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Evolution of the Stirling Cycle: Emphasis on Reliability, Durability, and Long-term Unattended Operation

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2012 ASEE Annual Conference & Exposition


San Antonio, Texas

Publication Date

June 10, 2012

Start Date

June 10, 2012

End Date

June 13, 2012



Conference Session

Engineering Technology Curriculum Issues

Tagged Division

Engineering Technology

Page Count


Page Numbers

25.593.1 - 25.593.13



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Paper Authors


Phillip R. Foster University of North Texas

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Phillip Foster is Associate Professor of engineering technology at the University of North Texas. He is Program Coordinator for the Mechanical and Manufacturing Engineering Technology programs in the department.

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Evolution of the Stirling Cycle: Emphasis on Reliability, Durability, and Long Term Unattended OperationThe Stirling cycle is characterized by high efficiency coupled with the ability to effectivelyfunction on a range of heat sources. Included are industrial process waste heat, biomass,geothermal heat, and conventional combustion. Some of these sources are considered to beenvironmentally friendly and have, therefore, interested researchers in the pursuit of pollutionfree or near pollution free electrical power generation. Drawbacks to the cycle include a highlevel of mechanism complexity which can impact reliability and durability. Further, the cycledemonstrates a relatively low power output per engine size when compared with that of otherprime movers. Contemporary Stirling engine classification, Alpha, Beta or Gamma, is based onthe physical layout of displacer and power cylinders with respect to a crankshaft.This report concerns a contemporary development of the Stirling cycle heat engine in whichreliability, durability, and long term unattended operation are key objectives. To meet theseobjectives, the engine design focused on several factors which included: minimizing the numberof moving parts, particularly reciprocating parts; incorporating materials not typicallyencountered in Stirling technology; use of liquid cooling; and, utilizing helium as the workingfluid. The initial design parameters, e.g., phase angle, volume compression ratio, etc., weretaken from those applicable to Gamma type engines. The literature suggests that Gammaengines represent state-of-the-art in the technology. Design efforts resulted in a workingprototype with three moving parts per power cylinder. Included are a rotary displacer, a powerpiston and a connecting rod. Operation of the prototype demonstrated that Gamma designparameters were less than ideal for the new engine. This report summarizes the design elementsof a new classification of Stirling engine and presents the results of optimization work to date. A.jpg showing the engine (patent pending) with the rotary displacer housing open is attached.

Foster, P. R. (2012, June), Evolution of the Stirling Cycle: Emphasis on Reliability, Durability, and Long-term Unattended Operation Paper presented at 2012 ASEE Annual Conference & Exposition, San Antonio, Texas. 10.18260/1-2--21350

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