"The technology behind the REC has a simple concept yet so innovative and powerful. The REC is an active heat exchanger which transforms a part of the heat to pressure pulses of a desired frequency. These can be used different ways to generate work (connecting to a piston engine, a turbine, a pump, an electricity generator…).
In thermodynamic terms, the REC acts as “a closed system with a moving boundary” that transforms an existing given temperature difference into kinetic energy which can connect to an electric generator."
More: https://www.nilsinside.com/nilsinside/Technology-EN.html
