Bitzer’s fresh approach to cascades

Bitzer’s fresh approach to cascades

The gourmet German food specialist Frische Paradies is using a state-of-the-art R134a/CO2 cascade system in its new supermarket in Stuttgart.

Opened in early July, the €10.5m supermarket has been designed in the style of a modern market hall and relies on Bitzer reciprocating compressors along with the German manufacturer’s attendant Varipack frequency inverters.

Every year, Frische Paradies supermarkets are required to refrigerate more than 21,000 tonnes of food and display more than 12,000 high-quality delicacies. Quality and freshness are its highest priorities.

Frische Paradies consulted with Michael Müller from Hamburg-based engineers Eneratio and decided on the R134a/CO2 solution to provide the best combination of energy efficiency, cost-effectiveness and operating reliability.

The R134a/CO2 cascade system was manufactured by Compact Kältetechnik GmbH and installed by Kratschmayer GmbH

The Varipack frequency inverters were connected to the control units planned and built by Kratschmayer in close coordination with Bitzer and data management equipment supplier Wurm.

Bitzer attended site for the initiation of the system in order to advise and assist the customer.

Separate frequency inverters are installed on the R134a and CO2 stages. The frequency range of the Varipack in Frische Paradies is 25 to 70Hz for the six-cylinder compressor for medium-temperature applications (R134a stage) and 30 to 65Hz for the two-cylinder compressor for low-temperature applications (CO2 stage). The speed of 65Hz meets the requirements of the customer. Generally speaking, CO2 compressors from Bitzer can be run at up to 70Hz for subcritical applications.

Five Bitzer Ecoline reciprocating compressors work in the R134a stage (one 6GE-30Y and four 4FE-25Y models). The 6GE-30Y is operated by an FHU+73 Varipack frequency inverter. This allows the compressor’s output to be adjusted to meet the actual demand, which results in excellent system efficiency and control quality. The R134a manages the temperatures of the medium-temperature consumers and dissipates the waste heat of the CO2 stage.

Four Bitzer Octagon reciprocating compressors (2ESL-4K) are used in the CO2 stage. In this stage, too, one of the compressors is operated by an FEU+16 Varipack frequency inverter …