Glycerol derivatives for diesel fuel reformulation

<div class="htmlview paragraph">The use of Diesel engines has strongly increased during the last years and now represents 30% of the sales in Europe and up to 50% of the number of cars in circulation for some countries. This success is linked not only to the economical aspect of the use of such vehicles, but also to the recent technological improvements of these engines. The new technical solutions (high pressure direct injection, turbocharging…) have indeed allowed the increase of these engine performances while decreasing their fuel consumption, pollutant emissions and noise level.</div> <div class="htmlview paragraph">From an environmental point of view, Diesel engines are nevertheless penalized by their particulate and NOx emissions. The study and the treatment of the particulate, highly criticized for their potential impact on health, are the subject of numerous works of characterization and developments.</div> <div class="htmlview paragraph">PSA Peugeot-Citroën has recently launched its particulate filter technology on several types of vehicles. In order to evaluate the durability of this technology over a long period of time, a study program has been set-up by ADEME (French environmental agency), IFP Powertrain, PSA Peugeot-Citroën and G7 (a Parisian taxi company). The objective is to study the evolution of several taxis and their after-treatment system performances over 80 000 km mileage in hard urban driving conditions, which corresponds to the recommended mileage before the first DPF maintenance.</div> <div class="htmlview paragraph">More specifically, the following evaluations are being performed at regular intervals (around 20 000 km):</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">Regulated gaseous pollutant emissions on NEDC cycle (New European Driving Cycle)</div></li> <li class="list-item"><div class="htmlview paragraph">Particulate emissions, by mass measurement on NEDC but also by particle number and size measurement with SMPS (Scanning Mobility Particle Sizer) technique on NEDC and on unconventional steady-state running points.</div></li> <li class="list-item"><div class="htmlview paragraph">Unregulated pollutant emissions (hydrocarbons speciation C<sub>1</sub>-C<sub>13</sub>, oxygenated compounds)</div></li> </ul> </div> <div class="htmlview paragraph">The results obtained until now have not shown any degradation of the particulate filter efficiency. This paper presents the methodology setup and the explanation of the first results obtained. Indeed, a more specific study has shown that most of the aerosols measured with SMPS are composed of liquid fractions, mainly sulfates due to sulfur coming from the fuel, but also from the lubricant. The impact of sulfates stored on the catalyst surface during low temperature running phases and removed during high temperature running phases has also been outlined.</div>

<div class="section abstract"><div class="htmlview paragraph">An experimental study on effects of high-pressure injections in conjunction with split fuel injections were conducted on an AVL single cylinder DI diesel engine. Various injection schemes were studied through the use of an electronically controlled, common rail injection system capable of injection pressures up to 200 MPa and a maximum of six injections per combustion event.</div><div class="htmlview paragraph">Up to 100 MPa of the fuel injection pressure, the higher injection pressures create faster combustion rates that result in the higher in-cylinder gas temperatures as compared to conventional low-pressure fuel injection systems. When applying high-pressure injections, particulate emission reductions of up to 50% were observed with no change in hydrocarbon emissions, reductions of CO emissions and only slightly higher NOx emissions.</div><div class="htmlview paragraph">Over 100 MPa, on the other hand, the higher injection pressures still reduced up to almost zero-level of particulate emission, at the same time that the NO emission is reduced greatly. Under these high-pressure injection conditions, strong correlations between soot and CO emissions were observed, which compete for the oxidizing OH species.</div><div class="htmlview paragraph">Multiple or split high-pressure injections also investigated as a means to decrease particulate emissions. As a result, a four-split injection strategy resulted in a 55% reduction in particulates and with little or no penalty on NOx emissions. The high pressure split injection strategy with EGR was more effective in reducing particulate and CO emissions simultaneously.</div></div>

<div class="htmlview paragraph">The aim of this study was to investigate the changes in mass and number based heavy duty diesel engine particle emissions with respect to various test conditions, engine technologies and fuel specifications. Comparative particle size data and regulated particulate matter are presented from three heavy duty engines and three fuels.</div> <div class="htmlview paragraph">This paper describes results from the DETR/CONCAWE/SMMT Particle Research Programme. Three heavy duty diesel (HDD) engines representing Euro I, II and III technologies were tested with a range of fuels. These fuels included UK ultra low sulphur diesel (UK-ULSD), EN590 (EU2000) specification and Swedish Class I fuels.</div> <div class="htmlview paragraph">Continuing research suggests that when changes in regulated particulate mass emissions are compared to both individual mode and total cycle mass and number weighted particle size distributions there is often no significant correlation. In an attempt to provide further data in this area the following measurement methodology was adopted.</div> <div class="htmlview paragraph">Two Scanning Mobility Particle Sizer (SMPS) instruments measuring number weighted particle size distribution were employed in order to cover a measurement range from ∼7nm to ∼710nm. The different configurations used with these two instruments operating over separate size ranges resulted in differences in the results obtained in the overlap region. Because of the perceived importance of the smallest particle range, the instrument measuring the lowest range (7-320 nm) was selected for data comparison. Conclusions may not be supported by a similar SMPS system working under an alternative configuration. Within this paper conclusions are therefore based upon data from that system only.</div> <div class="htmlview paragraph">Particle mass measurements were undertaken via the regulated method and with a Micro Orifice Uniform Deposit Impactor (MOUDI) covering a size range from <56nm to 10μm measuring the mass weighted size distribution. In addition to the particle size distribution, particulate matter and other regulated emissions were measured as mass emissions. Chemical composition of selected particulate samples was undertaken.</div> <div class="htmlview paragraph">The paper concludes that in these tests, at the accumulation mode between 50 and 320 nm, engine effects were greater than fuel effects, with particle numbers in general reducing with advanced engine technology when tested over regulated cycles. Nanoparticles however, seemed to be more sensitive to fuels. These particles were clearly more variable and sensitive to sampling conditions than the accumulation mode particles. Nanoparticles were observed to be more sensitive to fuels. More research in this area is required. As expected, the Swedish Class 1 fuel tended to achieve lower regulated cycle emissions in all three engines tested than the other fuels.</div> <div class="htmlview paragraph">None of the engine technologies or fuel specifications tested reduced particulate mass, nanoparticles (in the SMPS size range 7nm to ∼50nm) and accumulation mode particles (50nm to 320nm) concurrently at all test conditions.</div>

<div class="htmlview paragraph">An emissions and performance study was conducted to explore the effects of exhaust gas recirculation (EGR) and multiple injections on the emission of oxides of nitrogen (NOx), particulate emissions, and brake specific fuel consumption (BSFC) over a wide range of engine operating conditions. The tests were conducted on an instrumented single cylinder version of the Caterpillar 3400 series heavy duty Diesel engine. Data was taken at 1600 rev/min, and 75% load, and also at operating conditions taken from a 6-mode simulation of the federal transient test procedure (FTP). The fuel system used was an electronically controlled, common rail injector and supporting hardware. The fuel system was capable of as many as four independent injections per combustion event at pressures from 20 to 120MPa. NOx versus particulate trade-off curves were generated over a range of injection timings for each mode in a baseline condition, then trade-off curves were generated for several of the modes using multiple injections and/or EGR. A previous study, conducted at 1600 rev/min, and 75% of peak torque showed that by using an optimal triple injection, and a 6% EGR rate, NOx and particulate could be simultaneously reduced to as low as 2.2 and 0.07 g/bhp-hr, respectively. The present results first show that at the 1600 rev/min, 75% load running condition, NOx and particulate emissions can be further reduced to 1.58 g/bhp-hr NOx with 0.105 g/bhp-hr particulate by using 10% EGR with an optimized quadruple injection. The present results also show that NOx and particulate emissions as well as fuel consumption can be reduced over the entire engine operating map with the use of multiple injections and EGR. The emissions reductions effected on the test engine, through the use of optimized injection pressures, multiple injections and EGR, allowed an overall cycle emissions reduction from 5.17 g/bhp-hr NOx with 0.44 g/bhp-hr particulate to 3.70 g/bhp-hr NOx with 0.11 g/bhp-hr particulate while providing a reduction in overall cycle BSFC from 206 g/bhp-hr to 184 g/bhp-hr. When corrected to account for the reduced frictional losses of a multi-cylinder engine, these emission levels are in compliance with 1998 US EPA mandates.</div>

<div class="htmlview paragraph">The specific aim is to validate an engineering model for direct injection (DI) Diesel engine emissions. Characteristic times describing the controlling fluid mechanics and chemical kinetics will be employed in the model to correlate both NOx and particulate emissions. Because the model equations are algebraic, they are suitable for implementation in a phenomenological cycle simulation program, or as an emissions model option in a computational fluid dynamics code.</div> <div class="htmlview paragraph">An original premise was that earlier work on global NO chemistry based on pollutant emissions dominated by diffusion flame contributions had adequately elucidated the kinetic aspects of the model. It is shown here that this approach is not valid for modern engines. Rather, an improved two-zone flame model for NO formation/decomposition is required. Mellor et al. [<span class="xref">1</span>] propose such a model, but include only qualitative preliminary model validation. Here we further test the model using measurements from a high speed direct injection (HSDI) Diesel engine with a common rail fuel injection system. Exhaust gas recirculation variations from zero to maximum level possible are reported and correlated for parametric variations of engine speed, injection pressure, and load.</div> <div class="htmlview paragraph">The two-zone NOx HSDI Diesel characteristic time model (CTM) involves a skeletal mechanism consisting of seven elementary reactions [<span class="xref">1</span>]. A surrogate stoichiometric flame temperature around a spray plume at start of combustion conditions represents the environment for NO-forming eddies in the first zone. The second zone surrounds the stoichiometric region, and NO decomposition may occur depending on a surrogate flame temperature at the end of combustion computed from fuel/air dual (i.e., limited-pressure) cycle analysis. Both Zeldovich and nitrous oxide mechanisms are considered in each zone.</div> <div class="htmlview paragraph">Two objectives are accomplished in the present paper. First, in Mellor et al. [<span class="xref">1</span>] the N<sub>2</sub>O mechanism was postulated to be important to the NO formation kinetics under Diesel engine in-cylinder conditions. In addition, it was suggested that NO decomposition reactions may occur at high engine loads through the reverse N<sub>2</sub>O and Zeldovich mechanisms. These hypotheses are validated using the measured engine data. Second, we extend the previous work through preliminary development of the fluid mechanic aspects of the model. A characteristic mixing time that is a function of Reynolds number, Weber number, and engine geometry is developed. When used in combination with the kinetic time for NO formation as a Damköhler number, correlations of NOx emissions for the above parametric variations are obtained for conditions where NO decomposition does not occur.</div>

<div class="section abstract"><div class="htmlview paragraph">Increasing concerns due to global warming have led to stringent regulation of greenhouse gas (GHG) emissions from diesel engines. Specifically, for GHG phase-2 regulation (2027), more than 4% improvement is needed when compared to phase-1 regulation (2017) in the light heavy-duty (LHD) diesel engine category. At the same time, California Air Resources Board (CARB) and Environmental Protection Agency (EPA) have proposed the new Low NOx standards that require up to 90% reduction in tailpipe (TP) NOx emissions in comparison to the current TP NOx standards that were implemented in 2010. In addition, CARB and EPA have proposed new certification requirements – Low Load Cycle (LLC) and revised heavy-duty in-use testing (HDIUT) based on the moving average window (MAW) method that would require rigorous thermal management. Hence, strategies for simultaneous reduction in GHG and TP NOx emissions are required to meet future regulations.</div><div class="htmlview paragraph">This paper presents potential pathways to achieve the GHG phase-2 and the ultra-low NOx (ULN) regulations with minimum changes in engine design, while meeting the constraints that need to be considered for engine performance stability, component durability, and vehicle drivability. Experimental evaluations were performed focusing on transient cycles such as heavy-duty Federal Test Procedure (hereafter referred as FTP), LLC, and custom transient cycles for HDIUT assessment. We used a model-year (MY) 2021 production Isuzu diesel engine and an advanced dual-dosing aftertreatment system comprising of a close-coupled SCR (ccSCR), diesel oxidation catalyst (DOC), diesel particulate filter (DPF), selective catalytic reduction (SCR), and Ammonia Slip Catalyst (ASC). Conventional thermal management techniques such as multi-injection, intake, and exhaust throttling were implemented to achieve the emissions targets. In addition to the proposed system design, this paper presents following test results from a full-scale system evaluation: <ol class="list nostyle"><li class="list-item"><span class="li-label">1</span><div class="htmlview paragraph">Achieve rapid and sustained turbine-out exhaust temperatures (>200°C) while meeting the engine-out emissions constraints for soot and total hydrocarbon (THC) emissions.</div></li><li class="list-item"><span class="li-label">2</span><div class="htmlview paragraph">A summary of TP NOx, TP N2O and GHG emissions over a composite FTP and LLC.</div></li><li class="list-item"><span class="li-label">3</span><div class="htmlview paragraph">HDIUT assessment results and observations for LLC and custom transient cycles.</div></li><li class="list-item"><span class="li-label">4</span><div class="htmlview paragraph">Robustness evaluation of TP NOx emissions for composite HDT, LLC and custom transient cycles by imposing component variations.</div></li></ol></div></div>

<div class="section abstract"><div class="htmlview paragraph">Measuring lubricant related fuel economy of internal combustion [IC] engines presents technical challenges, due to the relatively small differences attributable to lubricants. As engine technology progresses, large benefits become harder to find; so the importance of precise measurement increases. Responding to the challenge of meeting CO<sub>2</sub> targets, many successful IC engine technologies have been deployed; these include downsizing/rightsizing[<span class="xref">1</span>], mechanical efficiency improvements, advanced charging and combustion systems, thermal management, sophisticated electronic control and calibration. These technologies have been deployed against a back-drop of increasingly stringent emission requirements. Increasing attention is focused on technologies which offer smaller but important contributions. The search for smaller improvements combined with growing engine and vehicle technology complexity increases the challenge of producing high quality data.</div><div class="htmlview paragraph">The aim of this paper is a practical engineering overview of the measurement of engine fuel economy using engine drive cycles.</div><div class="htmlview paragraph">As a global lubricant company, Castrol’s engine experience and customer base is broad, covering the whole spectrum from small handheld power tools to large truck and marine engines. Described here are aspects of our experience in testing passenger car engines, with a focus on detecting the impact of lubricant formulation on fuel economy. A facility delivering critical precise measurements is described, along with the equipment and methodology developed over many years by the engineers who use it.</div><div class="htmlview paragraph">Further, stop:start is investigated, an aspect of “micro-hybrid” technology.</div><div class="htmlview paragraph">Using simulation software, the vehicle load demand was varied to demonstrate the effect of typical vehicle parameters on lubricant differentiation.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Reducing the greenhouse emissions from on-road freight vehicles to meet the climate change mitigation objectives, has become a prime focus of regulatory authorities all over the world. Besides India, the United States, the European Union, Canada, Japan, and China have already established or planned heavy-duty vehicle efficiency regulations addressing CO<sub>2</sub> and NO<sub>X</sub> emissions. In addition, Argentina, Brazil, Mexico, and South Korea are all in various stages of developing policies to improve the efficiency of their commercial vehicle fleets. For CO<sub>2</sub> emissions reduction standards, the U.S. mandates 27% reduction by 2027, EU is calling for 15% reduction by 2025, China for 27% by 2019 over 2012 levels, and India is mandating 10%-15% reduction by 2021 for phase 2 of the new standard. There has also been considerable focus on further reduction in NO<sub>X</sub> emissions from current levels (0.2 g/hp-hr), to the proposed ultra-low NOx standards (0.02 g/hp-hr) in the U.S. for heavy duty engines by 2024.</div><div class="htmlview paragraph">Given these planned and proposed regulatory standards being implemented around the globe, there have been substantial studies and publications focusing on exploring and evaluating technologies that can help deliver the lower tailpipe NOx targets and understand the CO<sub>2</sub> impact associated with it. Majority of the NO<sub>X</sub> emissions from engine, occur during the cold-start portion of the transient regulatory cycles, like HD FTP and WHTC. This is because, a typical heavy-duty diesel aftertreatment system does not achieve substantial NO<sub>X</sub> reduction until approximately 400-500 seconds into the cold-start cycle due to lack of heat from the engine. The result is untreated NOx escaping through to tailpipe. To achieve low NOx emission levels over the composite transient cycles, the engine must provide rapid exhaust heat energy, during the cold-start portion, to reduce the time required by the SCR catalyst to reach catalyst light-off temperature, while controlling the NO<sub>X</sub> emissions. Moreover, high NO<sub>X</sub> conversion efficiency must be maintained during the hot-start portion of cycle. For a conventional heavy-duty engine, providing rapid exhaust heat while controlling NOx emissions has been a challenge, because these are competing demands. Implementing secondary or auxiliary heat sources downstream in the exhaust after treatment system (ATS) comes at CO<sub>2</sub> penalty and adds significant cost and complexity. This has been established in recent publications by organization like SwRI [<span class="xref">1</span>], CARB and Bosch [<span class="xref">2</span>].</div><div class="htmlview paragraph">Achates Power Opposed Piston (OP) engine technology provides ideal solution to this challenge. The opposed-piston engine has several inherent advantages over conventional four-stroke engines, like higher BTE (15-30% higher), higher power density, an air-system that results in reduced pumping work, the ability to control residual combustion gases, two fuel injectors per cylinder providing greater timing flexibility, and the ability to provide rapid engine out heat and temperature rise for the exhaust emission system while maintaining low engine out NO<sub>X.</sub></div><div class="htmlview paragraph">This paper demonstrates results from cold and hot start transient WHTC testing and WHSC testing, conducted at Achates Power, on a three-cylinder opposed-piston engine. Results show that the Achates Power OP Engine can deliver engine out heat and temperature rise that exceeded and sustained catalyst light-off temperature thresholds (250°C) within the first 60-100 seconds in the cold start cycle, while controlling engine out NOx to lower levels when compared to a conventional four-stroke heavy-duty diesel engine. As a result, the OP Engine not only meets current BS-VI and future regulatory emissions requirements but is also able to do so with a significant CO<sub>2</sub> emissions advantage. Furthermore, the inherent advantages of the OP Engine offer unique aftertreatment optimization and downsizing opportunities thereby enabling cost reduction.</div></div>

<div class="htmlview paragraph">The effects of engine operating conditions and fuel properties on diesel exhaust emissions and the effect of an additive on fuel-injector deposits were studied using four diesel engines.</div> <div class="htmlview paragraph">The test engines were swirl chamber type diesel engines for Japanese passenger cars: two with 1800cc. displacement, one with 2400cc displacement, and one with 2800cc displacement. Diesel exhaust emissions were collected using a dilution tunnel system, and concentrations of CO, HC, NOx and particulate were measured. Test fuels were formulated with emphasis on distillation properties (10% and 90% distillation temperatures), composition (aromatics content), and cetane number.</div> <div class="htmlview paragraph">CO, HC, NOx, and particulate emissions varied from one engine to another. The differences in these emissions among the test engines were notable at Sow load driving conditions. Regarding fuel properties: %CA considerably affected CO, HC, NOx, and particulate emissions. Also, 90% distillation temperature influenced particulate emissions, depending on engine type. Fuel injector deposits increased particulate emissions but certain detergent type additives had the effect of cleaning up injector deposits.</div>

<div class="htmlview paragraph">To limit pollutants from transport and to reach a low level of exhaust emission, Low Temperature Combustion (LTC) modes such as Homogeneous Charge Compression Ignition (HCCI) are being studied. HCCI process is based on the auto-ignition of a highly diluted air/fuel mixture. It allows very low level of NO<sub>x</sub> and particulate emissions. But several problems must be solved: firstly the limited combustion range, the difficulty to control the combustion process, the noise but also the high HC and CO emissions. Two ways appear as very promising to improve HCCI combustion: engine technology and fuel formulation.</div> <div class="htmlview paragraph">In this work, attention is paid on initiation and HCCI combustion control through fuel formulation. This article shows the effect of acetal addition (and in particular butylal addition) in a Diesel base fuel.</div> <div class="htmlview paragraph">It seems to be difficult to have only an “HCCI engine” because the operation zone of the engine is too small. More likely, it will be a Diesel/HCCI engine. The advantage of acetal is to reduce significantly particulate emissions of a Diesel engine. This is an advantage for a Diesel/HCCI engine, when the engine works in Diesel combustion but it is necessary to get a better understanding of the influence of acetal addition in a Diesel base fuel during the HCCI combustion.</div> <div class="htmlview paragraph">Butylal can have a good potential to improve the HCCI combustion by delaying the initiation of a Diesel base fuel but due to its versatile aspect, it is difficult to control, for all the experimental conditions, its effect on the initiation and the HCCI combustion of a Diesel base fuel.</div>

<div class="section abstract"><div class="htmlview paragraph">Achieving zero emissions across transportation is a tremendous challenge. The upcoming Euro 7/VII standards, set to be enforced in 2025, will mandate further reduction in ICEs exhaust emissions. Thus, additional improvements and potential new technologies and fuels are needed to design ultra-low emissions vehicles.</div><div class="htmlview paragraph">Hydrogen seems to be a very attractive fuel, thanks to its high lower heating value, clean combustion, and extremely low pollutant emissions, due to the zero-carbon content. Nevertheless, NOx emissions are still an issue in hydrogen fueled engines and optimized lean-burn combustion and suitable after-treatment NOx reduction are mandatory to reach high specific power and efficiency and near zero NOx emissions, thus enabling H2-ICE powered vehicles to be zero-impact emitting technology solution.</div><div class="htmlview paragraph">Selective Catalytic Reduction by using NH3 as the reducing agent is the most effective control technology for NOx abatement. Nevertheless, ongoing research and innovation are critical in developing new strategies for reducing NOx emissions, to overcome the NH3-SCR system main critical issues (extra equipment for urea storage and dosing, ammonia-slip, deactivation and fouling, low efficiency at low temperature).</div><div class="htmlview paragraph">The SCR of NOx by hydrogen is considered a promising alternative to traditional ammonia-based deNOx technology. The H2-SCR catalysts are suitable for engine exhaust after-treatment during cold-start and urban-driving operations, exhibiting higher catalytic activity for low-temperature NOx emissions conversion (180 – 200 °C). Furthermore, in H2-ICE powered vehicles, the additional tank to store the reducing agent is not needed with a significant simplification of the engine exhaust lay-out.</div><div class="htmlview paragraph">Experimental investigations on different H2-SCR catalysts have demonstrated that the conversion activity is greatly affected by the catalytic system configuration, the adsorption properties of the support material, the H2 spillover, that in turn are affected by H2/NO ratio and exhaust gas composition, temperature and flow rate.</div><div class="htmlview paragraph">In the present paper, a feed-forward neural network model of H2-SCR is presented, with the aim of performing real-time estimation of reduction efficiency and supporting the design of suitable H2 management to achieve maximum NOx reduction and minimum hydrogen consumption. Model training and identification are carried out against a large set of experimental data measured on a H2-SCR small scale prototype at the Synthetic Gas Bench. The experimental tests were designed to reproduce the real conditions expected at the exhaust of a H2-fueled engine.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The forthcoming introduction of the EURO VII regulation requires urgent strategies and solutions for the reduction of sub-23 nm particle emissions. Although they have been historically considered as particulate matter-free, the high interest for Natural Gas (NG) Heavy-Duty engines in the transport sector, demands their compliance with the new proposed regulations.</div><div class="htmlview paragraph">In order to obtain high conversion of gas pollutants and a strong abatement of the emitted particles, the use of Particle Filters in NG aftertreatment (CPF) in conjunction with the Three-Way Catalyst (TWC) may represent an attractive and feasible solution.</div><div class="htmlview paragraph">Performances of a cordierite filter were explored through an extensive experimental campaign both in Steady-State conditions and during transient engine maneuvers that involved a whole analysis of the emitted particles in terms of number and mass.</div><div class="htmlview paragraph">This investigation assessed different emitted particle reduction efficiency, highlighting distinct levels between no-load (low idle phases) and load operating conditions.</div><div class="htmlview paragraph">The analysis was supported by the development of a specific 1D filtration model to evaluate the particles abatement. This model was also validated during a World Harmonized Transient Cycle (WHTC), proving to be a valuable tool for understanding filtration phenomena during critical phases of the cycle.</div><div class="htmlview paragraph">The tested filter technology showed high filtration efficiency with global levels approaching 90% over the whole cycle, without significant increase in backpressures and fuel consumption.</div><div class="htmlview paragraph">The performed analysis lays the foundation for the use of innovative and simplified filtration models to support the optimization process of this device in view of the next stringent regulations.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori - CNR aimed at studying the capability of GM Combustion Closed-Loop Control (CLCC) in enabling seamless operation with high biodiesel blending levels in a modern diesel engine for passenger car applications. As a matter of fact, fuelling modern electronically-controlled diesel engines with high blends of biodiesel leads to a performance reduction of about 12-15% at rated power and up to 30% in the low-end torque, while increasing significantly the engine-out NOx emissions. These effects are both due to the interaction of the biodiesel properties with the control logic of the electronic control unit, which is calibrated for diesel operation. However, as the authors previously demonstrated, if engine calibration is re-tuned for biodiesel fuelling, the above mentioned drawbacks can be compensated and the biodiesel environmental inner qualities can be fully deployed.</div><div class="htmlview paragraph">In order to enable such calibration re-tuning, it is fundamental to achieve a reliable biodiesel blending detection, and to use it for real-time combustion optimization, chiefly by optimizing the injection train. Therefore, the authors investigated the capability of CLCC to detect biodiesel blending ratio on the recently released 2.0L Euro5 GM diesel engine equipped with embedded pressure sensors in the glow plugs.</div><div class="htmlview paragraph">Various blends of biodiesel were tested, notably 20% by volume (B20), 50% (B50) and pure biodiesel (B100). Tests on the multi-cylinder engine were carried out in a wide range of engine operating points for the complete characterization of the biodiesel performance in the NEDC cycle.</div><div class="htmlview paragraph">The results demonstrated the successful capability of the CLCC control to detect biodiesel blending with reasonable accuracy and to implement the corrective actions to avoid emission drift and performance losses.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Since diesel engines have higher thermal efficiency, superior power capability and better fuel economy than gasoline engines, diesel engines are widely used in vehicles, construction machineries and agricultural machineries. However, they emit more hazardous pollutants than gasoline engines, especially particulate emissions, which have negative impacts on human’s health and air quality in cities. In order to meet future increasingly stringent regulations for particulate emissions, exhaust gas aftertreatment technologies for diesel engines are essential. Particulate emissions from a heavy-duty diesel engine which meets the China national V emission regulation were studied, and the engine was equipped with/without diesel oxidation catalyst (DOC), catalyzed diesel particulate filter (CDPF) and selective catalytic reduction (SCR). The fuel used in this article is ultra low sulfur diesel fuel whose sulfur content is less than 10 ppm. A TSI 3090 Engine Exhaust Particulate Sizer was used to study the number and size distribution of particulate emissions. Results show that with the increase of engine load, the total number of particulate emissions increases, and especially under high engine load, the increase of total particulate number is drastic in consequence of the deterioration of combustion in the cylinder. Compared with the engine without exhaust gas aftertreatment devices, DOC+CDPF+SCR can evidently reduce the particulate number by 1~2 orders of magnitude, and the decreasing range can up to 2~3 orders of magnitude when the particulate diameter is between 10~60 nm. At the maximum torque speed of 1400 rpm and rated speed of 2200 rpm, the filtration efficiency of total particulate number from the engine can be over about 95%.</div></div>

<div class="htmlview paragraph">Air quality monitoring of PM<sub>10</sub> and associated health studies have focused interest on the size and the number of particles emitted to, and found in, the atmosphere. Automotive sources are one of the important elements in this, and CONCAWE have completed a study of heavy duty diesel particle emissions, complementing their previously reported light duty work. This heavy duty programme, presented here, investigated the nature of particulate emissions from two heavy duty engines (representative of different emissions levels), operating on three marketed fuels, over their respective European legislative heavy duty test cycles.</div> <div class="htmlview paragraph">The programme has investigated some of the complexities associated with obtaining credible data (e.g. dilution ratios, system stabilisation time etc.). The number distributions, which were measured over a wide size range (3 to 1000 nm), have been split into two size ranges, representative of nucleation mode and accumulation mode particles. These two ranges have been analysed in terms of the effects of engine technology, fuels and test conditions.</div> <div class="htmlview paragraph">Accumulation mode particles were found to be measurable to a satisfactory level of repeatability, and were relatively insensitive to changes in test conditions. However, nucleation mode particles, which have the greatest influence on total number measurements, were found to be very sensitive to changes in sampling conditions. Consequently, conclusions about engine technology and fuel effects based on particle number measurements are critically dependent on the sampling conditions.</div>