A review of dual-fuel combustion mode in spark-ignition engines

The growing pressure to comply with environmental agreements that establish strict limits concerning pollutant emissions in the atmosphere has been stimulating a prominent technological development in the area of internal combustion engines. Recently, advanced combustion modes and the expanding adoption of biofuels are among the most explored aspects to minimize the environmental impact of modern propulsion systems. The dual-fuel combustion mode is a well-known strategy that has been studied since the early 1900s as an effective means for improving the fuel conversion efficiency of compression ignition engines. In recent years, this approach has been extended to spark-ignition engines and has shown promising results related to the combination of fuels normally used in the Otto cycle, with reduced fuel consumption, lower exhaust gaseous emissions and performance improvements. In this sense, the purpose of this article is to provide a concise review of the main state-of-art literature research covering the dual-fuel mode in spark-ignition engines, with special attention to the use of renewable and alternative options to reduce the impact of fossil fuels.