Search Results

The heavy duty Particle Measurement Programme (PMP) inter-laboratory exercise consists of three parts: 1) the exploratory work to refine the measurement protocol, 2) the validation exercise where each lab will measure the emissions of a “golden” engine with two “golden” particle number systems simultaneously sampling from full and partial flow dilution systems, and 3) the round-robin where the emissions of a “reference” engine will be determined with a lab’s own particle number instrumentation. This paper presents the results of the exploratory work and describes the final protocol for testing in the validation exercise (and round robin) along with the necessary facility modifications required for compliance with the protocol. Key aspects of the protocol (e.g. filter material, flow rates at the full and partial flow systems, the pre-conditioning etc.) are explained and justified.

Fatty Acid Methyl Ester (FAME) products derived from vegetable oils and animal fats are now widely used in European diesel fuels and their use will increase in order to meet mandated targets for the use of renewable products in road fuels. As more FAME enters the diesel pool, understanding the impact of higher FAME levels on the performance and emissions of modern light-duty diesel vehicles is increasingly important. Of special significance to Well-to-Wheels (WTW) calculations is the potential impact that higher FAME levels may have on the vehicle's volumetric fuel consumption. The primary objective of this study was to generate statistically robust fuel consumption data on three light-duty diesel vehicles complying with Euro 4 emissions regulations. These vehicles were evaluated on a chassis dynamometer using four fuels: a hydrocarbon-only diesel fuel and three FAME/diesel fuel blends containing up to 50% v/v FAME. One FAME type, a Rapeseed Methyl Ester (RME), was used throughout.

The European Union road transport CO2 emissions regulation foresees mandatory targets for passenger vehicles. However, several studies have shown that there is a divergence between official and real-world values that could range up to 40% compared to the NEDC reference value. The introduction of the Worldwide Harmonized Test Protocol (WLTP) limited this divergence, but it is uncertain whether it can adequately address the problem, particularly considering future evolutions of vehicle technology. In order to address this issue, the recent EU CO2-standards regulation introduces the monitoring of on-road fuel consumption and subsequently CO2 emissions by utilizing On-Board Fuel Consumption Meters (OBFCM). In the near future, all vehicles should provide instantaneous and lifetime-cumulative fuel consumption signals at the diagnostics port. Currently, the fuel consumption signal is not always available.

This paper presents a new concept of a partial flow sampling system (PFSS), involving a two-stage dilutor which operates at underpressure, while exhaust is sampled through a capillary. The sample flowrate is in the order of few cubic centimeters per minute. Due to the low flowrate, no tight fixation is required between the exhaust line and the capillary inlet. The dilutor may sample from an opening in the exhaust line which freely exhausts to ambient pressure. As a result, the PFSS operates at constant pressure conditions even upstream of diesel particle filters (DPF). A straightforward mathematical model is then developed to calculate the dilution ratio (DR), depending on the dilution air flowrate and the dilutor underpressure. The model is validated using CO2 as a trace gas, and a very good agreement is demonstrated between the calculated and the measured DR values.

To meet future stringent emission regulations such as Euro6, the design and control of diesel exhaust after-treatment systems will become more complex in order to ensure their optimum operation over time. Moreover, because of the strong pressure for CO₂ emissions reduction, the average exhaust temperature is expected to decrease, posing significant challenges on exhaust after-treatment. Diesel Oxidation Catalysts (DOCs) are already widely used to reduce CO and hydrocarbons (HC) from diesel engine emissions. In addition, DOC is also used to control the NO₂/NOx ratio and to generate the exothermic reactions necessary for the thermal regeneration of Diesel Particulate Filter (DPF) and NOx Storage and Reduction catalysts (NSR). The expected temperature decrease of diesel exhaust will adversely affect the CO and unburned hydrocarbons (UHC) conversion efficiency of the catalysts. Therefore, the development cost for the design and control of new DOCs is increasing.

An investigation has been carried out to examine the influence of up to 300 MPa injection pressure on engine performance and emissions. Experiments were performed on a 4 cylinder, 4 valve / cylinder, 4.5 liter John Deere diesel engine using the Ricardo Twin Vortex Combustion System (TVCS). The study was conducted by varying the injection pressure, Start of Injection (SOI), Variable Geometry Turbine (VGT) vane position and a wide range of EGR rates covering engine out NOx levels between 0.3 g/kWh to 2.5 g/kWh. A structured Design of Experiment approach was used to set up the experiments, develop empirical models and predict the optimum results for a range of different scenarios. Substantial fuel consumption benefits were found at the lowest NOx levels using 300 MPa injection pressure. At higher NOx levels the impact was nonexistent. In a separate investigation a Cambustion DMS-500 fast particle spectrometer, was used to sample and analyze the exhaust gas.

The Pegasor Particle Sensor (PPS) is a small and lightweight sensor that can be used directly in raw exhaust to provide the mass and number concentration of exhaust aerosol. Its operation principle is based on the electrical charging of exhaust aerosol and determination of particle concentration by measuring the charge accumulated on the particles. In this paper we have applied the PPS in a variety of vehicle exhaust configurations to evaluate its performance characteristics. First, the output signal of the instrument was calibrated with diesel exhaust to deliver either the mass or the number concentration of exhaust aerosol. Linear response with the soot mass concentration measured by a Photo Acoustic Soot Sensor and number concentration measured by an Electrical Low Pressure Impactor was established.

The Particle Measurement Programme (PMP) developed an exhaust particle number measurement protocol that has been adopted by current light duty vehicle emission regulations in Europe. This includes thermal treatment of the exhaust aerosol to isolate solid particles only and a number counting device with a lower cutpoint of 23 nm to avoid measurement of smaller particles that may affect the repeatability of the measurement. In this paper, we examine a potential alternative to the PMP system, where the thermal treatment is replaced by a catalytic stripper (CS). This offers oxidation and not just evaporation of the volatile components. Alternative sampling systems, either fulfilling the PMP recommendations or utilizing a CS, have been explored in terms of their volatile particle removal efficiency. Tests have been conducted on diesel exhaust, diesel equipped with DPF and gasoline direct injection emissions.

The exhaust emissions of two Euro 6 diesel cars with different emissions control systems have been evaluated both on the road and over various chassis dynamometer test cycles. European emissions limits are currently set using the New European Driving Cycle (NEDC), but the European Commission is preparing additional test procedures to ensure that emissions are well controlled both in real-world use and over the legislative test cycle. The main focus of this work on ‘Real Driving Emissions’ (RDE) is on measurements using Portable Emissions Measurement Systems (PEMS) in truly representative, on-road, driving. A key focus of the test programme, undertaken as a collaboration between AECC (the Association for Emissions Control by Catalyst) and Ricardo UK, was therefore the use of PEMS systems to measure on-road emissions of both gaseous pollutants and particulate matter. This included measurement of particle number emissions with a new candidate system for this type of measurement.

Modern diesel vehicles utilize two technologies, one fuel based and one hardware based, that have been motivated by recent European legislation: diesel fuel blends containing Fatty Acid Methyl Esters (FAME) and Diesel Particulate Filters (DPF). Oxygenates, like FAME, are known to reduce PM formation in the combustion chamber and reduce the amount of soot that must be filtered from the engine exhaust by the DPF. This effect is also expected to lengthen the time between DPF regenerations and reduce the fuel consumption penalty that is associated with soot loading and regeneration. This study investigated the effect of FAME content, up to 50% v/v (B50), in diesel fuel on the DPF regeneration frequency by repeatedly running a Euro 5 multi-cylinder bench engine over the European regulatory cycle (NEDC) until a specified soot loading limit had been reached.

This paper investigates the effect of lubrication oil on the physical and chemical characteristics of the particulate matter (PM) emitted from a Euro 4 diesel vehicle. Two different lubrication oils were examined. A fully synthetic ACEA grade B3 service-fill oil of low sulfur content (1760 ppm wt.) falling into the OW-40 SAE viscosity grade and a mineral ACEA B2-98 motor oil of high sulfur (8890 ppm wt.), falling into the 15W-40 SAE viscosity grade. To exclude interferences from the fuel derived sulfur, a rather sulfur-free fuel (< 10 ppm wt.) was used in the experiments. The experiments included steady state tests, the certification cycle and real-world highspeed transient driving conditions. The properties measured included total particle mass collected on Teflon-coated filters, total particle number measured by a condensation particle counter, size distributions determined by a scanning mobility particle sizer.

Vegetable oils blended with diesel fuel are recognised as biofuels by the European legislation and their application is an interesting option for increasing the market share of biofuels. This paper presents results from a detailed study conducted on a Euro 3 compliant diesel passenger car and a high injection pressure test bench engine using 10% Cottonseed oil- 90% Diesel blends as fuel. The tests included fuel consumption and emissions measurements. Aim of the experimental analysis was to accurately evaluate the effect of biofuel application on a common rail engine. The measurement protocol included measurements of regulated emissions, fuel consumption and in-cylinder pressure at various operation modes. Results from the bench engine measurements are in line with those retrieved from the vehicle and indicate that the fuel tested presents good characteristics and that under certain conditions it can be applied as automotive fuel in a broader scale.

By early 2007, all major manufacturers of light-duty diesel vehicles are marketing models equipped with diesel particulate filters (DPFs). However, there is still a lack of understanding of the particles emitted when the DPF undergoes regeneration. This paper focuses on measuring particle emissions of a representative light-duty diesel vehicle equipped with DPF and employing a fuel-borne catalyst (FBC) to aid regeneration. Particulate Matter (PM) and non-volatile particle number emissions are measured throughout testing according to the Particle Measurement Programme (PMP) proposals. In addition, an Engine Exhaust Particle Sizer (EEPS) connected directly to the CVS is used to give real time size distributions of both volatile and non-volatile particles. The paper focuses on particle emissions during regenerating New European Driving Cycles (NEDCs).

This paper studies the effect of a Catalyzed Diesel Particle Filter (CDPF) on the emission profile of a Euro 4 diesel vehicle operated on low sulfur fuel and lubrication oil. The vehicle was tested in its original configuration and with the CDPF retrofitted in place of its main underbody catalyst. Experiments included steady state tests, the certification cycle and real-world high speed transient driving conditions. Measurements included total particle mass collected on Teflon-coated filters, total particle number measured by a condensation particle counter, size distributions determined by a Scanning Mobility Particle Sizer and chemical analysis of the mass collected for elemental and organic carbon, ions, PAHs, and trace elements. Results showed that the vehicle complies with the Euro 4 emission limits when tested over the type-approval NEDC, but it emits more nitrogen oxides and, in some cases, more particulate matter when tested over real-world test cycles.

This work studies the formation of nucleation mode (NM) particles from a Euro 3 passenger car operating on 280 ppm wt. sulfur fuel, during on-road plume chasing and in the laboratory. The vehicle produced a distinct NM when its speed exceeded 100 km/h in both sampling environments. A higher particle number (up to 8 times) after 4 min at constant speed was measured when this speed was approached from a lower than from a higher speed. The variability in the measurement of NM particles was explained using literature information on sulfur-to-sulfate conversion over a catalyst and, in particular, on the extent and rate of sulfate storage and release mechanisms. All evidence led to the conclusion that storage and release processes take several minutes to conclude after a step-wise change in speed and have significant implications in the total particle number measurements during steady-speed testing.

During a test programme on a modern heavy-duty engine, measurements were made at engine-out and tailpipe of particle number and particulate mass using the draft heavy-duty inter-laboratory correlation exercise guide prepared by the UN-ECE Particle Measurement Programme (PMP)1. In addition to the PMP measurements, the elemental carbon content of the particulate matter from this programme was analysed using thermogravimetric analysis of separate filters. The particle number measurement system proved to provide a reliable and repeatable measurement procedure. Test results over a variety of operational cycles showed a reduction in particle numbers of some 3 orders of magnitude. Particle number emissions were of similar magnitude regardless of the test cycle. Background-corrected particulate mass emissions results using the partial flow dilution method showed emissions levels below 5mg/kWh over all the transient cycles tested.

Reducing fuel consumption and emissions from road transport is a key factor for tackling global warming, promoting energy security and sustaining a clean environment. Several technical measures have been proposed in this aspect amongst which the application of low viscosity engine lubricants. Low viscosity lubricants are considered to be an interesting option for reducing fuel consumption (and CO2 emissions) throughout the fleet in a relatively cost effective way. However limited data are available regarding their actual “real-world” performance with respect to CO2 and other pollutant emissions. This study attempts to address the issue and to provide experimental data regarding the benefit of low viscosity lubricants on fuel consumption and CO2 emissions over both the type-approval and more realistic driving cycles.

Four state-of-the-art >500 cc Euro 3 and one 150 cc Indian specification motorcycles were selected and evaluated over the Euro 3 and world harmonized WMTC test cycles for regulated pollutants and particles. The objectives of the work were to examine the correlation between emissions on the WMTC and Euro 3 cycles, to compare those results with previous work completed before the European WMTC limits were set, to examine particulate emissions, and to then evaluate the durability of one machine. The correlation between Euro 3 and WMTC emissions results was used to extrapolate the appropriate level of WMTC limit values from the emissions limits on the Euro 3 test cycle. These WMTC extrapolated emissions limits were in line with the previous AECC motorcycle test program conducted in 2004 on Euro 2 motorcycles and also confirmed the appropriate level of the WMTC Euro 3 limits set in European Directive 2006/72/EC amending 97/24/EC.

This study examines the effects of neat soy-based biodiesel (B100) and its 50% v/v blend (B50) with low sulphur automotive diesel on vehicle PAH emissions. The measurements were conducted on a chassis dynamometer with constant volume sampling (CVS) according to the European regulated technique. The vehicle was a Euro 2 compliant diesel passenger car, equipped with a 1.9 litre common-rail turbocharged direct injection engine and an oxidation catalyst. Emissions of PAHs, nitro-PAHs and oxy-PAHs were measured over the urban phase (UDC) and the extra-urban phase (EUDC) of the type approval cycle (NEDC). In addition, for evaluating realistic driving performance the non-legislated Artemis driving cycles (Urban, Road and Motorway) were used. Overall, 12 PAHs, 4 nitro-PAHs, and 6 oxy-PAHs were determined. The results indicated that PAH emissions exhibited a reduction with biodiesel during all driving modes.

Today most of the European member states offer diesel fuel which contains fatty acid methylesters (biodiesel) at a range between 0.5 to 5% vol. In order to meet longer term objectives, the mixing ratio is expected to rise up to 10% vol. in the years to come. The question therefore arises, how current engine technologies, which were not originally designed to operate on biodiesel blends, perform at this relatively high mixing ratio. A number of experiments were therefore performed over several steady-state operation modes, using a 10% vol. biodiesel blend (palm oil feedstock) on a light-duty common-rail Euro 3 engine. The experiments included measurement of the in-cylinder pressure during combustion, regulated pollutants emissions and fuel consumption. The analysis showed that the blends tested present good fuel characteristics. Combustion effects were limited but changes in the start of ignition and heat release rate could still be identified.