Performance of Naphtha in Different Compression Ignition Combustion Modes under Various EGR Rates 2015-01-0804
Experimental research were carried out on a compression ignition engine with compression ratio of 17.5 with direct-run Naphtha. Exhaust recirculation ratio sweeps were carried out with three injection strategies. Premixed charge compression ignition, partially premixed combustion and low temperature combustion modes were realized and compared with each other. The first injection strategy is single injection. The injection timing is scanned to form partially premixed combustion and low temperature combustion. The second injection strategy features a large early first injection with fixed timing to form premixed charge and a small second injection near top dead center, which was scanned. The third injection strategy is similar to the traditional diesel injection strategy, which has a small pilot injection with fixed interval before the main injection. Results show that all injection strategies could realize both low NOx and low particulate matter emissions simultaneously. For the single injection strategy, large amount of exhaust gas recirculation ratio was needed, with also higher indicated thermal efficiency, but the maximum pressure rise ratio was also larger. For the second injection strategy, the maximum pressure rise rate was lower at the cost of increased fuel consumption. The third injection strategy can realize similar performance to the single injection strategy, but the noise was much smaller.