German compressor manufacturer BOCK is expanding its transcritical CO2 (R744) compressor portfolio with two efficiency-improving technologies: a new Line Start Permanent Magnet (LSPM) motor technology series, and the DCR22 CO2 compressor output controller.

“A sustainable increase in efficiency with little increase in system complexity,” is how Manuel Fröschle, Manager Application Engineering & PM Natural Refrigerants at BOCK describes the LSPM motor technology in a recent LinkedIn post.

“The LSPM compressors for use in refrigeration and heat pump systems combine the strengths of robust asynchronous motors with squirrel cage rotors and those of synchronous permanent magnet motors,” according to a statement (in German) by BOCK on its website.

The LSPM enables a compressor to achieve “a higher refrigerant mass flow with an optimized speed and thus more cooling or heating capacity,” said BOCK. “Since there are no power losses in the rotor, the motor and overall efficiency of the compressor are increased – by an average of around 6% compared to a standard asynchronous motor.”

“In times of high energy costs, improved compressor motor technologies bring significant savings in the operating costs of refrigeration systems and heat pumps,” said Fröschle in his post.

BOCK offers the new LSPM motors in three compressor sizes with a total of 16 displacement levels from 4.8 to 39.5m³/h (170 to 1,395ft3/h).

Adjusting to current output requirements

With the DCR22 CO2 compressor output controller, the output of transcritical BOCK CO2 compressors can be adjusted almost steplessly to the current output requirements of the system, said BOCK.

It is the first product in the BOCK flexxCO2NTROL series, available beginning in June.

Depending on the operating conditions, the system covers a bandwidth between 25 and 100% power (four cylinders). “This ensures great economic and technical advantages, especially in areas of application with strongly fluctuating power requirements, such as in many industrial processes or supermarket applications,” said BOCK.

According to BOCK, additional advantages include:

  • Higher average evaporating temperature
  • Minimized compressor start-stops with reduced risk of wear, and longer engine life
  • Possible use of existing compound controllers: integration into existing system control (with available digital power control for reciprocating compressors)
  • Increased system efficiency, reduced investment and operating costs
  • Universally applicable to digital and conventional power control
  • Alternative to frequency converters

BOCK’s motto is “Focus on the future: natural refrigerants” and the manufacturer has been expanding its CO2 compressor offering on an ongoing basis. In January, it unveiled a new semi-hermetic reciprocating compressor series for transcritical CO2 systems in small capacity ranges, the HGX12 CO2 T.

“In times of high energy costs, improved compressor motor technologies bring significant savings in the operating costs of refrigeration systems and heat pumps.”

– Manuel Fröschle, BOCK

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