Combustion and emission characteristics of E85 and diesel blend in conventional diesel engine operating in PPCI mode

Abstract

To study the possibility of operating a traditional diesel engine as a partially premixed compression ignition engine, E85 created from 85% bioethanol and 15% unleaded Iraqi gasoline blend was used as the main fuel. E85 blend fuel has a low evaporation temperature, large latent heat and low cetane number (CN). Iraqi diesel fuel was used as a pilot fuel to assure ignition. High rate of cooled exhaust gas recirculation was used. The engine performance and emissions, particularly NOx–smoke trade-off, was also investigated. In order to reduce the number of experiments to be performed, the tests were conducted at a speed of 1500 rpm, with changes in the recirculated exhaust gas rate (10%, 30% and 50%) and change in injection timing (20°, 22°, 25°, 28° and 32° BTDC).Practical results showed that a significant improvement could be achieved in the NOx–PM trade-off. The ignition delay period can be increased by using a low-CN fuel accompanied with a low oxygen intake charge. When using the PPCI system, low levels of NOx and PM can be achieved without affecting the brake thermal efficiency of the engine. Smoke can be reduced even when the EGR percentage is increased under a mixed condition. ED10 (90% E85 + 10% diesel) had the largest decline in NOx (84.66%) and smoke (55.8%) compared to diesel.