Ammonia (NH₃)

Ammonia (NH3) is a well-known refrigerant, particularly applicable in large, industrial plants where its advantages can be fully utilized without compromising safety. 

Ammonia is renowned for its favorable thermodynamic properties. In a wide range of applications, it outperforms synthetic refrigerants. However, it has a number of drawbacks that have so far prevented the use of ammonia for commercial applications, e.g. material compatibility, toxicity, and flammability. 

Efficiency

Ammonia is a highly efficient refrigerant, with a theoretical efficiency slightly higher than that of R134a or propane. In practice, there is evidence that ammonia systems perform even better than in theory.

Safety

Due to the toxicity and flammability of ammonia, installations using ammonia are governed by national regulations. Even with strict regulation in place to secure safety in operation, there is pressure on ammonia installations to reduce charge levels, especially when situated in populated areas.

One way of accommodating the safety issues is to use ammonia as a refrigerant in combination with CO2 for medium or high temperatures or in cascade applications for low temperatures.

Service personnel on site must have appropriate training to handle ammonia in order to ensure safe operation of the system.

Environment

Ammonia is a natural refrigerant. It has zero ODP and zero GWP. In combination with its efficiency, it is one of the most environmentally friendly refrigerants.

Pressure and size of plant

The operating pressures of ammonia are comparable to those of other common refrigerants (HFCs and HCs) and it has a relatively high normal boiling point (–33.3 °C). Ammonia has high volumetric capacity, so ammonia pipe lines are smaller than HFC pipe lines. It should be noted, however, that when ammonia is used for suction lines, the lines are larger compared to those of CO2.

Chemical properties

Ammonia is compatible with all common materials except copper and brass. This means that only welded steel pipes can be used. Furthermore, it is necessary to use either semi hermetic compressors or hermetic compressors with special motor coatings or aluminium motor wires.

Ammonia is not miscible with common oils. In addition, ammonia is lighter than oil, which makes oil return systems fairly simple.

Cost efficiency

Ammonia is an inexpensive and abundantly available refrigerant. Ammonia installations, however, tend to be relatively expensive due to the requirement for steel tubing, semi hermetic compressors, and the installation of a number of safety devices, such as gas detectors.

Applications

Today ammonia is primarily used in industrial refrigeration applications: 
• Distribution cold stores 
• Freezing tunnels 
• Breweries 
• Food processing plants (slaughterhouses, ice cream factories, etc.) 
• Fish trawlers 

 
 
These applications are high capacity charges however, there are on-going efforts to develop low-charge ammonia systems in order to take further advantage of the beneficial thermodynamic and environmental properties of ammonia. Some of the efforts undertaken by Danfoss and research partners are to develop low-charge systems with new, advanced control algorithms, further development of ammonia-optimised heat exchangers, DX systems and new cascade systems with CO2.

Ammonia in industrial refrigeration

Learn all about the use of ammonia in industrial refrigeration applications in our dedicated Industrial Refrigeration site.

Case studies

  • Sour cream recipe succeeds with ICF flexline™
    Sour cream recipe succeeds with ICF Flexline™

    Eating healthier, more natural foods is a growing trend that delights Daisy Brands - a family-owned, Garland, Texas-based firm that makes the best-selling brand of sour cream in the United States. Known for its "Pure and Natural" recipe using no additives, preservatives or artificial growth hormones, the company recently opened a plant in Casa Grande, Arizona, to expand its national distribution. The continuing success of Daisy Brands is based on a recipe that uses all-natural ingredients -- plus, the technology ingredient of the Danfoss Flexline™ family of motor control valves and control stations.

  • Ammonia conversion for cold storage facility is simple with ICV flexline™ Danfoss
    Ammonia conversion for cold storage facility is simple with ICV Flexline™

    Consumer retail stores are looking for tried-and-true ideas to thrive in turbulent economic times That’s why a major 190-store retail chain based in the Midwest switched to a proven refrigeration solution for one of its distribution centers - an environmentally friendly ammonia system that uses Danfoss ICV Flexline valve stations

  • Hot gas defrost of low temperature refrigeration evaporators with natural refrigerants Danfoss
    Hot gas defrost of low temperature refrigeration evaporators with natural refrigerants

    Industrial refrigeration systems predominantly use natural refrigerants, primarily ammonia and more recently CO2 Energy efficiency and the effective operation of those systems are the key parameters for operators of the plants The focus of the white paper is the comparisons of hot gas defrost strategy control methods, both on the hot gas side as well as on the condensate drain

  • High-Rise refrigerated fruit storage and distribution Danfoss
    High-Rise refrigerated fruit storage and distribution, using a NH₃/CO₂ fluid system, gives optimum results for stored products and company financials

    Internal transport is done using fully automated cranes and conveyor systems This ingenious system dispenses with the need for people and forklift trucks Forklift trucks are now only used on the dispatching floor, for loading and unloading trucks and containers