Compressor development boost for CO2

GERMANY: Bitzer has increased the capabilities of CO2 as a future-compliant refrigerant with a new compressor development launched at Chillventa this week.

The new six-cylinder Ecoline+ reciprocating compressor for transcritical CO2 applications is said to boast a number of key developments, These include a new higher efficiency motor technology and mechanical capacity control to increase full and part-load efficiency.

“We would like to make efficient CO2 technology simpler and easier to understand again, and thus significantly expand the range of applications with the forward-looking refrigerant,” said Rainer Große-Kracht, Bitzer’s chief technology officer. “The ability to provide refrigeration solutions that are reliable over the long term will require expanding access to CO2 technology. “CO2 is one of the refrigerants of the future – we at Bitzer believe that wholeheartedly,” he added.

The line-start permanent-magnet motor (LSPM) allows the compressor to be operated directly in networks with 50 or 60Hz. Bitzer says the incorporation of permanent magnets has made it possible to significantly increase motor efficiency in full and part-load operation. The technology has been undergoing testing at Bitzer and in selected systems out in the field for more than five years. The LSPMs will now be incorporated into the series production set for CO2 applications. These motors can be operated both directly in the network and in the familiar speed range with frequency inverters, says Bitzer.

In addition to accommodating operation with frequency inverters, the new Ecoline+ compressors can also be equipped with the new mechanical capacity control for the first time, enabling compressor operation with a refrigerating capacity between 10 and 100%. The capacity control, which can comprise one controller in two-cylinder compressors and up to three controllers in six-cylinder compressors, is adjusted just as it is with the well-known capacity control of HFC refrigeration compressors.

The intelligent operating concept of the CM-RC-01 IQ module, which comes as standard, also ensures optimal efficiency for the oil supply, the oil heater and the new CRII capacity control, which is specially developed for CO₂ applications. The interplay between CRII and CM-RC-01 is said to allow the capacity to be adjusted virtually infinitely between 10 and 100%. The CM-RC-01 IQ module makes it very easy and inexpensive to integrate the Ecoline+ reciprocating compressor into a whole host of system configurations. The IQ module not only improves protective measures and options for monitoring compressors, but also expands their range of applications and thus offers users greater flexibility. This in turn makes it easier, for instance, to compensate for differences between summer and winter operation. The new capacity control is said to increase overall efficiency, as the CRII enables a more stable and higher suction pressure