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Cool solution for CO2 refrigeration


2019-09-08

The new system is being hailed as being of particular importance for use in hot climates where CO2 refrigeration systems have traditionally performed poorly.

Adelaide-based company Glaciem Cooling Technologies is now on a commercialisation pathway with the system and plans to target the Middle East market.

Natural refrigerants such as CO2 (R744) have become more common in recent years as traditional synthetic refrigerants are phased out due to their harmful environmental impact.

Previous CO2 systems in hot climates use cascade systems, which is basically another refrigeration system operating in series with the CO2 system. These systems are efficient but the secondary refrigeration unit still contains a synthetic refrigerant.

Glaciem Cooling Technologies in conjunction with researchers from the University of South Australia have developed a unit that uses dew point technology to pre-cool air before it enters the refrigeration system’s condenser.

The system also has a thermal energy storage component that can store excess electricity from sources such as solar PV. The -6C Phase Change Material (PCM) storage system can then release the thermal energy as cold air to run the refrigeration system when electricity prices are high.

The dew-point cooling component is provided by fellow South Australian refrigeration company Seeley International, whose patented Climate Wizard indirect evaporative technology is among the most efficient in the world.

The air-cooled CO2 refrigeration system has been operating at The Bend Motorsport Park, about 100km southeast of the South Australian capital Adelaide for about 15 months, providing UniSA and Glaciem with more than a year’s worth of clean data in a commercial setting.

The first commercial freezer and cold room is servicing The Bend’s main restaurant and has a 23kWr capacity with 100kWh of thermal energy storage (TES).

Lead researcher Professor Frank Bruno said testing showed the R744-only system had operated efficiently over the past 12 months, including on a day in January when the ambient temperature at the track reached 47.5C and many conventional refrigeration systems around the state failed.

Glaciem’s commercial trial unit at The Bend Motorsport Park in South Australia uses a dew point cooler to pre-cool air before it enters the condenser.

Glaciem is a senior industry partner with UniSA and has its offices imbedded at the university’s Mawson Lakes Campus.

“Every day we’ve got our researchers working with people from the company and vice versa and this outcome would not have been achieved without the close collaboration that we have,” Professor Bruno said.

“CO2 is an efficient refrigerant but it is not efficient when ambient temperatures go above 25C so what we’ve done is we’ve been able to keep the ambient conditions around the condenser below 25C.

“We’re actually trying to get the message out there about CO2 refrigeration because the conventional HFC systems are being phased out due to the damaging effect they have on the environment whereas CO2 is an environmentally friendly refrigerant.”

The new refrigeration system was a finalist last week for the ANSTO Eureka Prize for Innovative Use of Technology, Australia’s top science awards.

Professor Bruno previously won a Eureka Prize for his low cost thermal energy storage invention, said Glaciem.