The European AGATA programme (Advanced Gas Turbine for Automobiles), is a programme dedicated to the development of three critical ceramic components — a catalytic combustor, a radial turbine wheel and a static heat exchanger — for a 60 kW turbogenerator in a hybrid electric vehicle. These three components, which are of critical importance to the achievement of low emissions and high efficiency, have been designed, developed, manufactured and tested as part of a full-scale feasibility study. The AGATA partners represent car manufacturers as well as companies and research institutes in the turbine, catalyst and ceramic material fields in both France and Sweden. The AGATA project commenced in early 1993 and has occupied a 5-year period until April 1998. This paper summarises the results from the development of the catalytic combustor.
The catalytic combustor operates at temperatures in the catalytic section from inlet 935°C to the exhaust 1350°C. Therefore all structural components in the hot section are made of ceramic materials.
The testing and validation have been run through a component test campaign from which it was concluded that:
• The catalytic section substrates showed good behaviour during the high temperature tests.
• Palladium was chosen as the active catalytic material after extensive testing at pilot scale. Ageing at high temperature (1270°C) has a strong effect on catalyst deactivation.
• Emissions levels of the preheater are in agreement with the state of the an for small aero-engines according to the ICAO legislation.
The complete full scale combustor testing was run in the following steps:
• Initial gas analysis tests at inlet temperature 200° lower than the nominal value
• CARS and gas analysis
• Comparison diesel and ethanol fuels
• Final testing at maximum design temperatures and pressure
The catalytic combustor was run on diesel fuel during the complete test period. A test campaign comparing exhaust emissions when running on ethanol fuel was performed at Volvo Aero Turbines. These results showed that the catalyst reaction rate and CO/HC/NOx emissions were similar. This means that the chosen catalytic combustor can be used as a dual fuel combustor diesel/ethanol.
The final test campaign at ONERA, France, was run up to temperatures slightly above the specified maximum design temperatures. Inlet temperature 962°C (design 935°C) and exhaust temperature 1362°C (design 1350°C). These tests showed that NOx emission levels below 4 ppm @15% O2 were obtained when low CO and HC emissions levels were measured at full load conditions. This promising performance level was reached with technologies that still have to be thoroughly evaluated in terms of durability and low cost potential for industrial applications.
