Ionic liquids in combination with CO2: promising technology?

A group of scientists at the University of Notre Dame, Indiana, USA, are now working on utilizing novel ionic liquids – pure salts that are liquid at ambient temperatures – in tandem with CO2.
A group of scientists at the University of Notre Dame, Indiana, USA, are now working on utilizing novel ionic liquids – pure salts that are liquid at ambient temperatures – in tandem with CO2.

According to the group, CO2 in combination with custom ionic liquid is deployed inside the “co-fluid vapour compression cycle” using a conventional heat exchanger and expansion valve but with a specially designed compressor. It is here where the “wet compression” takes place, creating a chemical reaction between the CO2 and ionic fluid.

The resulting system is said to be hugely energy efficient and lowers the pressures associated with CO2 so there is no need to go transcritical. Potential COPs of up to 4.5 are theoretically possible for the new system, which could have applications across the air conditioning and refrigeration spectrum.

Crucial to the technology’s success is the selection and production of proprietary ionic liquids. Materials compatibility and toxicity tests have not found any problems so far and choice of lubricant may not be a problem – the ionic liquids might also be capable of performing that task.

A start-up company – Ionic Research Technologies – has been created to commercialize the technology; the group is working with two other partners in its development. Market tests are scheduled for next year with expected commercialization in early 2015.