Tuesday, March 22, 2005

Reflected-Shock Ignition of CH4/C2H6/Air Fuel Blends

Jaap De Vries1, Joel M. Hall1, Anthony Amadio1, and Eric L. Petersen2. (1) University of Central Florida, Research Assistant, PO Box 162450, Orlando, FL 32816, (2) Mechanical, Materials & Aerospace Engineering, Assistant Professor, PO Box 162450, Orlando, FL 32816

The ignition and oxidation characteristics of a wide variety of CH4/C2H6/Air mixtures have been studied, with emphasis on power-generation gas turbine conditions. This effort is a direct result of a high demand from the power generation industry for reliable ignition and oxidation data. As the global demands for fuel flexibility rises, so does the demand for means of modeling the combustion characteristics of possible combinations. The oxidation and ignition characteristics of these different fuel blends can have a great impact on current combustor operation. Problems such as flame instability and premature auto ignition are ones commonly encountered in the industry. Experimental data can be used in combustor design or to validate chemical kinetics models for gas turbine conditions. Since the specific composition of mixtures varies widely from plant to plant and from country to country, the experimental data should be over a wide range of conditions, preferably from 100% CH4 to 100% C2H6. Mechanism validation further requires a wide range of stoichiometry, temperature, and pressure. To obtain the maximum amount of experimental information given this wide range of variables, a design of experiments method has been employed. This study presents the latest results from the test matrix, including several CH4/C2H6/Air mixtures at pressures up to 30 atm and post-shock temperatures up to 2000 K. The conditions were created using a helium-driven shock tube. Measurements of pressure and chemiluminescent emission from the CH* and OH* radicals were performed to monitor the combustion process. Presented in this paper are ignition results that support the specific needs of the power generation industry. A comparison is also made with kinetics models that had good agreement with previous studies conducted by the authors.