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Stirling engine

Ce site appartient au réseau de sites relatifs aux moteurs à air chaud ou moteurs à apport de chaleur externe

Stirling engine
Alpha model

The alpha engine dissociates in a clear way the hot source of the cold source. Indeed, a cylinder heats gas, another cools it. The kinematics is such as one makes pass gas of a cylinder to the other. See below succinct study of this type of engine.

1. The four basic stages :

Compared to the ideal cycle described in the page "The principles", the different phases of the cycle of an alpha engine are less differentiated. However, the following drawings seek to represent them.

1.1. Heating :

Heating Heating Heating

The gas arrives in the hot cylinder coming from the cold cylinder. it is heated.

1.2. Expansion :

Expansion Expansion Expansion

The two pistons descend. Total volume increases : it is the phase of relaxation.

1.3. Cooling :

Cooling Cooling Cooling

The gas goes towards the cold cylinder from the hot cylinder. During this phase, it is cooled.

1.4. Compression :

 Compression  Compression  Compression

The two pistons go up at the same time. Total volume decreases: it is the phase of compression.

The following animation shows the complete cycle of a alpha engine.

Animation of the complete cycle of a alpha engine

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2. The PV diagram :

2.1. The volume variations :

Volume variations

2.2. The PV diagram :

PV diagram

This diagram is characteristic of the engine described above.
The calculations were made with TM = 2 Tm.
The theoretical efficiency would be 0.5.
One can see that this cycle is clearly different from the theoretical cycle.
The important thing is to have the gray area as large as possible. It is representative of the work recovered during a cycle (see the page ."the principles").

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This site was created and is maintained by Pierre Gras. Thank you with all the people who contributed their shares: articles, photographs, videos, worksheets. The author is opened with any suggestion allowing to improve this site for happiness of everybody. Finally, a big thank you to Robert Stirling !

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