Search

The primary goal of this study was to compare emissions measurements between a 1065 compliant PEMS, and the NTK Compact Emissions Meter (NCEM) capable of measuring NOx, PM, and solid PN. Both units were equipped on a light-duty diesel truck and tested over local, highway, and downtown driving routes. The results indicate that the NOx measurements for the NCEM were within approximately ±10% of those the 1065 compliant PEMS, which suggests that the NCEM could be used as a screening tool for NOx emissions. The NCEM showed larger differences for PM emissions on an absolute level, but this was at PM levels well below the 1 mg/mi level. The NCEM differences ranged from −2% to +26% if the comparisons are based on a percentage of the 1.0 mg/mi standard. Larger differences were also seen for PN emissions, with the NCEM measuring higher PN emissions, which can primarily be attributed to a zero current offset that we observed for the NCEM, which has been subsequently improved in the latest generation of the NCEM system. The comparisons between the 1065 compliant PEMS and the NCEM suggest that there could be applications for the NCEM or other mini-PEMS for applications such as identification of potential issues by regulatory agencies, manufacturer evaluation and validation of emissions under in-use conditions, and potential use in inspection and maintenance (I/M) programs, especially for heavy-duty vehicles. [ABSTRACT FROM AUTHOR]

Continuous monitoring of exhaust flue gas has become a common practice in power plants in response to Federal Mercury and Air Toxics Standards (MATS) standards. Under the current rules, hydrochloric acid (HCl) is not continuously measured at most plants; however, MATS standards have been proposed for HCl, and tunable diode laser (TDL) absorption spectroscopy is one method that can be used to measure HCl continuously. The focus of this work is on the evaluation and verification of the operation performance of an HCL TDL over a range of real-world operating environments. The testing was conducted at the University of California at Riverside (UCR) spectroscopy evaluation laboratory. Laboratory tests were conducted at three separate temperatures, 25ºC, 100ºC, and 200ºC, and two distinct moisture levels for the enhanced temperatures, 0%, (2 tests) and 4%, over a concentration range from 0 ppmv to 25 ppmv-m at each of the elevated temperatures. The results showed good instrument accuracy as a function of changing temperature and moisture. Data analysis showed that the average percentage difference between the ammonia concentration and the calibration source was 3.33% for varying moisture from 0% to 4% and 2.69% for varying temperature from 25 to 100/200ºC. An HCl absorption line of 1.742 μm was selected for by the manufacturer for this instrument. The Hi Tran database indicated that CO2is probably the only major interferent, although the CO2absorption is very weak at that wavelength. Interference tests for NO, CO, SO2, NH3, and CO2for a range of concentrations typical of flue gasses in coal-fired power plants did not show any interference with TDL HCl measurements at 1.742 μm. For these interference tests, CO2was tested at a concentration of 11.9% concentration in N2for these tests. Average precision over the entire range for all 10 tests is 3.12%. Implications:The focus of this study was an evaluation of the operation performance of a tunable diode laser (TDL) for the measurement of hydrochloric acid (HCl) over a range of real-world operating environments. The results showed good instrument accuracy as a function of changing temperature from 25ºC to 200ºC and moisture from 0% to 4%. Such as an instrument could be used for continuous monitoring of exhaust flue gas in power plants once the Federal Mercury and Air Toxics Standards (MATS) standards have been fully implemented. [ABSTRACT FROM AUTHOR]

It is important to understand the differences between emissions from standard laboratory testing cycles and those from actual on-road driving conditions, especially for solid particle number (SPN) emissions now being regulated in Europe. This study compared particle mass and SPN emissions from a heavy-duty diesel vehicle operating over the urban dynamometer driving schedule (UDDS) and actual on-road driving conditions. Particle mass emissions were calculated using the integrated particle size distribution (IPSD) method and called MIPSD. TheMIPSD emissions for the UDDS and on-road tests were more than 6 times lower than the U.S. 2007 heavy-duty particulate matter (PM) mass standard. The MIPSD emissions for the UDDS fell between those for the on-road uphill and downhill driving. SPN and MIPSD measurements were dominated by nucleation particles for the UDDS and uphill driving and by accumulation mode particles for cruise and downhill driving. The SPN emissions were 3 times lower than the Euro 6 heavy-duty SPN limit for the UDDS and downhill driving and ~4-5 times higher than the Euro 6 SPN limit for the more aggressive uphill driving; however, it is likely that most of the "solid" particles measured under these conditions were associated with a combination release of stored sulfates and enhanced sulfate formation associated with high exhaust temperatures, leading to growth of volatile particles into the solid particle counting range above 23 nm. Except for these conditions, a linear relationship was found between SPN and accumulation mode MIPSD. The coefficient of variation (COV) of SPN emissions of particles >23 nm ranged from 8 to 26% for the UDDS and on-road tests. [ABSTRACT FROM AUTHOR]

The California Air Resources Board (CARB) has regulated the properties of diesel fuel sold in California since 1988 to lower emissions of particulate matter (PM) and oxides of nitrogen (NOx). Although many studies have shown that reduced levels of aromatics and higher cetane numbers can improve emissions, the actual impact of CARB fuels on in-use diesel emissions has not yet been extensively studied, especially as diesel engine and aftertreatment technology has evolved over the years. This study evaluates the differences between California and Federal diesel fuels with heavy-duty engine and chassis dynamometer tests. The engine dynamometer results showed that NOx emissions for the Federal fuels ranged from 4.7% to 9.5% higher than the CARB diesel. These NOx reductions are similar to the estimates being used in the latest regulations. The chassis dynamometer test results did not show as consistent trends for NOx as those seen for the engine dynamometer testing. For the chassis dynamometer testing, four out of ten vehicles showed consistent reductions in NOx, with emissions for the Federal fuels ranging from 3.3% to 9.9% higher than the CARB diesel, while the other six vehicles did not show consistent fuel impacts. On an absolute level, the NOx benefit for CARB diesel shows a decline with continuing advances in engine technology. The results showed that CARB diesel did not show strong benefits for PM. The results also showed that the introduction of aftertreatment systems for PM and NOx will, over time, largely eliminate any potential benefits that might be obtained through the use of CARB diesel, although NOx benefits will persist through to 2020. [ABSTRACT FROM AUTHOR]

Abstract: The study investigated the impact of ethanol blends on criteria emissions (THC, NMHC, CO, NO x ), greenhouse gas (CO2), and a suite of unregulated pollutants in a fleet of gasoline-powered light-duty vehicles. The vehicles ranged in model year from 1984 to 2007 and included one Flexible Fuel Vehicle (FFV). Emission and fuel consumption measurements were performed in duplicate or triplicate over the Federal Test Procedure (FTP) driving cycle using a chassis dynamometer for four fuels in each of seven vehicles. The test fuels included a CARB phase 2 certification fuel with 11% MTBE content, a CARB phase 3 certification fuel with a 5.7% ethanol content, and E10, E20, E50, and E85 fuels. In most cases, THC and NMHC emissions were lower with the ethanol blends, while the use of E85 resulted in increases of THC and NMHC for the FFV. CO emissions were lower with ethanol blends for all vehicles and significantly decreased for earlier model vehicles. Results for NO x emissions were mixed, with some older vehicles showing increases with increasing ethanol level, while other vehicles showed either no impact or a slight, but not statistically significant, decrease. CO2 emissions did not show any significant trends. Fuel economy showed decreasing trends with increasing ethanol content in later model vehicles. There was also a consistent trend of increasing acetaldehyde emissions with increasing ethanol level, but other carbonyls did not show strong trends. The use of E85 resulted in significantly higher formaldehyde and acetaldehyde emissions than the specification fuels or other ethanol blends. BTEX and 1,3-butadiene emissions were lower with ethanol blends compared to the CARB 2 fuel, and were almost undetectable from the E85 fuel. The largest contribution to total carbonyls and other toxics was during the cold-start phase of FTP. [Copyright &y& Elsevier]

Heavy duty emissions regulations have recently expanded from the laboratory to include in-use requirements. This paradigm shift to in-use testing has forced the development of portable emissions measurement systems (PEMS) for particulate matter (PM). These PM measurements are not trivial for laboratory work, and are even more complex for in-use testing. This study evaluates five PM PEMS in comparison to UCR's mobile reference laboratory under in-use conditions. Three on-highway, heavy-duty trucks were selected to provide PM emissions levels from 0.1 to 0.0003 g/hp-h, with varying compositions of elemental carbon (EC), organic carbon (OC), and sulfate. The on-road driving courses included segments near sea level, at elevations up to 1500 m, and coastal and desert regions. The photoacoustic measurement PEMS performed best for the non-aftertreatment system (ATS)-equipped engine, where the PM was mostly EC, with a linear regression slope of 0.91 and an R² of 0.95. The PEMS did not perform as well for the 2007 modified ATS equipped engines. The best performing PEMS showed a slope of 0.16 for the ATS-equipped engine with predominantly sulfate emissions and 0.89 for the ATS-equipped engine with predominantly OC emissions, with the next best slope at 0.45 for the predominantly OC engine. [ABSTRACT FROM AUTHOR]

Emission measurements of five 1996–2005 heavy-duty diesel vehicles (HDDVs), representing three engine certification levels, were made using a Mobile Emissions Laboratory under actual on-road driving conditions on surface streets and highways. The results show that emissions depend on the emission component, the age/certification of vehicle/engine, as well as driving condition. For NO x emissions, there was a trend of decreasing emissions in going from older to newer model years and certification standards. Some vehicles showed a tendency toward higher NO x emissions per mile for the higher speed events (⩾55mph) as compared to the 40mph cruise and the other surface street driving, while others did not show large differences between different types of driving. For particulate matter (PM), the three oldest trucks had the highest emissions for surface street driving, while the two newest trucks had the highest PM emissions for highway driving. For total hydrocarbons (THC) emissions, some vehicles showed a tendency for higher emissions for the surface street segments compared to the steady-state segments, while others showed a tendency for higher emissions for the 40mph cruise segments compared to the highway cruise segments. CO emissions under steady-state driving conditions were relatively low (1–3gmile−1). [Copyright &y& Elsevier]

This research is one of the largest studies of biodiesel in both on-road and off-road uses. The testing was conducted for the military and encompassed a wide range of application types including two medium-duty trucks, two Humvees, a heavy heavy-duty diesel truck, a bus, two stationary backup generators (BUGs), a forklift, and an airport tow vehicle. The full range of fuels tested included a California ultra-low sulfur diesel (ULSD) fuel, different blend ratios of two different yellow-grease biodiesels and one soy-based biodiesel, JP-8, and yellow-grease biodiesel blends with two different NO x reduction additives. The B20-YGA, B20-YGB, and B20-Soy did not show trends relative to ULSD that were consistent over all applications tested. Higher biodiesel blends were tested on only one vehicle, but showed a tendency for higher total hydrocarbons (THC) and carbon monoxide (CO) emissions and lower particulate matter (PM) emissions. The JP-8 showed increases in THC and CO relative to the ULSD. [Copyright &y& Elsevier]

There is considerable interest in portable emissions measurement systems (PEMS) for emission inventory and regulatory applications. For this study, four commercial PEMS were compared with a Federal Reference Method (FRM) for measuring emissions from a back-up generator (BUG) over steady-state loads and a diesel truck on transient and steady-state chassis dynamometer tests. The agreement between the PEMS and the FRM varied depending on the pollutant and the particular PEMS tested for both the BUG and chassis dynamometer testing. The best performing PEMS for both the BUG and chassis testing was within ~12% for NOx of the FRM. For the BUG testing, several PEMS showed agreement with the FRM within ~5% for CO2. For the chassis dynamometer testing, the best PEMS showed agreement typically within ~5% for CO2. PM measurements for the BUG testing were low compared to the FRM, with the best measurements ~20% lower. For the chassis testing, two PM PEMS showed a good correlation but a high bias, while the correlation was worse for the other two PEMS. For each emissions component, some PEMS under different test conditions showed considerably larger deviations than those for the best performing PEMS. [ABSTRACT FROM AUTHOR]

Oxygenate content and fuel volatility (distillation) variables are important parameters affecting vehicle exhaust emissions, and data on their effects on the latest technology vehicles are quite limited. For this study, 12 California-certified LEV to SULEV vehicles were tested on a matrix of 12 fuels with varying levels of ethanol concentration (0, 5.7, and 10 vol %), T50 (195, 215, and 235 °F), and T90 (295, 330, and 355 °F). There were statistically significant interactions between ethanol and T90for NMHC, ethanol, and T50 for CO and ethanol and T50 for NOR. NMHC emissions increased with increasing ethanol content at the midpoint and high level of T90 but were unaffected at the low T90 level. CO emissions decreased as the ethanol content increased from the low to the midpoint level for all levels of T50, but between the 5.7 and 10% ethanol levels, CO showed only an increase for the high level of T50. NOx emissions increased with ethanol content for some conditions. Non-methane organic gases (NMOG) and toxic emissions were examined for only a subset of fuels with the highest 190 level, with NMOG, acetaldehyde, benzene, and 1-,3-butadiene all found to increase with increasing ethanol content. [ABSTRACT FROM AUTHOR]

NH3 emissions from motor vehicles have been the subject of a number of recent studies due to their potential impact on ambient particulate matter (PM). Highly time-resolved NH3 emissions can be measured and correlated with specific driving events utilizing a tunable diode laser (TDL). It is possible to incorporate NH3 emissions with this new information into models that can be used to predict emissions inventories from vehicles. The newer generation of modal models are based on modal events, with the data collected at second-by-second time resolution, unlike the bag-based emission inventory models such as EMFAC and MOBILE. The development of an NH3 modal model is described in this paper. This represents one of the first attempts to incorporate vehicle NH3 emissions into a comprehensive emissions model. This model was used in conjunction with on-road driving profiles to estimate the emissions of SULEV, ULEV, and LEV vehicles to be 9.4 ± 4.1, 21.8 ± 5.2, and 34.9 ± 6.0 mg/mi, respectively. We also implement this new NH3 model to predict and evaluate the NH3 emission inventory in the South Coast air basin (SoCAB). [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is an important greenhouse gas (GHG) that can be formed over a catalyst in the vehicle exhaust. In this study, a total of 60 vehicles ranging from non-catalyst to super ultra low-emission vehicles (SULEV) technologies were tested over the Federal Test Procedure (FTP), with a subset of vehicles also tested over the cold start ST01, the hot running ST01, and more aggressive cycles, such as the US06 and Modal Emissions Cycle (MEC01v7). The N2O emission rate was highest for the earliest catalyst technologies and declined for more advanced technology vehicles. Of the 60 test vehicles, nearly half (25) of the vehicles had FTP N2O emission rates below 10mgmile-1, while the emission rate of the remaining vehicles varied significantly depending on the specific vehicle control technology, operating, cycle and sulfur content of the gasoline. Real-time data showed that N2O emissions are primarily formed during the early period of catalyst light-off, and decline significantly as the catalyst reaches its equilibrium temperature. Only cycles with a cold start component, such as the cold start ST01 and FTP, showed any substantial N2O emissions. N2O emissions for aggressive cycles, such as the US06 or MEC01v7, or cycles where the catalyst was always at operating temperature, were near detection limits. Increases in fuel sulfur from 30 to 330ppmw were found to increase N2O emissions by almost 4 times over the FTP and US06, while increases from 5 to 150ppmw in fuel sulfur increased N2O by between 3 and 8 times depending on the cycle. It is concluded that gasoline sulfur, control technology and start conditions must all be considered in estimating N2O emissions inventories. [Copyright &y& Elsevier]

Small utility engines represent an important contribution to the emissions inventory and have been subjected to increasingly stringent regulations in recent years. For this project, a Tanaka two-stroke engine was tested in its original condition and with a modified fuel/oil injection system. The modified fuel/oil injection system applied to the Tanaka two-stroke engine resulted in significant emissions reductions of ∼52% for carbon monoxide (CO), 70% for total hydrocarbons (THC), 70% for particulate matter (PM), and 67% for the regulated THC + nitrogen oxides metric. This technology met the California Air Resources Board's 2000 model-year regulations for all pollutants, with the exception of slightly higher PM emissions. Two additional two-stroke engines were tested under a new condition and after at least 100 hr of use to examine the effects of deterioration on in-use, two-stroke engines. For one engine, CO and PM emissions more than tripled after 162 hr of operation in the field, with smaller increases also observed for THC (20%). For the second engine, significant repairs were required throughout the 100 operating hours, which counteracted the effects of the emissions deterioration and resulted in lower CO and THC emissions. [ABSTRACT FROM AUTHOR]

The effects of diesel particulate filters (DPFs) on regulated emissions and organic species were measured for several medium-duty diesel vehicles. Vehicles were measured in three configurations: a baseline California in-use diesel fuel, a low-aromatic, low-sulfur diesel fuel, and a DPF with a low-aromatic, low-sulfur diesel and a more commercial low-sulfur diesel fuel. The organic species measurements included C1–C13 hydrocarbon species, C1–C8 carbonyls, and semi-volatile and PM-based polycyclic aromatic compounds (PACs). Tests on vehicles operating with DPFs showed reductions ranged from 89±2.3% to 98±0.7% for PM, 72±2.5% to 80±0.6% for THC, and 81±1% to 90%±1.3 for CO. Although some fuel effects were observed, they were considerably smaller than those found for the DPFs. Detailed C1–C13 organic gas measurements showed alkenes and carbonyls to be the most prominent compound classes, with formaldehyde, ethene, acetaldehyde, and ethyne having the highest emission rates. Large reductions in alkenes, alkynes, and aromatics were found for the DPF, with smaller reductions also found for alkanes and carbonyls. Total PAC emissions were 4.34, 2.25, and 0.69 mg/mi, respectively, for the baseline fuel, the low-aromatic, low-sulfur diesel fuel and DPF with low-sulfur diesel fuel. The majority of the PACs were found in the semi-volatile phase. [Copyright &y& Elsevier]

The impact of high-particulate-emission vehicles on the total light-duty vehicle particulate emission inventory in the South Coast Air Quality Management District (SCAQMD) has been estimated by an analysis of the SCAQMD's CUT-SMOG database, a field survey of smoking vehicles, and particulate emissions testing of representative smoking vehicles. The field study, carried out at 61 sites throughout the SCAQMD, showed that 1.11%-1.75% of the vehicles in the light-duty fleet emit visible smoke. This fleet of smoking vehicles is composed mainly of older vehicles, 8 to 18 years of age. Particulate emission testing of 23 smoking vehicles gave an average Federal Test Procedure (FTP) weighted emission rate of 399 mg/mi with a range of 64-2,323 mg/mi, while the average IM240 emission rate was 346 mg/mi, with a range from 13-1,807 mg/mi. The contribution of light-duty smoking vehicles to the particulate emissions inventory in the SCAQMD is estimated to be 0.51-0.81 tons per day. [ABSTRACT FROM AUTHOR]

Hybrid engine technology is a potentially important strategy for reduction of tailpipe greenhouse gas (GHG) emissions and other pollutants that is now being implemented for off-road construction equipment. The goal of this study was to evaluate the emissions and fuel consumption impacts of electric-hybrid excavators using a Portable Emissions Measurement System (PEMS)-based methodology. In this study, three hybrid and four conventional excavators were studied for both real world activity patterns and tailpipe emissions. Activity data was obtained using engine control module (ECM) and global positioning system (GPS) logged data, coupled with interviews, historical records, and video. This activity data was used to develop a test cycle with seven modes representing different types of excavator work. Emissions data were collected over this test cycle using a PEMS. The results indicated the HB215 hybrid excavator provided a significant reduction in tailpipe carbon dioxide (CO 2 ) emissions (from −13 to −26%), but increased diesel particulate matter (PM) (+26 to +27%) when compared to a similar model conventional excavator over the same duty cycle. [ABSTRACT FROM AUTHOR]

Focuses on the effects of repairs on tailpipe emissions for On-Board Diagnostics II (OBDII)-equipped vehicles with the malfunction indicator light illuminated. Test cycles that were conducted on On-Board Diagnostics II-equipped vehicles; Number of vehicles that were found with emissions greater than 1.5 times of their respective Federal Test Procedure emissions standards; Fundamental differences between identifying malfunctioning vehicles using OBDII as opposed to more traditional dynamometer tests.

Abstract: This study investigated the impact of varying natural gas composition on the exhaust emissions from a waste hauler equipped with a 2002 Cummins 8.3L, C Gas Plus, lean burn, spark ignited natural gas engine and an oxidation catalyst while operated on the William H. Martin Refuse Truck Cycle on a chassis dynamometer. The vehicle was tested on seven different fuel gas blends with varying compositions of light hydrocarbon species and inerts, resulting in different properties in terms of methane number and Wobbe number. The higher hydrocarbons gases exhibited higher fuel economy and CO2 (carbon dioxide) emissions. NOx (Nitrogen oxides) emissions were also impacted by fuel composition, and increased for gases with higher levels of heavier hydrocarbons. THC (Total hydrocarbons), CH4 (methane), CO (carbon monoxide), PM (particulate matter), and particle number emissions all showed some reductions for the gases with higher hydrocarbons, higher Wobbe numbers, and higher energy content. Formaldehyde and acetaldehyde were the most dominant aldehydes in the tailpipe, and decreased with the low methane number and high Wobbe number gases. Ammonia emissions did not show consistent fuel trends, however, ammonia emission levels were higher for the higher speed and load phase of the cycle. [Copyright &y& Elsevier]

Emissions from "low emitting" modern vehicles were measured on-road using a Fourier transform infrared (FTIR) on-board emissions measurement system. Twenty vehicles were tested on road and on a chassis dynamometer. A subset of four vehicles was tested on a test track as well as on the dynamometer. Comparison of on-board measurements with laboratory measurements while operating on the dynamometer showed agreement within measurement and test to test variability. Comparison of dynamometer measurements with test track measurements showed some larger differences attributable to track test conditions. On-road and dynamometer tests were conducted on the remaining 16 vehicles, with the on-road testing including freeway, arterial, and residential streets. The on-road testing showed that most of the low emitting vehicles under most operating conditions are operating below certification levels. Most vehicles reached a hot stabilized condition within 60 to 100 s. Hot running emissions were on average very low once the catalyst lights off. For NMHC, the majority of the "certification" emissions occur during the start-up, especially for PZEVs. NOx and CO also showed a high fraction of "certification" emissions during start-up, but also showed emission spikes under hot running conditions, especially during transients. [ABSTRACT FROM AUTHOR]

Knowledge of black carbon (BC) emission factors from ships is important from human health and environmental perspectives. A study of instruments measuring BC and fuels typically used in marine operation was carried out on a small marine engine. Six analytical methods measured the BC emissions in the exhaust of the marine engine operated at two load points (25% and 75%) while burning one of three fuels: a distillate marine (DMA), a low sulfur, residual marine (RMB-30) and a high-sulfur residual marine (RMG-380). The average emission factors with all instruments increased from 0.08 to 1.88 gBC/kg fuel in going from 25 to 75% load. An analysis of variance (ANOVA) tested BC emissions against instrument, load, and combined fuel properties and showed that both engine load and fuels had a statistically significant impact on BC emission factors. While BC emissions were impacted by the fuels used, none of the fuel properties investigated (sulfur content, viscosity, carbon residue and CCAI) was a primary driver for BC emissions. Of the two residual fuels, RMB-30 with the lower sulfur content, lower viscosity and lower residual carbon, had the highest BC emission factors. BC emission factors determined with the different instruments showed a good correlation with the PAS values with correlation coefficients R2 >0.95. A key finding of this research is the relative BC measured values were mostly independent of load and fuel, except for some instruments in certain fuel and load combinations. [ABSTRACT FROM AUTHOR]

The regulated emissions of five 2012 and newer, low-mileage, heavy-duty Class 8 diesel trucks equipped with diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems were evaluated over test cycles representing urban, highway, and stop-and-go driving on a chassis dynamometer. NOx emissions over the Urban Dynamometer Driving Schedule (UDDS) ranged from 0.495 to 1.363 g/mi (0.136 to 0.387 g/bhp-hr) for four of the normal emitting trucks. For those trucks, NOx emissions were lowest over the cruise (0.068 to 0.471 g/mi) and high-speed cruise (0.067 to 0.249 g/mi) cycles, and highest for the creep cycle (2.131 to 9.468 g/mi). A fifth truck showed an anomaly in that it had never regenerated throughout its relatively short operating lifetime due to its unusual, unladed service history. This truck exhibited NOx emissions of 3.519 g/mi initially over the UDDS, with UDDS NOx emissions decreasing to 0.39 g/mi after a series of parked regenerations. PM, THC, and CO emissions were found to be very low for most of the testing conditions, due to the presence of the DPF/SCR aftertreatment system, and were comparable to background levels in some cases. [ABSTRACT FROM AUTHOR]

The emissions and the potential health effects of particulate matter (PM) were assessed from two heavy-duty trucks with and without emission control aftertreatment systems when operating on CARB ultra-low sulfur diesel (ULSD) and three different biodiesel blends. The CARB ULSD was blended with soy-based biodiesel, animal fat biodiesel, and waste cooking oil biodiesel at 50 vol%. Testing was conducted over the EPA Urban Dynamometer Driving Schedule (UDDS) in triplicate for both trucks. The aftertreatment controls effectively decreased PM mass and number emissions, as well as the polycyclic aromatic hydrocarbons (PAHs) compared to the uncontrolled truck. Emissions of nitrogen oxides (NO x ) exhibited increases with the biodiesel blends, showing some feedstock dependency for the controlled truck. The oxidative potential of the emitted PM, measured by means of the dithiothreitol (DTT) assay, showed reductions with the use of biodiesel blends relative to CARB ULSD for the uncontrolled truck. Overall, the cellular responses to the particles from each fuel were reflective of the chemical content, i.e., particles from CARB ULSD were the most reactive and exhibited the highest cellular responses. [ABSTRACT FROM AUTHOR]

We assessed the emissions response of a fleet of seven light-duty gasoline vehicles for gasoline fuel aromatic content while operating over the LA92 driving cycle. The test fleet consisted of model year 2012 vehicles equipped with spark-ignition (Si) and either port fuel injection (PFI) or direct injection (Dl) technology. Three gasoline fuels were blended to meet a range of total aromatics targets (15%, 25%, and 35% by volume) while holding other fuel properties relatively constant within specified ranges, and a fourth fuel was formulated to meet a 35% by volume total aromatics target but with a higher octane number. Our results showed statistically significant increases in carbon monoxide, nonmethane hydrocarbon, particulate matter (PM) mass, particle number, and black carbon emissions with increasing aromatics content for all seven vehicles tested. Only one vehicle showed a statistically significant increase in total hydrocarbon emissions. The monoaromatic hydrocarbon species that were evaluated showed increases with increasing aromatic content in the fuel. Changes in fuel composition had no statistically significant effect on the emissions of nitrogen oxides (NOx), formaldehyde, or acetaldehyde, also found between the PM index and PM mass and number emissions for all vehicle/fuel combinations group being a significant contributor to the total PM index followed by naphthalenes and indenes. [ABSTRACT FROM AUTHOR]

Abstract: A Particle Measurement Program (PMP) compliant system, an AVL advanced particle counter (APC) and an alternative volatile particle removal system, a catalytic stripper (CS) were evaluated and compared for measuring solid particle number (PN) emissions. The evaluations and comparisons were conducted using sulfuric acid and hydrocarbon particles as model volatile particles in laboratory tests, and diluted exhaust from a diesel particle filter (DPF)-equipped heavy-duty diesel vehicle operated on a heavy-duty chassis dynamometer under steady speed conditions at two different engine loads. For the laboratory test, both the APC and CS removed more than 99% of the volatile particles in terms of PN when using aerosols composed of pure sulfuric acid or hydrocarbons. When using laboratory test aerosols consisting of mixtures of sulfuric acid and hydrocarbons more than 99% of the particles were removed by the APC but the surviving particles were no longer entirely volatile, 12–14% were solid. For the chassis dynamometer test, PN emissions between 3 and 10nm downstream the APC were ∼2 and 7 times higher than the PN emissions of particles above 10nm at the 74% and 26% engine load, respectively. At the 26% engine load, PN level of the 3–10nm particles downstream the APC were significantly higher than that in the dilution tunnel, demonstrating that the APC was making 3–10nm particles. The PN emission of 3–10nm particles downstream the APC was related to the heating temperature of the APC evaporation tube, suggesting these particles are artifacts formed by renucleation of semivolatiles. Considerably fewer particles between 3 to 10nm were seen downstream of the CS for both engine loads due mainly to removal of semivolatile material by the catalytic substrates, although some of this difference could be attributed to diffusion and thermophoretic losses. The findings of this study imply that improvement of the current PMP protocol would be necessary if the PMP were to be used in other applications where the PN emissions of particles below 23nm are important. [Copyright &y& Elsevier]