MIT Libraries homeMIT Libraries logoDSpace@MIT

MIT
View Item 
  • DSpace@MIT Home
  • MIT Open Access Articles
  • MIT Open Access Articles
  • View Item
  • DSpace@MIT Home
  • MIT Open Access Articles
  • MIT Open Access Articles
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Sharp Phase Change in Shape Memory Alloy Thermal Actuators for Subsea Flow Control

Author(s)
Gilbertson, Eric W.; Freeman, Bryan; Hover, Franz S.
Thumbnail
DownloadHover_Sharp phase.pdf (508.2Kb)
OPEN_ACCESS_POLICY

Open Access Policy

Creative Commons Attribution-Noncommercial-Share Alike

Terms of use
Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/
Metadata
Show full item record
Abstract
Gas-lifted oil wells are susceptible to failure through malfunction of gas lift valves (GLV). One failure mode occurs when the GLV check valve fails and product passes into the well annulus, potentially reaching the wellhead. This is a growing concern as offshore wells are drilled thousands of meters below the ocean floor in extreme temperature and pressure conditions and repair and monitoring become difficult. The authors have previously developed a thermally-actuated safety valve to prevent product backflow into the annulus in the event of check valve failure. The safety valve uses shape memory alloy (SMA) wires to translate a temperature change into a displacement and, based on commercially available SMA wire material properties, requires a 6°C temperature change to fully actuate. In some wells, however, check valve failure may result in less than 6°C temperature change. In this paper a new concept is developed to sharpen the austenitic phase change in SMA actuators. The concept has broad practical implications because it will allow thermally-activated devices, such as fluid control valves, to become much more precise, i.e., translating a small temperature change into a large displacement. The new concept uses the fact that SMA transition temperatures are stress dependent. By specifically controlling stress in the wire, the temperature difference required for austenitic transition can be decreased. This is achieved with a negative-differential spring — a spring that exerts a decreasing amount of force as it is displaced. The concept is tested experimentally by conductively and electrically heating SMA wires connected to a negative-differential spring. Results show a 2.9°C-5°C reductions, respectively, in the temperature difference required for austenitic transition.
Date issued
2012-07
URI
http://hdl.handle.net/1721.1/97475
Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Journal
Proceedings of the ASME 2012 31st International Converence on Ocean, Offshore and Arctic Engineering
Publisher
American Society of Mechanical Engineers
Citation
Gilbertson, Eric, Franz Hover, and Bryan Freeman. “Sharp Phase Change in Shape Memory Alloy Thermal Actuators for Subsea Flow Control.” ASME 2012 31st International Converence on Ocean, Offshore and Arctic Engineering. Volume 6: Materials Technology; Polar and Arctic Sciences and Technology; Petroleum Technology Symposium (July 1, 2012).
Version: Author's final manuscript
ISBN
978-0-7918-4493-9

Collections
  • MIT Open Access Articles

Browse

All of DSpaceCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

My Account

Login

Statistics

OA StatisticsStatistics by CountryStatistics by Department
MIT Libraries homeMIT Libraries logo

Find us on

Twitter Facebook Instagram YouTube RSS

MIT Libraries navigation

SearchHours & locationsBorrow & requestResearch supportAbout us
PrivacyPermissionsAccessibility
MIT
Massachusetts Institute of Technology
Content created by the MIT Libraries, CC BY-NC unless otherwise noted. Notify us about copyright concerns.