The refrigerator is one of the most important household appliances in every home, ensuring the safety of food. However, few people think about the fact that a complex physical process is constantly happening inside this device, due to which a low temperature is created. The heart of this system is a special working substance that circulates in a closed circuit, taking heat from the internal chamber and releasing it to the environment. It is this substance that we call refrigerant.
In everyday life, this gas is often mistakenly called simply “freon,” although in fact freon is only a trademark of one of the groups of refrigerants that has become a household name. Understanding what is refrigerant and how it functions will help owners of refrigeration equipment better understand the causes of malfunctions and operating rules. If you have ever noticed that the refrigerator has stopped freezing, but the compressor is humming, the problem may lie precisely in the leakage or degradation of this gas.
Modern environmental standards dictate their own rules, forcing manufacturers to abandon some substances in favor of others that are safer for the ozone layer of the planet. In this article, we will analyze in detail the structure of the refrigeration cycle, consider the main types of gases used today, and answer the questions that users most often have when servicing equipment.
The principle of operation of the refrigeration cycle
The basic principle of operation of any refrigeration equipment is based on the properties of substances to change their state of aggregation at different pressures and temperatures. Refrigerant is a liquid or gas that easily passes from a liquid to a gaseous state and back, absorbing or releasing a huge amount of thermal energy. This process occurs continuously as long as the device is connected to the electrical network.
The refrigeration cycle begins in the compressor, which compresses the gaseous substance, increasing its pressure and temperature. After this, the hot gas enters the condenser (usually a grate on the back wall), where it cools and turns into a liquid state, releasing heat into the room. Next, the liquid passes through a filter drier and a capillary tube, where the pressure drops sharply, and the substance again turns into gas, but at a very low temperature.
It is this cold gas that enters the evaporator located inside the freezer or refrigerator compartment. Passing through the evaporator tubes, working fluid boils at low temperatures, actively absorbing heat from the products and air inside the chamber. After this, the cycle repeats: the gas is again sucked into the compressor, and the process begins again. The efficiency of the entire system directly depends on the quality and quantity of the circulating gas.
⚠️ Attention: Violation of the tightness of the circuit leads to the release of refrigerant to the outside. Trying to turn on the refrigerator without gas can lead to overheating and combustion of the compressor, since the gas also performs the function of cooling the motor.
Main types of refrigerants and their characteristics
The history of the development of refrigeration technology goes back more than a hundred years, and during this time humanity has used many different substances for cooling. Previously, ammonia, sulfur dioxide and even methyl chloride were used, but they were abandoned due to toxicity and explosiveness. In the middle of the 20th century, the era of fluorinated hydrocarbons began, known as freonswhich were considered ideal because of their inertness and safety.
However, over time it became clear that some types of freons containing chlorine destroy the Earth's ozone layer. This led to the Montreal Protocol and the gradual banning of the most harmful substances. Modern refrigerators operate on new types of gases that either do not contain chlorine or quickly break down in the atmosphere without causing harm to the environment.
Below is a table comparing the main types of refrigerants that can be found in household appliances of different years of manufacture:
| Refrigerant type | Chemical formula | Effect on ozone | Application |
|---|---|---|---|
| R-12 (Freon-12) | CF2Cl2 | High (destroys) | Old Soviet and imported models (up to 90s) |
| R-134a | CH2FCF3 | Safe | Modern household refrigerators (standard) |
| R-600a (Isobutane) | C4H10 | Safe | Energy efficient models, quiet refrigerators |
| R-404A | Mixture | Safe | Industrial freezers and display cases |
The most common today is R-134awhich replaced the harmful R-12. It does not burn and is not toxic, but requires more careful sealing of the system. Another popular option is R-600a (isobutane). This is a hydrocarbon gas that has excellent cooling properties and allows you to make refrigerators quieter and more economical.
Why is R-600a dangerous?
Despite its environmental friendliness, isobutane (R-600a) is a flammable gas. In high concentrations, if leaked, it can ignite from a spark. However, in household refrigerators its amount (about 30-50 grams) is too small to create an explosive situation in an ordinary room, so such models are certified for use at home.
Environmental aspects and safety of freons
The issue of environmental safety has become a driver of changes in the refrigeration industry. For a long time it was believed that refrigerants based on chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are absolutely safe for humans. And this is true: they are odorless, non-toxic upon short-term contact and do not burn. But their stability played a cruel joke - getting into the upper layers of the atmosphere, they disintegrated under the influence of ultraviolet radiation, releasing chlorine, which destroyed ozone molecules.
Modern hydrofluorocarbons (HFC), such as R-134a, no longer contain chlorine, so they ozone depletion potential is zero. However, they have another disadvantage - high global warming potential (GWP). Once in the atmosphere, they act as greenhouse gases, increasing the heating of the planet. That is why the world community continues to look for alternatives, returning to “natural” refrigerants such as propane, butane or carbon dioxide.
⚠️ Attention: Although modern freons are considered safe for humans in household concentrations, inhalation of vapors in a confined space can cause asphyxiation, because the gas displaces oxygen. Ventilate the room if you suspect a leak.
The use of hydrocarbons, such as R-600a, is the most environmentally friendly solution at the moment. They completely decompose in nature and do not affect the climate. However, their flammability requires manufacturers to implement additional safety measures: the use of intrinsically safe automation, special markings and reducing the amount of charged gas to the minimum required level.
Leak Symptoms and Low Refrigerant Levels
The refrigeration circuit is a sealed system, and under ideal conditions, the refrigerant should circulate in it for decades without refilling. However, due to metal corrosion, vibration, mechanical damage or manufacturing defects, a microcrack may occur. Leakage is one of the most common reasons why a refrigerator stops performing its function. How to understand that the problem is in the gas?
The first and most obvious sign is an increase in temperature in the chambers. Food begins to spoil, the refrigerator compartment is warm, and the ice in the freezer is melting. In this case, the compressor can work continuously without turning off, trying to compensate for the lack of cold. In some cases, especially when used R-600a, the operation of the compressor may become intermittent or it may not start at all due to protection.
Visually it is difficult to detect a leak, since the gas is colorless and odorless. However, sometimes an oily spot may appear where the gas escapes. The fact is that a special compressor oil circulates through the system along with the refrigerant. If gas escapes, the oil remains on the surface, collecting dust. Frost or ice may also be unevenly distributed on the evaporator.
- ❄️ The compressor works constantly or turns on very often, but there is no cold.
- 🧊 In the freezer, the food is soft, the ice has turned into water.
- 🔊 Change in the sound of the motor (the humming becomes quieter or clicks appear).
- 💧 The appearance of oily traces on the tubes or walls of the refrigerator.
If you notice such symptoms, further operation of the equipment may be dangerous for the compressor. Working “dry” or with a low oil level leads to jamming of the piston group. In this case, repairs will cost much more than simple refueling.
☑️ Leak diagnostics
The process of replacing and refilling the refrigerator
Replacing or refilling the refrigerant is a complex technical process that cannot be performed at home without specialized equipment. It's not like refilling a printer or adding oil to a car engine. A full understanding of thermodynamics and the availability of tools for working with high pressures are required.
First, the technician must find the location of the leak. To do this, use nitrogen to pump the system and a leak detector or soap solution to look for bubbles. After detecting a defect, soldering is performed. Then the system must be evacuated. This is a critical step: all air and, most importantly, moisture must be removed from the circuit. The water in the system will freeze in the capillary tube, creating an ice plug that will stop the circulation of gas.
Only after creating a deep vacuum is refueling done. The amount of refrigerant is dosed to the nearest gram using an electronic scale. Overfilling or underfilling is equally detrimental to operating efficiency. For different types of gases, for example, for R-134a and R-600a, different equipment and oils are used, it is strictly forbidden to mix them.
Typical sequence of actions of the master:1. Leak detection (nitrogen + leak detector).
2. Elimination of the defect (soldering with a torch).
3. Evacuation of the system (up to 200-300 microns).
4. Refrigerant charging by scale.
5. Checking the tightness and test run.
⚠️ Attention: An independent attempt to fill the refrigerator with a can from a car store will lead to compressor failure. The pressure and type of oil in automotive and household systems are radically different.
Frequent questions and misconceptions of users
There are many myths around the topic of refrigerants that give rise to unreasonable fears or, conversely, carelessness. One of the most common myths is that freon needs to be “changed” or “renewed” periodically, like the oil in a car. This is incorrect. Refrigerant - this is a working fluid of a closed cycle; it is not consumed during the work process. If there is not enough gas, then there is a leak that needs to be repaired.
Another misconception concerns the smell. People often think that if the refrigerator has stopped freezing, they will smell gas. But modern freons do not smell. If you smell it, it's most likely burnt wiring, plastic, or spoiled food, not the refrigerant itself. The exception is ammonia in old industrial installations, but it is practically never found in everyday life.
It is also important to understand the difference between a refrigerant and a coolant. There is no “cold” in the refrigerator that you can touch. There is a process of heat selection. The gas takes heat energy from the food and releases it through the grille at the back. Therefore, to say that “the cold has ended” is technically illiterate, although this expression has taken root in everyday life.
Is freon dangerous for humans when inhaled?
Modern household refrigerants (R-134a, R-600a) are low-toxic. Brief inhalation of small vapors will not cause serious harm to health, but may cause dizziness or nausea due to lack of oxygen. The danger is a high concentration of gas in a small, unventilated room, which can lead to suffocation. In addition, R-600a is flammable, so in case of a strong leak, fire sources should be excluded.
Can car freon be used for a refrigerator?
Absolutely not. Car air conditioners and household refrigerators operate on different types of refrigerants (often R-134a is used in both cases, but not always) and, more importantly, different compressor oils. Mixing oils or using the wrong gas will lead to a chemical reaction, the formation of acids, destruction of the insulation of the compressor windings and instant failure.
Why do new refrigerators contain less gas than old ones?
This is due to the transition to more efficient refrigerants such as isobutane (R-600a). It has better cooling performance than older freons, so significantly less of it is required to create the same amount of cold (only 30-50 grams versus 150-200 grams of R-134a). This also reduces the load on the compressor and the noise level.
How often does the refrigerant need to be changed?
In a normally operating refrigerator, the refrigerant never needs to be changed. The system is sealed at the factory and is designed for the entire service life of the device (10-15 years or more). Replacement is required only in case of mechanical damage to the circuit (for example, when defrosting with a knife) or corrosion of the tubes, which is an emergency situation and not scheduled maintenance.