Prof. Jérôme Bellettre
Title of the Lecture:
Alternative fuel atomization assisted by water drops sudden vaporization. Application to pollutant emissions reduction in energy systems.
Prof. Jérôme Bellettre received his PhD in 1998 at INSA-Lyon (CETHIL) in the field of convective heat transfer. In year 2000, he joined Ecole des Mines de Nantes as associated professor and started to study alternative fuels combustion mainly in an experimental way. The investigations on emulsification began in 2003 with studies about the use of waste animal fat as a biofuel in CI engines. In 2007, he joined Polytech Nantes (LTeN CNRS-Nantes University) as Full Professor. He developed a new original topic regarding atomization of Water-in-Oil emulsion drops using phase change. A strong collaboration has started with Patrizio Massoli and his group at CNR (IM and now STEMS) in 2010 and is still going on in the field of optical diagnostics. In parallel, he developed and patented with Prof. Agnès Montillet (Nantes University) a new original device based on micro-channels. This device generates continuously liquid-liquid dispersions at very high flow rate. It has been successfully tested to feed energy systems and also in other industrial uses (food, cosmetics, pharma industries …). Prof. J. Bellettre supervised numerous PhD students in these areas of interest and published more than 70 archival papers in international journals.
Abstract of the Lecture:
Combustion of alternative fuels (such as vegetable oil, animal fat, …) remains a challenge if we want to achieve a “clean combustion” avoiding not only low CO2 but also low NOx, CO, Unburned and Soot emissions. These alternative fuels present indeed high viscosity and low volatility leading to a poor atomization and high pollutant emissions. Water-in-Oil emulsification can reduce this pollution very significantly. The difference in boiling temperature between the continuous and the dispersed phase can generate indeed a phenomenon named “Micro-Explosion” leading to a “second atomization”. This second atomization ends up in a cloud of numerous small oil child droplets, allowing an efficient vaporisation of the oil, a good air-fuel mixing and a low flame temperature. However, the “Micro-Explosion” itself is very complex with coupled phenomena regarding the dispersed phase inside the emulsified oil drops (sedimentation, convection, coalescence …). It needs to be studied in deep.
This lecture will focus mainly on experimental studies on Water-in-Oil (W/O) droplets atomization. These studies started more than 10 years ago in the context of a strong collaboration between CNR (IM and now STEMS) and LTeN at Polytech Nantes. Deep investigations of the water droplets inside the emulsion drop where performed using ad hoc optical diagnostics. Sizes, positions, velocities and temperatures of dispersed phase droplets have been measured and the conditions leading to an optimal Micro-Explosion are now rather well known. Micro-gravity experiments are still currently performed in order to check some of our assumptions.
This lecture will also present a new device that generates emulsified fuels at high flow rate in a continuous way. This new device is based on micro-channels. It has been deeply investigated thanks to optical diagnostics again. Some experiments using this device in order to feed an optical CI Engine will also be shown during the lecture.