Study of the water injection control parameters on combustion performance of a spark-ignition engine

This paper reports an experimental study of the water injection control parameters in a single-cylinder research engine at 1500 rpm, under 5 and 8 bar indicated mean effective pressure (IMEP). The results were used to validate a tridimensional numerical model, and simulations extrapolated the experimental test conditions up to 10 bar IMEP and 3000 rpm. The main purpose of this work was to assess the impact of different water injection strategies on the engine combustion parameters. An interesting finding was that variations in the water injection temperature did not significantly influence fuel conversion efficiency, as one could expect. Nevertheless, the proper water injection timing and pressure calibration reduced the indicated specific fuel consumption (ISFC) by 3% and 3.5%, respectively, with more pronounced effects at the highest engine load. Furthermore, if knock mitigation is prioritized over ISFC, the amount of water injected can be reduced. However, this strategy leads to in-cylinder temperature reductions that influence the burning speed and consequently the peak in-cylinder pressure. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study experimentally validated the impact of different water injection strategies on engine combustion parameters, finding that variations in water injection temperature had limited influence on fuel conversion efficiency, while proper injection timing and pressure calibration significantly reduced specific fuel consumption.