Nitinol Heat Engines
Thermally-related shape memory properties of certain Nickel-Titanium alloys were first observed at the Naval Ordnance Laboratory in the early 1960’s, and their application to thermomechanical energy conversion systems recognized.(1) The first successful application of these materials to a continuously operating heat engine was demosrated at the Lawrence Berkeley Laboratory in August 1973.(2) Since that time parallel programs in materials study, thermodynamic analysis, prototype concepts and design of Ni-Ti heat engines have been initiated at LBL principally under a grant from the National Science Foundation/RANN. As the specific mechanisms of the Ni-Ti phase transformation and the thermodynamic analysis of its energy conversion effeciency will be presented in detail elsewhere, this paper will deal with practical aspects of the use of the shape-memory material in low-temperature heat engines, and their application to energy conversion.
KeywordsShape Memory Effect Heat Engine Shape Recovery Wire Loop Linear Tension
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Footnotes and References
- 1.U. S. Patent No. 3,403, 238; Conversion of Heat Energy to Mechanical Energy, W. J. Buehler et al., assignors to the United States of America.Google Scholar
- 2.Proposal for Application of Solid State Energy Conversion to Cooling of Buildings, Lawrence Berkeley Laboratory, Energy and Environment Division, submitted to the National Science Foundation (RANN), Nov. 1973. NSF Grant AG-550, Proposal No. P416452.Google Scholar
- 3.H. Tabor and L. Bronicki, “Small Turbine for Solar Energy Power Package”; Proceedings of the United Nations Conference on New Sources of Energy; Rome, Italy; Vol. IV pp. 68–79; 1961.Google Scholar
- 4.H. Tabor, private communication to the author, Feb. 1974.Google Scholar
- 5.“55 Nitinol”is the generic name given to the nominally equiatomic Nickel-Titanium intermetallic compounds (~55% Ni, balance Ti by weight) exhibiting the shape memory effect. The name is derived from Nickel, Titanium and Naval Ordnance Laboratory (Silver Spring, Maryland) where the memory effect was first observed.Google Scholar
- 6.R. Banks, experiment in progress, April 1975.Google Scholar