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Heattransmission to the working fluid is done inside of expansion- and compression spaces, not outside as usual within a heater or cooler; therefore there is no heater and cooler dead volume. Heattransfer is done by irrigating the working fluid within the cylinders by -external- heated resp. by -external- cooled working liquid. So the heatexchanger surface grows with expansion space, and renews itself in the compression cylinder.
The engine is twice double acting. 4 working cycles are performed at each revolution. There are unique temperatures before and behind each piston in this engine. Heattransmission losses between hot and cold cylinderwalls do not exist. The very small energy losses are reduced to the area of the pistonrods at the hot cylinders.
2 Regenerators are combined in pairs to be heatexchangers for each other. This leads to smaller regenerator spaces.
Less problems in sealing. There are only 4 piston rod seals in this 8 cylinder engine, sealing the pressurized working liquid -not the working fluid- against the atmospheric pressure.
A compound working fluid can be achieved. If water is the working liquid under the pressurized working gas, the partial pressure of the vapor leads to a significant higher overall pressure during the expansion and to a much better heattransmission to the gas. So increased work output for a given working space is achieved. This is very important for the designed use of this engine with "low temperature" heat sources.
This engine is specially designed for working with heat sources of "low" to "medium" temperatures. D T = 80 to 250 degrees. The engine's heatsource may be:
An electric generator driven by this engine produces electricity (for more than 5 KWatt) at lower specific costs and with a better efficiency than photovoltaic cells will do.
This 4 times (= 2 times double-) acting Stirling engine is able to work as a room refrigerator. By this the one double acting Stirling engine drives the other double acting machine which is switched to a refrigerator. See the chapter Stirling engine drives Stirling refrigerator in the report of the engine.
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