UPDATED: DORIN broadens CD-2S range of double-stage transcritical CO2 compressors

By Silvia Scaldaferri, Apr 04, 2014, 15:15 3 minute reading

Dorin, a leading Italian compressor manufacturer, launches a new semi-hermetic reciprocating compressor range for CO2 transcritical applications. The new CD-2S Series offers the capability to work with extreme pressure ratios, allowing for the same functionality as standard CO2 low temperature equipment, with no need to implement a cascade or a booster system and therefore drastically cutting down the failure risk. CD-2S 4-cylinder models have been UL approved.

The use of CO2-based refrigeration equipment is attracting more and more end-users for a variety of applications; this trend is driven by several factors, such as:

  • Benign refrigerant properties in terms of environmental sustainability (GWP = 1)
  • Extremely high system efficiency and higher COP when compared to business-as-usual technology
  • Much lower maintenance costs in case of leakages due to the very low refrigerant price when compared to HFCs
In particular, clear signals from the market are arising, with an increasing demand for larger-scale CO2 applications. Thus, all the system component manufacturers are called to deliver since bigger equipment is needed.

Committed to the commercialization of its transcritical CO2 compressor range, Dorin exhibited the Series CD_2S at the flagship MCE 2014, held from March 18-21. This range represents the latest, cutting-edge developments in transcritical CO2 compressors. These models offer a wide application spectrum which permits them to:

  • Handle large pressure differences typical of direct expansion low-temperature systems (T_ev = -35°C), rejecting the heat directly to the ambient (up to 100 bar discharge pressure), thus providing for safer installation. Furthermore, in a booster system, any failure occurring in the low pressure side will automatically be reflected into the high pressure side, and vice-versa.
  • Have no issues related to standstill conditions: Pss = 100 bar.
  • Increase the system efficiency of medium temperature equipment (T_ev = -10°C) located in warmer areas using the sub-cooling effect obtainable by an inter-stage gas heat exchange with a gas cooler outlet which could boost energy efficiency, making CO2 also a viable solution for warmer climates such as southern Europe.
  • Safely operate a CO2 heat pump down to extremely low ambient temperatures (T_amb = -25°C) with no need for additional electric heaters, thus boosting equipment efficiency.

Applicable in 50 Hz and 60 Hz, with a weight from 75 to 191 kg, the Series constitutes two Ranges: the CD2S200 displacing from 1.45 m3/h in LP + 0.57 m3/h in HP to 2.36 m3/h in LP + 0.73 m3/h in HP, and CD2S400 displacing from 5.99 m3/h in LP + 5.06 m3/h in HP to 15.11 m3/h in LP + 8.98 m3/h in HP.

In total, these are 9 models are perfectly suitable for:

  • Heat pumps application
  • Commercial refrigeration (BT)
  • Commercial refrigeration (MT)
  • Refrigerated transport

Advantages of using a double stage compressor

The advantages of using a double stage compressor in place of two standard CO2 transcritical compressors relates to the high discharge temperatures. With low evaporative temperatures the use of an interphase refrigeration step is necessary. This is solved with a single compressor from the CD_2S Series, which can apply the complete compression process within itself, thus significantly reducing investment costs of the final refrigeration system.

DORIN is expecting a continuous global growth in this specific model sales inquiries and will welcome any information requests," comments Giovanni Dorin, Marketing Manager. 

The previously available models are:

  • CD2S-1200: 7.71 m3/h LP + 5.06 m3/h HP
  • CD2S-1500: 6.00 m3/h LP + 4.50 m3/h HP

These two new models fit smaller evaporator capacities and fulfil increasing market demands centred around: lower production arising from the use of glass-door cabinets, and single compressor condensing units.

Main Characteristics

  • Semi-hermetic reciprocating compressor
  • Generous electric motor size
  • Max. standstill pressure: 100 bar
  • Displacement (m3/h at 50Hz): 1.45 – 15.1 m3/h
  • Cylinders: 4
  • Suitable for frequency control regulation up to 75Hz


  • No longer need of booster/ cascade system in LT applications with single stage compressors, resulting in a safer installation
  • Standstill pressure boosted to 100 bar, allowing for: no issues during prolonged standstill; safer and better preservation
  • Extra-robust drive gear for proven reliability
  • Multi-layer self lubricating bearings for better robustness against liquid slugging
  • Silent and smooth operation in any operating condition
  • Wide application spectrum to suit all possible applications and systems
  • Reliability
  • High COP levels

About Dorin

In 1932 Dorin entered into the refrigeration sector with its first open-drive compressor range. Since the early 50s, Dorin has produced semi-hermetic compressors, commissioning the first CO2 transcritical model in 1999. The company produces more than 70,000 compressors per year. 



By Silvia Scaldaferri

Apr 04, 2014, 15:15

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