The 2018 Assessment Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee (RTOC) published by UN Environment in February 2019 provides a comprehensive overview of the refrigerants currently used and the refrigerant options for existing and new equipment in the various domains of the refrigeration sector. Additional chapters deal with energy efficiency and sustainability issues, Not-in-Kind Technologies (NIK), high ambient temperature issue, and the modeling of refrigerant banks, emissions and demand.
Several IIR experts participated in the drafting or the reviewing process of this reference report.
RTOC experts stress that perfect refrigerants do not exist. Whatever refrigerants are chosen they must balance availability and cost of the refrigerant and the associated equipment, efficiency, safety, environmental impacts, and other factors. Due to the phase down under the Kigali amendment, the target refrigerants for main applications will therefore include low GWP refrigerants, among them R-717 (ammonia), R-744 (CO2), hydrocarbons (HCs), unsaturated halochemicals such as hydrofluoroolefins (HFOs) and hydrofluorochloroolefins (HCFOs), and mixtures of these refrigerants possibly even with traditional fluids. Many new alternatives are proposed which create a challenge in finding the right refrigerant for each application, and many of the alternatives proposed are intermediate solutions in the HFC phase down.
It is expected that, by 2020, about 75% of new refrigerator production will use HC-600a and the rest may use HFC-134a and possibly HFO-1234yf or some blends, particularly in North America. In the USA, it is not yet clear whether the manufacturers will choose HC-600a or HFC-1234yf as both are flammable and still must adhere to current and emerging safety and energy efficiency standards.
Commercial refrigeration equipment, used for storing and displaying fresh and frozen food, are characterized by varied designs. HCFC-22, and more recently R-404A are the commonly used refrigerants. The choice of replacing lower GWP refrigerants for HCFC-22 and R-404A should therefore be made in a holistic manner, taking all factors into account. Lower GWP HFC/HFO blends and non-halocarbon options like R-717, R-744 and R-290 are growing in use, especially as research and development continues into improving system performance; this trend will increase once the new standards and codes go into effect in the next few years.
Industrial refrigeration and heat pump systems
Industrial refrigeration and heat pump systems are an integrated part of the global food cold chain from harvest to table. But industrial refrigeration is also used in a range of other industries such as fishing ships, pharmaceuticals, petrochemicals etc. The majority of large industrial systems in most parts of the world use R-717 as the refrigerant. Currently also a growing number of systems apply cascades with R-717 and R-744 that are used in a variety of low temperature systems worldwide. Existing HCFC-22 systems are substituted with R-717/R-744 cascade systems, particularly in warm climates where the latter have a better efficiency and durability than most competing technologies (such as R-744 only or HFC solutions).
Industrial heat pumps are gaining popularity because they can produce hot process water, cleaning water, pasteurisation or hot water for other purposes. R-717 is very used for high temperature heat pumps (up to 90°C). HFOs, like HFC-1234ze(E), are also a possible low-GWP alternative to HFC-134a for district heating systems.
In truck and trailer refrigeration, a major development since the last assessment has been the introduction of R-452A as alternative to R-404A. Both non flammability and its drop-in characteristics have led to a substantial penetration in new equipment in Europe, while Asia and North America are continuing using R-404A. As the phase down of equivalent CO2 emissions continues in Europe in aggressive steps, R-452A will probably not become a long term solution due its GWP of approximately 2000. A list of non-flammable blends (such as R-448A, R-449A) with GWP around 1400 are being evaluated, and may represent a second step of the GWP phase down. In parallel, mildly flammable blends, R-744 and R-290 are subjects of relevant research activity and of field trials, and may represent the next step.
Air-to-air conditioners and heat pumps
Globally, in 2018, about half of the installed units currently use HCFC-22 and approximately 60% of new units use non-ODP refrigerants.Enterprises within Article 5 (developing) countries, but mainly within non-Article 5 regions, are continuing to evaluate and develop products with various HFC/unsaturated HFC blends, such as those comprising HFC-32, HFC-125, HFC-134a, HFC-1234yf and HFC-1234ze. In addition to the widespread introduction of HFC-32 in residential split air conditioners in Japan, increased production is continuing in certain countries in South East Asia. Introduction of products has begun in Europe. Further conversion of production lines to HC-290 in China is underway, and (except for small and portable units) there is limited market introduction due to safety standards requirements for certain product groups. In India widespread production of HC-290 split air conditioners continues, with production line conversions underway in several other high ambient temperature countries. However, some enterprises within the Middle East still see R407C and HFC-134a as favourable alternatives to HCFC-22.
Water heating heat pumps
Most heat pumps commercialised today make use of non-ODS refrigerants. Refrigerants used are R-410A, HFC-134a, R-407C, HC-290, HC-600a, R-717, R-744 and recently HFC-32. The majority of new equipment uses R-410A. In some Article 5 countries, HCFC-22 is still used but there are no technical barriers in replacing HCFC-22 by a non-ODS refrigerant.
The phase-out of ozone-depleting refrigerants in chillers is nearly complete. They are still used very little in Article 5 countries. The current generation of chillers using zero-ODP refrigerants, dominated by HFCs with relatively high GWP, was introduced without a sacrifice in reliability or energy efficiency. Investigations into alternative refrigerants with lower GWP began some years ago, and is nearly over.
Vehicle air conditioning
HFC-134a will remain widely adopted worldwide while HFC-1234yf will continue its growth in new models mainly in the USA and Europe due to in force regulations. R-744 is expected to be reconsidered as an option for electrified vehicles due to its performance when used in heat pump systems.