Effects of Syngas Addition on Combustion Characteristics of Gasoline Surrogate Fuel

Syngas has the potential to become an alternative fuel for internal combustion engines. In this work, a detailed mechanism containing 1389 species and 5942 reactions was developed to examine the combustion of syngas/gasoline blends. The influence of syngas addition on the ignition delay time (IDT) and laminar flame speed of gasoline fuel was studied. Two influencing factors were considered: the mixing ratio of syngas and the H₂/CO ratio in syngas. The changes in heat release, free radical concentrations, and emissions were also studied. Syngas can boost the system's reaction activity and promote ignition in the high-temperature area over 1000 K. However, the diluting effect is visible at low temperatures below 1000 K, leading to an IDT lag. The effect of the H₂/CO ratio on the IDT was not as pronounced as expected. The addition of syngas can inhibit the knock combustion of the engine to a certain extent, but it will also lead to a violent exothermic process and a decrease in the total release of heat. Syngas addition increases the concentration of small molecule radicals and promotes the laminar flame speed. At higher temperatures and pressure levels, the trend of syngas/gasoline laminar flame speed is more dependent on changes in OH radical concentrations. The addition of syngas favors the promotion of complete combustion and the reduction of HC emissions but also results in an additional increase in CO. Combustion at lower temperatures has lower CO and HC emissions.