Automotive Can I have a multi-stage reciprocating compressor?

[royp]

TL;DR Summary

This is an enquiry about a multi-stage, reciprocating air compressor.

Hello,

This is an enquiry about a multi-stage, reciprocating air compressor. Imagine, there are 6 piston-cylinder-pair combination (numbered (P1, C1)...to (P6, C6) from the left); adjacent to each other. The arrangement is very similar to a 6-Cylinder internal combustion engine. Now, the pistons are moving in such a way that every alternate pistons are in sync. (and every adjacent pair of pistons are having a phase difference.) For instance, when piston P1 is pushing in, piston P2 is pulling out as they are out of phase and the compressed air from P1 will enter into P2 - (through the valve door) and so on.

My question is : with this arrangement, are we getting more compressed air at each successive stages in cylinders C1, C2, ..., C6?

Thanks in advance for your clarifications.

 

[Averagesupernova]

Two stage air compressors are common. On two cylinder two stage compressors that I have seen, one piston is always larger than the other.
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https://www.google.com/search?sourc...1j0j1...0...1..gws-wiz...0..0i131.eNsoaOAi18g-
I imagine the hits from the above link will provide you with a lot of good information.

 

[cjl]

The way you've described it, it won't increase compression in each subsequent stage. You need to be reducing volume with each step, so as AverageSupernova said, you'd need the second stage to be smaller than the first. Another option would be to have multiple cylinders acting as the first stage reducing down to a single cylinder for the second stage. Regardless though, the important factor is that the volumetric flow rate is reduced from each stage to the next as the pressure rises.

 

[royp]

Averagesupernova, Cjl: Thank you both very much. So, with my improved understanding: If I want to achieve more compression, I need to make each successive stage smaller (in volume) than the previous one. The actual quantity (reduction) will be determined by gas laws etc. Am I correct?

 

[Baluncore]

The highest efficiency compound steam piston engines employed triple pressure reduction. Using compound compressors is also more efficient. One benefit is that an inter-cooler can be used. Another benefit is that the maximum pressure is not limited by the compression ratio of a single cylinder.

I expect you should consider a three phase pump so as to generate a continuous flow. For a compound pump that would require 6 cylinders with two different bore sizes. Only one medium pressure inter-cooler would be needed in the flow from the low pressure to the high pressure cylinder bank.

 

[royp]

Thanks, Baluncore.

 

[Dr.D]

To see the process in reverse, look on the net for a triple expansion steam engine. For such a machine, the same steam is expanded through three stageds.

 

[royp]

Many thanks for indicating a clever idea, Dr. D. Excellent brainstorming!