The refrigerants are single component for refrigerant designation numbers below 400 and from 600 and up, while designation numbers in the 400’s and 500’s are mixtures of two or more components. The 400 series are blends with a temperature glide, known as zeotropes. If the glide is large then exchangers need to be designed suitably to take this into account. The 500 series are blends, which are azeotropic at some condition, thus inferring with negligible temperature glide and change in composition between the liquid and vapour phases.
CFC-11
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CFC-11 was introduced in 1932 as a replacement to flammable and or toxic refrigerants used at the time and gained popularity in Centrifugal chillers (Calm, 1997) and was widely used as a solvent and a blowing agent. CFC-11 is classed as an A1 refrigerant and is the reference substance for ODP and has a defined ODP of 1. It is a low pressure refrigerant, with similar pressure as HCFC-123, and has often been replaced with this refrigerant.
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CFC-12
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CFC-12 was introduced in 1931 as a replacement to flammable and or toxic refrigerants used at the time (Calm, 1997) and has been popular in both refrigeration applications and chillers for air-conditioning. CFC-12 is classed as an A1 refrigerant, and has high ODP, almost as high as CFC-11. The pressure is similar to HFC-134a, which replaced it in many applications.
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HCFC-22
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HCFC-22 was originally used for low temperature refrigeration and later air-conditioning, and is today the most popular HCFC refrigerant. It is classed as an A1 refrigerant and is the most used refrigerant in the world for commercial refrigeration, industrial processes, and mainly air-to-air air conditioning systems. The HCFC-22 bank is estimated to be 1,6 million metric tonnes at the global level. The energy efficiency of this refrigerant became a reference for the validation of its substitutes: R-404A in commercial and industrial refrigeration and R-407C and R-410A in air conditioning. HCFC-22 has a medium pressure similar to R-404A and R-407C, and as seen in section 2.2.2 below, alternatives to HCFC-22 has been getting attention in the industry.
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HFC-32
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HFC-32 was originally used as a component of refrigerant blends such as R-407C and R-410A. Pressure and capacity are around 1.5 times higher than HCFC-22 and slightly higher than R-410A. It is classed as A2L. The efficiency of HFC-32 systems are higher than R-410A but less than HCFC-22. Discharge temperatures are higher than R-410A and HCFC-22 and thus some mitigation device or controls may be necessary for handling the discharge temperature of the compressor especially at high ambient temperatures.
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HCFC-123
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HCFC-123 is mainly used in centrifugal chillers and is classed as a B1 refrigerant. HCFC-123 is a low-GWP HCFC refrigerant, but since it is an ODS it is being phased-out under the Montreal Protocol.
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HFC-125
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HFC-125 is used as a component of refrigerant blends such as R-404A and R-410A to lower discharge temperature and reduce flammability from other components.
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HFC-134a
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HFC-134a is used in a variety of equipment including heat pumps, chillers, mobile air conditioning and domestic refrigeration and has a pressure lower than HCFC-22 and similar to CFC-12. It is classed as an A1 refrigerant. Energy efficiency is good, provided that pipes and heat exchangers are suitably sized.
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HFC-152a
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HFC-152a has performance characteristics similar to HFC-134a as well as 10% lower vapour pressure and volumetric refrigeration capacity. It is classed as an A2 refrigerant. HFC-152a is used as a component in several new blends.
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HFC-161
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HFC-161 has with zero ODP and very low GWP of 4 (IPCC, 2014) and it is under evaluation to replace HCFC-22 in small air conditioning unit. It is not yet classified in ISO 817 (ISO 817: 2014) or ASHRAE 34 (ASHRAE 34-2013) but is likely to be classified A3. Performance is similar to HCFC-22 and HC-290. The lower flammability limit is about 4 times higher than for HC-290 allowing for a higher charge to be used and thereby higher cooling capacity to be achieved compared with a system using HC-290.
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HFC-245fa
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HFC-245fa has found limited use in centrifugal chillers, high temperature heat pumps, and organic Rankine cycle (ORC) power generation cycles and is classified as B1. Because the high temperature heat pump and ORC are still emerging markets the use may increase. It has operating pressures higher than for HCFC-123 but lower than for HFC-134a.
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HC-290
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HC-290 has thermodynamic properties similar to HCFC-22, although slightly lower pressure and capacity. It is classified as A3. Due to its excellent thermophysical properties the efficiency is good under most conditions, including high ambient, as well as having low discharge temperatures. It is the most frequently used hydrocarbon refrigerant in air conditioning applications. It is also used as a major component in many HC blends.
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R-404A
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R-404A is used widely in commercial refrigeration systems, and is classified as A1. The efficiency is acceptable. A major advantage of R-404A is the low discharge temperature, which makes it possible to have a high temperature lift in a single stage system, hence it being the primary substitute for R-501. R-404A is also used in industrial refrigeration, especially when R-717 is not desired for safety or technical reasons. R-404A and R-507A are very similar in composition and performance parameters.
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R-407A
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R-407A is a mixture of the same components of other 407 refrigerants but in slightly different proportions. It was originally developed to replace HCFC-22 and is now used as a replacement for R-404A. It is classified as A1. The efficiency is acceptable and better than R-404A. However, its moderate temperature glide and higher discharge temperature needs to be taken into account.
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R-407C
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R-407C is a mixture of the same components of other 407 refrigerants but in slightly different proportions. It has been used widely in air conditioning, chiller and heat pump systems, especially to help the transition from HCFC-22. It is classed as A1. The efficiency is acceptable and better than R-404A. However, its moderate temperature glide and higher discharge temperature needs to be taken into account.
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R-407F
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R-407F is a mixture of the same components of other R-407 refrigerants but in slightly different proportions. It is used as a replacement for R-404A. It is classified as A1. The efficiency is acceptable and better than R-404A. However, its moderate temperature glide and higher discharge temperature needs to be taken into account.
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R-410A
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R-410A is used widely in air conditioning, chiller and heat pump systems and is classified as A1. The pressure of R-410A is higher than HCFC-22, the R-407 series and R-404A. Generally the efficiency is equivalent to HCFC-22, especially at lower temperatures, although efficiency and capacity deteriorates at a greater rate at higher ambient temperatures.
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R-417A
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R-417A is mainly designed to replace HCFC-22 as a “drop-in” in air-conditioning systems, but is also utilised in refrigeration and heat pump applications in existing systems as well as in new equipment. It is classified A1 and has a higher GWP than HCFC-22.
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R-444A
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R-444A is a replacement for HFC-134a and is classified as A2L. It has efficiency, capacity and operating pressures close to HFC-134a.
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R-444B
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R-444B can replace HCFC-22 in new AC equipment without major modifications as its pressures are similar. It is classified as A2L. R-444B matches the capacity of HCFC-22 with a marginally lower efficiency although relative performance can be better in high ambient climates.
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R-445A
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R-445A is a replacement for HFC-134a and is classified as A2L. It has been tested in mobile air conditioning systems where its energy efficiency and capacity are close to HFC-134a and HFC-1234yf. Its temperature glide is about twice that of R-407C, which may influence system design.
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R-446A
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R-446A can replace R-410A in AC equipment and is classified as A2L. Efficiency of R-446A systems is comparable to R-410A whilst the capacity is lower than R-410A and discharge temperatures are slightly higher. Due to its relative higher critical point compared to other refrigerants, R-446A performs well at high ambient temperatures.
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R-447A
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R-447A can replace R-410A in AC equipment and is classified as A2L. The efficiency of R-447A systems is at the same level as R-410A, the capacity is slightly lower and discharge temperatures are slightly higher than R-410A. Due to its relative higher critical point compared to other refrigerants, R-447A performs well at high ambient temperatures.
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R-448A
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R-448A can replace R-404A in existing and new refrigeration equipment and is classified as A1. This refrigerant has capacity and efficiency similar to R-404A. However, its notable temperature glide may influence system design.
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R-449A
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R-449A can replace R-404A in new refrigeration equipment and is classified as A1. This refrigerant has a capacity marginally higher than R-404A and a slightly better efficiency.
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R-450A
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R-450A can replace HFC-134a in new equipment, where its lower volumetric capacity can be addressed in the design of the equipment. It is classified as A1. When used in reciprocating or scroll compressors, this refrigerant produces efficiency levels comparable to HFC-134a, although the capacity is lower.
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R-507A
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R-507A is used widely in commercial refrigeration systems, and is classified as A1. The efficiency is acceptable. A major advantage of R-507A is the low discharge temperature, which makes it possible to have a high temperature lift in a single stage system (thus being adopted as a replacement for R-502). It is also used in industrial refrigeration, especially when R-717 is not desired for safety or technical reasons. R-404A and R-507A are very similar in composition and performance parameters.
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HC-600a
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HC-600a is a low pressure hydrocarbon refrigerant classified as A3. The operating pressures and capacity is less than half that of HFC-134a, whilst efficiency is good. It is used extensively for small refrigeration systems such as domestic refrigeration and small commercial systems. It is also used as a component in many HC blends.
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R-717
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R-717 (ammonia, NH3) is classified as B2L. In principle, it has thermo-physical properties that lead to excellent efficiency. The vapour pressure and refrigerating capacity is similar to HCFC-22. However, R-717 has a very high discharge temperature, so for lower temperature applications two-stage-compression is normally needed. It is not practically compatible with copper and copper alloys, which limits the system to welded steel or aluminium components and piping. The application of R-717 in small to large absorption systems is also wide spread.
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R-718
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R-718 (Water, H2O) is used as refrigerant in vapour compression cycles at very low pressures, high compression ratios and high volumetric flow rates, leading to larger system sizes and a cost premium. It has also been tested for high temperature heat pumps with promising results, especially when it can be integrated in direct vapour compression cycles. It is also used in adsorption chillers, coupled with widely available adsorbents such as silica gel and zeolite, and in absorption systems either with LiBr as absorbent, or as absorbent of ammonia.
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R-744
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R-744 (carbon dioxide, CO2) is classified as A1, and has thermo-physical properties that lead to good efficiency for certain levels of temperatures (such as for refrigeration range). The vapour pressure is several times greater than usual refrigerants and the volumetric refrigerating capacity is correspondingly higher for conditions below 25°C. However, with a very low critical temperature, the cycle efficiency declines as the temperature before the expansion device increases and other features are needed to achieve similar (to HCFC-22) efficiency values at higher ambient conditions. Compared to a basic cycle, 10–20% energy efficiency improvement can be achieved by applying an ejector instead of an ordinary expansion device (Hafner, 2012) although using an expander alone can bring the efficiency to within 10% of HCFC-22 (Subiantoro, 2013). Other features to help improve efficiency in high ambient conditions include economiser (parallel compression), liquid-suction heat exchange and mechanical subcooling. Also, discharge temperatures are very high and therefore, where the high temperature cannot be utilised, technology options such as additional compression stages and inter-cooling may be adopted in the system design. These additional features add to the complexity and cost of the system.
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HCFC-1233zd(E)
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HCFC-1233zd(E) is an unsaturated HCFC and has similar pressure to that of HCFC-123. It is classified as A1. When used with centrifugal compressors, this refrigerant produces efficiency levels similar to HCFC-123, allowing the design of systems with very high energy efficiency.
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HFC-1234yf
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HFC-1234yf is an unsaturated HFC and can replace HFC-134a in same systems since the pressure-temperature characteristics are almost identical, It is classified as A2L. In general this refrigerant produces efficiency levels comparable to HFC-134a although the theoretical COP is a few percent below that of HFC-134a.
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HFC-1234ze(E)
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HFC-1234ze(E) is an unsaturated HFC and can replace HFC-134a in new equipment where its lower volumetric capacity can be addressed in the design of the equipment. It is classified as A2L.
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HC-1270
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HC-1270 is an unsaturated hydrocarbon with a vapour pressure and capacity almost identical to HCFC-22. It is classified as A3 and also has a distinctive odour. Due to its excellent thermophysical properties the efficiency is good under most conditions, including high ambient, as well as having low discharge temperatures.
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