Model of water injection process during closed phase of spark ignition engine

In the continuous quest for increased efficiency and reduced environmental impact in the use of internal combustion engines (ICEs), water injection has historically been one strategy used to achieve these objectives. However, practically all of the investigations carried out in this field are experimental tests in which water is injected into the air or combustible air mixture prior to entering the cylinder. The research presented in this paper demonstrates the results of a thermodynamic model simulation of two zones, which integrates the water injection directly into the combustion chamber. The model allows for prediction of the performance parameters of an ICE that uses water injection, as it adequately interprets the injection process phenomenology during the closed phase and the performances of important operating parameters. The model is validated by comparing its results to those reported by experimental research, using the same proposed water injection methodology and gasoline as fuel. The proposed simulation model offers significant flexibility, as it can be used to simulate different engine geometries, rotation speeds and fuels such as gasoline, ethanol, hydrated ethanol or mixtures thereof, in varying proportions. In addition, it provides a starting point for the implementation of a turbo charge and direct fuel injection model, which would allow the simulation of devices representing the current trend in the use of ECI. The results of the comparison between the experimental and simulated data show maximum error percentages of 11% in the case of BSFC, for different percentages of mass of water injection with respect to the mass of fuel, which shows the promising development of the model.