Types of refrigerants

[edit] Introduction

Natural refrigerants such as propane and ammonia have been used for many years, but as the need to then keep food safe and cool became more difficult with ice over longer transport distances, a variety of refrigerants were used. Prior to around the 1900s many refrigerants were unsafe and dangerous, by the late 1920s Thomas Midgley Junior developed the first synthetic refrigerant chlorofluorocarbon (CFC) R-12, or Freon, then a safer, non-flammable, and non-toxic refrigerant. It was stable, and could be used under different operating conditions, and could be combined with oil for use in compressors, its effect on the ozone layer was not at that time known, and its use was widespread.

Iterations of freon such as R-22 (a HCFC) and R-134a, are still found today in applications like refrigerators and vehicle air conditioners, whilst the increase in the use and popularity of heat pumps has placed an increasing focus on the use of refrigerant gases, their efficiencies and environmental impacts.

The range of potential refrigerants continues to be broad such as chlorofluorocarbons, ammonia, hydrocarbons, carbon dioxide, chlorodifluoromethane, tetrafluoroethane, freon, CO2, natural refrigerants, dichlorodifluoromethane and water. As such many are now referred to by a type and with a prefixed R, which was introduced by DuPont which eventually owned the brand Freon. There other classifications that may be used such as by class 1, 2 and three denoting the way the refrigerant works by storing latent heat, sensible heat or the ability to carry liquefiable vapours.

[edit] Types of refrigerants

[edit] Propylene (R1270)

R1270 (Propylene) is refrigerant-grade propylene which can be used in low and medium temperature refrigeration and air- conditioning applications. R1270 (Propylene) is a hydrocarbon and although highly flammable is an efficient refrigerant with low Global Warming Potential (GWP) and can be used as an alternative to R22.

[edit] Carbon dioxide (R744)

Carbon dioxide is not a new refrigerant. The use of carbon dioxide as a refrigerant lasted for well over a century, but was abandoned in the mid-1950s, with the widespread use of the CFC refrigerants, which were more efficient, more stable and safer. It was ‘rediscovered’ in the early 1990s. Due to its low environmental impact, low toxicity and non-flammability, CO2 is now regaining popularity with refrigeration system designers whilst an alternative to fluorocarbons is being sought.

[edit] Ammonia (R717 / R171)

Ammonia has been continuously used throughout modern refrigeration history, but has numerous drawbacks. It is toxic and flammable in concentrations between 15.5% and 28% in air. It is not compatible with copper, thus requiring other materialsfor construction. But ammonia’s thermodynamic and thermo-physical properties also yield very efficient refrigerationsystems. Because of its acute toxicity, stringent regulations apply for ammonia systems, which require close monitoring and highly-skilled engineers and technicians. It terms of industrial usage R717 is a suitable refrigerant for heat pumps as itsefficiency is relatively high and because it is a natural refrigerant it does not contribute to the greenhouse effect.

[edit] Isobutane (R600A)

Isobutane (R600A) a hydrocarbon, and hence is flammable. Its thermodynamic properties are very similar to those of R134a. Isobutane presents other advantages, such as its compatibility with mineral oil and better energy efficiency and it is cheaper than R134a. The use of isobutane requires minimal design changes, such as the relocation of potential ignition sources outside the refrigerated compartment.

[edit] R-454b

R-454b is a blend that consists of nearly 70% R-32. Whereas R-32 is a single component refrigerant.

[edit] R-410A

R-410A a hydrofluorocarbon compound (HFC), was considered to be the most common alternative to R-22, sometime after the convention after it was banned 2010. The Montreal Protocol, Kigali Amendment, then proposed to phase-down the use of all HFC refrigerants including R-410A.

[edit] Propane (R290)

Propane (R290) has a boiling point of –42°C, making it an excellent alternative to R22 as it requires similar working pressures. An added advantage is that, other than added safety measures because of its flammability, virtually no designchange is required in systems when switching from R22 to propane. The combination of its good thermodynamic and thermo-physical properties yields systems that are at least as energy efficient as those working with R22. The use of propane is increasing in countries where regulations allow it. R290 heat pumps have a higher coefficient of performance(COP) than R32 heat pumps at lower outdoor temperatures, making them a better choice for cold climates.

[edit] 1,1,1,2 - tetrafluoroethane (R134a)

1,1,1,2 - tetrafluoroethane (R134a) is a hydrofluorocarbon (HFC) used for domestic, commercial and industrial refrigerated applications, air conditioning, fluid cooling and in heat pumps. Popular in automotive and agricultural air-conditioning systems manufacturers, with a variation more likely to be used today named R-1234yf.

[edit] HFC-32 (R-32)

HFC-32 (R-32) is an organic hydrofluorocarbon compound with the formula CHF. The comparatively low GWP of R32 which is 675 and zero ODP means it might be considered a more environmentally-friendly choice than traditional refrigerants like R410A. It is a single-component refrigerant meaning it can be easier to recycle and indication is that such R32 systemsrequite 20% less refrigerant than say R410A models, so also more efficient and with a lower cost.

[edit] R-22

R-22, a hydrochlorofluorocarbon (HCFC) the standard refrigerant utilised in residential air conditioners from the 1930s. It was included in the 1987 Montreal Protocol list of substances noted for a step-by-step phase out of production.

[edit] R-12

R12 is a colourless and odourless CFC refrigerant that was phased out of production in 1995 due to its ozone-depleting nature.

[edit] Related articles on Designing Buildings

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• Air conditioning inspection.
• Air handling unit.
• BREEAM Impact of refrigerants.
• Chilled beam.
• Chiller unit.
• Chilled water.
• Chlorofluorocarbons CFCs.
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• Cooling systems for buildings.
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• Compression refrigeration.
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• EMEA compressor market 2020 - 2023.
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• Greenhouse gas.
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• Montreal Protocol.
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• Refrigerants in building services guide TG 21/2022.
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