Diesel Particulate Matter Emissions Research Articles

Soot Reduction Strategy: A Review

The aim of study is soot reduction strategy by using microwave radiation. As a first step toward the aim is a review. This study provides a review of soot particles generation and their influence on air pollution and illustrates the diesel particulate matter emission regulation, composition, and characterization including size, shape, process, and oxidation. The paper also discusses the effect of temperature, pressure, air/fuel ratio, exhaust flow rate, fuel type on soot process and heat release from soot combustion. The use of filter regeneration strategies for reducing soot emission from vehicles, stationary plants and factories due to the burning of diesel fuel have been presented with advantage and disadvantage of each method. The various strategies include catalyst, fuel injection, electric heating, engine operation condition control, non-thermal plasma, and absorbed microwave energy. The practical feasibility for soot oxidation by microwave heating technique has been explained depending on soot material property. The proposed new technique utilizing the reflected and absorbed energies of microwave for soot reduction strategy is presented to develop a new emission after-treatment system. The new system will be modeled and simulated using appropriate software. The simulation results will be validated experimentally. © 2012 Asian Network for Scientific Information.

A comparative study of the number and mass of fine particles emitted with diesel fuel and marine gas oil (MGO)

The current investigation reports on diesel particulate matter emissions, with special interest in fine particles from the combustion of two base fuels. The base fuels selected were diesel fuel and marine gas oil (MGO). The experiments were conducted with a four-stroke, six-cylinder, direct injection diesel engine. The results showed that the fine particle number emissions measured by both SMPS and ELPI were higher with MGO compared to diesel fuel. It was observed that the fine particle number emissions with the two base fuels were quantitatively different but qualitatively similar. The gravimetric (mass basis) measurement also showed higher total particulate matter (TPM) emissions with the MGO. The smoke emissions, which were part of TPM, were also higher for the MGO. No significant changes in the mass flow rate of fuel and the brake-specific fuel consumption (BSFC) were observed between the two base fuels.

Chemical Speciation of Vanadium in Particulate Matter Emitted from Diesel Vehicles and Urban Atmospheric Aerosols

We report on the development and application of an integrated set of analytical tools that enable accurate measurement of total, extractable, and, importantly, the oxidation state of vanadium in sub-milligram masses of environmental aerosols and solids. Through rigorous control of blanks, application of magnetic-sector-ICPMS, and miniaturization of the extraction/separation methods we have substantially improved upon published quantification limits. The study focused on the application of these methods to particulate matter (PM) emissions from diesel vehicles, both in baseline configuration without after-treatment and also equipped with advanced PM and NO(x) emission controls. Particle size-resolved vanadium speciation data were obtained from dynamometer samples containing total vanadium pools of only 0.2-2 ng and provide some of the first measurements of the oxidation state of vanadium in diesel vehicle PM emissions. The emission rates and the measured fraction of V(V) in PM from diesel engines running without exhaust after-treatment were both low (2-3 ng/mile and 13-16%, respectively). The V(IV) species was measured as the dominant vanadium species in diesel PM emissions. A significantly greater fraction of V(V) (76%) was measured in PM from the engine fitted with a prototype vanadium-based selective catalytic reductors (V-SCR) retrofit. The emission rate of V(V) determined for the V-SCR equipped vehicle (103 ng/mile) was 40-fold greater than that from the baseline vehicle. A clear contrast between the PM size-distributions of V(V) and V(IV) emissions was apparent, with the V(V) distribution characterized by a major single mode in the ultrafine (<0.25 μm) size range and the V(IV) size distribution either flat or with a small maxima in the accumulation mode (0.5-2 μm). The V(V) content of the V-SCR PM (6.6 μg/g) was 400-fold greater than that in PM from baseline (0.016 μg/g) vehicles, and among the highest of all environmental samples examined. Synchrotron based V 1s XANES spectroscopy of vanadium-containing fine-particle PM from the V-SCR identified V(2)O(5) as the dominant vanadium species.

Analysis of Diesel Particulate Matter Health Risk Disparities in Selected US Harbor Areas

People near major transportation emissions sources experience higher exposure to hazardous pollutants. We present population size and demographic composition estimates for exposure to diesel particulate matter (DPM) exhaust from US harbor activities. We examined 43 US marine harbor areas to determine outdoor, ambient concentrations from port-related DPM emissions and then determined intake fractions of those emissions in each harbor area. We estimated the distribution of health risk by combining ambient concentrations with exposure and carcinogenic risk factors. We assessed demographic differences by stratifying the health risks by race/ethnicity and income. Intake fractions for 42 of the harbor areas ranged from 0.02 × 10(-6) to 3.66 × 10(-6). A DPM-affected population of more than 4 million has a risk level greater than 100 per million; a population of 41 million, a risk level greater than 10 per million. Most exposures occur in a small number of marine harbor areas. Low-income households and both Hispanics and non-Hispanic Blacks are overrepresented in the affected populations. The most important factor for predicting DPM intake fractions for harbor activities is the proximate population density. The largest uncertainty in predicting DPM carcinogenic health risk is the carcinogenic inhalation unit risk factor.

Application and performance test of a micro-machined unipolar charger for real-time measurements of exhaust particles from a diesel engine vehicle

Characterization of particulate matter (PM) emitted from diesel vehicle exhaust requires a real-time measurement sensor to record particle concentrations under transient tests. Recently, a micro-machined unipolar charger (MUC) based on a micro-electromechanical system (MEMS) was introduced and evaluated to test aerosol particles on a laboratory scale. We present the performance characteristics of the MUC for its potential use as a sensor for diesel PM emissions. A correlation equation was derived from particle loss experiments and tandem differential mobility analyzer (TDMA) measurements in the laboratory, which was used to convert the current measurement datum into a total particle number concentration. Under various idling and driving conditions of a diesel vehicle, the electrical signals from the MUC were verified to have followed the trend of the total number concentrations of diesel PM measured using a condensation particle counter (CPC). When the diesel PM concentrations measured using the CPC were within the range of 2×10 4–2×10 5 #/cm 3, the total number concentrations, estimated using a correlation equation, were in agreement with the CPC data.

Physicochemical Characterization of Particulate Emissions from a Compression Ignition Engine Employing Two Injection Technologies and Three Fuels

Alternative fuels and injection technologies are a necessary component of particulate emission reduction strategies for compression ignition engines. Consequently, this study undertakes a physicochemical characterization of diesel particulate matter (DPM) for engines equipped with alternative injection technologies (direct injection and common rail) and alternative fuels (ultra low sulfur diesel, a 20% biodiesel blend, and a synthetic diesel). Particle physical properties were addressed by measuring particle number size distributions, and particle chemical properties were addressed by measuring polycyclic aromatic hydrocarbons (PAHs) and reactive oxygen species (ROS). Particle volatility was determined by passing the polydisperse size distribution through a thermodenuder set to 300 °C. The results from this study, conducted over a four point test cycle, showed that both fuel type and injection technology have an impact on particle emissions, but injection technology was the more important factor. Significant particle number emission (54%-84%) reductions were achieved at half load operation (1% increase-43% decrease at full load) with the common rail injection system; however, the particles had a significantly higher PAH fraction (by a factor of 2 to 4) and ROS concentrations (by a factor of 6 to 16) both expressed on a test-cycle averaged basis. The results of this study have significant implications for the health effects of DPM emissions from both direct injection and common rail engines utilizing various alternative fuels.

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

This paper is part of the Journal of the Air & Waste Management Association’s 2010 special issue on combustion aerosol measurements. The issue is a combination of papers that synthesize and evaluate ideas and perspectives that were presented by experts at a series of workshops sponsored by the Coordinating Research Council that aimed to evaluate the current and future status of diesel particulate matter (DPM) measurement. Measurement of DPM is a complex issue with many stakeholders, including air quality management and enforcement agencies, engine manufacturers, health experts, and climatologists. Adoption of the U.S. Environmental Protection Agency 2007 heavy-duty engine DPM standards posed a unique challenge to engine manufacturers. The new standards reduced DPM emissions to the point that improvements to the gravimetric method were required to increase the accuracy and the sensitivity of the measurement. Despite these improvements, the method still has shortcomings. The objectives of this paper are to review the physical and chemical properties of DPM that make gravimetric measurement difficult at very low concentrations and to review alternative metrics and methods that are potentially more accurate, sensitive, and specific. Particle volatility, size, surface area, and number metrics are considered, as well as methods to quantify them. Although the authors believe that an alternative method is required to meet the needs of engine manufacturers, the methods reviewed in the paper are applicable to other areas where the gravi-metric method detection limit is approached and greater accuracy and sensitivity are required. The paper concludes by suggesting a method to measure active surface area, combined with a method to separate semi-volatile and solid fractions to further increase the specificity of the measurement, has potential for reducing the lower detection limit of DPM and enabling engine manufacturers to reduce DPM emissions in the future.

Combustion and Emissions Characterization of Soy Methyl Ester Biodiesel Blends in an Automotive Turbocharged Diesel Engine

Recent increases in petroleum fuel costs, corporate average fuel economy (CAFE) regulations, and environmental concerns about CO2 emissions from petroleum based fuels have created an increased opportunity for diesel engines and non-petroleum renewable fuels such as biodiesel. Additionally, the Environmental Protection Agencies Tier II heavy duty and light duty emissions regulations require significant reductions in NOx and diesel particulate matter emissions for diesel engines. As a result, the diesel engine and aftertreatment system is a highly calibrated system that is sensitive to fuel characteristics. This study focuses on the impact of soy methyl ester biodiesel blends on combustion performance, NOx, and carbonaceous soot matter emissions. Tests were completed using a 1.9 L, turbocharged direct injection diesel engine using commercially available 15 ppm ultra low sulfur (ULS) diesel, a soy methyl ester B20 biodiesel blend (20 vol % B100 and 80 vol % ULS diesel), and a pure soy methyl ester biodiesel. Results show a reduction in NOx and carbonaceous soot matter emissions, and an increase in brake specific fuel consumption with the use of biodiesel. Further, traditional methodology assumes that diesel fuels with a high cetane number have a reduced ignition delay. However, results from this study show the cetane number is not the only parameter effecting ignition delay due to increased diffusion burn.

Enhancement of diesel particulate matter collection in an electrostatic water-spraying scrubber

Marine diesel engines are major sources of air pollution. They emit a large amount of pollutants, including diesel particulate matter (DPM), carbon oxide (CO x ), unburned hydrocarbons (HC), nitrogen oxide (NO x ), sulfur oxide (SO x ), and other products of combustion. Among these, DPM may cause respiratory and mutagenic diseases in humans, including lung and bladder cancer (see Donaldson et al. J Aerosol Sci 29:553–560, 1998). In this study, experiments were performed with an electrostatic water-spraying scrubber (EWSS) to evaluate its effectiveness for the collection of mass- and number-based DPM emissions from a marine diesel engine. The results show that the collection efficiency of the scrubber increases as the engine load increases due to an increase in the large DPM concentration and an increase in the amount of DPM collected by the charged droplets. The effect of water spraying performance on DPM collection at constant engine load was investigated experimentally. The strength of the electrical attraction between the charged water droplets and the charged DPM within the scrubber led to a significant increase in total DPM collection efficiency (up to 4–7 times). In addition, the total DPM collection efficiency was found to be directly related to the corona power, the electrical properties of water, water spraying performance and engine load. The EWSS appears to be a promising alternative method for controlling mass-based as well as number-based DPM emissions.

Predicting areas of high diesel particulate matter emissions in Phoenix, Arizona, using spatial analysis techniquesA paper submitted to the Journal of Environmental Engineering and Science.

Growing evidence suggests that inhalation exposure to diesel exhaust, including diesel particulate matter (DPM), causes acute and chronic health effects. As a result, interest in monitoring diesel exhaust has increased. Maps of emissions sources, emissions activity data, and meteorology were combined within a geographic information system (GIS) suitability model to produce a composite map identifying areas where DPM emissions are likely to be high. The results of the GIS model were compared with (i) the locations of existing monitoring sites in Phoenix, Arizona, and (ii) the spatial distribution of population. The results indicate that two existing sites are located in areas where DPM emissions are predicted to be high; however, incorporating meteorology as a factor showed that one site is located upwind of a predicted high DPM area. Consideration of population density showed high density in two areas that appear to be moderately influenced by DPM.

Effects of a Platinum−Cerium Bimetallic Fuel Additive on the Chemical Composition of Diesel Engine Exhaust Particles

The use of a platinum−cerium bimetallic fuel additive has been proposed as a cost-effective strategy for reducing particulate matter (PM) and NOx emissions from diesel-powered engines. Although previous studies have demonstrated that the use of platinum−cerium bimetallic fuel additive reduced emissions from diesel engines, there have been no reported investigations of how the use of these fuel-borne catalysts (FBCs) impact the chemical and physical properties of diesel PM emissions. The present study demonstrates that the use of a platinum−cerium bimetallic fuel additive has a significant impact on the detailed chemical composition and size distribution of PM emitted from a diesel engine. Tests were conducted to explore the impact of different fuel concentrations of the fuel-borne catalyst at different engine-operating conditions. These tests were performed with a medium-duty diesel engine that was not equipped with exhaust gas recirculation or a diesel particulate filter (DPF). The results demonstrated t...

Mitigating Diesel Truck Impacts in Environmental Justice Communities

This paper describes a series of sequentially implemented policies to mitigate local diesel truck impacts resulting from goods movement activity at two port facilities and simultaneously to improve traffic operations in the communities of Barrio Logan in San Diego, California, and Old Town in National City, California, both low-income communities of color. The paper provides the first comprehensive documentation of the unique process and solutions that emerged following the collaboration of all major stakeholders. Local impacts in Barrio Logan comprised air pollution, noise, and decreased pedestrian safety, while traffic operations in both communities were affected by congestion on the main freeway access, interchanges with insufficient capacity, and heavily mixed land uses both within and adjacent to the communities. These issues provided the impetus for the mitigation effort, the final implementation of which involved a permanent rerouting of all trucks weighing more than 5 tons to roads external to the community. Previous assessments of the project have described the extent to which mitigation strategies are expected to improve traffic operations or have assumed air quality improvements without carrying out an air quality analysis. A local-scale analysis of diesel particulate matter (DPM) emissions in Barrio Logan is given. The results show that while the mitigation did not result in improved regional air quality, it did significantly improve air quality in the primary affected corridor and resulted in a 99% reduction in DPM emissions and an 87% reduction in diesel truck vehicle miles traveled.

D304 MODELLING AND MEASUREMENT OF DIESEL PARTICULATE MATTER (DPM) COLLECTION PERFORMANCE IN AN ELECTROSTATIC WATER SPRAYING SCRUBBER(Environment Protection-5)

Long-term exposures to diesel particulate matter (DPM) emissions are linked to increasing adverse human health effects due to the potential association of DPM with carcinogenicity. Current DPM emission regulations are based solely upon total mass concentration, albeit it is the sub micrometer particles that are highly respirable and the most detrimental to human health. The electrostatic scrubber efficiency was measured under various engine loads. In addition, DPM collection efficiency was found to be directly related to exhaust gas capacity, the charge to mass of the water, water electrical properties and water spraying performance. The effect of the scrubber on the collection of DPM was investigated experimentally. The fine DPM which have diameter between 0.1 and 2.5 microns are removed at very high efficiency by highly electrical charging to the water droplets and DPM in opposite polarity. Simultaneously, all soluble acid and caustic gases are removed at the same levels as those of conventional scrubbers. Even though the primary mechanisms of scrubbing of DPM are known, the exact mechanism is not understood yet. Prediction of DPM collection efficiency is very important to evaluate pollution control of equipment. Hence verification of the overall efficiency achieved by any spray scrubbing system based on theoretical models is essential. In this paper an attempt has been made to theoretically predict the efficiency for an electrostatic water spraying scrubber. Results indicate that a maximum of overall collection efficiencies for fine DPM from marine diesel engine over 97% of all particle sizes and it allowed decreasing the water consumption up to about 4〜5 times. A comparison of the experimental and theoretical efficiencies has been made and systematically analyzed.

Simultaneous removal of NOx and fine diesel particulate matter (DPM) by electrostatic water spraying scrubber

In this study, experiments were performed with an electrostatic water spraying scrubber to evaluate its effectiveness for simultaneous removal of NOx and Diesel Particulate Matter (DPM) emissions in marine exhaust gas. The effects of several parameters, such corona power, gas flow rate and engine load, on the contaminant removals have been investigated intensively. The present study shows that for a given gas flow rate, the removal of DPM is enhanced with the increase of applied voltage. Total DPM removal efficiency was higher than 97% by electrostatic attraction, DPM with a range smaller than 1Όm is removed for higher efficiency. NO, NOx were removed with values higher than 20%, depending on Cl- concentration in the seawater and engine loads. As a result, the electrostatic water spraying scrubber would appear to be a promising alternative method for control of mass-based, as well as number-based DPM emissions.

Biodiesel Production via Rapid Transesterification

Biodiesel, an alternative diesel fuel derived from vegetable oil, animal fats, or waste vegetable oils, is obtained by reacting the oil or fat with monohydric aliphatic alcohols having 1–5 carbon atoms (ester exchange or transesterification) to their esters. Chemically, biodiesel is a fatty acid (m)ethyl ester. Biodiesel plays an important role in meeting future fuel requirements in view of its ability to reduce emissions from diesel engines for many air pollutant precursors, the lower toxicity of the diesel particulate matter emissions, and its edge over conventional diesel as they are obtained from renewable sources. In the supercritical alcohol transesterification method, the yield of conversion raises 50–95% for the first 8 min. In the catalytic supercritical methanol transesterification method, the yield of conversion raises 60–90% for the first minute. The reaction between sodium methoxide in methanol and a vegetable oil is very rapid; for example, they are completely transesterified in 4–6 min at room temperature.

Field Measurement of Diesel Particulate Matter Emissions

A primary means to reduce environmental levels of diesel particulate matter (DPM) exposure to miners is to reduce the amount of DPM emission from the engine. A quick and economic method to estimate engine particulate emission levels has been developed. The method relies on the measurement of pressure increase across a filter element that is briefly used to collect a DPM sample directly from the engine exhaust. The method has been refined with the inclusion of an annular aqueous denuder to the tube which permits dry filter samples to be obtained without addition of dilution air. Tailpipe filter samples may then be directly collected in hot and water-supersaturated exhaust gas flows from water bath-cooled coal mine engines without the need for dilution air. Measurement of a differential pressure (DP) increase with time has been related to the mass of elemental carbon (EC) on the filter. Results for laboratory and field measurements of the method showed agreement between DP increase and EC collected on the filter with R(2) values >0.86. The relative standard deviation from replicate samples of DP and EC was 0.16 and 0.11, respectively. The method may also have applications beyond mining, where qualitative evaluation of engine emissions is desirable to determine if engine or control technology maintenance may be required.

Diesel particulate matter, lung cancer, and asthma incidences along major traffic corridors in MA, USA: A GIS analysis

By examining the census tracts and towns that are intersected by Massachusetts’ major highway corridors, Diesel and Health along Massachusetts’ Highway Corridors ascertains whether these areas contain significantly higher rates of diesel particulate matter (DPM), lung cancer, and asthma. DPM was significantly higher for corridor towns than non-corridor towns. Hot spot analysis revealed statistically significant clustering of elevated DPM concentrations and asthma incidence in certain towns. The location of these towns was compared to the location of environmental justice neighborhoods. The authors recommend a series of steps that can be taken by policy makers and planners to curb DPM emissions.

Influence of Engine Operating Conditions on Diesel Particulate Matter Emissions in Relation to Transient and Steady-State Conditions

Airborne particulate matter is an important pollutant affecting air quality. Currently, diesel PM regulations are based on emitted particle mass; however, the particle size distributions are also important factors in air quality. While the distributions of particulate emissions under steady-state conditions are well-known and have been generalized, varying distributions undertransient conditions are not well-understood. This study investigates the size distributions of PM, focusing on the nuclei- and accumulation-modes, emitted from diesel engines under transient operations. Some engine conditions during transient testing produced particle size distributions that were notably different from those produced under steady-state conditions. During transient operation, the size distributions were either mono- or bimodal with peaks that were able to switch quickly between the nuclei- and accumulation-modes. These distributions have not been observed during steady-state testing but are significant because environmental and health effects and emission control solutions are highly dependent on particle size.

Removal of diesel particulate matter (DPM) in a tubular wet electrostatic precipitator

In this study, experiments were performed with a tubular wet electrostatic precipitator (wESP) to evaluate its effectiveness for the removal of mass- and number-based DPM emissions. A nonroad diesel generator utilizing a low sulfur diesel fuel (500 ppm w) operating under varying load conditions was used as a stationary DPM emission source. The US EPA Method 5 “Sampling Method for Stationary Sources” and Method 1A “Sampling and Velocity Traverses for Stationary Sources with Small Stacks or Ducts” were adopted as reference methods for measurement of DPM mass concentration. An electrical low-pressure impactor (ELPI) was used to quantify the DPM number concentration in the diluted exhaust gas at each tested condition. The wESP was evaluated with respect to varying engine loads and to different operational control parameters, such as corona power and gas residence time, to determine their effect on overall removal efficiency. The results show that the removal efficiency of the wESP increased as the engine loads decreased principally due to an increase in gas residence time and a decrease in DPM concentrations. At a constant wESP voltage and engine load, the increase of gas residence time within the wESP led to a significant increase in total DPM removal efficiency. In addition, total DPM removal efficiency was found to be directly related to the corona power, with increasing removal efficiency measured for increases in corona power. The linear correlation of DPM effective migration velocity and superficial gas velocity was established and an empirical equation is given. The wESP appears to be a promising alternative method for control of mass-based as well as number-based DPM emissions.

Collection of Ultrafine Diesel Particulate Matter (DPM) in Cylindrical Single-Stage Wet Electrostatic Precipitators

Long-term exposures to diesel particulate matter (DPM) emissions are linked to increasing adverse human health effects due to the potential association of DPM with carcinogenicity. Current diesel vehicular particulate emission regulations are based solely upon total mass concentration, albeit it is the submicrometer particles that are highly respirable and the most detrimental to human health. In this study, experiments were performed with a tubular single-stage wet electrostatic precipitator (wESP) to evaluate its performance for the removal of number-based DPM emissions. A nonroad diesel generator utilizing a low sulfur diesel fuel (500 ppmw) operating under varying load conditions was used as a stationary DPM emission source. An electrical low-pressure impactor (ELPI) was used to quantify the number concentration distributions of diesel particles in the diluted exhaust gas at each tested condition. The wESP was evaluated with respect to different operational control parameters such as applied voltage, gas residence time, etc., to determine their effect on overall collection efficiency, as well as particle size dependent collection efficiency. The results show that the total DPM number concentrations in the untreated diesel exhaust are in the magnitude of approximately108/cm(3) at all engine loads with the particle diameter modes between 20 and 40 nm. The measured collection efficiency of the wESP operating at 70 kV based on total particle numbers was 86% at 0 kW engine load and the efficiency decreased to 67% at 75 kW due to a decrease in gas residence time and an increase in particle concentrations. At a constant wESP voltage of 70 kV and at 75 kW engine load, the variation of gas residence time within the wESP from approximately 0.1 to approximately 0.4 s led to a substantial increase in the collection efficiency from 67% to 96%. In addition, collection efficiency was found to be directly related to the applied voltage, with increasing collection efficiency measured for increases in applied voltage. The collection efficiency based on particle size had a minimum for sizes between 20 and 50 nm, but at optimal wESP operating conditions it was possible to remove over 90% of all particle sizes. A comparison of measured and calculated collection efficiencies reveals that the measured values are significantly higher than the predicted values based on the well-known Deutsch equation.