Voorhees
Voorhees refrigeration cycle
G.T. Voorhees was an American inventor who had proposed a modified reciprocating compressor for CO2 systems.
A “suction port” placed in the cylinder near the lower dead center of piston allowed a certain flow rate of vapor to be sucked in by drawing from an intermediate pressure, generally the receiver/separator.
A significant increase in flow rate, and therefore in cooling capacity, could be obtained, as well as a slight increase in efficiency, at least according to the texts of the time (e.g. prof. Ostertag).
I had the opportunity to test a compressor of this type, a prototype derived from the modification of a production compressor, some years ago and we noticed that the performance was higher than theoretical estimate. We measured about 10-15% higher EER (Energy Efficiency Ratio) than the standard cycle, as well as about 20% higher capacity.
The disadvantage was rather the difficulty of connecting two or more compressors of this type in parallel, because there was generally a pressure leakage when one of the compressors was stopped.
However, such a system could be cost-effective with a single-compressor system. I remembered this fact after seeing an article by a team of Italian researchers in a scientific journal. These researchers, from the University of Tor Vergata (Rome) proposed to inject vapor from the intermediate pressure through electric valves. I think it is difficult, but the “rediscovery” of the method gives hope for a revisiting this technology and a future industrial use of this method.