Introduction

Freon refrigerant is a substance that is in gaseous form at normal room temperature, but when cooled and compressed, it changes state and becomes liquid. Some of the characteristics of Freon gas include being non-flammable, colorless, and odorless. One notable feature of this gas is that even when combined with moisture, it does not cause metal corrosion; the smell of Freon gas is similar to ether. Freon is actually a trade name for a group of chemicals (known as chlorofluorocarbons or CFCs) and is used as a refrigerant or coolant in air conditioning systems.

Freon refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps. In the early air conditioning systems, refrigerants such as fluorocarbons, especially chlorofluorocarbons (CFCs) like ammonia, sulfur dioxide, methyl chloride, or propane, were traditionally used as refrigerants, which were toxic or flammable gases that have been phased out due to their toxicity, flammability, and contribution to ozone depletion and climate change.

In this article, we intend to discuss topics related to Freon gas, its types, applications, effects of Freon gas, and its use in refrigeration systems.

History of Freon Refrigerant

In 1928, Thomas Junior created the first non-flammable and non-toxic chlorofluorocarbon gas, Freon R-12. Following the discovery of better synthesis methods, CFCs such as R-11, R-12, R-123, and R-502 dominated the market.

In the early 1980s, scientists discovered that CFCs were damaging the ozone layer, which protects the Earth from ultraviolet radiation and ozone holes in polar regions. This led to the signing of the Montreal Protocol in 1989, aimed at phasing out CFCs and HCFCs. HCFCs like R-22 and R-123 have ozone depletion potential (ODP).

In the 1990s and 2000s, hydrofluorocarbons (HFCs) such as R-134a, R-143a, R-407a, R-407c, R-404a, and R-410a replaced CFCs and HCFCs. HFCs do not deplete the ozone layer but have global warming potential (GWP) thousands of times greater than CO2 and can persist for decades.

Since 2010, the use of Hydrocarbon and HFO (hydrofluoroolefin) refrigerants R-32, R-290, R-600a, R-454b, R-1234yf, R-514A, R-744 (CO2), R-1234ze, R-1233zd, which have zero ODP and lower GWP, has begun. Hydrocarbons and CO2 are sometimes called natural refrigerants because they are found in nature.

Types of Freon Gas and Their Applications

Freon refrigerant is divided into various types based on compounds and applications:

R22 Refrigerant

R-22 gas has characteristics such as stability, non-toxicity, non-oxidizing properties, and non-flammability.

Freon refrigerant R-22 is one of the most well-known HCFC (hydrochlorofluorocarbon) refrigerants. After the prohibition of CFCs, it has found extensive use in refrigeration and air conditioning systems with low evaporation temperatures. In the past, due to its high density and ability to provide more cooling, this gas was used in almost all air conditioning systems and cooling devices, including gas coolers, compression chillers, gas coolers, split ducts, household refrigerators, etc.

In rapid freezing devices, R-22 gas is used to maintain their heat between 20 to 40 degrees Fahrenheit. R-22 is only used in piston compressors, and its operational pressure is such that it does not require lower-than-atmospheric pressures to reach low temperatures. Its latent heat per pound at 5 degrees Fahrenheit is 93.21 BTU. The normal compressor head pressure is 172.82 pounds per square inch absolute at 86 degrees.

Also, alongside the unique features of R22 gas, its negative effects should be mentioned. The production and use of this refrigerant have been banned since 2010 due to environmental reasons such as ozone depletion and global warming, and R410A refrigerant has replaced it. However, the use of R22 refrigerant in cooling equipment is allowed until the existing stock is depleted.

R134a Refrigerant

R134a refrigerant, which has replaced Freon 12 and 11 today, is heavier than air, with a chemical formula of CH2FCF3, a molecular weight of 102.03, and suitable thermodynamic properties. This gas is non-toxic, non-flammable, moisture absorbent, and has a purity level of 99.95%. It uses synthetic oil (polyester) and does not mix with natural oil. It is chlorine-free and has no negative impact on the ozone layer. Compared to R-12, it has a better heat conductivity coefficient, higher latent heat, and better heat transfer capability. R134 gas absorbs more moisture than R12 and should never have R134 compressors running for more than 30 seconds in an environment with high humidity, as the moisture in the air absorbs compressor oil and disrupts the cooling cycle. This gas is environmentally acceptable, making it suitable for use in household refrigerators and car air conditioners.

R290 Refrigerant

This refrigerant is better known as propane with high purity. With a chemical formula of C3H8, it is one of the natural gases known for its high cooling capacity and lower consumption compared to other gases. R290 refrigerant is an appropriate substitute for R22 and R12 gases, attracting attention in the refrigeration industry and being used in the production of freezers, gas coolers, and refrigerated display cases.

R404 Refrigerant

One of the industrial refrigerants, a combination of three other refrigerant gases, is called R404. The components of Freon gas R404 are gases R12, R22, and R502. An important point about composite refrigerants is that they must have a liquid state for charging. R404A gas is a non-ozone-depleting gas and a suitable replacement for R502 and R22 at low and medium temperatures, meaning temperatures with evaporation temperatures below zero degrees Fahrenheit.

Due to its production for low-temperature applications (operator temperature of -20 degrees Celsius) and medium-temperature applications (operator temperature of -5 degrees Celsius), R404 is used in the design of commercial freezers, refrigerated transport vehicles, display refrigerators, and ice makers.

R410a Refrigerant

R410a gas is a blend of two other gases. The components of Freon gas R410a are 50% R125 gas (pentafluoroethane) and 50% R32 gas (difluoromethane).

R410a gas has a boiling point of -4.51 degrees, which is much more efficient than R22 gas, which has a boiling point of -40.84 degrees. It is highly efficient and ozone layer-friendly, with excellent cooling capacity, making it one of the most widely used gases in residential and industrial sectors. Currently, R410 is the best choice for use in chiller systems and small heat exchangers such as inverter gas coolers and low-consumption systems.

It is worth mentioning that R11 and R12 refrigerants were the first generation of Freon refrigerant gases that have been phased out due to their ozone-depleting effects.

Refrigerant Gases and Their Comparison in Refrigeration Systems

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