Experimental and numerical studies of diesel-biodiesel blends in a counterflow diffusion flame

Hernando Maldonado¹; Dario Alviso¹; Juan Carlos Rolon¹; Rogerio Goncalves dos Santos²; Philippe Scouflaire³; Nasser Darabiha³

¹ Facultad de Ingenieria, Universidad Nacional de Asuncion; ² Faculdade de Engenharia Mecanica, UNICAMP, Brasil; ³ Centrale Supélec, Laboratoire d'Energétique Moléculaire et Macroscopique, Combustion (EM2C), Grande

doi:10.20906/CPS/COB-2015-1030

Resumo

Biodiesel is a complex mixture of methyl esters with different chain lengths and degrees of unsaturation and can be used in pure form or may be blended with diesel. In Paraguay, the percentage of diesel vehicles is about 80% of the fleet, and currently 100% of diesel fuel is imported and only B1 (1% biodiesel) is used. Therefore, the potential in the development of such alternative fuel is enormous. However, changing the fuel in diesel engines induces changes in combustion behavior. Indeed, the use of biodiesel in diesel engines decreases emissions of CO, THC, and PM, although a slight increase of NOx is observed in some cases. Most of experimental studies of real fuels blends combustion are performed using internal combustion engines. Fundamental study related to the combustion of these fuels blends is still scarce in literature. From the numerical point of view, many studies are performed using homogeneous reactors. Nevertheless, mainly due to the complexity of their chemical composition, there are only few studies on kinetic modeling of such fuels blends. This paper presents experimental and numerical studies of diesel-biodiesel blends combustion in laminar two-phase (spray) counterflow diffusion flame configuration. The key objective of the study is to understand the flame structure of different diesel-biodiesel blends and validate the kinetic models used in the simulations. The experiments were carried out in a counterflow burner. A mixture of diesel-biodiesel/nitrogen flow is injected from the upper side in a disperse spray phase, whereas an airflow is injected from the lower side, forming a diffusion flame. The chemiluminescence of the excited radicals CH* and C2* are studied experimentally by emission spectroscopic techniques. Opposed flames have a slight curvature, which creates in the line of sight of the camera an integrated signal. To obtain the profile in the center plane of the flame, we apply a numerical tomographic technique, the Abel inversion of the integrated 2-D image captured with

Palavras-chave: Biodiesel; Kinetic modelling; Numerical Simulation; Premixed flame; Diesel