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In SAE paper No. 860293, the first conclusions from application of the technique of forced regeneration of the ceramic trap by exhaust throttling of the diesel engine had been presented. The presentation is integrated in this paper, by a thorough interpretation and modelling of the effect of exhaust throttling on the diesel engine operation characteristics and thermal loading, as well as a discussion of the possibility and particularities of application to different types of engines. Behavior of the exhaust throttled 4-stroke diesel engine is exhaustively analyzed by use of computer simulation. Computer models are also used to study the effect of exhaust throttling on the diesel engine thermal loading. The validity of the results is tested by a large number of measurements conducted in the LAT the last five years.

A Diesel particulate trap oxidiser system suitable for retrofiting on urban buses is described. The system consists of a ceramic trap, a regeneration device and a control unit. The system is based on a new forced regeneration technique, by means of exhaust gas throttling. This technique establishes regeneration conditions on the road by the engine itself, with-out any external source of thermal energy or catalyst. Two buses in use with the Athens Public Transport Company (EAS) have been equipped with this system. The buses have been tested under real conditions on Athens urban bus routes and the results after the first 10000 km of operation are presented.

A regeneration system for the ceramic trap oxidiser is presented, based on the exhaust gas throttling of the engine. The trottling process, producing 1.5-3.0 bar overpressure, leads to a modified power flow in the engine, resulting in higher enthalpy exhaust gas, at the expense of the net power output of the engine. Thus exhaust temperature is raised over the lower regeneration limit (550°C) for a wide range of engine operation modes including also high speed-no-load modes. The effects of throttling on exhaust gas thermodynamic state and engine operational characteristics (volumetric efficiency, mean effective pressure, power output, consumption) are theoretically and experimentally analysed. An optimised regeneration system by exhaust throttling is described. This system includes: regulated throttling orifice for minimum net power output loss and reduction of fuel injected for acceptable smoke emission of the engine under high backpressure conditions.