Introduction

The refrigerant gas Freon is a substance that exists as a gas at normal room temperature but changes state and becomes a liquid when cooled and compressed. The characteristics of Freon gas include being non-flammable, colorless, and odorless. A prominent feature of this gas is that even when combined with moisture, it does not cause corrosion of metals; the smell of Freon gas is similar to that of ether. Freon is actually a trademark for a group of chemical substances (known as chlorofluorocarbons or CFCs), and thus it is used as a refrigerant or coolant in air conditioning systems.

The refrigerant gas Freon is a working liquid used in the refrigeration cycle of air conditioning systems and heat pumps. In the first air conditioning systems and refrigerators, fluorocarbons, especially chlorofluorocarbons (CFCs) such as 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 Refrigerants

In nineteen twenty-eight, Thomas Junior created the first non-flammable and non-toxic chlorofluorocarbon, 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 nineteen eighties, scientists discovered that CFCs damage the ozone layer, which protects the Earth from ultraviolet rays and ozone holes in polar regions. This led to the signing of the Montreal Protocol in nineteen eighty-nine, aimed at the gradual elimination of CFCs and HCFCs. The use of HCFCs such as R-22 and R-123 has ozone depletion potential (ODP).

In the nineteen nineties and two thousands, 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 potentials (GWP) thousands of times greater than CO2, with atmospheric lifetimes that can last for decades.

Since twenty-ten, 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, and R-1233zd, which have both zero ODP and lower GWP, has begun. Hydrocarbons and CO2 are sometimes referred to as natural refrigerants because they are found in nature.

Types of Freon Gas and Their Applications

The refrigerant gas Freon is divided into the following types based on its compounds and applications:

Refrigerant R22

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

The Freon refrigerant R-22 is one of the most well-known HCFC (hydrochlorofluorocarbon) refrigerants. After the ban on the use of CFCs, it found extensive applications in air conditioning and refrigeration systems that have low evaporation temperatures. In the past, due to its high compressibility and ability to create more cooling, this gas was used in almost all air conditioning systems and cooling devices, including air conditioners, compression chillers, ducted split systems, household refrigerators, etc.

In quick-freezing devices, R-22 gas is used due to maintaining their temperature between twenty to forty degrees Fahrenheit. R-22 is only used in piston compressors, and its operating pressure is such that to achieve low temperatures, there is no need to operate at pressures below atmospheric pressure. Its latent heat per pound at five degrees Fahrenheit is 21.93 BTU. The normal pressure at the compressor head at eighty-six degrees is 82.172 pounds per square inch absolute.

Also, due to R-22's stronger tendency to absorb moisture, more dehumidifiers are needed to dry it. R-22 dissolves in oil up to sixteen degrees Fahrenheit, after which the oil begins to separate and, being lighter than the liquid, collects at the surface.

However, alongside the unique features of R22 gas, it is essential to mention the negative effects of this gas. The production and use of this refrigerant have been banned since twenty-ten for environmental reasons such as ozone layer depletion and global warming, and the refrigerant R410A has replaced it. However, the use of R22 gas in cooling equipment is permitted as long as its stock is not exhausted.

Refrigerant R134a

The refrigerant gas R134a, which has now replaced Freon 12 and 11, is heavier than air, has a chemical formula of CH2FCF3, a molecular weight of 102.03, and has suitable thermodynamic properties. This gas is non-toxic and non-flammable. It is moisture-absorbing and has a purity degree of 99.95. It contains synthetic oil (polyester) and does not mix with natural oil. It lacks chlorine atoms and has no negative effect on the ozone layer. Compared to R-12, it has better thermal conductivity, higher latent heat, and greater heat transfer capability. The gas R134 absorbs more moisture than R12, and the R134 compressors should never be run for more than thirty seconds in high humidity ambient air for efficiency testing, as the moisture in the air gets absorbed by the compressor oil and disrupts the refrigeration cycle. This gas is environmentally acceptable, making it suitable for use in household refrigerators and car air conditioners.

Refrigerant R290

This refrigerant is more commonly known as high-purity propane. With the chemical formula C3H8, it is one of the natural gases that, due to its high cooling capacity and consequently lower consumption compared to other gases, R290 refrigerant is a suitable alternative to R22 and R12 and has gained attention in the refrigeration industries worldwide, being used in the manufacture of refrigerators and air conditioners.

Refrigerant R404

One of the industrial refrigerants that is a blend of three other refrigerant gases is called R404. The components of Freon gas R404 are gases R12, R22, and R502. An important point regarding blended refrigerants is that they must be charged in a liquid state. The gas R404A is a non-ozone-depleting gas and is a suitable replacement for R502 and R22 at low and medium temperatures, specifically at evaporation temperatures below zero degrees Fahrenheit.

Due to the production of this gas for low-temperature applications (evaporator temperature of minus twenty degrees Celsius) and medium-temperature applications (evaporator temperature of minus five degrees Celsius), it is used in the design of commercial freezers, food transport vehicles, display refrigerators, and ice makers.

Refrigerant R410a

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

The gas R410a has a boiling point of minus 51.4 degrees, which, compared to the boiling point of R22 at minus 40.8 degrees, has a much higher efficiency and is ozone-friendly, with a very good cooling capacity, making it one of the most widely used gases in both residential and industrial sectors. Currently, R410 is the best option for use in chiller cooling systems and small heat exchangers such as inverter and energy-efficient air conditioners.

It is worth mentioning that refrigerants R11 and R12 are the first generation of Freon refrigerants that have been phased out due to their destructive effects on the ozone layer.

Freon gases and their comparison in refrigeration systems

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