Stirling engine
A Stirling engine, named after Robert Stirling, clergyman and inventor of what he called an "air engine", is a type of engine that creates a time-phase relationship between hot and cold temperatures to move a piston, that is harnessed to provide power. Patented in 1816, Stirling's engines couldn't explode (unlike steam engines) and produced more power than the steam engines of the time.
Stirling engines are also used as a fast cooling device, using a motor to move the piston making the engine very cold.
From a new (1998) patent by John Kerwin, Dean Kamen, and others:
- A Stirling machine having two pistons coupled to a harmonic crank drive linkage for providing a specified phase relationship between sinusoidal displacements of each piston with respect to a fixed fiducial point. The harmonic crank drive linkage has a primary crankshaft and an eccentric crankshaft mounted internally to the primary crankshaft and coupled via a gear set to counterrotate with respect to the primary crankshaft. The eccentric crankshaft may be cantilevered with respect to the primary shaft, with the pistons of the engine coupled to the eccentric crankshaft externally to the supporting bearings. A flywheel coupled to the eccentric crankshaft provides for operation of the engine with a zero net angular momentum. [Zero net angular momentum would be very handy for a vehicle that had to balance on two wheels. It also is a good way to reduce vibration and make the engine easier to control.-bhv] An intake manifold provides for mixing air and fuel for combustion heating of the engine.
Stirling Engine Types
Stirling Engines come in three distinct types:
- An Alpha Stirling contains two separate power pistons, one "hot" piston and one "cold" piston. The hot piston is situated after the higher temperature heat exchanger and the cold piston is situated after the low temperature heat exchanger. This type of engine has a very high power to volume ratio but has technical problems due to the (often) high temperature of the "hot" piston and its seals.
- A Beta Stirling has a single power piston arranged coaxially with a displacer piston. The displacer piston does not extract any power from the expanding gas but only serves to shuttle the working fluid from the hot heat exchanger to the cold heat exchanger. This engine does not require moving seals in the hot portion of the engine and can achieve high compression ratios due to pistons being able to overlap in their motions.
- A Gamma Stirling is simply a Beta Stirling in which the Power piston is not mounted coaxially to it's displacer piston. This configuration produces a lower compression ratio but is often mechanically simpler and often used in multi cylinder stirling engines.
External links
Indexes
How it works
- How Stuff Works: Stirling-engine
- University of Canterbury: An introduction to Stirling-cycle machines (PDF), Stirling-Cycle Research Group
- About The Stirling Heat Engine
- (Good information to builders:) Why Aviation Needs the Stirling Engine by Darryl Phillips, main address, mirror Quote: "...This 4-part series appeared in the March 1993 through March 1994 issues of Stirling Machine World...Common four cylinder engines such as Lycoming and Continental show torque that varies from a negative 100% to a positive 350% of the nominal torque...A Stirling with the same number of cylinders and identical horsepower has a torque variation of +/- 5%!..."
- Stirling fly motor animation
- Israel Urieli: Stirling Engine Simple Analysis, main address, Alpha Stirlings, Beta Stirlings, Gamma Stirlings
- Peter Fette: Stirling Engine Research and Computer (simulation) Programm Development, animation, prozess, mirror
- Quote: "...One possibility of equalizing the regenerators loss in double acting engines is to design it as a counterflow heatexchanger as described in [1]..."
- Quote: "...This Stirling Engine with 8 cylinders is twice double acting. Its special highlight is the facility for the heat transfer from a liquid [eg. water] to the working fluid [eg. air] which results in extremely low temperature losses....Because of the nearly isothermalized heat transfer the efficiency is near carnot's ..."
- Amitabha Mukerjee: Stirling Engine, usage, How does it work? Quote: "...As a final note a solar powered stirling engine coupled with a generator achieved a record solar-to-electric efficiency of 30%!..."
Information media
Do-It-Yourself model Stirling/Hot-Air maskiner
Applications
Referenced By
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