When you open the refrigerator door and feel a pleasant chill, you rarely think about the most complex physical processes occurring inside a closed metal box. However, it cooling circuit is the heart of any household unit, ensuring the safety of products. This is a closed system where the refrigerant circulates, taking heat from the internal chamber and releasing it into the environment.
Understanding how this mechanism works helps not only to operate the equipment correctly, but also to promptly notice the first signs of malfunctions. Modern models may have one or two circulation systems, which directly affects energy consumption and the climate inside the chambers. Let's look in detail at what makes up the efficiency of your refrigerator.
It is based on the law of physics: when evaporating, a liquid absorbs heat, and when condensing, it releases it. Refrigerant, moving through the tubes, it constantly changes its state of aggregation, transferring thermal energy. This endless cycle allows you to maintain the set temperature even on a hot summer day. It is important to note that the tightness of the system is a critical parameter, the violation of which leads to a complete stop of operation.
Main elements of the cooling system
The heat removal system consists of several key components, each of which performs a strictly defined function. If one element fails, the pressure balance is disrupted and cold production ceases. The main engine of the process is compressorwhich is often called the refrigerator motor. It creates the necessary pressure for gas circulation through the tubes.
Next, the refrigerant enters the condenser, usually located on the back wall or on the sides of the housing. Here the hot gas cools and turns into liquid, releasing heat into the room. After this, the flow passes through a filter drier, where excess moisture is removed, preventing the formation of ice plugs. Only after this preparation the refrigerant enters evaporator.
- ❄️ Compressor - compresses the gaseous refrigerant, increasing its temperature and pressure.
- 🔥 Condenser - radiator grille, where the gas cools and turns into liquid condition.
- 💧 Evaporator —a hidden heat exchanger where the liquid boils at low pressure, absorbing heat from the chambers.
- 🔌 Capillary tube —a throttling device that sharply reduces the pressure before entering the evaporator.
It is in the evaporator that the “magic” of cooling occurs. The refrigerant boils at a very low temperature, turning into steam and actively taking heat from the walls of the chamber. Then this steam is again sucked in by the compressor, and the cycle repeats. Fine tuning The volume of each element is critical for the stable operation of the entire system.
The difference between single and double circuit systems
When choosing equipment, buyers often come across the terms “single compressor” or "two circuits". This is not the same thing, although it often happens. In a classic single-circuit system, cold from the freezer is forced or naturally flows into the refrigerator compartment. This leads to equalization of humidity and mixing of odors.
Double-circuit system (or two-compressor) assumes the presence of two independent cooling circuits. Each compartment has its own evaporator and its own operating mode. This allows you to set different temperatures independently and, more importantly, not dry out the air in the refrigerator compartment. Products in such conditions are stored much longer.
⚠️ Attention: Do not confuse the dual-circuit system with technology No Frost. In the latter case, one compressor can be used, but the fan drives dry air through both compartments through common channels, which still leads to some exchange of odors, although less than in older models.
There is also an intermediate option - Full No Frost with one compressor, but with the possibility of shutting off the cold air supply to one of the departments. However, a true double circuit provides better insulation. If you often store strong-smelling foods or large quantities of fresh vegetables, separating the circuits will be a significant advantage.
The principle of refrigerant circulation
The movement of the working substance through the tubes occurs due to the pressure difference created by the compressor. At the outlet of the engine, the pressure can reach 15-20 atmospheres, and at the inlet it can be close to vacuum. This delta allows the refrigerant to boil at temperatures below zero degrees Celsius.
Passing through capillary tube, the liquid is throttled. Its pressure drops and it enters the evaporator, where it instantly boils. This process is accompanied by active absorption of thermal energy. The gas formed as a result of boiling returns to the compressor, where it is compressed again. The cycle is continuous as long as the motor is running.
It is important to understand that the system does not have valves that open and close the path of gas in the usual sense. The adjustment occurs due to the balance between the compressor performance and the throughput of the capillary tube. Violation of this balance, for example, due to a freon leak, leads to the compressor running empty, without creating the required pressure.
Why can’t you quickly defrost a refrigerator with a knife?
By breaking off the ice with a knife, you risk damaging the thin evaporator tubes, which are often mounted directly into the back wall of the chamber. A breakdown of the tube will lead to the immediate release of all refrigerant and the entry of moisture and air into the system. Repair in this case will require a complete replacement of the evaporator, evacuation and refilling, which is often not economically feasible.
Problems and malfunctions of the circuit
The most common problem is refrigerant leak. It can occur due to corrosion of the condenser tubes (especially in models where the grille is built into the housing) or mechanical damage. The symptom is long operation of the compressor without shutting down and lack of cold.
The second common problem is a clogged capillary tube. An ice plug may form in the system due to moisture or an oil-acid mass due to engine destruction. In this case, the circulation stops and the refrigerator stops freezing, although the compressor may hum.
| Symptom | Probable cause | Action |
|---|---|---|
| The compressor does not turn on | Malfunction of the thermostat or start relay | Checking the electrical circuit |
| The motor runs constantly | Freon leak or compressor wear | Call a technician to search leaks |
| Ice in only one corner | Clogged capillary system | Purge the system with nitrogen |
| Loud knocking during operation | Wear of compressor valves | Replacing the compressor |
Independent repair of the circuit is almost impossible without specialized equipment. You will need a vacuum pump, a pressure gauge station and a scale for accurate gas dosing. In addition, knowledge of the circuit diagram of a particular refrigerator is required.
⚠️ Attention: An attempt to independently replace the compressor or solder tubes without evacuating the system will result in the moisture remaining inside freezing in the capillary after several hours of operation. The new compressor will burn out due to lack of cooling or water hammer.
☑️ Diagnostics before calling a technician
Features of maintenance and prevention
Although the cooling circuit is sealed and does not require regular replacement of consumables, it requires the correct operating conditions. The main enemy of the system is overheating. If the condenser (grill at the back) is covered with a thick layer of dust, heat exchange with the air is impaired. The compressor is forced to work longer, trying to relieve pressure, which leads to its overload.
Regular defrosting (for drip systems) is also important. Although ice forms in the hidden evaporator, improper operation can lead to freezing of the inlet pipes. In systems No Frost it is important to monitor the serviceability of the defrost heating element, since its failure will lead to ice fouling in the air ducts and the cessation of air circulation.
Do not place the refrigerator close to the wall. A minimum gap of 5-10 cm is required for free convection of air around the heat exchanger. Built-in models require mandatory ventilation of the niche, otherwise the life of the compressor will be reduced significantly.
The influence of the type of refrigerant on the operation of the system
In older models, freon R-12 was used, which was highly efficient, but was banned due to the destruction of the ozone layer. Modern refrigerators run on R-134a or isobutane R-600a. The latter is a hydrocarbon, it is explosive in high concentrations, but is environmentally friendly and requires less quantity for refilling.
The transition to new types of refrigerants required a change in the design of the circuit. The tubes have become thinner, and the requirements for system cleanliness have become higher. Isobutane has excellent cooling performance, but its filling requires high precision. A deviation of a few grams can disrupt the operation of the entire unit.
If you hear a whistling sound when your old refrigerator is running, this may be a sign of a leak. New gases are odorless, so R-600a leaks can only be detected using a gas analyzer or soap emulsion. Safety comes first here.
FAQ: Frequently asked questions
Why are the side walls of the refrigerator hot?
This is normal. In modern models, the condenser (heat exchanger) is often built into the side walls of the case, and not moved back in the form of a grill. During operation, the compressor compresses the gas, heating it, and this heat is transferred to the walls, which release it into the kitchen air.
Is it possible to refuel the refrigerator yourself?
Theoretically, yes, if you have a license, vacuum equipment and scales. In practice, without experience, you will ruin the compressor or will not be able to achieve the desired temperature. Filling “by eye” by pressure for modern systems with R-600a is unacceptable; accuracy down to the gram is required.
What is a “crying” evaporator?
This is the popular name for a drip defrosting system. In such refrigerators, the back wall of the refrigerator compartment is periodically covered with frost, which then melts during a pause in the compressor. The water flows into the gutter and evaporates. This is normal operation, not a breakdown.
How long does a compressor last in a refrigerator?
The average service life of a modern compressor is 10-15 years, subject to operating conditions. However, frequent power outages, power surges and overheating due to dust can reduce this period by half.