Particle Size Distribution Of Material Research Articles

Emission characteristics and size distribution of polycyclic aromatic hydrocarbons from coke production in China

Coking is regarded as a major source of atmospheric polycyclic aromatic hydrocarbons (PAHs), but few researches have been conducted on the emission characteristics of PAHs from coke production. In this study, emissions of size-segregated particulate matter (PM) and particle-bound PAHs emitted from charging of coal (CC) and pushing of coke (PC) in four typical coke plants were determined. The emission factors on average, sums of CC and PC, were 4.65mg/kg, 5.96mg/kg, 19.18μg/kg and 20.69μg/kg of coal charged for PM2.1 (≤2.1μm), PM, PAHs in PM2.1 and total-PAHs, respectively. PM and PAHs emission from plants using stamp charging were significantly more than those using top charging. The profile of PAHs in PM with size ≤1.4μm (PM1.4) emitted from CC process were similar with that from PC, however, it revealed obviously different tendency for PAHs in PM with size >1.4μm, indicating the different formation mechanism for coarse particles emitted from CC and PC. Size distributions of PM and PAHs indicated that they were primarily connected with PM1.4, and the contributions of PM1.4 to PM and PAHs emitted from the plants using stamp charging were higher than those using top charging. Some improved technology in air-pollution control devices should be considered in coke production in future based on the considerable impacts of PM1.4 and PAHs on human health and ambient air quality.

Bioslurry for Stationary Applications: Particulate Matter Emission during Combustion under Air and Oxyfuel Conditions

As a new type of fuel, bioslurry is prepared from mixing bio-oil and biochar produced from biomass fast pyrolysis and is suitable for stationary combustion applications. This study reports the emission of particulate matter (PM) from bioslurry combustion in a lab-scaled drop-tube furnace at 1400 °C under various atmospheres, including air, 20% O2/80% CO2, and 30% O2/70% CO2. Similar to biomass combustion, the particle size distribution (PSD) of PM with an aerodynamic diameter of less than 10 μm (i.e., PM10) during bioslurry combustion also follows a bimodal distribution. Increasing the char loading level in bioslurry leads to an increase in the emission of PM10, especially PM1–10, as a result of the high contents of inorganic species in biochar. Emissions of PM1 and PM1–10 during bioslurry combustion under 20% O2/80% CO2 conditions are lower than those under air conditions, apparently attributed to the lower char combustion temperature. However, under 30% O2/70% CO2 conditions, emission of PM10 during bio...

Reducing energy consumption and increasing filter life in HVAC systems using an aspiration efficiency reducer: Long-term performance assessment at full-scale

The concept of using an aspiration efficiency reducer (AER) in building heating ventilation and air conditioning (HVAC) systems to control particulate air pollution concentrations was previously demonstrated using a 1:4 scale experimental device. The AER acted as a passive form of air pollution control and reduced the particulate loading rate on filters in HVAC systems, thus reducing fan energy consumption. This paper discusses the design considerations that were accounted for in developing a full-scale AER device during a long-term performance assessment. A field assessment of a new full-scale AER device was performed at an urban commercial building in Dublin, Ireland. The results from two air handling units (AHUs), one Control-AHU and one AER-AHU (with an attached AER device), allowed for a comparison of energy consumption and filter lifespans. Particulate matter (PM) and energy consumption in both AHUs were monitored over time for each AER design. The full-scale AER device reduced PM concentration entering the HVAC system by 34% over the operational life cycle of a filter, reducing energy consumption by up to 14%. Alternatively the AER could be used to extend the lifespan of a filter by 75%. The size distribution of PM deposited on the AER and Control filters established that the device was more effective for coarser particles. Energy and filter savings can be achieved using this passive technique, which can translate to environmental, resource and economic savings in the building HVAC sector.

Effects of H2O and HCl on Particulate Matter Reduction by Kaolin under Oxy-coal Combustion

Little work has been performed on the effects of H2O and HCl to particulate matter (PM) reduction by kaolin under oxy-coal combustion. To determine the effect mechanism, a combustion experiment of pulverized coal mixed with kaolin was performed in a drop tube furnace. First, a low-pressure impactor was used as a sampling device to investigate the particle size distribution of PM when H2O and HCl were added during the first stage, and then a special sampling tube was used to collect the combustion products at 950 °C. Besides, the HSC Chemistry 6.0 thermodynamic software was also used for equilibrium calculations of sodium species in the drop tube furnace. The results indicate that H2O can enhance the absolute amount of PM0.2 captured by kaolin through promotion of the generation and diffusion of sodium hydroxide during oxy-coal combustion. However, the increase in PM0.2 generated from coal in the presence of H2O overrides the increase in the PM0.2 captured by kaolin; thus, the ratio of PM0.2 captured by ka...

Important role of volatile–char interactions in enhancing PM1 emission during the combustion of volatiles from biosolid

A three-stage pyrolysis/combustion reactor was used to demonstrate the importance of volatile–char interactions in inorganic particulate matter (PM) emission from the combustion of biosolid volatiles. It consists of a two-stage quartz reactor (including an inner drop-tube/fixed-bed pyrolyser as Stage I and an outer fixed-bed as Stage II) cascaded into a large drop-tube furnace (DTF, Stage III). The unique reactor design enables the volatiles that are produced in situ from the fast pyrolysis of cellulose, polyethylene or acid-washed biosolid in Stage I to pass through a preloaded bed of slow-pyrolysis biosolid char in Stage II then be immediately combusted (achieving complete combustion) in the DTF as Stage III at 1300°C. Limited by quartz maximum working temperature (in Stages I and II), two temperatures (800 or 1000°C) were considered for preparing the bed of char and generating the in situ volatiles. The results clearly show that volatile–char interactions lead to significant changes in the particle size distributions (PSDs) of PM emitted from the combustion of volatiles produced in situ from cellulose, polyethylene or acid-washed biosolid pyrolysis. The volatile–char interactions increase the yield of PM1 (i.e. PM with aerodynamic diameter<1µm), dominantly PM0.1 (i.e. PM with aerodynamic diameter <0.1µm). The results show that small non-oxygenated reactive species (especially H free radicals) in the fresh volatiles can react with the chars to enhance the release of alkalis (Na and K) as well as P and S in the chars. The released Na, K, P and S can react to form alkali metaphosphate and sulphate which subsequently form PM1 during volatiles combustion. It is also evident that volatile–char interactions convert some of Pb and Cr in the biosolid chars into volatile forms which are released and then contribute to PM1 emission.

Experimental Study on Purification of Diesel Particulate Matter by Non-thermal Plasma Technology

In order to investigate the effects of non-thermal plasma (NTP) on diesel particulate matter (PM), an engine test bench was built up. An engine exhaust particle sizer (EEPS) was introduced to analyze the emission concentration and size distribution of PM and a thermo-gravimetric analyzer was used to analyze the effects of NTP on the composition of the particulate matter in the exhaust gas. The results show that the size distribution interval of the particle mass concentration falls behind that of the quantity concentration under various loads. When the diesel engine operating speed is 2400 rpm and the load is 25%, after NTP, the proportions of the nucleation mode particles and the accumulative mode particles exhibit a small fluctuation while the proportion of ultrafine particles decreases by 10% due to their large quantity concentration. Under the dual effect of DPF and NTP, the particle quantity concentration decreases by 98%. In order to investigate the effect of NTP on the composition of the PM, a thermo-gravimetric analysis of the particles obtained before and after NTP was carried out. The results show that the proportion of volatile matter falls by 16.05% and solid carbon accounts for an increase of 7.29%. NTP has the ability to improve reduction activity of particles and make particles easier to be oxidized at a lower temperature.

Experimental study of the gaseous and particulate matter emissions from a gas turbine combustor burning butyl butyrate and ethanol blends

This paper reports the gaseous pollutants and Particulate Matter (PM) emissions of a gas turbine combustor burning butyl butyrate and ethanol blends. The gas turbine has been tested under two operational conditions to represent the cruising (condition 1) and idling (condition 2) conditions of aero engines. Aviation kerosene RP-3 and four different biofuels using butyl butyrate (BB) and ethanol blends were tested and compared to evaluate the impact of fuel composition on CO, NOx, unburnt hydrocarbon (UHC) and PM emissions under selected two operational conditions. The PM number (PN) concentration and size distributions were measured by a scanning mobility particle sizer (SMPS). The compositions of filter borne PM were analysed by ion chromatograph technique. The concentrations of CO, NOx and UHC were detected and analysed by a gas analyser. Results indicated that under idling and cruising conditions the CO emissions from butyl butyrate and ethanol blends were higher than that of RP-3 due to the relatively lower combustion temperature of the biofuels compared with that of RP-3. Results of the NOx emission comparison indicated the biofuels produced less NOx than RP-3 and the increase of ethanol content in the biofuels could reduce the NOx and UHC emissions. The particles smaller than 20nm played a dominant role in PN emissions at condition 1 with the range from 2×106/cm3 to 4×107/cm3. There was a peak value of particle number concentration with the particle size ranging from about 25nm and 40nm. The PN emission index at condition 1 was higher than that at condition 2 for the biofuels, whilst the trend was opposite to that of RP-3. The ions analysis indicated Ca2+ and SO42− were the two dominant ions in the PM emissions of biofuels.

Comparison of airway deposition distributions of particles in healthy and diseased workers in an Egyptian industrial site

The objective of this study is the prediction and comparison of airway deposition patterns of an industrial aerosol in healthy workers and workers suffering from silicosis. Mass concentrations and related size distributions of particulate matter were measured in the industrial area of Samalut in Minia, Egypt. A novel stochastic lung deposition model, simulating the symptoms of silicosis by chronic bronchial (Br) obstruction and emphysema in the acinar (Ac) region, was applied to compute mass deposition fractions, deposition density, deposition rate and deposition density rate distributions in healthy and diseased workers. In the case of healthy workers, both mass deposition fractions and deposition rates are highest in the first half of the Ac region of the lung, while the corresponding deposition density and deposition density rate distributions exhibit a maximum in the large Br airways. In the case of diseased lungs, bullous emphysema causes a large deposition peak in the region of the bronchioli respiratorii. Regional mass deposition fractions adopt maximum values in the extrathoracic region, except during mouth breathing for bullous emphysema, where Ac deposition can be the most prominent. In general, lung deposition is significantly higher in diseased than in healthy lungs. Indeed, workers suffering from silicosis receive significantly higher Ac doses than healthy workers exposed to the same aerosol. Thus, this illness may progress faster if a diseased worker remains in a strongly polluted area.

Size distributions of coastal ocean suspended particulate inorganic matter: Amorphous silica and clay minerals and their dynamics

Particulate inorganic matter (PIM) is a key component in estuarine and coastal systems and plays a critical role in trace metal cycling. Better understanding of coastal dynamics and biogeochemistry requires improved quantification of PIM in terms of its concentration, size distribution, and mineral species composition. The angular pattern of light scattering contains detailed information about the size and composition of particles. These volume scattering functions (VSFs) were measured in Mobile Bay, Alabama, USA, a dynamic, PIM dominated coastal environment. From measured VSFs, we determined through inversion the particle size distributions (PSDs) of major components of PIM, amorphous silica and clay minerals. An innovation here is the extension of our reported PSDs significantly into the submicron range. The PSDs of autochthonous amorphous silica exhibit two unique features: a peak centered at about 0.8 μm between 0.2 and 4 μm and a very broad shoulder essentially extending from 4 μm to >100 μm. With an active and steady particle source from blooming diatoms, the shapes of amorphous silica PSDs for sizes <10 μm varied little across the study area, but showed more particles of sizes >10 μm inside the bay, likely due to wind-induced resuspension of larger frustules that have settled. Compared to autochthonous amorphous silica, the allochthonous clay minerals are denser and exhibit relatively narrower PSDs with peaks located between 1 and 4 μm. Preferential settling of larger mineral particles as well as the smaller but denser illite component further narrowed the size distributions of clay minerals as they were being transported outside the bay. The derived PSDs also indicated a very dynamic situation in Mobile Bay when a cold weather front passed through during the experiment. With northerly winds of speeds up to 15 m s−1, both amorphous silica and clay minerals showed a dramatic increase in concentration and broadening in size distribution outside the exit of the barrier islands, indicative of wind-induced resuspension and subsequent advection of particles out of Mobile Bay. While collectively recognized as the PIM, amorphous silica and clay minerals, as shown in this study, possess very different size distributions. Considering how differences in PSDs and the associated particle areas will effect differences in sorption/desorption properties of these components, the results also demonstrate the potential of applying VSF-inversion in studying biogeochemistry in the estuarine-coastal ocean system.

Emission of particulate matter from gasification and melting furnace for municipal solid waste in Japan

The size distribution and removal efficiency of particulate matter (PM) as primary particles from three gasification and melting furnaces for municipal solid waste (MSW) with state-of-the-art technologies for air pollution control devices (APCDs) were investigated by direct PM sampling using a nine-stage cascade impactor to show emissions and impact of PM2.5 from thermal treatment of MSW in Japan. PM distributions showed that most PM was fine particles, and that coarse particles were more efficiently removed than fine particles. PM and PM2.5 concentrations at the APCD inlets were 1312±63 and 794±119mg/Nm3, and 1415±225 and 763±327mg/Nm3 from shaft-type furnaces and fluidized bed and swirl-flow furnaces, respectively. The removal efficiencies of PM and PM2.5 by APCDs were over 99.96% in all plants, and one plant with a bag filter–selective catalytic reduction (BF–SCR) system and another with a BF–wet scrubber–SCR–BF system achieved over 99.99%. PM and PM2.5 emissions from gasification and melting of MSW in Japan were 8.85 and 5.52 Mg/yr, respectively, contributing 3.0% and 2.5% of total PM and PM2.5 emissions from thermal treatment of MSW in Japan. The PM and PM2.5 emissions were effectively controlled by state-of-the-art APCDs.

Impact of size distributions of major chemical components in fine particles on light extinction in urban Guangzhou

To evaluate the impact of fine particulate matter (PM2.5) size distribution on aerosol chemical and optical properties, dominant chemical components including water-soluble inorganic ions (WSII), organic carbon (OC) and elemental carbon (EC) in PM1 and PM2.5, aerosol scattering coefficient (bsp), and aerosol absorption coefficient (bap) were collected synchronously at an urban site in Guangzhou, south China during a typical summer month in 2009 and a winter month in 2010. PM1 (sizes smaller than 1μm) constituted 77% and 63% of PM2.5 in summer and winter, respectively. From the reconstructed mass concentrations, the sum of SO42−, NO3− and NH4+ (SNA) distributed more in PM1 than in PM1–2.5 (PM2.5 minus PM1) in summer and the opposite was found in winter, while carbonaceous aerosols distributed more in PM1 in both summer and winter. With the aggravation of PM2.5 pollution, the mass fraction of PM1/PM2.5 increased for (NH4)2SO4 (AS), NH4NO3 (AN) and EC but decreased for organic matter (OM) in summer, and the opposite was found in winter. Bsp of PM1 and PM1–2.5 was estimated from the mass extinction efficiencies (MSEs) of the dominant chemical components, which showed good correlations (R2=0.99) with measured ones and those estimated using the IMPROVE formula. The fractional contributions of dominant chemical components to extinction coefficient (bext) were consistent with their respective mass size distributions, indicating the importance of chemically-resolved aerosol size distributions on aerosol optical properties and haze formation.

Detailed Analysis of Criteria and Particle Emissions from a Very Large Crude Carrier Using a Novel ECA Fuel.

Ocean going vessels (OGVs) operating within emission control areas (ECA) are required to use fuels with ≤0.1 wt % sulfur. Up to now only distillate fuels could meet the sulfur limits. Recently refiners created a novel low-sulfur heavy-fuel oil (LSHFO) meeting the sulfur limits so questions were posed whether nitric oxide (NOx) and particulate matter (PM) emissions were the same for the two fuels. This project characterized criteria pollutants and undertook a detailed analysis of PM emissions from a very large crude oil carrier (VLCC) using a distillate ECA fuel (MGO) and novel LSHFO. Results showed emission factors of NOx were ∼5% higher with MGO than LSHFO. PM2.5 emission factors were ∼3 times higher with LSHFO than MGO, while both were below values reported by Lloyds, U.S. EPA and CARB. A detailed analysis of PM revealed it was >90% organic carbon (OC) for both fuels. Elemental carbon (EC) and soot measured with an AVL microsoot sensor (MSS) reflected black carbon. PM size distributions showed unimodal peaks for both MGO (20-30 nm) and LSHFO (30-50 nm). Particle number (PN) emissions were 28% and 17% higher with the PPS-M compared to the SMPS for LSHFO and MGO, respectively.

Particle size distribution of cultivable airborne microbes and inhalable particulate matter in a wastewater treatment plant facility

A field study was performed to identify the size distribution characteristics of viable, cultivable airborne microorganisms (heterotrophic bacteria, fungi, and total coliforms) at a municipal wastewater treatment facility, and their association with inhalable particulate matter (PM1, PM2.5, and PM10), as well as hydrogen sulfide concentrations and ambient meteorological parameters. The highest concentrations of cultivable, airborne heterotrophic bacteria, total coliforms, mass and number concentration of particulate matter, as well as hydrogen sulfide were observed at the aerated grit removal chambers at the pretreatment stage (3 to 2030 times higher than the values of the background ambient air). In contrast, the mean concentrations of cultivable, airborne mesophilic fungi at the aerated grit chambers were 0.6 time lower than the background site, where fungi presented the most abundant taxonomic group in the ambient air. Although the highest concentrations of the airborne fungi were determined at aerodynamic diameters between 2.1 and 3.3 μm, a nearly equal distribution of the mean concentrations of the cultivable, airborne heterotrophic bacteria were observed in the six different size fractions at the primary settling tanks and in the ambient air. Interestingly, their size distribution profiles at the aerated grit chambers were different and showed a maximum aerodynamic diameter at the size range from 3.3 to 4.7 μm, similar to that of the cultivable, airborne total coliforms. In general, low positive or no significant linear relationships could be found between the cultivable airborne heterotrophic bacteria, total coliforms, or fungi at the two wastewater treatment stages and the ambient background microbial community.

Mass Concentration and Size-Distribution of Atmospheric Particulate Matter in an Urban Environment

To investigate the ambient mass concentration, size-distribution and temporal variability of atmospheric particulate matter (PM), a long-term monitoring campaign was undertaken at an urban background site in Como, Northern Italy, from May 2015 to March 2016. A 13-stage Low Pressure Impactor (DLPI) was used for the collection of size-segregated particulates in the 0.028-10 μm size range. The results revealed a good level of agreement between DLPI and a co-located Harvard-type PM_(2.5) Impactor, allowing them to be classified as comparable and characterized by a reciprocal predictability. The PM concentration levels varied greatly between the different 5-days monitoring sessions, with higher mean mass concentrations during the heating season. Appreciable seasonal differences were found for particles between 0.15 and 1.60 μm that, on average, registered concentration levels 3.5 times higher during the heating season (mean: 28.2 μg m^(-3); median: 24.4 μg m^(-3)) compared to the non-heating season (mean: 8.3 μg m^(-3); median: 7.6 μg m^(-3)). No relevant and significant differences were detected for the coarser ranges (＞ 1.60 μm). Temporal variabilities were influenced by typical PM urban sources (e.g., household heating, traffic), that significantly affected fine and submicrometer particles, and were related to meteorological factors. Ambient air particles exhibited a trimodal distribution: a first and sharp peak more pronounced during the heating season was identified between 0.3 and 0.5 μm and two other slight peaks in the coarse mode were centered on approximately 3 and 8 μm. No relevant differences were found in the shape of the size-distribution between the two investigated seasons. The mean PM_(2.5) (22.4 μg m^(-3)) and PM_(10) (27.7 μg m^(-3)) concentrations monitored in the study area exceeded the annual Air Quality Guideline Values (respectively equal to 10 μg m^(-3) and 20 μg m^(-3)) established by the World Health Organization.

Coarse-Particle Passive-Sampler Measurements and Single-Particle Analysis by Transmitted Light Microscopy at Highly Frequented Motorways

ABSTRACTMeasuring and characterizing airborne particulate matter (PM) is an important research area because PM can lead to impacts on health and to visibility reduction, material damage and groundwater pollution. In regard to road dust, suspension and re-suspension and the contribution of non-exhaust PM to total traffic emissions are expected to increase as a result of predicted climate scenarios. European environmental regulations have been enforced to reduce exhaust particle emissions from road traffic, but little attention has been paid to reducing non-exhaust coarse particle emissions due to traffic. Therefore, a monitoring program for coarse PM has been initiated in early 2013 to assess the predicted increase in the abundance of non-exhaust particles. Particle sampling was performed with the passive-sampler technique Sigma-2. The subsequent single-particle analysis allows for characterization of individual particles, determination of PM size distribution, and calculation of PM mass concentrations. Two motorways near Cologne (Koln), Germany were selected as sampling sites, and the experimental setup in the field was realized with a so-called twin-site method. The present study reports single-particle analysis data for samples collected between May 31, 2013 and May 30, 2014. Coarse PM, generated through multi-source mechanisms, consists of, e.g., tire-wear, soot aggregates, and mineral dust. The highest mass concentration occurs at both motorways in spring, and the observed PM mainly contains traffic-abrasion particles. The field measurements show that the minimum PM concentration was found in the 5 to 12°C temperature range, whereas the maximum concentration was observed in both the –5 to 5°C and the 12 to 24°C ranges, in agreement with previous laboratory measurements. Correlation between super-coarse (dp 10–80 µm, geometric equivalent diameter) PM concentration and precipitation displays a significant increase in concentration with decreasing number of precipitation events (dry weather periods).

A novel Ti-based sorbent for reducing ultrafine particulate matter formation during coal combustion

Ultrafine particulate matter (PM) is an important part of PM2.5, which is enriched with hazardous components and more harmful; meanwhile it cannot be effectively removed by the common-used dust collectors. In-furnace sorbent injection is an emerging technology to reduce the emission of PM in the coal combustion and the sorbent is a key factor determining its feasibility. In this study, to seek new PM sorbents, eight minerals were first separately added into a pulverized coal and burned in a drop-tube furnace (DTF) at 1773K. The derived PM was collected via a Dekati Low pressure impactor (DLPI) sampling system and impacts of each mineral on the PM emission were evaluated. Then, the tested minerals were burned with pure sodium acetate (NaAc) under the same conditions to determine their Na fixation abilities. Finally, the PM reduction mechanism of the sorbent was discussed based on the particle size distribution, mass yield, composition and micromorphology of PM and the chemical and physical properties of the sorbent. A novel Ti-based PM reduction sorbent was screened out, which exhibited an ultrafine PM (PM0.2) reduction efficiency of ∼39% under the experimental conditions at an addition ratio of 5% (wt.%, coal basis). The Ti-based sorbent reacted with Na-contained vapour and formed sodium titanates. Fixation of the Na-contained vapour by the sorbent was considered to be the primary PM capture mechanism. What’s more, the high sintering temperature of the Ti-based sorbent facilitates its PM reduction performance. Under the high temperature combustion conditions, the Ti-based sorbent exhibited a good performance in capturing ultrafine PM and Na-contained vapour, indicating its potential of being a high temperature sorbent.

Size distribution analysis of airborne wear particles released by subway brake system

Contributions of exhaust and non-exhaust sources to traffic-related particulate matter (PM) pollution in the atmosphere are almost identical and the most important non-exhaust source is known to be brake wear particles. In order to understand the properties and harmful effects of wear particles on people, accurate information on size distribution of brake wear particles is needed. Our previous study investigated the measured changes in size distribution of nanoparticles of 500nm or smaller to understand the origin of nanoparticles due to temperature increases on the friction surface. The present study was intended to investigate the characteristics of size distribution (5.6nm–32μm) of PM released under different braking conditions by using different instruments. The measurement results under 9 braking conditions using 3 different instruments showed that the size distribution characteristics of particles can be divided into two main types according to braking energy. The first type is of PM up to 10 μm in size and with a peak number concentration at 0.2–0.75μm regardless of braking energy, while the second type is of PM around 10nm in size generated only when braking energy increased and particles that increased up to 100nm. In addition, we found that the size distributions measured by the optical particle counter (OPC) and the aerodynamic particle sizer (APS) were consistent by assuming a mean diameter ratio of two instruments.

Influence of PM Size Distribution and Ingredients on DPF Regeneration by Non-thermal Plasma Technology

Experimentation was conducted to analyze the diesel particulate filters (DPF) trap under four different engine loads with particle size analysis and thermo-gravimetric analysis introduced to characterize particulate matter (PM) samples. DPF regeneration was achieved utilizing an oxygen-fed non-thermal plasma (NTP) injection system. Results indicated that accompanying the increase of engine load, the concentration of nucleation mode particles decrease while that of accumulation mode particles and the total concentration number increase at first and then decrease with the total concentration number of PM peaking at 50% load. H2O and soluable organic fraction in PM demonstrate a downward trend while dry soot exhibits an upward trend in mass fraction with the increasing load. NTP may then separate PM into CO and CO2. Size distribution and ingredients of PM trapped by DPF under different loads vary, thus the intensity of reaction between PM and radical gases produced by NTP is different. C1 (C in CO) exhibited a declining trend with the increasing of engine load, while C2 (C in CO2) and C12 (sum of C1 and C2) increase first and decrease after. Mass of PM removal maximizes at 50% load while DPF regeneration effect is the most remarkable.

A network model to assess base-filter combinations

Granular filters retain base material within the narrowest constrictions of their void network. A direct comparison of the base material particle size distribution (PSD) and the filter constriction size distribution (CSD) cannot easily be used to assess filter-base compatibility. Here a conceptually simple random-walk network model using a filter CSD derived from discrete element modelling and base PSD is used to assess filter-base compatibility. Following verification using experimental data the model is applied to assess empirical ratios between filter and base characteristic diameters. The effects of filter density, void connectivity and blocking in the first few filter layers are highlighted.

Implications of the aerosol size distribution modal structure of trace and major elements on human exposure, inhaled dose and relevance to the PM2.5 and PM10 metrics in a European pollution hotspot urban area

The size distributions of atmospheric aerosol mass and several major and trace elements were studied in an urban area in South Poland. 24h ambient aerosol samples were collected by means of the thirteen stages Dekati low pressure impactor, in an industrial urban area during summer and winter campaigns in 2007 and 2008. Ambient PM (particulate matter) mass size distribution appeared to have a tri-modal pattern, with a predominant peak in the fine fraction (<1µm). The elemental mass (EM) size distributions also appeared to have multi-modal structure. Based on the patterns of the mean elemental mass size distributions, the detected elements were classified into three groups. The 1st group (A) contains elements with multimodal size distribution and predominant fine mode, namely: S, Zn, Pb, Br, Sb, As, Cl and Cd. The 2nd group (B) includes elements (Fe and Ca) with a predominant mode in the coarse size range. The 3rd group (C) contains elements with broad size distributions (K, Cr, Mn and Cu); both fine and coarse particles significantly contribute to the total elemental mass concentration. The total and regional inhaled dose of ambient PM and the detected elements in human respiratory tract (RT) was estimated, applying the Multiple Path Dosimetry model (MPPD-V2.11). Overall, the total PM mass deposition fractions in the Head air ways (H), Trachea and Bronchiolar (TB) and Pulmonary alveolar (P) regions were found equal to 0.42, 0.04 and 0.08, respectively. The same dosimetry analysis was applied for each element, taking into account the characteristics of their size distribution patterns. It was found that the highest amount of the elemental masses was deposited in the upper region of the RT. The average elemental mass deposition fractions were 0.35±0.08, 0.77±0.07 and 0.49±0.06 for the elements included in the groups A, B and C, respectively. The mass deposition fractions for the lower region of the RT were: 0.05±0.01 (TB) and 0.09±0.01 (P) for group A, 0.02±0.01 (TB) and 0.05±0.02 (P) for B, and 0.04±0.01 and 0.09±0.02 for C. Additionally, a comparison was performed between the inhaled dose estimated from concentration levels corresponding to the PM2.5 and PM10 mass fractions, when a mean particle size is allocated to the fine and coarse fractions of the aerosol mass, and the inhaled dose calculated from highly resolved mass size distribution of PM and individual trace and major elements. The results revealed that for most elements the total inhaled dose in the TB&P region can be adequately estimated from concentration levels and mean particle size characteristics of either PM10 or PM2.5 size fractions; average absolute difference 13% (6% (A), 41% (B), 11% (C)) and 26% (16% (A), 56% (B), 29% (C)), respectively. Significant deviations may be observed in the estimation of the inhaled dose in the H-region, particularly when calculation is based on PM2.5 concentration levels; average absolute difference 59% (44% (A), 92% (B), 71% (C)).