Combustion systems for power-MEMS applications

As part of an effort to develop a micro-scale gas turbine engine for power generation and micro-propulsion applications, this thesis presents the design, fabrication, experimental testing, and modeling of the combustion system. Two fundamentally different combustion systems are presented; an advanced homogenous gas-phase microcombustor and a heterogeneous catalytic microcombustor. An advanced gas-phase microcombustor consisting of a primary and dilution-zone configuration is discussed and compared to a single-zone combustor arrangement. The device was micromachined from silicon using Deep Reactive Ion Etching (DRIE) and aligned fusion wafer bonding. The maximum power density achieved in the 191 mm³ device approached 1400 MW/m³ with hydrogen-air mixtures. Exit gas temperatures in excess of 1600 K and efficiencies over 90% were attained. For the same equivalence ratio and overall efficiency, the dual-zone microcombustor reached power densities nearly double that of the single zone configuration. With more practical hydrocarbon fuels such as propane and ethylene, the device performed poorly due to significantly longer reaction time-scales and inadequate fuel-air mixing achieving maximum power densities of only 150 MW/m³. Unlike large-scale combustors, the performance of the gas-phase microcombustors was more severely limited by heat transfer and chemical kinetics constraints. Using all available gas-phase microcombustor data, an empirically-based design tool was developed, important design trades identified, and recommendations for future designs presented. Surface catalysis was identified as a possible means of obtaining higher power densities with storable hydrocarbon fuels by increasing reaction rates. Microcombustors with a similar

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Spadaccini, Christopher M. (Christopher Michael), 1974-

Advisor dc:contributor.advisor

• Ian A. Waitz.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17813

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17813