Analysis of Catalytic Degradation Reaction Mechanism on Gasoline Engine Three-Way Catalysts

2014 ◽  
Vol 628 ◽  
pp. 249-252
Author(s):  
Jun Ji Li

The control of automobile exhaust emission has become one of the most important technologies for a modern vehicles. Catalytic conversion technology of three-way catalytic converter in the outer purification system is very mature and stable, which has been the first choice of exhaust emission control technology in China. The organic combination of the purification systems outside and inside machine can fully improve the performance and the fuel economy of vehicles on the basis of low emission levels.

Author(s):  
S. Sendilvelan ◽  
K. Jeyachandran ◽  
K. Bhaskar

Abstract The environmental pollution is one of the major strategic factors for decision-makers both in industry as well as in government. It has been established beyond doubt that the tailpipe emission shows significant effect on environment. It is clear that the vehicles form the predominant source of regulated and unregulated pollution. The environmental degradation all over the world has led to research, which resulted in the development of low emission vehicle and ultra low emission vehicle. In this work, performance of Low Mass Electrically Heated Metal Catalyst (LMEHMC) on the emission from SI engine has been experimentally investigated. Behaviors of chromium and copper oxides under various conditions were studied. It is found that the HC and CO emissions were reduced considerably when LMEHMC used with existing catalytic converter.


Author(s):  
C Jang ◽  
J Lee

The aim of this study was to investigate the effects of various factors on the emission characteristics of dedicated natural gas vehicles (NGVs). A conventional light-duty gasoline engine was modified to run on natural gas (NG) by a gas injection system. Experiments were mainly conducted on the optimization of an oxygen sensor, a catalytic converter, and an electronic control unit (ECU) control strategy affecting the emission characteristics of NGVs. Also presented are the emission results of the NGV as a low-emission vehicle by evaluating non-methane organic gases (NMOG). The experimental results present the optimization of the fuel control and exhaust system in NGV that is needed to meet the more stringent emission regulations. It is also suggested that non-methane hydrocarbons (NMHC) constitute about 95 per cent of NMOG, and light-end HCs (C2-C5) account for 91 per cent of total NMOG emissions.


2011 ◽  
Vol 130-134 ◽  
pp. 1749-1752
Author(s):  
Xing Bo Yuan ◽  
Zhi Jun Li ◽  
Shao Shu Chen ◽  
Ying Zhang

Lean-burn engines operate at a very lean air-to-fuel (A/F) ratio under light-load and part-load regions, in order to analyze the effect of engine speed and load on the BSFC (Break Specific Fuel Consumption) and exhaust emission of Lean-burn engine, an experimental research was conducted on a 4 cylinder lean-burn gasoline engine using different A/F ratios. The results show that the CO emission level decrease significantly, HC emission level becomes lower at the same A/F ratio, while the NOx emission increases, hence, advanced technologies are needed to carry out the NOx storage and purge operations in the lean-burn engines. Additionally, the experiment also reveals that the BSFC becomes lower as the engine speed and load increase.


Author(s):  
Sandro P. Nüesch ◽  
Anna G. Stefanopoulou ◽  
Li Jiang ◽  
Jeffrey Sterniak

Highly diluted, low temperature homogeneous charge compression ignition (HCCI) combustion leads to ultra-low levels of engine-out NOx emissions. A standard drive cycle, however, would require switches between HCCI and spark-ignited (SI) combustion modes. In this paper a methodology is introduced, investigating the fuel economy of such a multimode combustion concept in combination with a three-way catalytic converter (TWC). The TWC needs to exhibit unoccupied oxygen storage sites in order to show acceptable performance. But the lean exhaust gas during HCCI operation fills the oxygen storage and leads to a drop in NOx conversion efficiency. Eventually the levels of NOx become unacceptable and a mode switch to a fuel rich combustion mode is necessary in order to deplete the oxygen storage. The resulting lean-rich cycling leads to a penalty in fuel economy. In order to evaluate the impact of those penalties on fuel economy, a finite state model for combustion mode switches is combined with a longitudinal vehicle model and a phenomenological TWC model, focused on oxygen storage. The aftertreatment model is calibrated using combustion mode switch experiments from lean HCCI to rich spark-assisted HCCI and back. Fuel and emissions maps acquired in steady state experiments are used. Two depletion strategies are compared in terms of their influence on drive cycle fuel economy and NOx emissions.


Author(s):  
Myoungjin Kim ◽  
Sihun Lee ◽  
Wootae Kim

In-cylinder flows such as tumble and swirl have an important role on the engine combustion efficiencies and emission formations. In particular, the tumble flow, which is dominant in-cylinder flow in current high performance gasoline engines, has an important effect on the fuel consumptions and exhaust emissions under part load conditions. Therefore, it is important to know the effect of the tumble ratio on the part load performance and optimize the tumble ratio of a gasoline engine for better fuel economy and exhaust emissions. First step in optimizing a tumble flow is to measure a tumble ratio accurately. In this research the tumble flow was measured, compared and correlated using three different measurement methods: steady flow rig, 2-Dimensional PIV, and 3-Dimensional PTV. Engine dynamometer test was performed to find out the effect of the tumble ratio on the part load performance. Dynamometer test results of high tumble ratio engine showed faster combustion speed, retarded MBT timing, higher exhaust emissions, and a better lean burn combustion stability. Lean limit of the baseline engine was expanded from A/F=18:1 to A/F=21:1 by increasing a tumble ratio using MTV.


2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110381
Author(s):  
Li Wang ◽  
Zhaoming Huang ◽  
Wang Tao ◽  
Kai Shen ◽  
Weiguo Chen

EGR and excess-air dilution have been investigated in a 1.5 L four cylinders gasoline direct injection (GDI) turbocharged engine equipped with prechamber. The influences of the two different dilution technologies on the engine performance are explored. The results show that at 2400 rpm and 12 bar, EGR dilution can adopt more aggressive ignition advanced angle to achieve optimal combustion phasing. However, excess-air dilution has greater fuel economy than that of EGR dilution owing to larger in-cylinder polytropic exponent. As for prechamber, when dilution ratio is greater than 37.1%, the combustion phase is advanced, resulting in fuel economy improving. Meanwhile, only when the dilution ratio is under 36.2%, the HC emissions of excess-air dilution are lower than the original engine. With the increase of dilution ratio, the CO emissions decrease continuously. The NOX emissions of both dilution technologies are 11% of those of the original engine. Excess-air dilution has better fuel economy and very low CO emissions. EGR dilution can effectively reduce NOX emissions, but increase HC emissions. Compared with spark plug ignition, the pre chamber ignition has lower HC, CO emissions, and higher NO emissions. At part load, the pre-chamber ignition reduces NOX emissions to 49 ppm.


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