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Ideal expansion in heat engine?

Ideal expansion in heat engine?

Ideal expansion in heat engine?

(OP)
I am considering using an a/c rotary vane compressor as an expander in a solar generating project. The working fluid is R134a refrigerant. From volume measurements I've determined it takes a 12cc space to a 36cc space before dumping, or 1:3. From what I've heard it should be more like 1:9. I've considered using a smaller and larger unit in a compound configuration or installing a cutoff device at the inlet. My questions are:
1) What is the ideal expansion ratio for efficiency regardless of resulting power/speed output?

2) What is the correct sizing steps for double and triple compound expansion?

3) Does throttling behave in any way like the results from a admission percentage cutoff device?

Thanks

RE: Ideal expansion in heat engine?

Expansion is limited by thermodynamic characteristics of the working media (gas making work)and ambient conditions where it is exhausted to. In other words the exhaust total pressure (dynamic + static) has to be larger than surrounding ambient pressure.

Thus it would be nice to have expansion 1:9 but you have to provide sufficient compression first.

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