Dissertation
A novel MEMS-based micro heat engine and operating cycle
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2008
DOI:
https://doi.org/10.7273/000005865
Abstract
This dissertation presents operating characteristics of a MEMS-based micro heat engine. The engine is shown to operate in two distinct modes. First, at sub-resonant frequencies, then at resonant frequencies. Each operating mode is shown to have distinct thermodynamic characteristics. Integration of a thermal switch is shown as an effective means to introduce heat or reject heat from the micro-engine. The engine is shown to operate from a constant temperature heat source via thermal switch operation. Additionally, use of the thermal switch to reject heat from the micro-engine results in the ability to increase operating speeds. This enables high frequency sub-resonant operation (beyond 100 Hz) and operation at resonant frequency. To improve micro-engine performance and power output at sub-resonant frequencies, several designs are considered. These include micro-engines constructed with both 25 mm2 and 100 mm2 top membranes. Maximum power output is 2.6 mW using a micro-engine constructed with a 100 mm2, 2 m thick silicon top membrane and evaporator membrane with 40 m high, SU-8 based fluid wicking structures. The maximum efficiency obtained is .15 % using a 25 mm2, 300 nm thick silicon-nitride top membrane and evaporator membrane with 10 m high, SU-8 based fluid wicking structures. Increasing operating speed to the micro-engine resonant frequency is shown to produce cycle work. The micro-engine produces up to 6.7 W of cyclic mechanical power when operating at a resonant frequency of 125 Hz.
Metrics
7 File views/ downloads
29 Record Views
Details
- Title
- A novel MEMS-based micro heat engine and operating cycle
- Creators
- Leland W. Weiss
- Contributors
- Robert Foster Richards (Chair)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Mechanical and Materials Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 219
- Identifiers
- 99901055138901842
- Language
- English
- Resource Type
- Dissertation