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Technical Paper

A Study of the Durability of Diesel Oxidation Catalysts

1995-11-01
952650
Diesel emission control is being addressed worldwide to help preserve the global environment. In 1994, emission controls in the U.S. called for reduction of diesel particulate matter (PM) to 10 to 20% of 1986's initial limit. In the same year, we developed and marketed small and medium duty trucks which were equipped with PM reduction systems that oxidize soluble organic fraction (SOF) contained in the PM, in order to satisfy these new regulations. Prior to their marketing, a catalyst was selected from among several types of candidate catalysts. Durability tests were performed using a catalytic converter-equipped small duty truck to verify the durability of the chosen catalyst. The durability test course was set up combining urban areas and expressways in the southern part of California, U.S.A.. The cumulative total distance covered on the test course reached 200,000 km. During the durability test, the catalyst was evaluated by measurement of PM emission using a chassis dynamometer.
Technical Paper

A Diesel Oxidation Catalyst for Exhaust Emissions Reduction

1993-11-01
932958
The authors used a mass spectrometer to determine an SOF reduction mechanism of a diesel oxidation catalyst. The results indicate that SOF reduction lies in the catalytic conversion of high molecular organic matter to low molecular organic matter. And unregulated emissions are also reduced through this conversion. It is also found that the SOF reduction performance is highly dependent up on the condition of the wash coat. There is some limitation to improving diesel oxidation catalyst performance because of the sulfur content found in diesel fuel. Finally, the authors have determined what we think are the specifications of the presently best catalytic converter.
Technical Paper

Technology for Meeting the 1994 USA Exhaust Emission Regulations on Heavy-Duty Diesel Engine

1993-10-01
932654
Recent global environmental problems which have come to light must be solved for ensuring the survival of the human race. And it is of the utmost importance that we give to our descendants a world full of nature and beauty. In the past years Mitsubishi Motors Corporation (MMC) has long been positive in research and the development activities so as to satisfy the demands for low emission and good fuel economy vehicles. (1) As one example of our research efforts, the technology that will meet the US '94 HDDE exhaust emission regulations, which is one of the most stringent regulations in the world, is described in this paper. The exhaust emissions were reduced by improvement of combustion, using the pre-stroke control type fuel injection pump and optimizing the combustion chamber shape. Efforts were also made to improve the oil consumption, in order to reduce PM (Particulate Matter) emission.
Technical Paper

Technology for Meeting the 1991 U.S.A. Exhaust Emission Regulations on Heavy Duty Diesel Engine

1990-10-01
902233
Protection of the Earth's environment by means of energy saving and cleaning up of air pollution on a global scale is one of the most important subjects in the world today. Because of this, the requirements for better fuel economy and cleaner exhaust emissions of internal combustion engines have been getting stronger, and, in particular, simultaneous reduction in nitrogen oxides (NOx) and particulate matter (PM) from heavy-duty diesel engines (HDDEs) without degrading fuel economy has become a major subject. Mitsubishi Motors Corporation (MM) has been selling diesel-powered heavy-duty trucks in the U.S. market since 1985 and has agressively carried out development work for meeting the 1991 model year exhaust emission standards.
Technical Paper

Measurement of Unregulated Exhaust Emissions from Heavy Duty Diesel Engines with Mini-Dilution Tunnel

1990-02-01
900643
Many reports on characterization of unregulated exhaust emissions from diesel engines and its measurement methods have been presented, but the number of objective chemical compositions used in those experiments are limited. Those reports have referred to use of a large and expensive full-flow dilution tunnel specified by US EPA, and also to the fact that, in case of a partial-flow dilution tunnel which is called “mini-tunnel”, the use should be limited only to steady state engine operations. The authors reported in SAE Paper 890181 that a multi-tube type mini-dilution tunnel, which was compact and less expensive, had good agreement with the full-flow dilution tunnel required by US FTP for heavy-duty diesel engines, when the regulated exhaust emissions were measured on a heavy-duty diesel engine under steady state and transient operaton conditions.
Technical Paper

Measurement of Diesel Exhaust Emissions with Mini-Dilution Tunnel

1989-02-01
890181
A compact transient mini-tunnel (multi-tube type) inducing only a part of the exhaust gas, has been newly developed as a device for measuring the quantity of regulated exhaust emissions in the exhaust gas from diesel engines. This device allows measurement of exhaust emissions even for transient mode operating conditions of the engines, such as U.S. EPA FTP transient mode (FTP mode). The size of this mini-tunnel can be reduced to approximately twenty percent of the dilution tunnel (full-flow tunnel) specified by EPA and the flow rate in the mini-tunnel is a few percent thereof. The results have been demonstrated that the mass emissions of particulate, CO, NOx and HC measured with the mini-tunnel have good agreement to that measured with the full-flow tunnel under FTP mode and also steady state operating conditions of the engines (correlation coefficients of particulate, CO, NOx and HC are not less than 0.97).
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