MDA/Compressed Air-Compressors: Miniature Low-Vibration High-Pressure Air Compressor

Chicago, Illinois - The problem of supplying compressed air at miniature scale with minimal vibration becomes more important in medical, defense and other applications where vibration is not acceptable. However, state-of-the-art miniature rotary compressors cannot achieve pressures over 10-20 psig, and piston compressors are the common solution for pressures from 10-150 psi. The downside of piston compressors is associated noise and vibration due to reciprocating motion. To overcome these problems, engineers use rubber damping and enclosures with thick walls that add mass and cost. A high-pressure rotary compressor operating with minimal vibrations would be a preferred solution.

Vert Rotors based in Edinburgh, Scotland, has developed and tested a novel miniature rotary compressor with two conical screw rotors, an Inner rotor revolving inside the Outer rotor. In comparison, conventional twin-screw compressors consist of three elements, two screws revolving side-by-side inside the housing.
In tests the Vert’s miniature rotary compressor achieves a maximum pressure ratio of up to 16:1 without lubrication (dry). Design pressure ratio of this machine is 3:1 to 5:1 (40-70 psig) depending on the required length of continuous operation.

This compressor was developed for cryocooling in “nano”-satellites under a contract with UK Ministry of Defense in 2015. The purpose of the project was to demonstrate a feasibility of low-vibration refrigeration system for optical sensors that are very sensitive to vibration. Very soon after that commercial customers started showing a great degree of interest as well. 
Perhaps the most important difference between the Vert’s conical compressor and conventional twin-screw compressors is that, within the Vert’s compressor, the Inner rotor uses the full volume inside the Outer rotors, therefore the CRC does not have a “blowhole”. The “blowhole” is a typical feature of twin-screw compressors and is a leakage path from the high-pressure side to the low-pressure side. Vert’s compressor, not having a “blowhole”, runs at a higher volumetric efficiency. 

Back-to-back tests of larger 3kW lubricated modifications confirm that Vert’s conical compressor has a 20% better volumetric efficiency than a twin-screw compressor with a similar flow rate.

About the speaker
Olly Dmitriev is a Member of American Society of Mechanical Engineers and CEO if Vert Rotors, the producers of low-vibration & high-pressure conical compressors from Edinburgh, Scotland. Olly moved to Edinburgh from Moscow, Russia in 2012 and started Vert Rotors in 2013. He and his team developed the novel conical compressor and started selling to customers in the aerospace, defense and medical industries. Olly is an author of multiple patents and publications on the conical technology.

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