Ammonia trends in Europe

As the only refrigerant to have been used in refrigeration technology for nearly 130 years, ammonia has already proven its efficiency in large-scale refrigerating plants. In recent years, however, ammonia (R717) has been employed more and more in medium and small capacity systems, including cascade systems in supermarket applications, where it could solve technical challenges faced by smaller installations. In the latest “Condenser” magazine of the International Institute of Ammonia Refrigeration, Monika Witt from the European initiative eurammon explains drivers that could spur the natural refrigerant’s more widespread use in Europe.

Development trends for R717 in Europe

eurammon concludes that in the future, ammonia will still be used in large-scale refrigeration, especially at evaporation temperatures of -33°C. However, great potential exists for systems in the middle and lower capacity range with small refrigerant charges. The major trend towards smaller ammonia systems is based on the following developments identified in Europe:

• Lower charges: Recent developments in system and component design as well as new blends of refrigerants containing ammonia pave the way towards refrigeration systems using smaller quantities of ammonia refrigerant charge. This is especially important given the natural refrigerant’s potential toxicity and looking at overall plant safety.
   
• Use of cascade systems: One possible solution to enhance the safety of ammonia use is the use of secondary refrigerants, such as CO₂ (R744) or potassium acetate. In both cases, the reduction in ammonia charge does not lead to performance compromises. Another major advantage of cascade systems is the restricted use of ammonia only in the plant room, reducing the presence of ammonia in the cold store.
   
• Heat exchanger developments: Developments in compact tubular and plate heat exchanger systems with high-efficiency surfaces enhance heat transfer, allowing for a reduced quantity of ammonia in the circuit by up to 80% compared to a conventional bare-tube heat exchangers. In addition, various heat exchanger parameters such as dimensions and the number of passes and tubes, as well as the price, are now more favourable than in comparable systems. Further potential, however, is provided by exchanger tubes with inner fins on the inside tailor-made for R717 applications.
   
• New blends: New blends promising high-efficient and low global warming operation include those with the hydrocarbons propane (R290), octafluoropropane (R218), octafluorocyclobutane (RC318), or isobutane (R600a). Compared to pure ammonia, some of blends feature advantages that relate to lower discharge outlet temperature, a lower compression pressure ratio, and a 5-10% better refrigerating capacity. The blend R723, consisting of 60% ammonia and 40% dimethyl ether, promises further potential regarding oil solubility, the use of air-cooled condensers, and better heat transfer.

• Heat recovery: Cold store operators or food processing companies are increasingly recovering waste heat to generate hot service water and realise significant heating cost savings. In addition, progress has been made in the field of using ammonia for residential heat pumps, with initial prototypes with an output of 6 kW having reportedly been working reliable with ammonia charges of less than 100g.

Background

eurammon is a joint European initiative of companies, institutions and individuals who advocate an increased use of natural refrigerants. Its main targets are creating a platform for information sharing and the promotion of public awareness and acceptance of ammonia, CO2 and other natural refrigerants.

The International Institute of Ammonia Refrigeration (IIAR) aims to be the world’s leading advocate for the safe, reliable and efficient use of ammonia and other natural refrigerants for industrial applications. The organisation provides advocacy, education, standards, and information for the benefit of the refrigeration industry worldwide.