Newsletter Archives; Fall 1996
Low-Emission Gas Turbine Engines
For the past three years, the Combustion Group of the Mechanical Engineering Department has participated in a collaborative research study in support of the development of very low emission gas turbine engines. The study, sponsored by the Advanced Gas Turbine Systems Research Division of the U.S. Department of Energy, has also involved Vanderbilt University, the California Institute of Technology, and Hughes Associates, Inc., of Baltimore, Maryland. The University of Washington effort has been directed by Professors Philip C. Malte and David T. Pratt.
Several recent graduates of ME have participated in the study, including Scott Capehart (MSME 1995), Jason Cooke (BSME 1996), Steve Glenn (BSMS 1996), David Horning (MSME 1996), Andrew Jarrett (MSME 1995), David Nicol (PhD 1995), Robert Steele (PhD 1995), Michael Stormbach (BSME 1996), Jon Tonouchi (PhD 1996), Joseph Williams (MSME 1995), and Jonathan Yourkoski (BSME 1996). Current students who have participated are John Lee (PhD), Scott Martin (PhD), Douglas Rosenbaum (BSME), and Teodora Rutar (PhD). The study has provided the UW students with an opportunity to interact with students at the other universities involved, and with engineers representing the major gas turbine engine manufacturers in the U.S. Several of the students have received assistantships, and have presented and published technical papers at Gas Turbine and Aeroengine Congresses, Combustion Symposia, and Combustion Institute Meetings.
The UW effort has used both laboratory combustors and computer models to understand how pollutants form in gas turbine engine combustors and how the pollutants can be reduced to very low exhaust emission levels. The pollutants of greatest significance for these engines are the oxides of nitrogen (NOx) and carbon monoxide (CO). Additionally, computer models and chemical kinetic mechanisms have been developed for use by the gas turbine industry for the purpose of predicting emissions of new engine designs.
The research has been focused on gas turbine engines fired on natural gas with a lean-premixed flame and used for electrical power generation and mechanical drive applications, such as gas pipeline compressor stations. Gas turbine engines used in combined cycle power plants and in combined heat and power (CHP) energy systems, and used for peaking power, now account for over 50% of the new electrical generation equipment being installed in the U.S. and worldwide. This trend in market share is expected to continue for at least the next decade. The combined cycle power plant is very attractive for generating electrical energy, since efficiency of the best systems is 58%, and this is expected to reach 60% within a few years. The high efficiency and the chemical composition of natural gas give the combined cycle power plants about a 2-to-1 advantage over coal-fired power plants in electrical energy produced per pound of greenhouse gas emitted. The primary greenhouse gas implicated in global climate change is carbon dioxide (CO2). With the very low emissions of NOx and CO of about 10 parts per million or less each, the combined cycle power-plants become doubly attractive.
Several challenges and opportunities exist for future research in this field, and the UW Combustion Group looks forward to this work. Some of the challenges are: 1) improving the margin between lean flame-out and stable low-emission combustion, 2) attaining very low emissions for liquid fuel-fired gas turbine engines, 3) developing advanced computer controlled combustion, and 4) developing combined cycles of very high efficiency, perhaps by combining the gas turbine engine with the fuel cell.
