Ammonia as a future-proof alternative to R22

By Clémence Girard-Reydet, Nov 05, 2013, 11:14 4 minute reading

After a successful first installation of an ammonia-based chiller as a replacement for its R22 systems in 2011, German wireless communication manufacturer Rohde & Schwarz decided to convert an additional building to ammonia technology. GEA Refrigeration Technologies compact chillers were provided to cool the conference rooms, as well as for heat extraction from laboratory and testing rooms. 

Today the new building is equipped with central air-conditioning and a number of sophisticated technical features. One particular challenge of the project was the connection of all rooms, some of which had ceiling heights of only 2.8m, to a sufficiently dimensioned cold-water circuit.

The chiller to be installed would be required to run at full capacity for only a few hours a day and under part load the rest of the time. The dimensions of the unit also prompted discussion of an installation site for the unit. A chiller that could provide the required cooling duty with a minimal footprint was necessary. For this, the GEA Grasso BluAstrum 1000 was selected.

Not only does the BluAstrum have a high full-load energy efficiency ratio (EER = 4.6) and a high modified European seasonal energy efficiency ratio (M-ESEER = 7.16), but with its dimension of 1 meter on its narrow side, the GEA Grasso BluAstrum 1000 also fits through most doors. Based on the dimensions of the BluAstrum 1000, the engineers of the project started to work on the idea of moving the refrigeration systems from the upper floor into the basement.

Efficiency of the system

To ensure a uniform output distribution, two GEA Grasso BluAstrum 1000 chillers were connected. Both are protected in noise-abatement enclosures. With new screw compressors that feature roller bearings, an electrical drive system with speed control, as well as an inverter, this compact unit offers potentially high efficiency and a cooling duty of 1000 kW.

The cold-water lines were routed through six shafts, each designed to enable a total of 500 kW of transfer output. The entire recirculation-air system is operated in summer with 6/12 degrees °C supply/return temperatures and in winter with 10/16 degrees °C. This solution allows maximum use of the time window for free cooling. The capacity of this system has been calculated at approximately 500 kW. A completed well-water source, planned to provide similar capacity, will be used as a backup if necessary.

Service requirements were also reduced and the recommended service interval was lengthened to 25 000 operational hours (for oil change). Major service is required only after double operating time is reached, while fully welded steel pipes minimise loss of refrigerant.

Flexibility of the system

A third GEA BluAstrum has already been included in building blueprints but has not yet been installed. Due to its compact dimensions, this third system will also fit in the basement in case there is a need for additional capacity once the new building is completed.

The entire cold-water network was installed with extra-dimensioned piping so that new equipment can be easily interfaced with the pipes at all output points.

Safety of the system

Since ammonia is lighter than air, and since the gas in the event of a leak could disperse through the stairwell, the installation of the system in the basement posed an additional risk.

As the new chiller will contain 145 kilograms of refrigerant, numerous safety functions are necessary according to EN 378, to prevent accidents and to immediately provide alarm for even minimum leaks: the lock chamber with ppm gauge, respiratory protection masks, warning lamps and instructions and emergency OFF buttons.

In addition, an ammonia neutralisation system must be located in the main room for the refrigeration equipment. For each chiller, one blow-off pipe leads from the chiller to the vessel of the neutralisation unit. When the pressure on the low-pressure side rises above 21 bars, a safety valve opens to “blow off” the NH3 refrigerant into the water vat with its liquid-level indicator.

In an ancillary room, the entire distribution system is installed to include the required pumps and all monitoring devices such as differential-pressure sensors. The 8000-litre buffer storage takes up the entire height of the room. A rainwater storage vat and the required water softener are located on the opposite wall.

Ammonia technology: a sensible choice

The Montreal Protocol plans a total ban on R22 as of January 2015. From that date on, the refrigerant will be prohibited for use in the maintenance and servicing of refrigeration and air conditioning equipment.

As synthetic alternatives are likely to be banned in the future as well, the replacement of R22 systems by ammonia-based systems seems to be the most sensible choice to ensure protection of today’s investment.

About GEA Refrigeration Technologies

GEA Refrigeration Technologies, part of the internationally active GEA Group, is a leader in industrial refrigeration. The company designs, engineers, installs, and maintains innovative key components and technological solutions. These solutions are present in the food and beverage sector, in the petrochemical, chemical and pharmaceutical industries, on fishing ships, in natural gas liquefaction, in infrastructure facilities and in ice factories. GEA Refrigeration Technologies primarily uses natural refrigerants, particularly ammonia (R717), thus combining its excellent thermodynamic characteristics with its ecological advantages.


By Clémence Girard-Reydet

Nov 05, 2013, 11:14

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