Expanding cold generation at the University Hospital of Bern

Hospitals must be able to rely on the safe cooling of equipment and rooms. The University Hospital of Bern, for example, relies on a customised CTA chiller for their expanded cooling system. This operates using the environmentally friendly hydrofluoroolefin (HFO) refrigerant and produces reliable cooling for a number of hospital buildings, with an output of around 1.6 MW.
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A delicate moment: setting down the chiller.

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The customised CTA chiller

  • 1.6 MW output

  • Four output-regulated worm compressors with eight output levels servicing two cooling circuits

  • 18 tonnes in weight

  • HFO refrigerant

  • Water and buildings heated using waste heat from the cooling system

  • Specific dimensional requirements for installation

Reliable cooling and air conditioning

Around 300,000 outpatients and 40,000 inpatients a year, 8,000 employees, and 1,000 researchers and trainees—the University Hospital of Bern is one of the most important health centres in Switzerland and a major employer in the city and canton of Bern. In this environment, there are no compromises when it comes to cold production. Radiology, laboratories, IT, air conditioning—virtually all areas of the hospital depend on reliable cooling and air conditioning. And as the hospital grows, so does the internationally renowned university hospital’s demand for cooling. The centralised cold production for the university hospital site in Bern was therefore expanded.
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After being transported to the University Hospital of Bern, the system is lifted by crane into the entry portal to the building.

Demand-dependant, energy-efficient cooling

The new, customised CTAexklusiv chiller has four output-regulated worm compressors with eight output levels, which service two cooling circuits. This design enables needs-based, energy-efficient cold production. At full load, up to 1.6 MW of cooling can be generated. At the same time, the waste heat from the cooling system is used for the building’s domestic hot water and heating. For this reason, the "warm side" was integrated into the site’s existing heating network. When there is no demand for heat—during the summer months for example—non-usable heat is ejected via the recoolers on the roof. 
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The 18-tonne system in the production building

Conscious decision for HFO

Just as important as the system’s high performance was the choice of refrigerant. Therefore, the HFO refrigerant R-1234ze was chosen. Hydrofluoroolefin (HFO) refrigerants are synthetic refrigerants with all the advantages of natural refrigerants. This means they have an extremely low greenhouse potential and simultaneously enable highly efficient operation. High safety standards apply to HFO systems. The chiller is enclosed in a separate room within the plant. This way, it can be optimally monitored and safely operated. The system has also been specially certified for category IV of the Swiss Pressure Equipment Ordinance—the highest category, depending on refrigerant content volume and working pressure.