Use of Water Injection Technique to Improve the Combustion Efficiency of the Spark-Ignition Engine: A Model Study

In the paper, the effect of water injection and different air/fuel ratio on the gasoline engine performance and emissions was investigated theoretically. A four cylinder SI engine model was built using GT-Power professional software. The gasoline fuel was injected directly to the cylinder and water was injected into the intake manifold with different mass flow rate. The calculated engine parameters were: cylinder pressure and temperature, brake torque, brake power, mean effective pressure, thermal efficiency, carbon monoxide, hydrocarbon, and nitrogen oxide emissions. The results of simulations show that the increased water mass flow rate resulted in an improved engine performance and decreased emissions compared to neat gasoline fuel. However, we found that the excessive increase of the water amount inside the cylinder resulted in a deteriorated engine performance and, consequently, poor combustion efficiency.