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It has been recently shown that (Ce, Zr)O2 mixed oxides provide improved catalytic performances compared to pure CeO2. Cerium oxide is the active Oxygen Storage Capacity (OSC) component in three way catalysts. However, higher performances, including OSC enhancement, can be achieved with thermally stable solid solutions of Ce and Zr oxides. In the present paper, we describe the structure and the advantages of Ce rich (Ce, Zr)O2 solid solutions and the improved catalytic properties of these materials when used in association with platinum. Various analytical techniques were used including thermo-reduction methods, OSC measurements, surface area measurements, XRD, HRTEM, XPS, and XANES/EXAFS.

Limited and non-regulated emissions of scooters were analysed during several annual research programs of the Swiss Federal Office of Environment (BAFU) *). Small scooters, which are very much used in the congested centers of several cities, are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centers. In the present work detailed investigations of particle emissions of different 2-stroke scooters with direct injection and with carburettor were performed. The nanoparticulate emissions were measured by means of SMPS, (CPC) and NanoMet. Also the particle mass emission (PM) was measured with the same method as for Diesel engines. Extensive analyses of PM-residuum for SOF/INSOF, PAH and toxicity equivalence (TEQ), were carried out in an international project network. Particle mass emission (PM) of 2-S Scooters consists mostly of SOF.

The objectives of the present work are to investigate the regulated and unregulated (particle) emissions of a classical and modern 2-stroke and a typical 4-stroke scooter with different ethanol blend fuels. There is also comparison of two different ethanol fuels: pure ethanol (E) *) and hydrous ethanol (EH) which contains 3.9% water and is denatured with 1.5% gasoline. Special attention is paid in this research to the hydrous ethanol, since the production costs of hydrous ethanol are much less than those for (dry) ethanol. The vehicles are with carburettor and without catalyst, which represents the most frequent technology in Eastern Asia and offers the information of engine-out emissions. Exhaust emissions measurements have been performed with fuels containing ethanol (E), or hydrous ethanol (EH) in the portion of 5, 10, 15 and 20% by volume. During the test systematical analysis of particle mass (PM) and nano-particles counts (NP) were carried out.

A direct injection system in which fuel was injected through the cylinder wall was developed and detailed investigation was made for the purpose of reducing short-circuit of fuel in 2-stroke engines. As a result of dynamo tests using 430cc single cylinder engine, it was found that the injector was best attached at a location as close to TDC as possible on the rear transfer port side, and that the entire amount of fuel should be injected towards the piston top surface. Emissions were worsened if fuel was injected towards the exhaust port or spark plug. Although the higher injection pressure resulted in large emissions reduction effects, it did not have a significant effect on fuel consumption. When a butterfly exhaust valve, known to be effective against irregular combustion in the light load range, was applied, it was found to lead to further reductions in HC emission and fuel consumption while also improving combustion stability.

The CBR [1] (Controlled Burn Rate) is a port deactivation concept developed by AVL and is already applied in series production cars. The benefit of this concept is the low engine-out emission (CO, HC and NOx) and good fuel economy. By creating turbulent kinetic energy at the correct time and place in the combustion chamber a rapid and stable combustion occurs which allows to run the engine well above a Lambda Excess Air Ratio of 1.5. The CBR system features two different intake ports, one charge motion port and one filling port. Additionally a device for port-deactivation (slider, butterfly) is applied. At part load points and lower engine speeds the filling port is switched off. The CBR concept was now evoluted for compact engines as CCBR - with carburetor and as CBR Light - for engines with electronic fuel injection. CCBR stands for Carbureted Controlled Burn Rate.

NOx emissions from diesel passenger vehicles affect the atmospheric environment. It is difficult to evaluate the NOx emissions influenced by environmental conditions such as humidity and temperature, traffic conditions, driving patterns, etc. In the authors’ previous study, real-driving experiments were performed on city and highway routes using a diesel passenger car with only an exhaust gas recirculation system. A statistical prediction model of NOx emissions was considered for simple estimations in the real world using instantaneous vehicle data measured by the portable emissions measurement system and global positioning system. The prediction model consisted of explanatory variables, such as velocity, acceleration, road gradient, and position of transmission gear. Using the explanatory variables, NOx emissions on the city and highway routes was well predicted using a diesel vehicle without NOx reduction devices.

This paper focuses on an assessment of predictive combustion model using a 0D/1D simulation tool under high load, different excess air ratio λ , and different combustion stabilities (based on coefficient of variation of indicated mean effective pressure COVimep). To consider that, crank angle resolved data of experimental pressure of 500 cycles are recorded under engine speed 1000 RPM and 2000 RPM, wide-open throttle, and λ=1.0, 1.42, 1.7, and 2.0. Firstly, model calibration is conducted using 18 cases at 2000 RPM using 500 cycle-averaged in-cylinder pressure to find optimized model constants. Then, the model constants are unchanged for other cases. Next, different cycle-averaged pressure data are used as inputs in the simulation based on the COVimep for studying sensitivity of the turbulent model constants. The simulation is conducted using 1D simulation software GT-Power.

A simulation method is presented for the analysis of combustion in spark ignition (SI) engines operated at elevated exhaust gas recirculation (EGR) level and employing multiple spark plug technology. The modeling is based on a zero-dimensional (0D) stochastic reactor model for SI engines (SI-SRM). The model is built on a probability density function (PDF) approach for turbulent reactive flows that enables for detailed chemistry consideration. Calculations were carried out for one, two, and three spark plugs. Capability of the SI-SRM to simulate engines with multiple spark plug (multiple ignitions) systems has been verified by comparison to the results from a three-dimensional (3D) computational fluid dynamics (CFD) model. Numerical simulations were carried for part load operating points with 12.5%, 20%, and 25% of EGR. At high load, the engine was operated at knock limit with 0%, and 20% of EGR and different inlet valve closure timing.