Case studies

CO2 Technology Centre / Brazil

Planning / Implementation / Main components: Bitzer Kühlmaschinenbau GmbH
Refrigerant: Carbon dioxide (CO2)
System start-up: 2009

In the current energy and environment situation, carbon dioxide is an excellent refrigerant. To promote the use of carbon dioxide as a natural refrigerant particularly in North and South America, compressor manufacturer Bitzer has opened a Technology and Training Centre in Sao Paulo, Brazil.


To inform technicians, engineers, planners, system engineers and students about new procedures and know-how for using carbon dioxide as a refrigerant. In addition, the Centre should offer the possibility of comparing the energy efficiency of systems operating with different refrigerants.


Altogether Bitzer has installed three refrigerating systems with similar cooling capacities. These consist of a cascade system with carbon dioxide for subcritical operation and the HFC R404A (pump circuit for normal refrigeration and direct expansion for deep-freezing), an R404A system, and a system with the HCFC R22. They cool two storage rooms down to 0 to 2 °C and a deep-freeze room to -25 °C. There are also two deep-freeze islands working at -25 °C that are connected just to the carbon dioxide circuit. The cooling capacity for normal refrigeration is about 20 kW, and about 10 kW in the deep-freeze range. The evaporators of the three refrigerating systems are designed as air coolers and fitted under the ceiling of each cold room. The condensers operate with either air or water cooling. All machines and cold rooms are equipped with infrared sensors and a carbon dioxide extraction system. Only one system is in use at any one time to permit energy comparisons.

Bitzer has equipped all three refrigerating systems with its very latest semihermetic compressors. The carbon dioxide circuit (cascade) is fitted with compressors that have been optimised especially for use with this refrigerant: their design makes them very energy efficient in operation. The use of carbon dioxide also brings advantages when it comes to material usage. It is possible for example to considerably reduce the cross sections of the suction and discharge gas pipes, thus reducing the costs of the piping installation. Test runs have also shown that the carbon dioxide system also consumes less energy than the R404A and R22 systems.

Technical data:


pe of system: CO2/R404A cascade system
R404A system
R22 system
Refrigerant: CO2 / R404A / R22
Refrigerant charge: 32 kg / 125 kg / 115 kg
Evaporating and condensing temperature (MT):

CO2/R404A cascade system:
tC = -5 °C (CO2 pump circuit
tO = -10 °C (R404A cascade stage)
tC = 40 °C (R404A cascade stage)

R404A system:
tO = -10 °C
tC = 40 °C

R22 system:
tO = -10 °C
tC = 40 °C

Evaporating and condensing temperature (LT):

CO2/R404A cascade system:
tO = -30 °C (CO2 DX)
tC = -5 °C (CO2)

R404A system:
tO = -30 °C
tC = 40 °C

R22 system:
tO = -30 °C
tC = 40 °C

Cooling capacity (MT): 21,0 kW / 21,0 kW / 19,82 kW
Cooling capacity (LT): 9,81 kW / 10,66 kW / 9,9 kW
Main components: evaporators, condensers, semihermetic compressors
Special features / Comments: Each circuit is equipped with an electronic control for constant monitoring of the machines. All the relevant information comes together in a central monitoring unit that the service staff can control also via LAN and the internet. If staff should happen not to be on site, the central control informs them of any irregularities by SMS and fax.

Bitzer Kühlmaschinenbau GmbH
Albrecht Höpfer
Eschenbrünnlestr. 15
D-71065 Sindelfingen

Phone : +49 (0)7031 932 155
Fax: +49 (0)7031 932 147
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