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IdleMind · 11-17-16, 02:21 PM

I'm glad you posted your project, I am especially interested in why you choose that compressor. Was it for longevity, efficiency, availability? I have some opinions about compressor efficiency and thought I would post them here for anyone to challenge.

I believe for low cost small displacements reciprocating piston compressors like the one you are using are more efficient than low cost rotary compressors. The oscillating piston in a rotary compressor has possible leak paths at both ends, on the OD where it contacts the chamber wall as well as where it contacts the vane. It could also leak around the vane. The reciprocating piston compressor can only leak at the piston OD. In larger rotary compressors I believe the total length of potential leak paths Vs the displacement volume becomes more favorable. I speculate that is why reciprocating compressors are used in refrigerators and rotary compressors are used in larger AC's. In fact I think the only advantage of rotary compressors is cost and possible less vibration.

Another difference is in a reciprocating compressor the cool low pressure inlet gas enters and fills the housing, in a rotary compressor the inlet gas goes directly to the pump and the housing is filled with the high pressure hot outlet gas.

I am working on small hot water heat pumps and am trying to determine if one type is more efficient, so far I have not been able to convince myself either way.

11-17-16, 02:21 PM	#3
IdleMind Helper EcoRenovator Join Date: May 2016 Location: SE Wisconsin Posts: 55 Thanks: 3 Thanked 14 Times in 10 Posts	I'm glad you posted your project, I am especially interested in why you choose that compressor. Was it for longevity, efficiency, availability? I have some opinions about compressor efficiency and thought I would post them here for anyone to challenge. I believe for low cost small displacements reciprocating piston compressors like the one you are using are more efficient than low cost rotary compressors. The oscillating piston in a rotary compressor has possible leak paths at both ends, on the OD where it contacts the chamber wall as well as where it contacts the vane. It could also leak around the vane. The reciprocating piston compressor can only leak at the piston OD. In larger rotary compressors I believe the total length of potential leak paths Vs the displacement volume becomes more favorable. I speculate that is why reciprocating compressors are used in refrigerators and rotary compressors are used in larger AC's. In fact I think the only advantage of rotary compressors is cost and possible less vibration. Another difference is in a reciprocating compressor the cool low pressure inlet gas enters and fills the housing, in a rotary compressor the inlet gas goes directly to the pump and the housing is filled with the high pressure hot outlet gas. I am working on small hot water heat pumps and am trying to determine if one type is more efficient, so far I have not been able to convince myself either way.