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This paper describes the development and proof-of-concept testing of an electrically based (i.e., non-optical) smoke sensor for diesel engines. The sensor is intended to provide a means of detecting smoke levels that exceed certain pre-defined limits. Potential applications for the sensor include closed loop control of Exhaust Gas Recirculation (EGR) and the diagnosis of fuel injection faults. Engine dynamometer tests were carried out using a heavy duty diesel engine equipped with a laboratory EGR system. EGR levels were adjusted to vary exhaust smoke levels at a fixed speed/load test point. Reference smoke measurements were provided by an AVL 415S variable sampling smoke meter. The experimental results showed a correlation between the sensor signal and the Filter Smoke Number (FSN) at FSN values between approximately 1 and 3. The sensor was able to detect relative changes in smoke levels, but its absolute sensitivity was not consistent.

This paper describes an experimental study of the effects of ignition spark characteristics on combustion behaviour in a light duty automotive engine. A prototype programmable energy ignition system was used to investigate the influence of both spark energy and the current/time profile used to deliver a given amount of energy. The engine was tested under part load conditions using a stoichiometric air/fuel ratio and relatively high levels of exhaust gas recirculation (EGR). In addition to tests with port-injected gasoline, tests were also carried out using propane (premixed upstream of the throttle) in order to investigate the possibility that improvements in the homogeneity of the mixture might influence the impact of varying the spark characteristics.