Experimental burning velocities of ethanol-water-air at elevated pressure and temperature

Anhydrous ethanol can be considered as one of the main alternatives to replace fossil fuels. However, the removal of water consumes the greatest fraction of the energy necessary for its production. Thus, the use of hydrous ethanol arises from a new fuel possibility and it has been successfully tested in a device such as a spark-ignition engine. For this reason, there is a need for the determination of fundamental properties of the ethanol-water-air mixtures. There are few experimental works in this area and the majority of them have been carried out in test conditions of pressure up to 1 atm. Thus, the main goal of the present work is to bridge this data gap. For this, the laminar burning velocities and Markstein length of ethanol-water-air flames at water content up to 30% v/v over a range of equivalence ratios from 0.7 to 1.4 up to 5 MPa and 380 and 450 K were experimentally determined. The method used was a constant volume bomb method with a central ignition. The results were compared to literature data and with predictions carried out with CHEMKIN-PRO using the three different kinetic mechanisms. In general, the results of the mechanisms lead to an overprediction in relation to the experimental results, though all of them predicted the burning velocity peaks at an equivalence ratio close to 1.1, which agreed with the experiments. The experiments conducted that increased water content of water fuel mixtures have a tendency to remain stable under a stretch influence. Also, it is possible to observe a linear relationship describing the influence of the diluent on the laminar burning velocity.