–19.8 %) of PM number concentrations. As expected, PM number concentrations were dominated by factors with smaller mode diameters, such as traffic and nucleation. On the other hand, PM volume and mass concentrations in the study area were mostly affected by sources with larger mode diameters, including secondary aerosols and soil/road dust. Results from the present study can be used as input parameters in future epidemiological studies to link PM sources to adverse health effects as well as by policymakers to set targeted and more protective emission standards for PM.

Determination of PM mass emissions from an aircraft turbine engine using particle effective density

Inventories of particulate matter (PM) emissions from civil aviation and air quality models need to be validated using up-to-date measurement data corrected for sampling artifacts. We compared the measured black carbon (BC) mass and the total PM mass determined from particle size distributions (PSD) and effective density for a commercial turbofan engine CFM56-7B26/3. The effective density was then used to calculate the PM mass losses in the sampling system. The effective density was determined using a differential mobility analyzer and a centrifugal particle mass analyzer, and increased from engine idle to take-off by up to 60%. The determined mass-mobility exponents ranged from 2.37 to 2.64. The mean effective density determined by weighting the effective density distributions by PM volume was within 10% of the unit density (1000 kg/m3) that is widely assumed in aircraft PM studies. We found ratios close to unity between the PM mass determined by the integrated PSD method and the real-time BC mass measurements. The integrated PSD method achieved higher precision at ultra-low PM concentrations at which current mass instruments reach their detection limit. The line loss model predicted ∼60% PM mass loss at engine idle, decreasing to ∼27% at high thrust. Replacing the effective density distributions with unit density lead to comparable estimates that were within 20% and 5% at engine idle and high thrust, respectively. These results could be used for the development of a robust method for sampling loss correction of the future PM emissions database from commercial aircraft engines.

Patterns of Retention of Particulate Matter in Lung Tissues of Patients With COPD: Potential Role in Disease Progression

Particulate matter (PM) is present in lung tissues of smokers and urban dwellers. This study was designed to quantify the burden of PM in different lung tissues of subjects with COPD and determine its relationship to disease severity. Surgical lung tissue samples from nonsmokers (control subjects) were compared with those from smokers with normal spirometry and subjects in the four other categories of the GOLD (Global Initiative for Obstructive Lung Disease) classification of COPD severity using quantitative histologic techniques. PM was present in the lung parenchyma, blood vessel walls, airways, lymphoid follicles, and alveolar macrophages. The total burden of PM (volume fraction [Vv]) in all tissues of the lung was higher in smokers than nonsmokers (P < .001) and also in smokers with airflow obstruction compared with the smokers with normal spirometry (P < .01). There was an incremental increase in total PM burden with increased COPD severity that peaked in GOLD II and then trended downward in GOLD III and IV COPD. This same pattern of PM retention was also observed in alveolar walls. The total burden of PM in lung tissues correlated with a decline in FEV(1)/FVC as well as pack-years smoking. mRNA expression of fibrinogen (γ chain) correlated with total lung burden of PM and burden of PM in lung parenchyma (r(2) = 0.22, P < .001). We conclude that retained PM is widely distributed in lung tissues of subjects with COPD and that cigarette smoke exposure and airflow obstruction are associated with retention of PM in lung tissues. We attribute the downward trend in PM burden in severe COPD to either less deposition and retention or selective removal of PM containing tissues by emphysematous destruction.

PMF Analysis of Wide-Range Particle Size Spectra Collected on a Major Highway

Particle number concentration data have been collected on a very busy road in central London (Marylebone Road). Continuous size distributions from 15 nm to 10 μm diameter, collected over 21 days, were analyzed using positive matrix factorization which identified 10 factors, five of which were observed to make major contributions (greater than 8%) to either the total number or volume of particulate matter. The sources associated with each factor were identified from the size distribution, directional association, diurnal variation and their relationship to meteorological pollution and traffic volume variables. The factors related to the emissions on Marylebone Road accounted for 40.5% of particle volume and 71.9% of particle number. These comprised nucleation mode exhaust particles (3.6% of total volume and 27.4% of total number), solid mode exhaust particles (18.8% of total volume and 38.0% of total number), brake dust (13.7% of total volume and 1.7% of total number and resuspension (4.4% of total volume and 4.8% of total number). Another six factors were associated with the urban background accounting for 59.5% of total volume and 28.2% of total particle number count. The method is extremely successful at separating the components of on-road emissions including brake wear and resuspension.

A comparative study of nucleation parameterizations: 2. Three‐dimensional model application and evaluation

Following the examination and evaluation of 12 nucleation parameterizations presented in part 1, 11 of them representing binary, ternary, kinetic, and cluster‐activated nucleation theories are evaluated in the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) modeling system version 4.4. The 12–28 June 1999 Southern Oxidants Study episode is selected as a testbed to evaluate simulated particulate matter (PM) number and size predictions of CMAQ with different nucleation parameterizations. The evaluation shows that simulated domain‐wide maximum PM2.5 number concentrations with different nucleation parameterizations can vary by 3 orders of magnitude. All parameterizations overpredict (by a factor of 1.4 to 1.7) the total number concentrations of accumulation‐mode PM and significantly underpredict (by factors of 1.3 to 65.7) those of Aitken‐mode PM, resulting in a net underprediction (by factors of 1.3 to 13.7) of the total number concentrations of PM2.5 under a polluted urban environment at a downtown station in Atlanta. The predicted number concentrations for Aitken‐mode PM at this site can vary by up to 3 orders of magnitude, and those for accumulation‐mode PM can vary by up to a factor of 3.2, with the best predictions by the power law of Sihto et al. (2006) (NMB of −31.7%) and the worst predictions by the ternary nucleation parameterization of Merikanto et al. (2007) (NMB of −93.1%). The ternary nucleation parameterization of Napari et al. (2002) gives relatively good agreement with observations but for a wrong reason. The power law of Kuang et al. (2008) and the binary nucleation parameterization of Harrington and Kreidenweis (1998) give better agreement than the remaining parameterizations. All the parameterizations fail to reproduce the observed temporal variations of PM number, volume, and surface area concentrations. The significant variation in the performance of these parameterizations is caused by their different theoretical bases, formulations, and dependence on temperature, relative humidity, and the ambient levels of H2SO4 and NH3. The controlling processes are different for PM number, mass, and surface areas. At urban/rural locations, some PM processes (e.g., homogeneous nucleation) and/or vertical transport may dominate the production of PM2.5 number, and emissions, or PM processes, or vertical transport or their combinations may dominate the production of PM2.5 mass and surface area. Dry deposition or some PM processes such as coagulation may dominate PM2.5 number loss, and horizontal and vertical transport, and cloud processes (e.g., cloud scavenging and wet deposition) may dominate the loss of PM2.5 mass and surface area concentrations. Sensitivity simulations show that the PM number and size distribution predictions are most sensitive to prescribed emission fractions of Aitken and accumulation‐mode PM and the assumed initial PM size distribution, in addition to different nucleation parameterizations.

An evaluation of indoor and outdoor biological particulate matter

The incidences of allergies, allergic diseases and asthma are increasing world wide. Global climate change is likely to impact plants and animals, as well as microorganisms. The World Health Organization, U.S. Environmental Protection Agency, U.S. Department of Agriculture, U.S. Department of Health and Human Services, and the Intergovernmental Panel on Climate Change cite increased allergic reactions due to climate change as a growing concern. Monitoring of indoor and ambient particulate matter (PM) and the characterization of the content for biological aerosol concentrations has not been extensively performed. Samples from urban and rural North Carolina (NC), and Denver (CO), were collected and analyzed as the goal of this research. A study of PM 10 (<10 μm in aerodynamic diameter) and PM 2.5 (<2.5 μm in aerodynamic diameter) fractions of ambient bioaerosols was undertaken for a six month period to evaluate the potential for long-term concentrations. These airborne bioaerosols can induce irritational, allergic, infectious, and chemical responses in exposed individuals. Three separate sites were monitored, samples were collected and analyzed for mass and biological content (endotoxins, (1,3)-β- d-glucan and protein). Concentrations of these bioaerosols were reported as a function of PM size fraction, mass and volume of air sampled. The results indicated that higher concentrations of biologicals were present in PM 10 than were present in PM 2.5, except when near-roadway conditions existed. This study provides the characterization of ambient bioaerosol concentrations in a variety of areas and conditions.

Relationships of food uptake and body components of Calanus finmarchicus, C. glacialis and C. hyperboreus to particulate matter and water characteristics in Fram Strait

During MIZEX'83 and MIZEX'84 food composition and food uptake by three Calanus species were investigated in the northern Greenland Sea. Samples were obtained from open water, the marginal ice zone, the pack ice region and the East Greenland shelf polynya. Food uptake of Calanus spp. was determined in ship-board incubation experiments under in situ conditions and volume of particulate matter in the upper 300 m of the water column was measured. Principal components analysis was used for data evaluation. Under the pack ice strongly reduced amounts of particulate matter in the euphotic zone were found while concentrations were elevated in the marginal ice zone and the East Greenland shelf polynya. Food uptake of C. finmarchicus was correlated to food concentration. In the pack ice region ingestion was close to zero for all species investigated. Likewise body weights were significantly lower than in MIZ or polynya. Principal components analysis of physical data shows a clustering of MIZ station groups at high temperature and salinity, clearly separated from pack ice and polynya stations. Analysis of biological data results in the same grouping of stations demonstrating a strong influence of hydrographic conditions on plankton development. It is concluded that herbivorous copepods cannot sustain themselves in the pack ice region but only at places of high productivity like marginal ice zone and East Greenland shelf polynya.

The relation of concentration and size distribution of suspended particulate matter to hydrography in Onslow Bay, North Carolina

The volume and size distribution of particulate matter was related to hydrographic conditions in bottom water masses (intrusions) that move on to the continental shelf off North Carolina from greater depths of the Gulf Stream. In all instances, the volume of particulate matter in intruded waters was greater than that in surface waters. Particle volumes, compared in three particle size ranges between 2 and 101 μm, had maxima in the range of 25 to 101 μm. Juvenile stages of zooplankton were abundant in the intrusions. These presumably feed only on particles smaller than 25 μm dia. and thus have little impact on large diatoms.