Skip to main content
Duke University Libraries
DukeSpace Scholarship by Duke Authors
  • Login
  • Ask
  • Menu
  • Login
  • Ask a Librarian
  • Search & Find
  • Using the Library
  • Research Support
  • Course Support
  • Libraries
  • About
View Item 
  •   DukeSpace
  • Theses and Dissertations
  • Masters Theses
  • View Item
  •   DukeSpace
  • Theses and Dissertations
  • Masters Theses
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

The Design of a Micro-turbogenerator

Thumbnail
View / Download
9.2 Mb
Date
2011
Author
Camacho, Andrew Phillip
Advisor
Protz, Jonathan M
Repository Usage Stats
1,030
views
4,709
downloads
Abstract

The basic scaling laws that govern both turbomachinery and permanent magnet generator power density are presented. It is shown for turbomachinery, that the power density scales indirectly proportional with the characteristic length of the system. For permanent magnet generators, power density is shown to be scale independent at a constant current density, but scale favorably in reality as a result of the scaling laws of heat dissipation.

The challenges that have affected micro-turbogenerators in the past are presented. Two of the most important challenges are the efficiency of micro-turbomachinery and the power transfer capabilities of micro-generators.

The basic operating principles of turbomachinery are developed with emphasis on the different mechanisms of energy transfer and how the ratio of these mechanisms in a turbine design relates to efficiency. Loss models are developed to quantify entropy creation from tip leakage, trailing edge mixing, and viscous boundary layers over the surface of the blades. The total entropy creation is related to lost work and turbine efficiency. An analysis is done to show turbine efficiency and power density as a function of system parameters such as stage count, RPM, reaction, and size. The practice of multi-staging is shown to not be as beneficial at small scales as it is for large scales. Single stage reaction turbines display the best efficiency and power density, but require much higher angular velocities. It is also shown that for any configuration, there exists a peak power density as a result of competing effects between the scaling laws and viscous losses at small sizes.

The operating principles of generators and power electronics are presented as are the scaling laws for both permanent magnet generators and electro-magnetic induction generators. This analysis shows that permanent magnet generators should have higher power densities at small sizes. The basic concepts of permanent magnet operation and magnetic circuits are explained, allowing the estimation of system voltage as a function of design parameters. The relationship between generator voltage, internal resistance, and load power is determined.

Models are presented for planar micro-generators to determine output voltage,internal resistance, electrical losses, and electromagnetic losses as a function of geometry and key design parameters. A 3 phase multi-layer permanent magnet generator operating at 175,000 RPM with an outer diameter of 1 cm is then designed. The device is shown to operate at an efficiency of 64\%. A second device is designed using improved geometries and system parameters and operates at an efficiency of 93%.

Lastly, an ejector driven turbogenerator is designed, built, and tested. A thermodynamic cycle for the system is presented in order to estimate system efficiency as a function of design parameters. The turbo-generator was run at 27,360 RPM and demonstrated a DC power output of 7.5 mW.

Type
Master's thesis
Department
Mechanical Engineering and Materials Science
Subject
Engineering
Energy
efficiency
micro generator
micro heat engine
micro turbine
micro turbogenerator
Permalink
https://hdl.handle.net/10161/3792
Citation
Camacho, Andrew Phillip (2011). The Design of a Micro-turbogenerator. Master's thesis, Duke University. Retrieved from https://hdl.handle.net/10161/3792.
Collections
  • Masters Theses
More Info
Show full item record
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

Rights for Collection: Masters Theses


Works are deposited here by their authors, and represent their research and opinions, not that of Duke University. Some materials and descriptions may include offensive content. More info

Related items

Showing items related by title, author, creator, and subject.

  • Thumbnail

    Assessing cardiac injury in mice with dual energy-microCT, 4D-microCT, and microSPECT imaging after partial heart irradiation. 

    Lee, Chang-Lung; Min, Hooney; Befera, Nicholas; Clark, Darin; Qi, Yi; Das, Shiva; Johnson, G Allan; ... (9 authors) (Int J Radiat Oncol Biol Phys, 2014-03-01)
    PURPOSE: To develop a mouse model of cardiac injury after partial heart irradiation (PHI) and to test whether dual energy (DE)-microCT and 4-dimensional (4D)-microCT can be used to assess cardiac injury after PHI to complement ...
  • Thumbnail

    Stretch-Induced Effects on MicroRNA Expression and Exogenous MicroRNA Delivery in Differentiating Skeletal Myoblasts 

    Rhim, Caroline (2009)
    The research presented here represents a quest to understand and address limitations in the field of skeletal muscle tissue engineering, with hopes to better understand the factors involved in producing viable engineered ...
  • Thumbnail

    Macro to Micro Legacies of Landuse at the Calhoun Critical Zone Observatory 

    Brecheisen, Zachary (2018)
    In this dissertation, human-critical zone (CZ) dynamics are explored at the Calhoun Critical Zone Observatory (CCZO). The 190km2 CCZO is part of a broader landscape in the southeastern US which was subjected to extensive ...

Make Your Work Available Here

How to Deposit

Browse

All of DukeSpaceCommunities & CollectionsAuthorsTitlesTypesBy Issue DateDepartmentsAffiliations of Duke Author(s)SubjectsBy Submit DateThis CollectionAuthorsTitlesTypesBy Issue DateDepartmentsAffiliations of Duke Author(s)SubjectsBy Submit Date

My Account

LoginRegister

Statistics

View Usage Statistics
Duke University Libraries

Contact Us

411 Chapel Drive
Durham, NC 27708
(919) 660-5870
Perkins Library Service Desk

Digital Repositories at Duke

  • Report a problem with the repositories
  • About digital repositories at Duke
  • Accessibility Policy
  • Deaccession and DMCA Takedown Policy

TwitterFacebookYouTubeFlickrInstagramBlogs

Sign Up for Our Newsletter
  • Re-use & Attribution / Privacy
  • Harmful Language Statement
  • Support the Libraries
Duke University