Exhaust Aftertreatment Devices Research Articles

In-depth characterization of exhaust particles performed on-board a modern cruise ship applying a scrubber

To comply with environmental regulations, ship operators may adopt exhaust after-treatment devices such as scrubbers or selective catalytic reduction (SCR). Beyond gaseous emission control, these technologies impact the exhaust particles emitted from marine engines to the atmosphere. This study characterizes comprehensively the chemical composition and physical properties of exhaust aerosol particles upstream and downstream a hybrid scrubber operating in open loop mode on-board a modern cruise ship. The study considers two engines, one equipped with SCR and both with scrubber, during engine load conditions of 75 % and 40 %, and the influence of marine gas oil (MGO) use in addition to heavy fuel oil (HFO). At least 4 different particle types were observed in the exhaust based on transmission electron microscopy (TEM) studies both upstream and downstream scrubber, and both scrubber and SCR affected the particle number size distribution (PSD). The geometric mean diameter (GMD) of the particles increased over scrubber both due to removal of nucleation mode particles and particle growth in the scrubber. The scrubber effectively decreased particle number (PN) and, also, non-volatile particles, but the effect depended on particle size and no significant decrease was observed in number of particles above 50 nm, typically comprising black carbon (BC) and in the case of HFO combustion, also asymmetrical metal containing particles. In addition to PN, concentrations of PAH compounds were reduced in the scrubber. The results may be further utilized when including the exhaust aerosol characteristics from ships applying scrubbers to emission inventories, as well as climate and air quality models.

Experimental Investigation on OBD Signal and PN Emission Characteristics by Damaged-DPF Types of 2.0 L Diesel Vehicle

A diesel particulate filter (DPF) is an exhaust after-treatment device designed to capture and store exhaust particulate matter, such as soot and ash, to reduce emissions from diesel-powered vehicles. A DPF has a finite capacity and typically uses a substrate made of ceramic material that is formed into a honeycomb structure. Diesel particulate filters play an important role in diesel-fueled vehicles. Failure to maintain these filters can have significant consequences for vehicles. In this study, we investigated the failure type in cordierite DPF substrates. In addition, we experimentally characterized the particle number (PN) emission and on-board diagnostics (OBD) signal of a 2.0 L diesel-fueled vehicle generated by three types of DPF failure (crack, melting, and hollow). Specifically, X-ray photography analysis of the cordierite DPF was performed. The PN and OBD signals were assessed via the KD-147 vehicle driving mode and measured using a DMS-500 (PN measurement device) and global diagnosis tool (GDS) scanner (OBD diagnostic device), respectively. X-ray photography was used to characterize the internal structure of the three DPF-failure samples. A key result was that the maximum value of the OBD data, including airflow mass, boost pressure, and VGT actuator, was distinctly different for each DPF sample. The exhaust temperature gradient for the normal DPF and crack-damaged DPF followed the KD-147 driving pattern. This was because there was no volume damage inside the cordierite DPF substrates. However, in the case of the hollow and melting-damaged DPF, the volume inside the cordierite DPF substrates was reduced or the time for the exhaust gas to stay in the DPF substrates was decreased. The melting-damaged DPF continuously emitted the largest number of nanoparticles (of the order of 109 #/cc). This was regardless of the vehicle driving speed in the KD-147 driving mode. Eventually, an OBD-based algorithm to determine whether a DPF is damaged was derived in this study.

A European Regulatory Perspective towards a Euro 7 Proposal

<div class="section abstract"><div class="htmlview paragraph">The implementation of emission standards has brought significant reductions in vehicle emissions in the EU, but road transport is still a major source of air pollution. Future emission standards will aim at making road vehicles as clean as possible under a wide range of driving conditions and throughout their complete lifetime. The current paper presents the methodology followed by the Consortium for ultra LOw Vehicle Emissions (CLOVE) to support the preparation of the Euro 7 proposal.</div><div class="htmlview paragraph">As a first step, the emission performance of the latest-technology vehicles under various driving conditions was evaluated. Towards this direction, an emissions database was developed, containing data from a wide range of tests, both within and beyond the current RDE boundaries. The results revealed that harsh accelerations, extreme ambient temperatures, very short trips (particularly at urban conditions), DPF regeneration and uphill driving, or combination of those conditions, can result to high emissions. Next, suitable technology packages to address such high emissions were defined and evaluated, using simulation models. On top of this analysis, additional elements were assessed, namely on-board emissions monitoring, additional species to be regulated and instrumentation for future on-road emission testing.</div><div class="htmlview paragraph">The overall analysis revealed that existing state-of-the-art emission control technologies can achieve very low emission levels, but not under all driving conditions. Thus, additional improvements and potential new technologies are needed to bring ultra-low emissions. These technologies include larger exhaust aftertreatment devices, optimized engine and aftertreatment thermal management (mainly during cold-start) and further penetration of electrification. Particularly the latter is heavily enforced by the CO<sub>2</sub>-related measures and can strongly support the limitation of pollutant emissions, as well.</div></div>

Detailed Characterization of Solid and Volatile Particle Emissions of Two Euro 6 Diesel Vehicles

The solid particle number emissions of Diesel vehicles are very low due to the particulate filters as exhaust aftertreatment devices. However, periodically, the trapped particles are oxidized (i.e., active regeneration) in order to keep the backpressure at low levels. The solid particle number emissions during regenerations are only partly covered by the regulations. Many studies have examined the emissions during regenerations, but their contribution to the overall emissions has not been addressed adequately. Furthermore, the number concentration of volatile particles, which is not included in the regulations, can be many of orders of magnitude higher. In this study, the particulate emissions of two light-duty Euro 6 vehicles were measured simultaneously at the tailpipe and the dilution tunnel. The results showed that the weighted (i.e., considering the emissions during regeneration) solid particle number emissions remained well below the applicable limit of 6 × 1011 #/km (solid particles > 23 nm). This was true even when considering solid sub-23 nm particles. However, the weighted volatile particle number emissions were many orders of magnitude higher, reaching up to 3 × 1013 #/km. The results also confirmed the equivalency of the solid particle number results between tailpipe and dilution tunnel locations. This was not the case for the volatile particles which were strongly affected by desorption phenomena. The high number of volatiles during regenerations even interfered with the 10 nm solid particle number measurements at the dilution tunnel, even though a catalytic stripper equipped instrument was also used in the dilution tunnel.

Critical Review of Diesel Exhaust Exposure Health Impact Research Relevant to Occupational Settings: Are We Controlling the Wrong Pollutants?

Diesel exhaust emissions and exposure of workers in occupational settings are topics which have attracted increased attention after IARC classification as a group 1 carcinogen (IARC. Agents classified by the IARC monographs, Vols. 1–120. International Agency for the Research on Cancer. http://monographs.iarc.fr/ENG/Classification/ . Accessed 21 Feb 2018; 2018). There is ongoing debate over appropriate exposure limits for occupationally exposed workers. This review consolidates recent research findings relevant to setting appropriate exposure limits, with a specific focus on newer engine and after-treatment technologies. Appropriate online databases were searched for studies published since 2005 focussing on the health effects of whole diesel exhaust exposure. Engines that used exhaust after-treatment devices including both a diesel oxidation catalyst and a diesel particulate filter were classified as new technology engines. All other studies were classified as using older technology engines. Exposure to diesel exhaust from both engine classifications resulted in negative health impacts on the lungs, heart and brain. Study participants with asthma, allergy or respiratory disease were more at risk of negative effects caused by diesel exhaust exposure than healthy subjects. Based on the published literature, an occupational limit of an average diesel exhaust concentration below 50 μg/m3 of diesel exhaust particles, 35 μg/m3 of elemental carbon, is appropriate to limit health effects. To meet this limit, many diesel engines will need to be equipped with after-treatment technology such as a DPF. However, the use of a DPF had little to no impact on measured health effects despite the removal of over 90% by weight of particles. This negates the feasibility of using particle mass-based limits.

Computational Study of Urea–Water Solution Sprays for the Analysis of the Injection Process in SCR-like Conditions

Exhaust after-treatment devices for NOx reduction have become mandatory for achieving strict diesel emission standards. The Selective Catalytic Reduction (SCR) method has proven to be efficient in ...

Ground Level Ozone Formation Near a Traffic Intersection: Lisbon “Rotunda De Entrecampos” Case Study

Ground-level ozone in cities is increasing mainly due to traffic exhaust aftertreatment devices, i.e., tailpipe catalytic converters. The chemical reaction of O3 formation indicates radiation and nitrogen oxides as main players. Thus, we investigate correlations between O3, global radiation, nitrogen oxides, temperature, and precipitation in several periods of the year (2017) near a traffic roundabout in Lisbon city (coordinates 38°44’55’’ lat, −9°08’56’’ long). The weekend effect, school break versus school period, day and night, and seasonal effect were explored. Low-cost sensors (LCS) of O3, NOx, and temperature were tested to see if they can be used to get historical data on other cities and locations. The main innovation is the calibration of the sensor directly with real data (uncontrolled environment). Raw data were compared and led us to conclude that MQ-131 has a better performance than the MICS-4514 sensor. The results indicate that the diurnal cycle of ozone concentration has a mid-day peak around 1–2 pm and a lower nighttime concentration below 5 ppb Weekends and school break period (251 days a year) have the highest values of Ozone, this is due to lower NOx emissions and thus lower levels of ozone destruction reaction (NOx-titration reaction). August is a hotspot month with a maximum concentration of 71 ppb.

Modifying Exhaust After-Treatment Device for Complying with Future Emission Norms

Day to day increase in air pollution is one of the serious issues nowadays. One of the main contributors is automobile emissions. It contains gases like carbon dioxide, carbon monoxide, hydrocarbon, nitrogen oxides, and particular matters. In order to address such issues, this paper is focused on the reduction of emissions by modifying the design of an exhaust after-treatment device. The analysis is carried out on a 4-stroke single-cylinder 149cc FZ-S BS4 bike two-wheeler gasoline engine.CO and HC emissions absorbed by an aqueous solution having different TDS of aqua 90ppm RO water, 1000ppm Municipality water, and 10000ppm seawater. Such aqueous solution contains calcium powder and activated carbon in 10:0.5:0.5, 10:1:1 and 10:2:2 in proportion respectively. An optimum solution derived which having a mixture of 10:1:1 proportion having 10000ppm seawater is derived which shows reduction in CO by 50% and HC emission by 40% as compare conventional muffler exhaust emission. The IoT device is used with the MQ-7 sensor to measure CO emission from a modified device and data obtained are compared with PUC (Pollution under control) certified center. This research is to optimize emission from the existing gasoline engine, from April 2017 BS4 is implemented in INDIA nationwide & BS6 will be going to implement by 2020. From April 2017 manufacturer are not allowed to build new engines below BS4 standard but customer those who are having an older version of engines are not having any effect of BS4 & their engines are still emitting more pollution than the current emission norms. More than 100 million of twowheeler engines were sold in between Feb‘06- March’17. This study aims to provide a solution for such engines not from the manufacturer side but from the consumer side to upgrade their vehicle to satisfy future emission norms so that human health will be less affected by such emissions.

Improvement of diesel engine startability under low temperatures by vortex tubes

Cold start is one of the most problematic combustion phases for diesel engines. During this phase, a large proportion of pollutants are produced within the cylinder due to misfiring and incomplete combustion due to the low engine temperatures. Furthermore, exhaust after-treatment devices work inefficiently since their minimum operation temperatures cannot be reached. In addition to this, at temperatures below 0 °C the possibility of continuous misfiring could actually impede the engine start. Ambient temperature is one of the most important factors affecting the diesel engine cold startability.The aim of this study is to improve diesel engine startability under low temperatures by vortex tubes. A vortex tube was used to increase the intake air temperature in a six cylinders, four stroke and direct injection diesel engine of a truck. The hot air obtained from the hot outlet of the vortex tube was mixed with the air coming from the inlet of the intake manifold and the warmer air was sent to the cylinders. The compressed air required for the operation of the vortex tube was provided from the air tank of the compressed-air brake system of the truck. The effects of variation in ambient temperature on the engine cranking speed and in-cylinder pressure were analyzed and presented. Experiments were conducted for ambient air temperatures of −5, 0 and +4 °C. It was found that the reduction in ambient temperature resulted in prolonged cranking periods along with the longer time taken to reach idling speed as well as increased combustion instability for the engine without vortex tube. The use of the vortex tube increased the intake air temperature, which decreased durations of engine starting–cranking, cranking–idling, and idling–stabling. These results indicate that the cold starting performance of the diesel engine could be improved by using vortex tubes.

Retrofitting and re-powering as a control strategies for curtailment of exposure of underground miners to diesel aerosols.

A study was conducted to examine the potential of diesel emissions control strategies based on retrofitting existing power packages with exhaust aftertreatment devices and repowering with advanced power packages. The retrofit systems, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), were evaluated individually using a US EPA tier 2 (ter 2) engine operated under four steady-state conditions and one transient cycle. The DOC effectively curtailed emissions of CO, and to some extent organic carbon (OC), elemental carbon (EC), and aerosol number concentration. The DPF system offered substantially higher reductions in OC and EC mass and aerosol number concentrations. Both, the DOC and DPF achieved reductions in the aforementioned emissions without adversely affecting emissions of NO2 and nano-sized aerosols. The strategy of repowering with an advanced system was examined using a US EPA tier 4 final (tier 4f) engine equipped with a cooled exhaust gas recirculation system and diesel exhaust fluid-based selective catalytic reduction system, but not with a DPF system. The tier 4f engine contributed substantially less than the tier 2 engine to the EC and OC mass, aerosol number, and CO, NO, and NO2 concentrations. The tier 4f engine was very effective in reducing aerosol mass, NO, and NO2 concentrations, but it was not equally effective in reducing aerosol number concentrations. The implementation of viable exhaust after treatment systems and advanced diesel power packages could be instrumental to the underground mining industry to secure a clean, economical, and dependable source of power for mobile equipment.

Exhaust Gas Condensation during Engine Cold Start and Application of the Dry-Wet Correction Factor

Gas components, like carbon monoxide (CO) and dioxide (CO2), can be measured on a wet- or dry-basis depending on whether the water is left or removed from the sample before analysis. The dry concentrations of gaseous components in the exhaust from internal combustion engines are converted to wet concentrations with conversion factors based on the combustion products and the fuel properties. Recent CO2 measurements with portable emissions measurement systems (PEMS) compared to laboratory grade equipment showed differences during the first minutes after engine start. In this study we compared instruments measuring on a dry- and wet-basis using different measuring principles (non-dispersive infrared detection (NDIR) and Fourier-transform infrared spectroscopy (FTIR)) at the exhaust of gasoline, compressed natural gas (CNG), and diesel light-duty and L-category vehicles. The results showed an underestimation of the CO2 and CO mass emissions up to 13% at cold start when the conversion factor is applied and not direct “wet” measurements are taken, raising concerns about reported CO2 and CO cold start emissions in some cases. The underestimation was negligible (<1%) for CO2 when the whole test (20–30 min) was considered, but not for CO (1%–10% underestimation) because the majority of emissions takes place at cold start. Exhaust gas temperature, H2O measurements and different expressions of the dry-wet corrections confirmed that the differences are due to condensation at the exhaust pipes and aftertreatment devices when the surface temperatures are lower than the dew point of the exhaust gases. The results of this study help to interpret differences when comparing instruments with different principles of operation at the same location, instruments sampling at different locations, or the same instrument measuring different driving test cycles or at different ambient temperatures (e.g., −7 °C).

Nanostructure and reactivity of soot produced from a turbodiesel engine using post injection

Post injection is commonly used for triggering regeneration of exhaust aftertreatment devices such as diesel particulate filters and NOx adsorber catalysts. Post injection is also a method to reduce engine-out particulate matter (PM) emissions while maintaining efficiency, to reduce or potentially eliminate exhaust aftertreatment. This study explores post injection in a light duty multi-cylinder turbodiesel engine to reduce PM. The impact of post injection dwell and duration on soot reduction and reactivity are investigated in this study. Soot samples were collected from the engine exhaust and subjected to analyses of oxidative reactivity and nanostructure of the primary soot particles. Close-coupled post injections conditions reduce soot emissions by 11–21%, while long-dwell post injection conditions reduce soot emissions by 28–33%. The reaction rate constants of soot collected from close-coupled post injection conditions decrease by 10–13% compared to baseline condition, while the reaction rate constants of soot collected from long dwell post injection conditions increase by 37–39% compared to the baseline condition. The difference in soot reactivity indicates fuel from the post injection interacts with the main injection flame. Moreover, with the increase of injection dwell and post injection size, soot surface oxygen content and amorphous carbon content increase. This explains the change in reactivity of soot from different injection dwells. Primary soot particle and particle aggregate sizes do not vary much with post injection. Soot from post injection conditions show shrinking-core-type oxidation without graphene layer rearrangement.

Unsteady Simulation of Conjugate Heat Transfers with Exhaust Pulsating Temperature for Vehicle Thermal Management

Unsteady simulation of heat transfers for vehicle exhaust system plays an important role in vehicle development process. Based on STAR-CD software, a sedan exhaust system model, which includes the exhaust gas, the exhaust pipes and aftertreatment devices, was established. In this model, the complicated boundary conditions between fluid and solid, which need to be specified in the non-coupled models, are now part of the solution and do not need to be specified. A three-dimensional unsteady simulation was undertaken for the heat transfer characteristics of vehicle exhaust system. The heat transfer characteristics with the periodic pulsating exhaust temperature were obtained and analyzed, and the unsteady mean value were compared with the steady results, and the discipline between the steady heat transfer characteristics and the periodic pulsating exhaust temperature were found.

Regeneration of diesel particulate filters: Effect of renewable fuels

Current trends in diesel transport anticipate that in the upcoming future a range of renewable fuels will be necessary to comply with emission and sustainability legislations. Exhaust after-treatment devices such as diesel particulate filters –DPFs– will have to operate satisfactorily with this pool of biofuels. In particular, DPF regeneration is crucial to cut the fuel penalty and guarantee an acceptable lifetime for this device. In the present work, an automotive diesel engine was run with fossil fuel and three renewable fuels: a conventional biodiesel, a fuel manufactured through Fischer-Tropsch –FT– process and a HVO biofuel. The DPF was loaded and regenerated through an active process with fuel post-injections. Additionally, soot samples were investigated with thermo-gravimetry (TGA) and calorimetry (DSC) to confirm whether these techniques obtain relevant information for explaining DPF behavior. Both methods proved that biodiesel leads to a more economical regeneration being the biodiesel soot, more reactive than the other samples, the main reason. DPF regenerations with paraffinic fuels (FT-derived and HVO) did not reveal strong differences compared to diesel, though TGA and DSC results suggested that soot from paraffinic biofuels is more reactive than that from diesel. The exhaust gas temperature and composition are behind this apparent discrepancy.

단기통 디젤엔진에서 LNT/DPF + SCR/DPF 하이브리드 시스템의 NOx 및 PM 동시저감 특성

The market demand for diesel engine tends to increase in general passenger cars as well as commercial vehicles because of its advantages. However, to meet the vehicle emissions regulation which will be more stringent in the future, it is necessary to plurally apply all after-treatment technologies such as diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (CDPF), lean NOx trap (LNT) and selective catalytic reduction (SCR), and so on. Accordingly, the exhaust after-treatment system for diesel vehicle requires the technology of minimizing the numbers of catalysts by integrating every individual catalysts. The purposes of this study is to develop hybrid exhaust after-treatment device system which simultaneously uses LNT/DPF and SCR/DPF catalyst concurrently reducing NOx and particulate matter (PM). As the results, the hybrid system with <TEX>$NH_3$</TEX> generated at LNT/DPF working as a reducing agent of SCR/DPF catalyst, improving NOx conversion rate, was found to be more excellent in de-NOx performance than that in LNT/DPF alone system.

Intermediate Volatility Organic Compound Emissions from On-Road Diesel Vehicles: Chemical Composition, Emission Factors, and Estimated Secondary Organic Aerosol Production.

Emissions of intermediate-volatility organic compounds (IVOCs) from five on-road diesel vehicles and one off-road diesel engine were characterized during dynamometer testing. The testing evaluated the effects of driving cycles, fuel composition and exhaust aftertreatment devices. On average, more than 90% of the IVOC emissions were not identified on a molecular basis, instead appearing as an unresolved complex mixture (UCM) during gas-chromatography mass-spectrometry analysis. Fuel-based emissions factors (EFs) of total IVOCs (speciated + unspeciated) depend strongly on aftertreatment technology and driving cycle. Total-IVOC emissions from vehicles equipped with catalyzed diesel particulate filters (DPF) are substantially lower (factor of 7 to 28, depending on driving cycle) than from vehicles without any exhaust aftertreatment. Total-IVOC emissions from creep and idle operations are substantially higher than emissions from high-speed operations. Although the magnitude of the total-IVOC emissions can vary widely, there is little variation in the IVOC composition across the set of tests. The new emissions data are combined with published yield data to investigate secondary organic aerosol (SOA) formation. SOA production from unspeciated IVOCs is estimated using surrogate compounds, which are assigned based on gas-chromatograph retention time and mass spectral signature of the IVOC UCM. IVOCs contribute the vast majority of the SOA formed from exhaust from on-road diesel vehicles. The estimated SOA production is greater than predictions by previous studies and substantially higher than primary organic aerosol. Catalyzed DPFs substantially reduce SOA formation potential of diesel exhaust, except at low speed operations.

Effects of antiwear additives in the base oil on the tribological performance of hydrogen-free DLC coating

Purpose – The purpose of this study is to investigate the effects of zinc dialkyl dithiophophates (ZDDP) and ash-less triphenyl phosphorothionate (TPPT) on hydrogen-free diamond-like carbon (DLC) coatings. For many years, ZDDP have traditionally been used in engine oils as antiwear (AW) and extreme pressure (EP) additives. However, additives containing sulfated ash, phosphorus and sulfur (SAPS) have a detrimental effect on the exhaust after-treatment device found on modern vehicles. Besides the automotive industry, DLC is also used in hydraulic applications where zinc-free and ash-less hydraulic fluids have gradually gained popularity in recent years. Design/methodology/approach – The tribological tests were performed using a disk-on-cylinder tribometer, where the stationary hydrogen-free DLC-coated steel disk formed a line contact with an uncoated rotating steel shaft under lubricated conditions. Findings – It was found that TPPT and ZDDP separately at a concentration of 1.0 wt% increased the amount of friction of the base oil by approximately four times. TPPT appeared more effective than ZDDP in minimizing wear on the DLC-coated surface. Also, primary ZDDP seemed to have a more detrimental effect on the DLC-coated surface compared to a mixture of primary and secondary ZDDP. With regard to surface roughness of the hydrogen-free DLC-coated surface, the values corresponding to a lubricant containing TPPT were lower than those obtained for a lubricant with ZDDP and a lubricant without any additive. Originality/value – This is the first report on the effects of ZDDP and ash-less TPPT on the tribology of hydrogen-free DLC coatings.

Vehicle Engines Produce Exhaust Nanoparticles Even When Not Fueled

Vehicle engines produce submicrometer exhaust particles affecting air quality, especially in urban environments. In on-road exhaust studies with a heavy duty diesel vehicle and in laboratory studies with two gasoline-fueled passenger cars, we found that as much as 20-30% of the number of exhaust particles larger than 3 nm may be formed during engine braking conditions-that is, during decelerations and downhill driving while the engine is not fueled. Particles appeared at size ranges extending even below 7 nm and at high number concentrations. Their small size and nonvolatility, coupled with the observation that these particles contain lube-oil-derived metals zinc, phosphorus, and calcium, are suggestive of health risks at least similar to those of exhaust particles observed before. The particles' characteristics indicate that their emissions can be reduced using exhaust after-treatment devices, although these devices have not been mandated for all relevant vehicle types. Altogether, our findings enhance the understanding of the formation vehicle emissions and allow for improved protection of human health in proximity to traffic.

Gaseous and Particulate Emissions from Diesel Engines at Idle and under Load: Comparison of Biodiesel Blend and Ultralow Sulfur Diesel Fuels.

Diesel exhaust emissions have been reported for a number of engine operating strategies, after-treatment technologies, and fuels. However, information is limited regarding emissions of many pollutants during idling and when biodiesel fuels are used. This study investigates regulated and unregulated emissions from both light-duty passenger car (1.7 L) and medium-duty (6.4 L) diesel engines at idle and load and compares a biodiesel blend (B20) to conventional ultralow sulfur diesel (ULSD) fuel. Exhaust aftertreatment devices included a diesel oxidation catalyst (DOC) and a diesel particle filter (DPF). For the 1.7 L engine under load without a DOC, B20 reduced brake-specific emissions of particulate matter (PM), elemental carbon (EC), nonmethane hydrocarbons (NMHCs), and most volatile organic compounds (VOCs) compared to ULSD; however, formaldehyde brake-specific emissions increased. With a DOC and high load, B20 increased brake-specific emissions of NMHC, nitrogen oxides (NOx), formaldehyde, naphthalene, and several other VOCs. For the 6.4 L engine under load, B20 reduced brake-specific emissions of PM2.5, EC, formaldehyde, and most VOCs; however, NOx brake-specific emissions increased. When idling, the effects of fuel type were different: B20 increased NMHC, PM2.5, EC, formaldehyde, benzene, and other VOC emission rates from both engines, and changes were sometimes large, e.g., PM2.5 increased by 60% for the 6.4 L/2004 calibration engine, and benzene by 40% for the 1.7 L engine with the DOC, possibly reflecting incomplete combustion and unburned fuel. Diesel exhaust emissions depended on the fuel type and engine load (idle versus loaded). The higher emissions found when using B20 are especially important given the recent attention to exposures from idling vehicles and the health significance of PM2.5. The emission profiles demonstrate the effects of fuel type, engine calibration, and emission control system, and they can be used as source profiles for apportionment, inventory, and exposure purposes.

Modelling lubrication oil particle emissions from heavy-duty diesel engines

The impact of lubrication oil on particle exhaust emissions has attracted increasing attention as emissions of fuel-derived particles have been reduced. This paper presents a model for assessing the oil-related exhaust particle emissions of heavy-duty diesel engines. The model contains four sub-models describing the hydrocarbon, ash, carbon and sulphate particles. All sub-models were developed based on the results of a literature review, complemented by controlled engine tests to fill the knowledge gaps and verify assumptions where necessary. Exhaust after-treatment devices, such as diesel particulate filters, are not included in the model at this stage; in engines equipped with such devices, the modelling results could be used to assess the input of oil-related particulate matter into the exhaust after-treatment system or serve as a basis for further development. The modelling results indicate that the contribution of oil to airborne exhaust particles is substantial under low-load and motoring conditions. Reducing oil consumption is an effective way to reduce oil-related particle emissions.