THE CHEMISTRY BEHIND THE LACK OF VACUUM IN REFRIGERANT PIPELINES

Chemistry as a fundamental axis of science has allowed the development of different disciplines, aimed at improving the quality of life of people, so that through this science has managed to develop advances in technological, agricultural, nuclear, pharmaceutical, environmental issues, among others that affect positively and negatively the development of humanity.

However, I believe that the above is well known and perceived by each of the readers who visit us, hence through this writing would like to deepen the chemistry present in the internal structure of a refrigerant.

You may ask Why do we need to become literate about it? continue reading samples I put them in context, recently I saw the need to buy an air conditioner 18.000 BTU Split version, obviously as I do not know refrigeration I had to locate a technician to perform the installation, everything was perfect, until two days later, when they ask me if the technician made a vacuum to the pipes of the equipment, obviously my answer was no, because he did not, at that moment the doubt entered my head and I started to investigate the matter and what obtained I share the information with you.

As chemists recognize the processes that occur is if simple task, since the equations follow principles already known and we have previously shared in this space disclosure, however, this time we will apply the scientific knowledge associated with chemical reactions and their relevance to the level of refrigeration, specifically when there is the absence of the respective vacuum and the implications of this in the performance and life of the system. Therefore, it is necessary to study the following variables:

1. Formation of corrosive acids:

Remember that we are dealing with a system that has not been subjected to the respective vacuum during its installation process, therefore, we can expect the presence or traces of air and moisture in the system that can react with the refrigerant and generate the formation of corrosive acid.

In this sense, we have to take into account that the model of equipment with which we are working is a Soneview ASV18-3000 working with a modern refrigerant gas R- 410A, the same contains fluorine elements, although some believe that traces of chlorine is still present in the molecular structure of the same, an aspect that will deepen in future issues.

Therefore, when studying the R-410A gas, we get that it is a mixture of two components: the R-32 (difluoromethane) and R-125 (pentafluoroethane), so that when the gaseous mixture of the refrigerant, comes into contact with the water present in the system as impurities, an acid hydrolysis reaction can occur, a process that we represent through the following chemical equation:

In this sense, when talking about acid hydrolysis, we must be aware that the resulting product hydrofluoric acid is extremely corrosive, so that the presence of this inside the pipes, can attack the metal surface of the compressor, generating an accelerated corrosion of the same and reducing the life of the equipment, as they can generate leaks and premature failure of the compressor.

2. Lubricating oil degradation:

A chemical process that threatens the metal surfaces is oxidation, which is why the moving components of compressors are usually lubricated, in the first instance for better performance that reduces friction and on the other hand to prevent rust, however, in the presence of air and moisture, the oil can degrade due to oxidation thereof.

Chemically, oxidation is, if you will, a linear and normal process within the lubricant, since time and use cause it to degrade, in other words, there is a deterioration in the physical and chemical properties of the oil and the additives that cause the antioxidant material to be exhausted. However, when conditions are more extreme, due to the presence of oxygen and moisture, this process is accelerated and is a mechanism known as induction period, which generates a breaking point in the lubricant.

As a consequence of the oxidation present, we will observe an increase in the viscosity of the lubricant, generating the formation of sludge and varnish in the deposits, which implies that the friction protection of the machine has ended.

To understand in detail what happens, it is enough to describe the following chemical equation, where we realize that the oxygen present in the pipes due to the lack of vacuum ends up reacting with the hydrocarbon molecules present in the lubricant and generating unwanted secondary products that affect the efficiency of the system and contaminate the pipes.

3. Formation of coolant bubbles:

Another problem caused by the lack of vacuum in air conditioners is the formation of refrigerant bubbles in the system, bubbles that are able to accumulate in the evaporator and condenser.

The presence of air in the split air conditioning system can lead to the formation of refrigerant bubbles in the circuit. These air bubbles can accumulate in the evaporator and condenser, reducing heat transfer efficiency and affecting the performance of the air conditioner, so that the formation of bubbles is the result of drastic changes in pressure and temperatures at different points in the system.

Chemically what happens is that the refrigerant in liquid form, when in contact with air, causes the gas to dissolve in the liquid thus generating the formation of bubbles and the presence of these in the system can interfere with the flow of refrigerant and reduce the ability of the system to cool effectively. They can also cause instabilities in the refrigerant flow and sudden changes in pressure, which adversely affects the overall performance of the air conditioning system.

In conclusion, the lack of an adequate vacuum during the installation of a split air conditioner as we have studied, can generate negative effects on the operation of the equipment that affects the chemical and physical behavior of the substances involved in the system and decreases the efficiency and life of the equipment.

Having addressed the different mechanisms that affect the lack of vacuum, it is necessary to understand that it is human error that ends up limiting the operation of a system, hence the need for technicians in any field to adopt proper installation practices to avoid affecting the operation of the equipment.

In this specific case, it is necessary to perform the respective vacuum process during the installation of the system, as a measure to eliminate air and moisture, thus avoiding the formation of corrosive acids, the degradation of the lubricating oil and the formation of coolant bubbles.

By following proper evacuation and charging procedures, technicians can ensure efficient and prolonged operation of split air conditioners, reducing the risk of premature failure and costly repairs for end users.

In summary, the lack of adequate vacuum in a split air conditioner can have significant consequences on the performance and life of the system causing the appearance of chemical and physical problems mentioned above, such as the formation of corrosive acids, degradation of the lubricating oil and the formation of refrigerant bubbles that generate damage to components and decrease in the efficiency of the cooling system.

[1] Roberts, S. R., & Brunsting, N. C. (2018). Understanding and Diagnosing Refrigeration System Failures. Refrigeration Magazine, 48(11), 18-22.

[2] Rao, A. R., & Thomas, J. (2020). Refrigeration and Air Conditioning Systems: A Comprehensive Overview. John Wiley & Sons.

[3] Serna-González, M., Reyes-Barranca, A., & Cárdenas-Chávez, D. L. (2019). Impact of Air Conditioning System Improper Installation on Energy Consumption in Residential Buildings. Energies, 12(6), 1011.

[4] Arora, C. P. (2018). Introduction to Refrigeration and Air Conditioning Systems: Theory and Applications. CRC Press.