Second Nature – SNLTX2

CO2 Direct Expansion Cascade Refrigeration System


SNLTX2 CO2 Direct Expansion Cascade Refrigeration System

SNLTX2 CO2 Direct Expansion Cascade Refrigeration systems utilize CO2 as a low-temperature, direct expansion (DX) refrigerant in a cascade system. The CO2 removes heat from display cases and walk-in freezers via copper piping that is also significantly smaller than what is typically required in traditional HFC-based, direct expansion systems and even smaller than in our SNLT2 secondary systems. The upper cascade (primary system) is a medium-temperature refrigeration system.

Features & Benefits

  • CO2 is considered a natural refrigerant with very low global warming potential (GWP=1).
  • CO2 is inexpensive refrigerant compared with HFC and is widely available.
  • An excess of 70 percent reduction in HFC refrigerant charge can be achieved. The entire primary refrigerant charge is confined to the machine room and condenser to enable simple leak detection and servicing.
  • The piping system utilizes a modified-loop copper piping system – CO2 lines are typically one to two sizes smaller than traditional DX piping systems.
  • System uses efficient and quiet CO2 subcritical compressors.
  • CO2 has better heat transfer properties compared to conventional HFCs.
  • Excellent material compatibility – most components for commercial refrigeration can be used.
  • System energy performance equivalent or better than conventional HFC systems.
  • System footprint is smaller than Second Nature LT2
  • CO2 secondary technology.

Systems Options

  • System features either Copeland CO2 hermetic scroll or Bitzer reciprocating compressors and a high-efficiency plate suction-liquid heat exchanger.
  • HFC system refrigerant charge can be further minimized by using water-cooled condensers and hydronic heat-reclaim loops.
  • HFC system can also be used to refrigerate other medium-temperature loads including Second Nature MT secondary systems.
  • Low-temperature display cases and freezers can be equipped with the Hill PHOENIX Smart Valve™ system with EEV’s for steady, automatic control of superheat leaving the evaporators.
  • Available as stand-alone rack or installation in Mechanical Center or WeatherPacenclosure.
  • Optional glycol-cooled CO2 condensers allow smaller systems to be packaged for modular indoor systems (similar to InviroPac).
  • Multiple CO2 suction groups on low-temperature system can further improve energy efficiency.
Second Nature Low Temperature Direct Expansion Cascade Refrigeration System

Liquid CO2 is expanded in the EEV and heat is absorbed in the display case through evaporators similar to those used in traditional DX systems, but specially designed for use with carbon dioxide direct expansion cascade systems. The CO2 completely evaporates in the coils and the suction gas returns to the system through a highly-efficient suction-liquid heat exchanger (SLHE). The CO2 is then compressed and discharge gas from the compressors is condensed in the condenser-evaporator heat exchanger by the HFC system operating at medium-temperature conditions. Liquid is then directed to a COreceiver and SLHE before being distributed in the liquid supply piping.

Intertek Certification

Better Practices Make Better Systems

There are many reasons why Hillphoenix® Refrigeration Systems continues to lead the industry. Why? No matter what the application or the specific refrigeration need, we can offer our customers a wide variety of options and configurations. The simple answer is that we harness the best technologies and field-proven procedures and fit them to a higher set of standards.

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