Transcritical CO2 start-ups are straightforward if pre-installation steps are taken, says Andreas Meier of the German OEM.

“Starting with CO2 [R744] is no problem at all if you pay attention to certain aspects,” said Andreas Meier, Managing Director of German natural refrigerant OEM Teko.

Meier outlined a number of factors companies should consider prior to installing CO2 racks to ensure an easier start-up during a webinar on March 30 at the ATMO Virtual Trade Show (VTS) 2021 for natural refrigerant technologies. (ATMO VTS 2021 was organized by shecco, the publisher of this website.)

“Proper installation of CO2 is important for the well-being of the building, occupants and sustainability of the project,” noted Meier.

Among the key steps are evaluating the system’s ability to handle CO2’s higher pressures. “Pay attention that you’re dealing with higher pressures because these require new testing processes and need to be tested before the start-up,” he said.

In addition, an HVAC engineer or contractor installing a CO2 rack needs to be aware of the different circuits and piping dimensions the refrigerant uses, as well as availability of parts. “Are spare parts easily available for maintenance purposes or if breakdowns occur? Additionally, what is the availability of the refrigerant and oil in the country?” he asked.  Engineers should also consider how they’ll prevent contamination.

Meier summarized the six basic components of a proper CO2 start-up as:

  • Dimensioning of components
  • A clean system, racks and components
  • Performing pressure tests
  • Conducting a full evacuation before initial start-up
  • Having the correct filling, and
  • Having regular maintenance during operation

Nitrogen bottles with 300bar, hoses, fittings and adapters are also some of the equipment required for a start-up, according to Meier.

Mount safety valves outside

Contractors must also have the correct safety measures in place for high-pressure, medium-pressure, medium- temperature and low-temperature suction lines. “These must be tested to ensure proper working conditions,” he said.

He warned that safety valves must never be mounted inside the building. “All mounting goes outside, always, so that there is no risk of harming the building occupants.”

Unlike other gas installations, a CO2 rack doesn’t have a separate installation for medium-temperature and low- temperature compressors. This should be taken into account during the planning phase of the project. “Keep in mind that medium temperature can run independently; however, low temperature requires medium temperatures because it works as a booster.”

Prior to installation, special attention must also be paid to the following:

  • Ensure all components are sealed during storage and transportation
  • Be careful of humidity and water as they are contamination hazards
  • The building must be completely evacuated
  • All components must be cleaned
  • All vacuum pressures must be below the ambient temperature of the water boiling point

Lastly, he stressed that once the system is up and running, regularly change the filters to prevent contamination. “This must be done after start-up and every time the unit is maintained or serviced.”

Teko offers natural refrigerant solutions for both small and large projects. Meier presented other natural refrigerant options available for chillers at the conference. ATMO VTS 2021 presentations can still be viewed until the end of April on the show platform. To register, click here.

Author Ntsako Khosa