The effects of hydrogen peroxide-ethanol blend/gasoline on the combustion and emission performance of a combined injection spark ignition engine

Hydrous ethanol is a green fuel with great potential to deal with crises in the environment and energy. The study on the ethanol life cycle showed hydrous ethanol with 10%-20% water content had the best benefit, but the water content >10% would deteriorate engine power and emission performance. In this paper, the effects of the 30 vol% laboratory-grade H2O2 on the combustion performance and emission characteristics were explored in an ethanol/gasoline combined injection engine. At the engine operating condition of engine speed/manifold air pressure = 1500 rpm/49.5 kPa, the H2O2-ethanol blend direct injection (DI) and gasoline port injection were conducted. Results showed that H2O2 greatly improved the operating performance of the hydrous ethanol/gasoline engine. As the 30 vol%-H2O2 ratio in the H2O2-ethanol blend (H(2)O(2)r) increased, the P-max and the T-max first increased and then decreased. Both CA0-10 and CA10-90 were slightly extended. For the DI ratio = 10%-40%, the optimal IMEP was obtained at H(2)O(2)r = 15%, which was 0.09 bar-0.11 bar higher than H(2)O(2)r = 0%. The optimal BTE was 0.86%, 0.75%, 0.71% and 0.75% higher than H(2)O(2)r = 0%, respectively. As the H(2)O(2)r and DI ratio increased, HC and NOx emissions descended, and CO emissions decreased first and then ascended slightly with the critical H(2)O(2)r = 10%-15%. Optimal CO, HC and NOx emissions were 21.76%, 58.83% and 42.02% lower than gasoline, respectively. H2O2 could reduce particulate emissions, while the H(2)O(2)r < 15% at the DI ratio = 30%-40% should be adopted.