Date : Wednesday, January 16, 2002
Time : 4:30 PM
Location: Willet Science Center Room 109
Professor Randall Peters
Department of Physics
"Thermomechanics of the Stirling Engine"
Abstract: Although it has been around since the ingenious work of the Rev. Robert Stirling in 1816, it is only in recent years that the Stirling engine is receiving attention, for some applications, as a serious competitor with the internal combustion engine. With energy crises ever more probable in the future, alternative fuels are an important consideration--as evidenced in the recent announcement, by the Bush Administration, of a federal initiative involving fuel cells. Two factors make the Stirling engine important in this regard: (i) as an external combustion type, it can operate with virtually any fuel, and (ii) its efficiency exceeds that of other engines. Even though the first theoretical treatment of the Stirling engine was done by Rankine many years ago, and in spite of thousands of internet sites devoted to the engine; it appears that a recent paper by Peters* is the first occasion for a synergetic model of both flywheel mechanics and system thermodynamics. This combination of mechanics and thermo is rich in physics pedagogy, especially because of (i) symmetry breaking by the thermal gradient between hot and cold reservoirs; and (ii) the simple, yet nonlinear equation of motion for the flywheel. These fascinating properties were recognized, following the instrumentation of a Low-Delta T demonstration engine with two symmetric differential capacitive (SDC) sensors patented by Peters--one to measure pressure inside the cylinder, and the other to simultaneously measure the position of the power piston. In the seminar, a brief history of existing Stirling technologies will be presented--including the recently developed acoustic Stirling engine of Los Alamos, which has received international acclaim. Then it will be shown, incredibly to most, that the Low-Delta T engine can run by the heat from one's hand. Finally, and for the more technical members of the audience, there will be some discussion of the thermomechanics model.
* "The Stirling Engine-Refrigerator: Rich Pedagogy from Applied Physics" (archived in the Los Alamos National Laboratory at http://xxx.lanl.gov/html/physics/0112061)