| Abstract |
The task of the University of Rouen in the Acrevo project was to characterize
soot formed in a rapeseed oil ame. In order to allow complete computations of
emitted pollutants, the choice was made of a laminar, di usion ame of prevapor-
ized oil in air.
Since the use of vegetable oil was the rst constraint, the largest part of the
project duration has been constituted by the set-up of the process. To measure
soot particles with accuracy needs to use laser light scattering (LLS) diagnostic.
However it is impossible to distinguish soot and ne droplets, if located in the same
area of the ame, by using the classical optical techniques. The major di culty,
which has been encountered in this project, was then to be able to survey the oil
vaporization continuously, and to validate the hypothesis of a gaseous ame. After
a feasibility study described in a previous report, this part of the project has been
successfully realized. Then the classical techniques (LLS) can be applied ; this
work is now in progress. A complementary report will be provided in june for the
ACREVO nal meeting.
The main result obtained by the task consists in a vaporizing process, for
vegetable oil or other viscous fuel, which is optically controlled during the whole
experiment duration. This ensemble can be applied to the other groups set-up.
Our study can be summarized in the following steps:
1. the design of an experimental oil atomization set-up, with a good knowledge
of formed droplets (stabilities of the sizes distribution and concentrations)
2. the design of the warming of the droplets cloud. The rapeseed oil droplets
are completely evaporated ; a small amount of butane has been added to
stabilize the laminar oil di usion ame.
3. in order to distinguish the soot particles and the oil droplets, a numerical
procedure has been performed to analyze the experimental data obtained
by an optical extinction technique. An inversion code has been written and
validated to extract the characterizations of residual droplets and soot from
the extinction spectra. The presence of gas absorption bands in the ame
had to be taken into account, too.
4. the complete characterization of soot particles emitted by the laminar rape-
seed oil ame, based on LLS technique at several angles, is currently devel-
oped. |