European Contractors Association issues guide to low GWP refrigerants

Titled ‘Low GWP Refrigerants: Guidance on use and basic competence requirements for contractors’, the position recognises that international legislation is likely to gradually decrease the use of high GWP refrigerants, effectively encouraging a greater use of low GWP refrigerants such as well known natural refrigerants ammonia, CO₂ and hydrocarbons.

Ammonia should find broader applications than it currently enjoys

Ammonia offers three distinct advantages over other commonly used refrigerants:

• Environmentally sound: Ammonia is an environmentally compatible refrigerant because it has an ozone depletion potential (ODP) of zero and a global warming potential (GWP) of zero.
• Efficient: Because of its superior thermodynamic properties, ammonia as a refrigerant requires less energy than other refrigerants when used in large industrial systems.
• Safe: Ammonia refrigeration has a proven safety record, in part because of the refrigerant’s physical properties (not the least of which is its well-recognizable and easily-detectable smell), compliance with voluntary industry standards and an industry of well-trained operators.

AREA concludes, that from a purely economic point of view and without unnecessary regulatory burdens, ammonia should find broader applications as a refrigerant than it currently enjoys. Limitations on the use of ammonia are generally due to national legislation. But, as regulatory and code officials become informed of its relative safety, ammonia’s use should be expanded.

Applications for ammonia-based refrigeration systems include thermal storage systems, HVAC chillers, process cooling and air conditioning, district cooling systems, supermarkets, convenience stores, air conditioning for the International Space Station and Biosphere II, and increasing output efficiencies for power generation facilities. Further implementation of ammonia use can be foreseen in smaller applications (domestic and commercial) under certain safety conditions.

NH₃’s main technical differences to HFCs and basic contractors know-how requirements

According to the paper, the main technical differences include:

• Generally ammonia compressors are of open-drive design due to the incompatibility of copper and NH₃.
• No compatibility with copper or zinc, so these materials must be avoided.
• Differences in oil return to the compressor must be considered in ammonia refrigeration systems.
• Oils used in ammonia refrigeration systems are insoluble in NH₃ while oil solubility is absolutely essential with the halocarbons in order to facilitate oil return.
• Need for pressure vessels

Regarding basic competence requirements for RAC contractors dealing with ammonia, the paper makes reference to the Leonardo da Vinci project AREA Refrigeration Craftsman. However, particular attention should be given to the above-mentioned technical differences to HFCs as well as safety issues:

• Tables of toxicity (breath, eyes, skin)
• First Aid First Intervention
• Wear the correct personal protective equipment (PPE)
• Miscibility with water and compatibility with other materials

Refrigerant suitability by system size

Overall, AREA asserts that no refrigerant represents the ideal solution in all cases and for every type of equipment. However, assessing the suitability of a refrigerant in RAC equipments according to their size in terms of energy efficiency, AREA makes out that:

• In large systems, CO₂ or ammonia are generally more energy efficient 
• In small systems, hydrocarbons tend to be more energy efficient 
• In between these scales, each equipment should be analysed on a case by case basis

About AREA

AREA is the European organisation of refrigeration, air-conditioning and heat pump contractors. Established in 1988, AREA voices the interests of 21 national members from 19 European countries, representing more than 9,000 companies across Europe (mainly small to medium sized enterprises), employing some 125,000 people and with an annual turnover approaching €20 billion.