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Much attention has been paid to the emissions from diesel transit coaches culminating in the 1990 EPA bus standard.(1)* A primary pollutant that has been singled out for advanced controls is diesel particulate. In order to meet the low levels of particulate emissions in the standard, diesel particulate filters are one of the principle methods being studied. To this end, the Ministry of Transportation and Communications of Ontario and Engine Control Systems Ltd. entered into a cooperative development program for a low cost, simple and retrofitable diesel particulate control system.(2) The paper outlines the various components of the system and the results of field testing.

Following the initial studies of applicability of particulate control of the exhaust from diesel-powered vehicles in underground mines, the Canadian fleet trial has continued. A report is given on the status of the installations currently in service together with analysis of the problems and benefits that have been observed. Additionally, the success of a range of other applications is reported, ranging from stationary sources, locomotives, mechanical handling to specialised applications in the military sector.

Following considerable laboratory studies concerning particulate control systems for underground use, a program was commenced to develop practical real life implementation systems. This program covers the implementation in seven mines of particulate system to 14 engine models from four engine manufacturers in 18 different vehicle types, a total of 23 vehicles. Partially funded by the Canadian National Research Council, under its IRAP program, this program requires detailed analysis of operating cycles, maintenance variabilities and installation implementation problems. This paper summarizes the work carried out todate to define real world targets for practical underground particulate control.

The city bus has been targeted for special emission regulations. This examination of the practical problems of day-to-day use of a Catalytic Trap Oxidizer was undertaken. Installation problems and vehicle adaptation are discussed together with safety requirements. The initial concept of muffler replacement CTO's was found to be practical but the logistics required a redesign of the unit for more practical fit and service. A failure of the initial system demonstrated the need to design for safety. A second design, simpler to fit and with safety aspects foremost, was also examined. The effects of the CTO system on vehicle performance, smoke and odor are given, together with details of the work carried out to practically achieve the positive benefits of the CTO, smoke and odor control, in a real life application.

Public awareness of center city bus emissions is high, especially on transit ways where at peak load times a bus passes every 15 seconds. To investigate the potential reduction in smoke and odor levels, a typical bus with a 6V71 engine was equipped with a Catalytic Trap Oxidizer. An in-service test procedure was developed and the reductions in measured smoke and subjective odor were significant. The bus was returned to revenue service in Philadelphia at an average speed of 7.5 mph. The effects of the CTO on smoke, smell, fuel consumption and maintenance during service are reported.

Considerable work has been carried out to develop particulate control systems for light duty vehicles. These systems are required to operate under widely varying conditions of service. Examination of the extremes of operation shows the importance of the regeneration ability of the control system employed. In addition, a major requirement for a practical control system is minimum complexity. Discussed here is a catalyst system and the extension of the technology to allow for minimum complexity and the ability to operate at the defined extremes of use. The theory of the TRIM System and the results of evaluations on vehicles and test benches are given.

Public concern with city bus diesel emissions is worldwide. The operation of public transport in center city areas generates considerable localized pollution. This paper discusses the application of catalytic particulate control to various types of buses and gives details of the performance achieved in widely differing operating environments. On-road, in-service evaluations are reported and details given on the developments to arrive at the socially acceptable or “Friendly” bus.

Current emissions control legislation requires significant reductions of particulate emissions from light duty diesel engined vehicles in California for model year 1986 and Federally for model year 1987. In addition, NOx emissions levels will be reduced. This compounds control requirements due to the inverse relationship between NOx and particulate emissions. To meet these standards, a catalytic trap oxidizer (CTO) based on a radial flow metal mesh filter was developed for use as an after-treatment device on light duty diesel vehicles. A complete system for assisted regeneration was devised to enable this unit to operate without blocking during all normal driving modes. The integration of the catalyzed trap and regeneration system with the vehicle to provide a practical system for the reduction of diesel particulate emissions is discussed.

The widespread use of diesel engines for industrial power plants in enclosed environments has long caused concern over the health effects of long-term exposure to diesel exhaust emissions. This concern has led to developments in engine design and exhaust after-treatment aimed at significantly reducing the pollutant levels in diesel exhaust. The basic principles of diesel emissions control using a Catalytic Trap Oxidizer were developed by Johnson Matthey for use on light-duty road vehicles. The system makes use of a radial-flow impingement filter structure supporting a specially formulated precious metal catalyst. The filter is effective in trapping particulates and enables their removal, by catalytic oxidation, at attainable temperatures. The catalyst is also effective in enabling oxidation of gaseous organic and carbon monoxide emissions at low temperature.