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This paper presents a real-time optimizing control strategy based on real-time engine torque observer and variation rate limiting of throttle plate for single-shaft HEV. In order to make the engine work more steadily and to reduce the fuel consumption and emission, experiments are performed to research the influences of the variation rate of the engine throttle plate on actual air-fuel ratio inside the cylinder and emission performance, with an engine torque observer constructed through artificial neural network. The influence of the engine's fuel consumption, the motor's equivalent fuel consumption and the emission of the main exhaust are taken into consideration by the real-time optimization evaluation function. This control strategy is simulated on the forward type HEV model and certificated on the HEV powertrain testbed with AC motor dynamometer. The result shows that this control strategy is able to perform multi-energy management and coordinative control in transient conditions.

NOx -SCR over Ag/ Al2O3 catalyst using ethanol (C2H5OH) as a reductant has proven its ability to significantly reduce NOx emission in a simulated engine exhaust gas environment. However the real engine exhaust gas environment is too complicated to be simulated. Therefore, the performance evaluation of the Ag/ Al2O3 catalyst in real exhaust gas environment is necessary. Moreover, the ethanol dosing device and control strategy also need to be validated for the practical use. In this paper, firstly the catalyst performance and its sulfur tolerance was tested on an engine test bench and the effect of the catalyst on PM emission was investigated. Then the aftertreatment system composed of Ag/Al2O3 catalyst + Cu/TiO2 catalyst + Pt/TiO2 catalyst and ethanol dosing control based on open loop control was designed, and the diesel engine emission with the aftertreatment system was tested according to ESC test cycle.

Urea Selective Catalytic Reduction (SCR) has been proven to significantly reduce NOx emissions from diesel engines. The thermal decomposition of urea, which forms the ammonia as the reactant, has a crucial effect on the performance and durability of the NOx-SCR system. The incomplete thermal decomposition of urea not only reduces the NOx conversion ratio and increases the ammonia slip, but also leads to deposit formation on the catalyst surface, which will block the pore and the active sites of the catalyst and then decreases the durability of the SCR systems. In this paper, the urea thermolysis was measured using the Thermal Gravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Then, the performance of the SCR systems under different injection parameters of the Urea-water solution was investigated on a diesel engine test bench. Finally, the deposits on the catalyst were also analyzed using TGA and FTIR.

Beijing will implement the 4th stage emission regulations (equivalent to Euro IV) in 2008 ahead of other provinces or cites in China. Beijing Environmental Protection Bureau (EPB) organized petroleum corporations, automobile and engine manufactories as well as research institutes to test the adaptability of the fuels from Chinese refineries to the modern vehicles or engines on the road running conditions in China. In this paper, the effects of diesel fuel quality on combustion and emission of a Euro IV heavy-duty diesel engine as one part of the program were studied to provide technical data to stipulate the feasible diesel fuel standard, which should guarantee modern vehicles or engines to meet the 4th stage regulations. Eight kinds of diesel fuels with different properties, such as cetane number, distillation temperature (T90) and sulfur content, were tested on a Euro IV Cummins heavy-duty diesel engine with urea SCR after-treatment.

Beijing will implement the national 4th stage emissions standards (equivalent to Euro IV emissions standards) in advance in China from 2008. The objective of this study was to provide some technical support for proposing automotive gasoline fuel standards matching with the emission standards. In this paper, tests were conducted on two engines and one gasoline passenger vehicle meeting Euro III or IV emission standards to study the correlation between gasoline fuel properties and engine performances, including power, fuel consumption and emissions. Test results showed that the effect of octane number on engine power depended on engine technologies. High octane number had a negative effect on fuel consumption and emissions. As olefin content increased, the engine-out THC emissions decreased significantly. The vehicle test results also showed that high olefin content greatly reduced the tailpipe THC emissions.

According to China's “oil-poor, gas-litte, coal-rich” structure of energy resources, to promote the development of coal-based methanol fuel as a clean alternative to gasoline and diesel fuel is one of the most realistic options. So the adaptability of methanol gasoline blend fuel used in the gasoline engine and vehilce should be investigated. Engine load performance, engine out emission, air fuel ratio variation and combustion characteristics were tested in a PFI Euro III gasoline engine using gasoline, M10, M15, M20, M30 as fuel without any modification of the engine. Air fuel ratio, light-off temperature and load characteristics of catalystic conversion coefficient were also investigated. And effects of methanol content on fuel consumption and vehicle out emissions of a Euro - vehicle are analyzed.

The effects of charge stratification on homogenous charge compression ignition (HCCI) combustion high load extension were studied in a gasoline direct injection engine with negative vale overlap. The stratified charge was created by a first injection during the middle of intake stroke and a second injection during the compression stroke. 3D simulation results showed that a stratified mixture can be formed by the dual injections and stratification degree can be adjusted by changing the second injection timing and ratio. Experimental results show that slight charge stratification will lead to advancement of ignition and increase of the maximum rate of pressure rise (MRPR) and NOx emissions. The earliest ignition, maximum MRPR, lowest cycle variation occurs under the conditions of rich zone is around stoichiometric.

Spark induced compression ignition (SICI) is a practical control technology for ignition enhancement in gasoline HCCI combustion. In this paper, SICI combustion mechanism was studied using combustion visualization, engine test and numerical simulation respectively. It provided a useful combustion optimization guide for gasoline HCCI engines. Firstly, the ignition process of SICI was captured by combustion visualization in an optical engine. The results show that SICI is a combined combustion mode with partly flame propagation and main auto-ignition. The spark ignites the local mixture near the spark electrodes and flame propagation occurs before the homogeneous mixture auto-ignition. Heat release from the burned zone due to flame propagation which increases the in-cylinder pressure and temperature, and causes the entire mixture auto-ignition.

A catalyst surfaced on Ag/Al2O3 substrate for the selective catalyst reduction (SCR) of NOx by ethanol was evaluated in a diesel engine, and the effect of the catalyst on the reduction of NOx from the diesel engine under the EURO III ESC test modes was also investigated. The reductant injecting device was designed by means of computational fluid dynamics (CFD) analysis, and the engine test bench including the reductant injection system for the evaluation of the NOx-SCR catalyst performance was established. On the bench, the SCR catalyst with the ethanol reductant was tested at different temperatures and space velocities (SV), and integrated with an oxidation catalyst to reduce the diesel exhaust emissions of NOx, HC and CO. Under the conditions of the SV=30,000 h-1 and the exhaust temperature range of 350∼420°C, the NOx conversion efficiency is high over 90% and low beyond the temperature range.

HCCI combustion was studied in a 4-stroke gasoline engine with a direct injection system. The electronically controlled two-stage gasoline injection and spark ignition system were adopted to control the mixture formation, ignition timing and combustion rate in HCCI engine. The engine could be operated in HCCI combustion mode in a range of load from 1 to 5 bar IMEP and operated in SI combustion mode up to load of 8 bar IMEP. The HCCI combustion characteristics were investigated under different A/F ratios, engine speeds, starts of injection, as well as spark ignition enabled or not. The test results reveal the HCCI combustion features as a high-pressure gradient after ignition and has advantages in high thermal efficiency and low NOx emissions over SI combustion. At the part load of 1400rpm and IMEP of 3.5bar, ISFC in HCCI mode is 25% lower and NOx emissions is 95% lower than that in SI mode.

In order to enhance the thermal efficiency of gasoline engines, a combustion mode namely Homogeneous Charge Induced Ignition (HCII) was introduced and examined in this paper. Port-injected gasoline was used as the main fuel and formed a homogeneous charge in the cylinder. Diesel was used as the pilot fuel, directly injected into the cylinder, and self-ignited and this induced the ignition of the premixed gasoline-air charge. The images of HCII combustion process were taken on an optical engine through a high-speed CMOS camera. The multi-point induced ignition phenomena were observed and the parameters like flame luminance, ignition delay and combustion duration were analyzed by image analysis. The result shows that as the gasoline/diesel ratio increases with a fixed low pilot amount, the ignition delay increases, the initial ignition area extends from the center towards the periphery of the combustion chamber, and the combustion velocity increased.

Gasoline Direct Injection (GDI) engines developed at nineties of the twentieth century can greatly improve the fuel economy. But the combustion chamber design and mixture control of the engines are very complex compared with Port Fuel Injection (PFI) gasoline engines. A two-stage gasoline direct injection (TSGDI) combustion system is developed and aimed to solve the problem of the complexity. Two-stage fuel injection and flexible injection timings are adopted as main means to form reasonable stratified mixture in the cylinder. A simple combustion chamber and helical intake port are designed to assist the mixture's stable combustion, which reduces the difficulties of the combustion system design. Systematical simulation and experimental studies of the effects of injection strategies such as different first,second injection timings and injection ratios, on the mixture formation processes and engine performanc are made in detail.