High pressure air compression/expansion
The high-pressure compression/expansion of air is performed in HyPES systems by a reciprocating compressor/expander module based on an innovative “Liquid Piston” concept. This technology results from more than 10 years of strong R&D collaboration with our academic partners from the University of Applied Sciences of Yverdon-les-Bains (HEIG-VD), Switzerland, and some industrial partners.
In this concept uses water as heat/cold carrier and as “liquid piston” in dedicated compression/expansion chambers with integrated heat exchangers, to compress the air while cooling it simultaneously during the storage process, and to expand the air while heating it simultaneously during the discharge process as illustrated below. The resulting “near-isothermal” compression/expansion processes allow achieving high pressure under high conversion efficiency.
This video presents a 2-stage Demonstrator built by students of the Swiss Federal Institute of Technology Lausanne (EPFL) to demonstrate the operating principle of “Liquid-piston” compression/expansion concept implemented in HyPES systems.
The water in the demonstrator was expressly coloured in blue so that its movements are easily visible. It can be noted that the air temperature remains almost constant throughout the compression/expansion processes.
Thanks to its near isothermal processes a “Liquid Piston” compressor will consume far less energy than a “Mechanical Piston” compressor of same capacity and discharge pressure.