EXHAUST EMISSIONS FROM HEAVY-DUTY DIESEL ENGINED VEHICLES

Conventional procedures for the control of emissions from heavy duty vehicles are based on tests of engines which may, if granted type approval, be used in a variety of different vehicle applications. Because rates of exhaust emission from a vehicle in use depend on many factors, such as the vehicle's duty cycle and state of maintenance, the relationships between engine type approval standards, in-service vehicle emissions and their environmental impacts must be understood in order to ensure that emission control legislation is technically, economically and environmentally acceptable. This paper presents interim results from a programme of research that is being carried out to provide information on the various aspects involved. Emission tests are being conducted on a range of heavy duty engines and the results analyzed as a function of the engine operating conditions. A survey of commercial vehicle operations is taking place, in which a wide range of vehicles are instrumented to measure both engine and vehicle operating conditions during normal use. In combination, these results will provide a substantial data base of performance related emission rates characteristic of the UK heavy duty vehicle fleet. Vehicle mounted equipment for the sampling and analysis of exhaust emissions has been developed and is in use, in a parallel test programme, to measure emission rates directly from vehicles on the road. The information will permit interpretation of the more comprehensive data from the engine and vehicle operating condition studies. © 1990.