• CO2 Transcritical Booster Rack System
  • CO2 Transcritical Booster Rack System

CO2 Transcritical Booster Rack System


This system has a refrigerant cycle that partially operates above the critical point of CO2 and uses refrigeration cycles such as two stage expansion.  Unlike cascade systems, this system uses only single CO2 refrigerant. It is used to refrigerate merchandisers and walk-in coolers/freezers operating in both transcritical and subcritical modes depending of ambient temperatures. This global design is completely HFC-free, has a smaller footprint while also providing excellent energy efficiency.


  • Improved life cycle cost advantage

  • Reduces or eliminates refrigerant charge

  • Environmentally safe, 100% HFC single refrigerant system

  • Significantly faster pull down times when compared to traditional HFC systems


To combat the loss of efficiency that can occur at high temperatures with transcritical CO2 systems, Kysor Warren’s ECO2Boost modular design easily allows for advanced technology solutions –without changing the rack footprint,  that can provide significant improvements in warmer climates.

We offer warm climate solutions:  

Parallel Compression

In standard transcritical CO2 booster systems, flash gas is generated through the high pressure valve (HPV) and removed from the tank through a flash gas bypass valve (FGBV) to the medium temperature compressor suction. This process is inefficient in warm climates due to the large amounts of flash gas generated and the pressure drop across the FGBV.  To mitigate this effect a compressor is connected to the top of the flash tank so the flash gas is removed at a higher suction pressure causing an increase in the energy efficiency of the system. It provides 5-10% energy benefit when compared to a standard CO2 TC booster system.

Ejector with Parallel Compression

The ejector is an expansion device with virtually no moving parts that further enhances the efficiency of transcritical CO2 booster systems in warm climates. It works by converting internal energy and high pressure related flow work held in the gas cooler outlet stream into kinetic energy to entrain and effectively pump the refrigerant from the medium temperature suction into the flash tank. This allows the medium temperature compressors to be unloaded and transfer such load to the parallel compression group that operates at higher suction pressure and therefore uses less energy to pump the refrigerant around the system. It provides 5-10% energy benefit when compared to parallel compression by itself.



CO2 Transcritical Booster Rack

CO2 Booster Rack High Pressure Testing