Comparative evaluation of different operating parameters on performance, combustion, and emission characteristics in gasoline compression ignition (GCI) engine by using carbon neutrally biofuels

The stringent emission regulations and energy shortage put forward strict requirements for highly efficient and clean combustion for internal combustion engines. The gasoline compression ignition (GCI), which is a new advanced combustion concept, can obtain high efficiency and low emissions simultaneously without many modifications of standard diesel engines. However, little research has been carried out to synergistically optimize the operation parameters in a wide load range, especially fueled with the carbon neutrally biofuels. Therefore, in this paper, the effects of various operating parameters on engine performance, combustion, and emission characteristics of the gasoline compression ignition (GCI) strategy fueled with a blend of butanol and biodiesel were investigated. Specifically, the impact of butanol energy ratio, fuel direct injection timing, and exhaust gas recirculation (EGR) at the indicated mean effective pressure (IMEP) of 4, 8, and 14 bar and the butanol energy ratio of 60%, 70%, and 80% were examined. Result shown that the increase in butanol energy ratio decreased the fuel reactivity and worsen the combustion process, while the lower butanol energy was also disadvantage to the engine performance. The indicated thermal efficiency could achieve 48.5% when the butanol energy ratio was 70% at medium engine load. The earlier fuel injection timing was needed at low engine load, the EGR was necessary to inhibit the in-cylinder pressure rise at high engine load, in which the EGR rates of 20% at the IMEP of 8 bar and 30% at the IMEP of 14 bar could achieve the optimum engine performance, respectively. Meanwhile, the nitrogen oxides emissions shown a greatly decrease with the EGR rates increase, and it was less than 200 ppm at the IMEP of 14 bar when the EGR rates were 50%.