A modern refrigerator is a complex engineering a device that ensures the safety of food by maintaining a low temperature. Its work is based on a continuous physical process, which is impossible without a special working fluid. It is this component, often called “gas” in everyday life, that performs the critical function of transferring heat from the internal chamber to the outside.
Many owners of household appliances mistakenly believe that cold is created magically or simply by consuming electricity. However, electricity only ensures the operation of the compressor, which makes circulation refrigerant. Without this substance, which changes its state of aggregation in a closed loop, cooling would be physically impossible. Gas acts as a transport medium that takes thermal energy from products and releases it into the environment.
Understanding exactly how this substance works helps to better operate equipment and notice malfunctions in time. If you've ever wondered why you can't just put ice in the freezer or why your refrigerator gets hot at the back, the answer lies in the properties of the refrigerant used. This is not just an inert gas, but an active participant in the thermodynamic cycle, the efficiency of which determines the service life of your products and the equipment itself.
The principle of operation of the refrigeration circuit
To understand why gas is needed, it is necessary to consider the basic operating diagram of the refrigeration unit. The whole process is based on the ability of substances to absorb heat during evaporation and release it during condensation. The refrigerant circulates through a sealed circuit consisting of a compressor, condenser, capillary tube and evaporator. The driving force here is compressorwhich compresses the gaseous substance, increasing its pressure and temperature.
Next, the heated gas enters the condenser (usually a grate on the back wall), where it cools and turns into a liquid state, giving off heat to the room. The liquid then passes through a narrow capillary tube, where the pressure drops sharply. Entering the evaporator inside the chamber, the refrigerant boils at a very low temperature, actively absorbing heat from the internal space. It is this stage that provides the very cold that we feel when opening the door.
⚠️ Attention: The tightness of the circuit is an absolute requirement. Any microscopic crack will lead to the release of gas and a complete stop of cooling.
It is important to note that the gas itself is not consumed during operation. It just changes its state and moves in a circle. If the system is completely sealed, one charge is enough for the entire service life of the device. However, if the integrity of the tubes or heat exchangers is damaged, the substance evaporates and the cycle is interrupted. The compressor begins to work in vain, trying to pump air, but no cooling occurs.
Types of refrigerants used and their evolution
The history of the development of refrigeration technology is a constant search for the ideal working substance. In the early days of mass production of refrigerators, toxic and explosive compounds such as ammonia or sulfur dioxide were used. Later, the industry switched to synthetic compounds that were considered safe for humans, but turned out to be destructive to the ozone layer of the planet. Freons freons - synthetic compounds that were considered safe for humans, but turned out to be destructive to the planet’s ozone layer.
The main types of refrigerants that you may encounter:— tetrafluoroethane, widely used in the 90s and 2000s, is safe for ozone, but has a high potential for global warming.(isobutane) - the most popular gas in modern household refrigerators, it is environmentally friendly, but flammable, which requires special care during repairs.(propane) - similar to isobutane, often used in industrial installations and some models of household appliances.Each type of gas requires specific oil for compressor lubrication and a certain pressure in the system. That is whyis a complex technical process, and not just “adding air.” An incorrectly selected type of gas can lead to compressor failure or even an explosion if flammable mixtures are used in an unprepared system.refilling a refrigerator📊 What brand of refrigerator do you have?OtherThe role of pressure and temperature in cycleThe key physical law on which the operation of a refrigerator is based is the dependence of the boiling point of a liquid on pressure. At normal atmospheric pressure, water boils at 100°C, but if you lower the pressure, it will boil at room temperature. The refrigerant in the refrigerator works on the same principle, but with much lower boiling points.A vacuum is created in the evaporator, which is located inside the freezer or refrigerator. When liquid gas enters this low-pressure zone, it instantly boils. To transition from a liquid to a gaseous state, energy is required, which the substance takes from the surrounding space - that is, from the air inside the chamber and the products. This process is calledendothermic reactionThen the compressor sucks out this already gaseous refrigerant and compresses it. During compression, the gas temperature increases sharply, sometimes up to 80-90°C. This is why the back wall of a running refrigerator is always hot. In the condenser, the hot gas releases the accumulated heat into the room, cools down and again becomes a liquid, ready to repeat the cycle.The effectiveness of cooling directly depends on the tightness of the circuit and the ability of the compressor to create the necessary pressure for boiling and condensation of the gas.Symptoms of a refrigerant leakSince the refrigeration circuit is a closed system, under normal conditions the gas does not disappear anywhere. However, over time, the metal can corrode, especially at solder joints or in the evaporator if it is damaged during defrosting. A leak is one of the most common reasons why a refrigerator stops freezing. This can be noticed by a number of characteristic signs.First of all, pay attention to the operation of the compressor. If it hums almost non-stop, trying to gain temperature, but it’s warm inside, this is a sure sign of a problem. There may also be swelling of the side walls of the case or the appearance of swelling on the inner surface of the freezer, which indicates the accumulation of oil that has escaped along with the gas.Other signs of depressurization:🌡️ The temperature in the chambers does not fall below +10°C even with the maximum thermostat setting.🔇 The compressor turns on for a short time and immediately turns off (thermal protection is triggered).💧 The appearance of oily spots under the refrigerator or at the leak site (oil is mixed with gas).⚠️ Attention: Independent search for leaks using soapy water is only possible in open sections of the tubes. In the foamed parts of the case, it is impossible to detect where the gas is escaping without special equipment.If you notice that the refrigerator is humming but not cooling, under no circumstances continue to operate it for a long time in this mode. Operating a compressor without cooling (which is provided by circulating gas) leads to overheating and burnout of the windings. Repair in this case will cost much more than a simple refueling or searching for a fistula.Dangers and safety measures when working with gasContrary to popular belief, modern refrigerants such as isobutane (R600a) are flammable gases. Although their concentration in the air must be quite high to ignite, there is a risk, especially in the confined space of a kitchen during renovation work. Old freons (R12, R134a) do not burn, but when heated with an open flame they can release phosgene, a deadly gas.When interacting with gas, you must follow strict safety rules. Any work related to breaking the tightness of the system (soldering, compressor replacement, refueling) must be carried out in a well-ventilated area. The use of open flame near a leak or when soldering without first purging the system is strictly prohibited.Basic safety rules:
The main types of refrigerants that you may encounter:
- 🧊 R134a — tetrafluoroethane, widely used in the 90s and 2000s, is safe for ozone, but has a high potential for global warming.
- 🔥 R600a (isobutane) - the most popular gas in modern household refrigerators, it is environmentally friendly, but flammable, which requires special care during repairs.
- ❄️ R290 (propane) - similar to isobutane, often used in industrial installations and some models of household appliances.
Each type of gas requires specific oil for compressor lubrication and a certain pressure in the system. That is why refilling a refrigerator is a complex technical process, and not just “adding air.” An incorrectly selected type of gas can lead to compressor failure or even an explosion if flammable mixtures are used in an unprepared system.
The role of pressure and temperature in cycle
The key physical law on which the operation of a refrigerator is based is the dependence of the boiling point of a liquid on pressure. At normal atmospheric pressure, water boils at 100°C, but if you lower the pressure, it will boil at room temperature. The refrigerant in the refrigerator works on the same principle, but with much lower boiling points.
A vacuum is created in the evaporator, which is located inside the freezer or refrigerator. When liquid gas enters this low-pressure zone, it instantly boils. To transition from a liquid to a gaseous state, energy is required, which the substance takes from the surrounding space - that is, from the air inside the chamber and the products. This process is called endothermic reaction.
Then the compressor sucks out this already gaseous refrigerant and compresses it. During compression, the gas temperature increases sharply, sometimes up to 80-90°C. This is why the back wall of a running refrigerator is always hot. In the condenser, the hot gas releases the accumulated heat into the room, cools down and again becomes a liquid, ready to repeat the cycle.
Symptoms of a refrigerant leak
Since the refrigeration circuit is a closed system, under normal conditions the gas does not disappear anywhere. However, over time, the metal can corrode, especially at solder joints or in the evaporator if it is damaged during defrosting. A leak is one of the most common reasons why a refrigerator stops freezing. This can be noticed by a number of characteristic signs.
First of all, pay attention to the operation of the compressor. If it hums almost non-stop, trying to gain temperature, but it’s warm inside, this is a sure sign of a problem. There may also be swelling of the side walls of the case or the appearance of swelling on the inner surface of the freezer, which indicates the accumulation of oil that has escaped along with the gas.
Other signs of depressurization:
- 🌡️ The temperature in the chambers does not fall below +10°C even with the maximum thermostat setting.
- 🔇 The compressor turns on for a short time and immediately turns off (thermal protection is triggered).
- 💧 The appearance of oily spots under the refrigerator or at the leak site (oil is mixed with gas).
⚠️ Attention: Independent search for leaks using soapy water is only possible in open sections of the tubes. In the foamed parts of the case, it is impossible to detect where the gas is escaping without special equipment.
If you notice that the refrigerator is humming but not cooling, under no circumstances continue to operate it for a long time in this mode. Operating a compressor without cooling (which is provided by circulating gas) leads to overheating and burnout of the windings. Repair in this case will cost much more than a simple refueling or searching for a fistula.
Dangers and safety measures when working with gas
Contrary to popular belief, modern refrigerants such as isobutane (R600a) are flammable gases. Although their concentration in the air must be quite high to ignite, there is a risk, especially in the confined space of a kitchen during renovation work. Old freons (R12, R134a) do not burn, but when heated with an open flame they can release phosgene, a deadly gas.
When interacting with gas, you must follow strict safety rules. Any work related to breaking the tightness of the system (soldering, compressor replacement, refueling) must be carried out in a well-ventilated area. The use of open flame near a leak or when soldering without first purging the system is strictly prohibited.
Basic safety rules:
- 🚫 Never try to seal the pipes yourself if there is still gas under pressure in the system.
- 🔥 Do not use open fire to warm up frozen areas if you are not sure about the type of refrigerant.
- 👃 If you feel a sharp specific odor (often it smells like solvent or just "chemistry"), immediately ventilate the room.
It is also worth remembering that the oil circulating along with the gas is an aggressive chemical environment. Contact with skin or mucous membranes may cause irritation. Therefore, even when visually inspecting the technical area of the refrigerator, it is recommended to exercise caution and use gloves.