A gamma Stirling engine is most like a beta Stirling engine in which the power piston is mounted in a separate cylinder beside the displacer piston cylinder, but is still connected to the same flywheel. The gas in the two cylinders can run freely between them and remains in a single body. This configuration generates a lower compression ratio but is mechanically simpler and often used in multi-cylinder Stirling engines.
Alternator Processing Cycle.
An alternator is an electrical generator that
alters mechanical energy to electrical energy
in the form of alternating current. An alternator
does not contain permanent magnets. Rather,
there are two concentric wound coils of wire within the alternator, a stator coil (the outer coil which does not rotate) and a rotor coil (the inner coil, attached to the alternator’s pulley, which rotates). The rotor is also mentioned as the alternator’s “field.”
An electromagnet is generated when current flows through the field coil.
Since the magnetic field moves backward and forward through the stator coil, an alternating current is produced. The alternating current has a frequency with which the alternator’s pulley is rotating.
For alternator to start, the alternator’s field must initiate with some kind of current. Rotating the rotor coil itself does produce absolutely nothing, unless there is current flowing through the rotor coil, producing a magnetic field. Thus, it is necessary to have the alternator hooked up to a battery to provide this initial current.Once the alternator is able to produce electricity, it is self-sustaining.
The output voltage of the alternator depends on two variables, the amount of current flowing through the field coil and the speed at which the alternator’s field is rotating. The alternator has a regulator that tries to maintain the terminal voltage at a steady 14.4V (the optimal voltage to recharge 12V). It does this by regulating the amount of current flowing in the field coil. Once the alternator is self-sustaining, the only current flowing to the field coils begins from the alternator itself. If the output voltages are too high, the regulator lowers the current flowing to the field coil. If the output voltage is too low, the regulator rises the current flowing to the field coil. As long as the alternator can maintain at least 14.4V across its terminals, making the pulley spin faster or slower will have absolutely no effect on the power output. Power output in such cases rests on only the load attached to the alternator. Connection Diagram of alternator is shown is figure
Vanguard 25-kW System Through Stirling Engine
Advanco Corporation (now defunct), building on the work done at the Jet Propulsion Laboratory (JPL) made the 25-kWe Vanguard dish/Stirling system in 1984. It created the highest recorded net conversion of sunlight into electricity, 29.4%. The complete system is installed at Rancho Mirage, California.
The Vanguard concentrator is approximately 11 m
(36 feet) in diameter and is made up of 336 mirror
facets placed on a truss structure each facet measures
45 by 60 cm (18 by 24 in.). The facets are fashioned of
foamglass with glass backsurface mirrors bonded to them. The mirrors are mechanically bent into a shallow round curvature. On the Vanguard concentrator of two different curvatures are used. Tracking is done by an advanced exocentric gimbal mechanism that has less torque requirements and results into rapid emergency detracking. The United Stirling AB (USAB) Model 4-95 Mark II engine installed in this system is a four cylinder Stirling engine that contains displacement of 95 cm 3 (5.8 in 3) per cylinder. The working gas used is hydrogen and temperature is 720’C. Engine power is controlled by changing the pressure of the working gas. A viable 480-VAC, 60-Hz alternator is coupled to the output shaft.