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The paper presents electronically controlled ignition system with exhaust gas recirculation (EGR) in two-cylinder, four-stroke SI research engine. Exhaust gas recirculation was achieved by the special spark plugs enabling flow of exhaust gases between cylinders. The flow of recirculated exhaust gas (the angle of start of recirculation and its duration) is controlled with the use of two electromagnetic valves controlled by programmable electronic unit. The designed and practically tested system was used in the studies of the influence of EGR on emissions and efficiency in SI engine. It was found that with EGR system the engine operates practically with the same efficiency as a conventional combustion system and the emission of NOx considerably decreases at full load. The results of calculations confirm the tendency of NOx emission decrease with EGR increase.

The performance of classical spark ignition system and PJC ignition system developed by A.K. Oppenheim, has been tested in IC piston engine operating at full and partial load. Tests were conducted in the four stroke two cylinder engine. Differences in efficiency and emission for both ignition systems were tested for the power range from half load to full load. It was found that with the PJC system the engine operates more economically at the partial load and emission of hydrocarbons and CO was decreased at partial load. This was basically due to improvement of lean mixture combustion. However, the emission of NO was always higher for PJC than for conventional spark ignition.

Research of combustion process was made in a specially designed research engine in which simultaneous pressure measurement and Schlieren visualization of the combustion process were possible. Pressure as well as the timing of each picture was recorded by the data acquisition computer system. The whole operation of the experimental apparatus is also controlled by PC computer connected to a special control unit. Combustion studies were focused on the comparison of classical spark ignition system to the jet ignition, initiated by a specially produced Pulsed Jet Combustion (PJC). Comparison of the flame propagation velocity and variation of the pressure in the chamber for different ignition systems and different equivalence ratio of combustible mixtures were made. It was found that under all experimental conditions jet ignition is superior over conventional spark ignition system. Comparison of pollutants emission was also made.