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July 2024

What Is Refrigerant?

Refrigerant makes your air conditioner work and your refrigerator keeps food cold. This chemical compound can switch from liquid to gas and back again, absorbing heat and throwing it away in a closed refrigeration cycle.

It’s used in everything that cools, from fridges and freezers to your home AC system and vehicle air conditioning. Refrigerants have been on a constant path of improvement for decades, balancing thermodynamic properties, refrigeration power, pressure level, action on the ozone layer, and the greenhouse effect. All Temp Air Conditioning & Refrigeration professionals can take care of this for you.


The working fluid in a refrigerator, the refrigerant, circulates a closed loop, absorbing heat from one end of the cycle and releasing it at the other. The heat transfer happens through a combination of chemistry and physics. Chemical reactions that release heat are called exothermic, while those that absorb heat are endothermic. To be a viable working fluid in a freezer, the thermodynamics of the refrigerant must be such that it alternately releases and absorbs heat without changing its internal energy.

The entropy of the system is also an important factor. The higher the entropy, the more random the activity of the molecules. Rising temperatures increase entropy because more energy excites the particles, giving them more room to whiz randomly around. Conversely, compression decreases entropy because the molecules are squeezed closer together.

As the refrigerant transforms from a liquid to a gas in the evaporator, its molecular structure becomes more disorderly, increasing its entropy even further. This explains why a vapor has more energy than a liquid.

If a refrigerant has a low entropy of vaporization, it will not be able to absorb as much heat from the cold air in its evaporator. Therefore, it will need to use more power to raise its temperature, which reduces the efficiency of the refrigeration system.

This is why it is important to choose a good refrigerant with a high entropy of vaporization. The higher the entropy, or free energy, of the refrigerant, the less energy it will need to raise its temperature in the evaporator.

A good refrigerant for the refrigeration industry will have a high-pressure ratio (P/Q), which is important because it increases the effectiveness of the cycle. A higher pressure ratio means that less refrigerant will need to be used per ton of cooling, which cuts costs and lowers the risk of environmental damage.

Researchers are investigating several different types of refrigerants, including single-walled carbon nanotubes and R-407c. These materials have the potential to improve the entropy of the refrigerant and make it easier for it to evaporate. They may even increase the COP of refrigeration systems.


Refrigerants are dangerous when they leak or are exposed to fire or extreme temperatures. They also pose several other physical hazards such as toxicity and asphyxiation. These risks are generally mitigated by design, engineering controls, and proper maintenance. However, refrigerant is particularly dangerous when it is lost due to equipment failure or human error. This is especially true for highly flammable and toxic refrigerants such as hydrocarbons.

In addition, many refrigerants require specific handling and storage procedures to minimize environmental and safety risks. These requirements include maintaining the correct cylinder pressures and ensuring that the right mix of liquid and vapor is in the system when it is used. This requires the use of safety interlocks and disconnects, as well as a full range of personal protective equipment (PPE) including face masks, gloves, eye protection, and respiratory protection.

Technicians need to understand these risks when they work on refrigeration equipment. They must be aware of the potential damage to the environment and the human and animal health impacts, and they must follow the organization’s written EPA policies and procedures. This will help ensure that they are not causing unnecessary harm to the environment and protect them from civil penalties or imprisonment.

Flammable refrigerants must be stored in specialized containers and handled with care to avoid accidental spillage. They should never be mixed with other substances, and they must always be handled by qualified technicians wearing the appropriate PPE. In addition, flammable refrigerants should be stored at a safe distance from ignition sources such as open flames or hot surfaces.

All refrigerants, whether flammable or non-flammable, can cause chemical burns to the skin and eyes. They are also corrosive and may be fatal if inhaled.

Most refrigerants are flammable, but a few do not have an auto-ignition temperature or HSIT. AIT is a test performed to classify a refrigerant as nonflammable by UL-Underwriters Laboratories. HSIT is more relevant to the dynamic conditions of an RAC equipment leak event and is now the preferred test for determining the classification of a refrigerant under ASHRAE 34.

Environmental Impact

Refrigerants are a significant part of your HVAC/R system’s environmental impact. They leak from the compressors and evaporators of your air conditioner, absorbing and releasing heat into the atmosphere as they go. This releases chemicals that can reach the stratospheric ozone layer, which is important to our health because it absorbs most of the sun’s harmful ultraviolet radiation.

In recent decades, refrigerants have improved significantly in terms of safety and efficiency. Global policy has focused on reducing ozone depletion, and the latest refrigerants, like R-410A (a hydrofluorocarbon), have a low GWP and zero ozone depletion potential.

Because the ozone layer is a critical component of our natural climate, the gases that escape from AC systems must be managed appropriately to minimize their impact. The ozone layer protects us from the sun’s harmful UV radiation, and ozone depletion can lead to skin cancer, cataracts, and other diseases.

The ozone layer is made up of small molecules of nitric oxide and oxygen that float in the air. To protect it, we need to reduce the amount of nitric oxide and nitrogen gasses in the atmosphere. Nitric oxide is produced by human activities such as burning fossil fuels. Nitrogen gasses are also a major contributor to the ozone layer’s decline.

As the global community continues to address climate change, refrigerants are under increasing scrutiny for their contribution to greenhouse gases. By enhancing your carbon literacy and understanding the environmental impact of your refrigerants, you’ll be better equipped to make environmentally responsible choices that align with evolving regulations.

Refrigerant GWP values are based on their atmospheric lifetime and relative effect on the climate system. Different refrigerants have differing impacts, depending on the time horizon used to calculate them. For example, some refrigerants have high GWPs over the 20-year horizon but much lower GWPs over the 100-year horizon. This factor can influence how regulators and industry stakeholders prioritize the phase-out of certain refrigerants.

Energy Efficiency

Refrigerants have been a vital part of cooling, refrigeration, and heat pump systems for many years. The ability of these chemical compounds to transition from liquid to gas and back again has been the basis for air conditioning and refrigerators. Often known by the trademark name, refrigerants have helped people enjoy more comfortable homes and businesses for decades. However, recent legislation and newer technology are pushing us away from old refrigerants like CFCs, HCFCs, and HFCs. The EPA and other agencies are working to replace these harmful chemicals with more eco-friendly options.

While most refrigerants are gases, their specific properties have a major impact on energy efficiency. For example, refrigerants with higher heat transfer coefficients require less compressor horsepower and pressure drop, lowering the operating costs. This is particularly important in large industrial facilities where the refrigeration system may be operating continuously for long periods.

In addition to these properties, a refrigerant must be stable, non-flammable, and low in toxicity. This makes it important to understand what is in the refrigerant and how it is regulated. Some of the most common refrigerants include hydrocarbons, carbon dioxide, ammonia, and hydrofluorocarbons. The toxicity of these chemicals depends on the concentration and exposure limits. Most are not poisonous to humans or food products.

Most refrigerants have a low ozone depletion potential (ODP). This means that they do not destroy the ozone layer. However, they still have a global warming potential that can affect the climate. This value varies from one refrigerant to the next.

The lower the GWP, the better. The GWP of a refrigerant is directly related to its electricity consumption during operation. It also determines the emissions of other gases, such as CO2. In addition to the lower GWP, the refrigerant must have stable physical and chemical properties.

A company is currently developing refrigeration solutions with natural refrigerants with a low GWP. These include propane (R290), which is used in our industrial units and chillers; CO2 (R744) for direct expansion commercial refrigeration stations; and R152a, which is used in high-efficiency indirect refrigerant systems.