BITZER CSVH Screw Compressors “On air” 24/7

    Südwestrundfunk (SWR) is one of Germany’s largest regional public broadcasting agencies. A great deal of foresight went into planning the new refrigeration system commissioned at the Baden-Baden site last year, reducing operating costs by 40%.  In the world of radio “on air” refers to live broadcasting but in a 24-hour operation the station always needs to be ready to broadcast. And because the inside heat loads generated by computers, electronics, broadcasting equipment and, of course, people are higher than the heat loss most of the year, the air conditioning needs to be on at all times. Though it is one of Germany’s warmest regions, the nights are usually mild even in the summer – ideal conditions for the ANSOR concept.

    Combitherm’s ANSOR concept 

    “When we renovated and expanded the radio building in 2014, we had to plan a new refrigeration system,” recalls Stefan Schwenk, member of the team who manages the specialist group Air Conditioning Technology. “The old system’s cooling capacity was no longer sufficient. Plus, the high energy consumption suggested that a modern system would reduce costs significantly.” 

    As it turns out, the required public investment would be much higher than the specialist had originally predicted. The result the new refrigeration system should reduce annual energy consumption by 488,000 kWh or 41%, which is equivalent to a decrease in CO2 emissions of 339 metric tons and fixed operating costs of up to USD320,000 a year. 

    Closer inspection revealed that investment in a high-tech refrigeration system would pay for itself in six years. The setup comprised three R22 refrigeration systems with two cooling towers and a condenser. There was no cooling water pump for the third system. At least one refrigeration system was in operation all year round to cover the inside cooling, while the other two would turn on or off depending on the outside loads. There was no capacity control – neither for the refrigeration nor for the pumps in the cooling/chilled water distribution net. 

    The refrigerant had become a ticking time bomb because, since January 1, 2015, using R22 in existing systems for maintenance, repairs and services has been redundant. System malfunctioning due to refrigerant loss would have been a nightmare scenario in mid-summer. 

    The ANSOR concept
    Manufactured by Combitherm, ANSOR is a refrigeration system for building cooling, featuring speed-controlled screw technology, free cooling, online monitoring and intelligent control technology. A decision was ultimately made to install two KWG 2/26I glycol-cooled ANSOR refrigeration systems (cooling capacity 2× 700 kW). Even if one machine breaks down, 80% of the maximum required cooling capacity can still be maintained. The free cooling function at outside temperatures of up to 13°C is particularly useful, as it bypasses the refrigeration systems. This in turn reduces the operating hours and electricity costs of the compression refrigeration system, as the cooling water pump is the only component consuming energy. The refrigerant in use today is R134a, automatically reducing global warming potential (GWP) from the previous 1,810 for R22 to 1,430. And unlike R22, it’s also ozone-friendly. 

    “The conditions requiring full-load cooling capacity operation only occur around 3% of the year, making part-load operation the primary mode”

    The conditions requiring full-load cooling capacity operation only occur around 3% of the year, making part-load operation the primary mode. The frequency inverter is the most efficient way to adjust the compressor speed. Both of the two-circuit compound systems feature two of BITZER’s CSVH26-200Y-40A compact screw compressors, each of which is infinitely adjustable in the capacity range between 16 and 100%. The maximum total cooling capacity of 2 × 700 kW can be reduced to just 5% in the two-circuit compound of each ANSOR compact screw compressor unit. It’s only when the required cooling capacity exceeds 700 kW that the screw compressors activate in both systems. 

    The chilled water is directed to primary and cooling distributors along a large hydraulic network and delivered to the five ventilation stations with a total air delivery volume of 160,000 m³/h.