A new catalytic gas generator (GG) was successfully built and tested with a turbine power unit (TPU) to demonstrate nontoxic power generation for launch vehicle applications that require high power for short durations, such as flight-control systems. Unlike the space shuttle’s hydrazine auxiliary power unit (APU) and other similar APU’s, which provide mechanical power to the hydraulic flight-control system, the GG/TPU combination provides electrical power for an all-electric flight-control system or for loads requiring high electrical power for short durations. The GG is designed to operate with gaseous hydrogen and oxygen. The GG/TPU (left photograph) was successfully demonstrated with gaseous hydrogen and oxygen propellants through catalytic reaction to produce 138.7 kWe. Hot restart was also demonstrated successfully with the GG/TPU configuration. The hot restart testing verified that the GG/TPU can be shut down at anytime and restarted after any shutdown interval.
Left: GG tested with TPU. Right: Catalytic GG.
The GG (right photograph) properly mixes the gaseous hydrogen and gaseous oxygen propellants, initiates their reaction through a Honeywell 405 granular catalyst, and channels the hot gas to the TPU to spin the turbine. The turbine directly drives a generator that produces electrical power. The GG is designed to operate at a combustion gas temperature of 1500 °F, an oxygen-to-fuel ratio of 0.80 (fuel rich), a flow rate of 0.336 lb/sec at maximum power, and a pressure of 170 psia to the TPU. It is pulsed on and off at 0.25 to 2 Hz to regulate power.
Numerous GG/TPU integration and GG design issues have been solved with the new catalytic GG. A remaining technical challenge for the GG is extending the catalyst operating life. The GG catalyst has a cumulative demonstrated operating life of about 55 min, with a projected life of about 1.1 hr. Extending the GG’s operating life for longer durations or for reusable applications like the shuttle APUs will require significant catalyst life improvement for the GG design. Leveraging from this GG effort, Honeywell, under their internally funded research development, recently explored modifications to the GG and has demonstrated a significant increase in the GG catalyst operating life. With modifications to the GG, the catalyst operating life is projected to have 17 to 90 times the original catalytic GG life. The GG effort was led by the NASA Glenn Research Center, with a Lockheed Martin Space Systems Company prime contract and a subcontract with Honeywell for nondissipative charge control for the GG development, integration, and testing.
Find out more about Exploration Systems research at Glenn: http://exploration.grc.nasa.gov
Glenn contacts:
Nang Pham, 216-433-6165, Nang.T.Pham@nasa.gov
Clint Ensworth, 216-433-6297, Clinton.B.Ensworth@nasa.gov
Scott Graham, 216-977-7123, Scott.R.Graham@nasa.gov
Authors:
Nang T. Pham and Clinton B. Ensworth
Headquarters program office:
Exploration Systems Mission Directorate
Programs/projects:
Exploration Systems Research and Technology
Last updated: December 14, 2007
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