Ammonia from 1850s to today: convincing technology

By Sabine Lobnig, Jul 24, 2009, 15:36 3 minute reading

With its superior thermodynamic properties and its recognised higher efficiency, ammonia is proving to be a refrigerant of choice in large refrigeration and freezing systems. In its Cool Technologies paper, Greenpeace outlines successful ammonia applications in various companies across the world.

From Canada, to Denmark, Germany, Japan, Luxembourg, Norway, Spain, Sweden, the UK, and the US, ammonia is being successfully used as a refrigerant in universities, hospitals, hotels, office buildings, convention centers.

Below are chosen examples of success stories in ammonia applications.

Ammonia in refrigeration and freezing

Kältetechnik Dresen and Breme
n built an ammonia system for a total floor space of approx. 5,000 m², with desired temperatures ranging from -30°C to 7°C. This was to be equipped with a number of different refrigeration and processing rooms. A three-stage ammonia refrigeration (2,850 kg charge) plant was built with a glycol cycle. The deep-freeze warehouse and the shock-freeze rooms with a refrigeration output of 410 kW at -40°C are directly supplied with ammonia. An ethylene glycol cycle with a flow temperature of -12°C cools the production rooms. In a spray humidified chilling tunnel that is also linked into the cycle, roughly 9,000 chickens per hour are cooled down to a temperature of 2°C.

In a similar environmental and efficiency concern, Dresen and Bremen built a refrigeration and air-conditioning system, using ammonia for a confectionery. Process refrigeration is responsible for controlled heat removal during the production of chocolate, sweets and fruit gums, and for cooling the machines. The consumers are supplied with refrigeration via two liquid circuits at temperatures between 5°C and 11°C. The process refrigeration circuit uses cold water, while the air-conditioning system works with a propylene glycol circuit.

For the manufacturing of filled fresh and frozen pasta the Austrian market leader Recheis Teigwaren GmbH required conditioned storehouses, regular and deep-freeze storehouses and a combined spiral/freezer-cooler. To answer all the demand without using HFCs, KWN Engineering-Gesellschaft mbH designed a refrigeration facility using ammonia. A CO2 cascade was additionally installed for the deep-freeze storehouse and the spiral freezer and cooler.

The Swiss healthcare company Roche, is installing ammonia cooling in its new facilities in Germany, Ireland and the US. At Roche’s Indianapolis facilities HFC chillers are in the process of being replaced with ammonia in the facility’s 16,000 m2 chiller plant building. In Ireland, a similar replacement reduces Roche’s CO2 emission by 575 tonnes annually.

Guinness had planned to increase its production volume to twelve million barrels of stout per year. Star Refrigeration extended the 5 MW system up to 8.9 MW. Six additional variable speed drive glycol pumps were installed which increased the condenser capacity. With a refrigeration capacity of 8.9 megawatts at an evaporating temperature of -4.5°c, the ammonia refrigerant charge was not noticeably increased.

Johnson Controls Systems & Service installed a two-stage ammonia system involving screw compressors to meet food retailer Edeka’s need for a system consisting of refrigeration and deep-freeze rooms. It produces refrigeration output of 5,500 kW with a refrigerant charge of 10,000 kg. The cooling fluid piped through the processing rooms is ethylene glycol (34%).

Ammonia Chillers in small applications

Although ammonia is usually associated with larger cooling installations, Danish York Company produces smaller ammonia chillers with a single piston compressor, plate heat exchanger, liquid separator, automatic oil return, and electronic control in front panel. These have been installed in radio studios, computer centres and offices. It would be technically possible to build ammonia chillers for domestic use. However, economies of scale are needed to make these commercially feasible.


By Sabine Lobnig

Jul 24, 2009, 15:36

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