EURO 6 STANDARDS

The legislation for Euro 5 Phase 2 was implemented from September 2011, and the more stringent Euro 6 will begin in September 2014. Once this comes into force member states must refuse the approval, registration, sale, and introduction of vehicles that do not comply with the tougher new emissions limits. OEMs are hastily preparing. “The NOx emissions reduction [dictated by] Euro 6 will increase the health benefi ts by approximately 60-90% over Euro 5,” says Nikolaus Steininger, Enterprise and Industry Directorate-General at the European Commission. “Europe as a whole welcomes any initiative that reduces pollution from vehicles.” “New emissions standards are always a challenge,” adds Walter Puetz, director for certifi cation,environment, and regulatory affairs at Daimler. “The key is to make customers understand that our engines are as clean as all other engines. The process may cost us a little but if it means making engines cleaner today, that’s a good thing.”

Euro 6: The factsThere are two major changes in the move to Euro 6 from the current Euro 5. The fi rst is the introduction of a solid particle number standard (PN) for positive ignition (PI) gasoline direct injection (GDI) vehicles. This level was fi nalized in December 2011. The decision was to set the limit as 6 x 1012 particles per kilometer for three years and to reduce this to 6 x 1011 (the same level as Compression ignition vehicles) from September 2017. The decision to delay implementation of the lower limit gives manufacturers of light-duty vehicles suffi cient time to develop improved injection/combustion technology and vehicle calibrations to avoid the use of particulate fi lters that would adversely affect fuel consumption and CO2 emissions. The second change is the requirement to more than halve the current NOx standard for compression ignition vehicles from 180mg/km under Euro 5 to 80mg/km under Euro 6. The introduction of the new PN standard for gasoline direct injection (GDI) vehicles will require research and development into direct injection systems and combustion if the use of particulate fi lters is to be avoided. For some vehicles, however, it may be necessary to install particulate fi lters in order to meet the new limits, especially bearing in mind future requirements to demonstrate compliance under ‘off-cycle’ driving (when the engine is tested in an unknown random test and also for in-service compliance), which can be expected under new procedures currently under discussion. Meanwhile the reduction of the NOx limits for compression ignition vehicles is likely to require the use of aftertreatment systems for some vehicles. The aftertreatment could be LNT (lean NOx trap) or SCR (selective catalytic reduction), depending on the vehicle’s specifi cation and duty.

Number crunchingHoriba Group has been a key supplier of exhaust emissions measurement systems for certifi cation and R&D for more than 40 years, and its Automotive Test Systems (ATS) division is a leading supplier of engine test systems, driveline test systems, brake test systems, wind tunnel balances, and emissions test systems. “Horiba developed the fi rst production-level solid particle number counting system, the MEXA-1000SPCS,” says Les Hill, ATS product planner at the company. “This was to meet the initial draft specifi cations and procedures introduced by the PMP [Particle Measurement Programme], a working group that was formed to study low-level PM emissions and to develop new instruments and procedures for its measurement. Further modifi cations and refi nement of the specifi cations and procedures enabled a new model [MEXA-2000SPCS] to be developed that is much smaller and simpler in design.” According to Hill, the introduction of the PM and PN standards for GDI vehicles means that some chassis dynamometer test cell systems are now being upgraded for measurement by the installation of dilution tunnels, PM samplers, and PN counting systems.

“The extension of the PN standard to the PI direct injection gasoline vehicles means this parameter will be critical for the development and calibration of these powertrains in he engine test cell stage,” he says. “Accordingly, Horiba has recently introduced a new model [MEXA-2100SPCS] that is designed to measure the PN from the raw, undiluted exhaust gas without the need for the CVS and dilution tunnel equipment that is necessary for the chassis dynamometer based certification. Similarly, the reduction of NOx emissions for Compression ignition vehicles will require improved instrumentation for the measurement of nitrogen compounds.” In addition to the FTIR (Fourier transform infrared) analyzer that has been available for many years, Horiba has introduced a new type of analyzer (MEXA-1400QLNX) that uses a mid-infrared energy source called the Quantum Cascade Laser, which has become commercially available in the last few years. “The MEXA-1400QL-NX measures the NO, NO2, NH3 and N2O concentrations from the engine exhaust with a lower limit of detection and wider dynamic range than other infrared-based instruments. Its performance will be very important in the research and development of engine combustion as well as the research and development of a number of exhaust aftertreatment devices such as CRTs [continuous regenerating traps], LNTs, and SCRs that are expected to be used for Compression ignition light-duty vehicles to meet Euro 6 and beyond.”

AnalysisCambustion is a spin-off company from the Cambridge University Engineering Department, and was formed in 1987 with the invention of a fast FID for measurement of “These new aftertreatment requirements will drastically increase the cost and complexity of emission control for vehicle manufacturers, making diesel-engined vehicles more expensive for the consumer. Many OEMs (and Cambustion’s Engineering Services division) are actively evaluating and applying such technology to meet the legislative requirements.” The prevailing Euro 5b legislation for diesel PN has already meant the fitting of DPFs to most diesel passenger cars, and Cambustion has been heavily involved in the implementation of this technology. DPF development requires repeatable and reliable systems for evaluating DPF characteristics, and Cambustion has developed a diesel particulate generator (DPG) that can help vehicle manufacturers, filter substrate manufacturers, and catalyst coaters optimize their products. The DPG enables rapid loading of soot onto a DPF to allow pressure-drop and regeneration characteristics to be assessed without use of an engine dyno or vehicle chassis rolls. Peckham believes the most challenging aspect of Euro 6 for gasoline vehicles is the proposed application of a (staged) PN limit applied to GDI vehicles. Such engines generally emit higher numbers of nanoparticles than conventional port-fuel-injected gasoline engines, but the suggestion that such particles may pose a public health risk has brought about this legislation, and now engine researchers and calibrators are investigating methods of meeting the stringent number standard. “The use of gasoline particulate filters (GPFs) has been proposed, but considerable efforts are also being made to optimize direct injection hardware and calibration,” states Peckham. “Cambustion’s DMS500 fast-response particulate analyzer is being used by OEMs and suppliers across the world to investigate measures to improve the engine-out particle number and hence avoid the use of additional aftertreatment to control GDI particle emissions.”

MeasurementAVL Emission Test Systems GmbH is, according to its company officials, the world’s largest privately owned independent company for the development of powertrain systems with IC engines as well as instrumentation and test systems. Uwe Krummenöhler is chairman of its management board. “We believe our emissions measurement system, the iGeneration, meets the current and future challenges of the industry,” he says. “It is already the technology leader

and will soon be the most used system and reference. We were able to prove our ability to fulfill future legislations, and this is why emissions legislators the Environmental Protection Agency (EPA) and TÜV decided to go for the AVL emissions test solution. Our particulate measuring device PSS/APC – a combination of the conventional gravimetric particulate sampler and first for EU5+ implemented advance particulate counter – enables our customers to upgrade their existing testbeds to be ready for Euro 6.” The iGeneration is claimed to have improved every aspect of emissions testing, from improved gas analyzers to more accurate and optimized sampling systems. The testing requires less floor space and has a lower total cost of ownership. iGeneration certainly appears to have the backing of Dr Werner Kummer, manager of Audi’s exhaust gas and endurance test center at Ingolstadt. “Productivity and availability are two of the most important requirements for an exhaust gas measurement system,” he explains. “I generally appreciate the increased repeatability and detection sensitivity of the AVL iGeneration devices as well as the possibility of a complete remote-controlled maintenance down to analyzer level. ‹