1 Copyright ©2013 by the American Institute of Aeronautics and Astronautics Inc. All rights reserved ISABE-2013-1506 CFD REDESIGN OF MICRO GAS TURBINE COMBUSTOR FOR BIO-FUELS FUELING A. Cappelletti, A.M. Rizzo, D. Chiaramonti, F. Martelli CREAR - Università degli Studi di Firenze Via S. Marta, 3 – 50139 Firenze Italy Abstract Bio-fuels could be a interesting possibility for small CHP plants based on a Micro Gas Turbine (MGT). The aim of this study is the CFD redesign of a micro gas turbine combustor to permit a stable pyrolysis oil (PO) combustion. The work needed to define a new operative point to reduce the modification on the gas turbine and the using of original injector, because the target fuel very different than diesel mainly about the viscosity and heating heat. The redesign activity was based on the support of CFD 3D RANS simulation. In this work the main modeling aspect was the using of a injection model for liquid fuels and the chemical kinetic aspects for the bio-fuels. The combustion model is based on mixture-fraction and the equilibrium approach. The activity started from the analysis of the original diesel fueled combustor that show a very low temperature field, confirmed by the high experimental CO emissions. This situation wasn’t able to permit a stable flame in pyrolysis oil fueling. The redesign approaches were many: increase the equivalence ratio in the primary and secondary zones for the new operating point, reduction of the cold zones and the considering the higher combustion time of the pyrolysis oil. The new geometry was verified by CFD, which confirmed the quality of the design in fact in PO case the combustion is stable. A preliminary experimental activity with diesel fueling shows very lower CO emission than the original case. This results demonstrate the improved combustion, prerequisite for the possibility of a good pyrolysis oil combustion. Nomenclature k Turb. kinetic energy [m2/s2] T Temperature [K] V Velocity [m/s] y+ y plus [-] L length of combustor [m] Greek Φ Equivalence ratio [-] ε Dissipation rate [s-1] Abbreviation AFR Air Fuel Ratio PO Pyrolysis Oil LCV Lower calorific value MGT Micro Gas Turbine PDF Probability density function RANS Reynolds Averaged Navier- Stokes Introduction In a reduction of fossil–fuel dependence contest the PO fueling could be a new opportunity for an agriculture based economy [1], because it makes the solid organic waste more valuable. In fact it permit the little farms to produce own energy: thermal and electrical.