How a refrigerator compressor works. The principle of operation of a refrigerator with one and two compressors, a different number of chambers and modes

In a single-chamber refrigerator, cooling of the refrigerating chamber takes place using the main evaporator, which is located in the upper part of the refrigerating cabinet. Cold air descends and cools the food in the refrigerator compartment. To prevent the cooling from being very strong, a tray with small windows is installed under the main evaporator through which cold air enters the refrigerator compartment. You can adjust the temperature in the refrigerator compartment by opening and closing the windows. The freezer in single-chamber refrigerators is located only in the upper part of the refrigerator. As a rule, the evaporator is the body of the freezer.

scheme of a single-chamber refrigerator

A single-chamber refrigerator works as follows: the motor-compressor pumps out freon vapors from the evaporator and pumps them into the condenser. Here the vapors are cooled, condense and pass into the liquid phase. Further, liquid freon is sent through a filter-drier and a capillary tube to the evaporator.

The filter drier (drying cartridge) is used to clean and dry the refrigerant passing through it. It is a cylinder filled with a substance that absorbs water (silica gel or zeolite). Spilling into the channels of the evaporator, liquid freon boils and begins to take heat from the surface of the evaporator, thereby cooling the internal volume of the refrigerator and the products stored in it. After passing through the evaporator, the liquid freon boils away, turning into steam, which is again pumped out by the motor-compressor.

The cycle is continuously repeated until the temperature on the surface of the evaporator reaches the required value, after which the motor is turned off. Under the influence of the environment, the temperature in the freezer rises, and the motor turns on again. Thus, the required temperature is maintained inside the refrigerator.

To prevent the formation of condensate on the surface of the suction pipeline, a capillary tube is soldered to it along its entire length. During operation of the refrigerator, the capillary tube heats up, heating the suction pipe. In modern models of refrigerators, the capillary tube is located inside the suction pipe. Since in single-chamber refrigerators, the thermostat sensing element (bellows tube) is attached to the surface of the evaporator and cools and heats up together with the evaporator, the compressor is turned on and off when the required temperature in the freezer is reached.

Adjusting the temperature (i.e. how often the compressor starts) raises (or lowers) the temperature in both the freezer and refrigerator compartments at the same time. To prevent cooling from being very strong, a tray with small windows is installed under the evaporator (that is, under the freezer), through which cold air enters the refrigerator. By opening and closing these windows, you can adjust the temperature in the refrigerator compartment. At the same time, the temperature in the freezer will remain the same.

DOUBLE CHAMBER REFRIGERATOR

two-chamber refrigerator

A two-chamber refrigerator differs from a single-chamber refrigerator by the presence of its own evaporator for the refrigerator and freezer.

The principle of operation of a two-chamber refrigerator is as follows: liquid freon pumped by a motor-compressor passes through the condenser and capillary tube, enters the evaporator of the freezer, boils and, evaporating, begins to cool the surface of the evaporator. In this case, the evaporation of liquid freon and, accordingly, cooling begins at the point where the capillary tube enters the evaporator and gradually moves along its channels to the outlet of the freezer evaporator (see figure). Until the surface of the evaporator cools down to minus temperature, freon does not enter the evaporator of the refrigerating chamber. After freezing of the evaporator of the freezing chamber, liquid freon begins to flow into the evaporator of the refrigerating chamber, cools it to a temperature of -14 ° C, after which the motor-compressor is turned off. After turning off the motor, the air in the refrigerator compartment gradually heats up under the influence of the environment, which heats up the evaporator of the refrigerator compartment. When a certain temperature is reached, the motor starts up again.

"Crying" evaporator

This is usually called the evaporator of the refrigerating chamber in two-chamber refrigerators. As a rule, a small-sized evaporator (several times smaller than in a freezer) is installed in a refrigerating chamber of a sufficiently large volume, which freezes up to a temperature of minus 14 ° C in a fairly short time. After that, the sensitive element of the thermostat, fixed on the surface of this evaporator, "gives a command" to turn off the motor-compressor. During the operation of the motor, the evaporator has time to cool the volume of the refrigerating chamber to a temperature of plus 4 ° C.

After turning off the motor-compressor, the air in the refrigerator compartment begins to heat the surface of the evaporator. The water formed from the melted frost drips down the evaporator into a special tray on the chamber wall. By adjusting the power of the compressor, you can change the temperature in both the refrigerator and freezer.

If the temperature sensor is installed only in the refrigerator compartment, then the temperature will be controlled by the refrigerator compartment, i.e. when the temperature in the refrigerator compartment drops from +4° to +2°C, the temperature in the freezer will also drop by 2°C, for example, from minus 20°C to minus 22°C.

If the temperature in the refrigerator compartment is increased, the temperature in the freezer compartment will also increase. Note that the refrigerator unit is designed in such a way that even with the minimum value of the thermostat, the temperature in the freezer does not rise above the set norm of minus 18 ° C.

REFRIGERATOR WITH SOLENOID VALVES

Independent temperature control in the refrigerator and freezer compartments is possible if two independent compressors with their own evaporators are installed. Another option is a two-circuit system, which provides for the possibility of independent operation of each circuit.

The easiest way to implement this idea is to install a valve that shuts off the refrigerant supply to the evaporator of the refrigeration chamber (Minsk 126; 128 and 130 refrigerator series). When the valve is closed, the refrigerant begins to enter the evaporator through an additional capillary pipe, which is soldered into the unit's condenser. The amount of refrigerant supplied decreases, as a result of which the evaporator of the refrigerator compartment ceases to freeze (due to the reduced amount of refrigerant, the liquid refrigerant simply does not reach it, boiling away in the evaporator of the freezer compartment). The operation of the valve is linked to the readings of the refrigerator compartment thermostat, which makes it possible to control the temperature in the refrigerator compartment separately from the freezer compartment. The compressor in such refrigerators is turned off in accordance with the readings of the thermostat installed in the freezer.

In refrigerators of a more complex design, valves can be installed that block the flow of refrigerant into the evaporators of the refrigerator chambers in turn, allowing you to control the temperature in each of the chambers separately. In such refrigerators, the operation of the valves and the motor-compressor is controlled by an electronic unit. The temperature in the chambers is read by special sensors, and based on this information, as well as on the basis of the ambient temperature sensor, the temperature in the refrigerator chambers is regulated.

SUPER FREEZING

The forced freezing mode is used in freezers and two-compartment refrigerators to freeze a large amount of food. In the normal freezing mode, the frozen food placed in the freezer begins to cool on the outside and only after a while freeze inside.

The thermostat monitors the temperature of the evaporator or the air in the freezer, but not the temperature of the food to be frozen. Therefore, the motor-compressor turns off when a certain temperature inside the freezer is reached, and not at the moment when the food is completely frozen. When using the forced freezing mode, in which the temperature controller is turned off, and the motor-compressor will work without turning off until the user turns off this mode on his own (or the automation does).

The implementation of the superfreeze mode can be different:
1. Direct connection of the compressor to the network, bypassing the temperature sensors and setting the maximum possible temperature value on the thermostat
2. Switching on a weak heating element on the evaporator in close proximity to the temperature sensor. This element does not allow the sensor to cool, and the compressor starts to work without turning off. In systems with an electronic control system, this mode is activated by the control processor. Since the motor-compressor operates without turning off in the forced freezing mode, it must be remembered that such operation of the motor-compressor for more than three days can lead to a reduction in its resource. It must be borne in mind that in most models, when the Super Freeze mode is turned on, the temperature drops both in the freezer and in the refrigerator.

NO FROST SYSTEM

device of a two-chamber refrigerator of the NO FROST system

Refrigerators of the NO FROST system differ from refrigerators with a conventional cooling system in that they do not have the usual evaporator in the form of a metal shelf or plate in the freezer.

The evaporator (usually one), which in such models is more correctly called an air cooler, can be located at the top or bottom of the freezer or behind a panel on the back wall of this chamber, and the refrigerator does not have its own evaporator at all. Structurally, the air cooler in most models looks like a car radiator. A fan is installed behind it, which pumps air from the freezer and refrigeration chambers.

When passing through the evaporator, the air is cooled and directed through a system of channels to the cooled products. At the same time, most of the cooled air enters the freezer, and the smaller part - through an additional channel into the refrigerator. The exception is FROST FREE refrigerators, in the refrigerator compartment of which a "weeping" evaporator is installed, and cold air circulates only within the freezer compartment.

Contrary to the name of the system NO FROST ("no frost"), frost still forms - it's just not visible, because. it is formed on the evaporator closed from the eyes. Periodically, after 8-16 hours, this frost is thawed by heating elements located on the evaporator or under it.

The temperature in the freezer is controlled by turning off the compressor when a certain temperature is reached in the freezer or in the air duct through which cold air from the freezer enters the refrigerator.

The temperature in the refrigerating chamber is regulated either by a special damper installed in the air duct of the refrigerating chamber (the damper can be manually controlled or controlled by a thermostat), or by turning on and off an additional fan that supplies cold air from the freezer to the refrigerating chamber.

DOUBLE COMPRESSOR REFRIGERATORS

In two-compressor systems, two separate units for each of the chambers are installed in one refrigeration cabinet, and they work independently of each other. Each unit has its own thermostat, the readings of which are a signal to turn off the corresponding compressor. It's the same as if we put a free-standing refrigerator on top of a freezer (or vice versa). Temperature, super-freeze (super-cooling) modes, "holiday", etc. can be turned on completely independently.

DOOR HEATING

To prevent the appearance of condensed moisture on the surface of doorways, they are heated. Condensation on these surfaces occurs due to the temperature difference between the inside of the freezer (chamber) and the ambient temperature. For example, if the temperature in the room where the refrigerator is installed is plus 30°C, and inside the freezer is minus 18°C, then the formation of condensate on the ends of the freezer at the places where the sealing rubber fits is almost inevitable.

In some refrigerators, the doorway heating function can be turned off with a special key. This is done in cases where the room where the refrigerator is located is cool enough. The function of turning off the heating of the doorway is energy-saving, since the heating is carried out by electric heating elements. However, in most modern refrigerators, the heating of the doorway is carried out due to the hot refrigerant pumped by the motor-compressor into the condenser of the refrigeration unit.

In such models, the hot refrigerant pumped by the motor-compressor passes through the pipeline laid in the wall of the refrigerating cabinet, then goes through the pipeline laid inside the cabinet along the perimeter of the doorway, heats this opening and, having already cooled down a little, through the pipeline in the cabinet wall enters unit condenser. In refrigerators and freezers with such a heating system, when the refrigeration system enters the mode, the walls of the refrigerator and the doorway can become quite hot, which is not a malfunction.

ZERO ZONE

The zero zone is a special compartment of the refrigerating chamber, designed to store fresh meat, fresh poultry and fish. As a rule, this compartment is drawers, which are usually located between the freezer and refrigerator compartments. Manufacturers declare the maintenance of a certain humidity and temperature of about 0 ° C in such a department.

In some models, the freshness zone is made in the form of an isolated chamber. Thanks to such storage conditions, many products retain their freshness on average two to three times longer than in a conventional refrigerator. The freshness zone may not have its own evaporator, and the cooling of this chamber can be carried out due to the natural influx of cold air from the freezer located on top through a small channel connecting the freezer and zero chambers.

In some refrigerators, the zero zone is made in the form of a separate plastic container installed near the weeping evaporator. The cooling of this tank comes from a weeping evaporator. A guaranteed temperature of 0°C can only be ensured when the zero zone is a chamber with a separate evaporator, or a chamber into which cooled air is supplied in portions from the freezer (NO FROST), especially if the processes are controlled by an electronic unit.

HEAT AND AIR FLOWS

Refrigerators use the basic laws of thermodynamics. How this happens must be considered in detail. First of all, it is necessary to note simple, intuitive facts:

• The refrigerator takes heat from the objects that are inside it, and does not purposefully cool the food.
• Heat spreads from warm objects to cold ones. The higher the temperature difference between the objects, the faster the heat moves, and this happens until the temperature becomes the same everywhere.

When warm food is placed in the refrigerator, heat energy is released from the food into the ambient air of the freezer or freezer compartment. The content is cooled as a result, and we mark this effect as desirable. But since the air is heated, it, in turn, needs to be cooled somewhere.

To remove excess heat from the heated air and replace it near the cooled products, the correct organization of air flows is important. Air movement is carried out by forced ventilation. The air passes through an evaporator equipped with a fan. There, heat is transferred to the refrigerant (usually freon gas) quickly, since the temperature difference is large. Freon temperature is quite low - from -10ºС to -40ºС. In classic refrigerators, the refrigerant flows through channels in the walls of the freezer and radiators protruding into the main chamber. They are placed on top so that heavier cold air descends by gravity.

DEFROST SYSTEM

When you open the refrigerator door, a lot of warm and moisture-saturated air enters. The evaporator is very cold, and water immediately condenses on its surface, covering it with frost, and then with an increasingly thick layer of frozen ice. Ice prevents heat exchange between air and freon. The efficiency of the refrigerator decreases, it consumes more electricity and wears out more. To prevent this, you need to defrost the refrigerator from time to time.

Modern systems are defrosted by a timer - after 6-12 hours, the cooling of the air stops, the ice melts for a few minutes, and the surface of the evaporator is freed from it. The timer can be mechanical or automatic. Sophisticated electronics or a manual timer regularly stops the compressor and turns on a defrost (electric heater) that heats the evaporator. The flowing water is collected in a pan through the drainage holes, from where it evaporates, if there is a lot of water, you will have to pour it out manually. To protect the cooling circuit from overheating during defrosting, a thermostat is installed. It opens the electrical circuit when a certain temperature is reached.

TEMPERATURE CONTROL

Chilled food releases less heat, the air stays cold for a long time. The thermostat regulates the process by turning the compressor on and off based on the thermometer readings. The operating temperature range is adjusted with the adjustment knob, usually it is a few degrees.

As a rule, in the refrigerator there is only one evaporator, it supplies cold air everywhere - to the freezer and the main compartment. To maintain a lower temperature in the freezer, the cooled air is mainly in it, only a small amount of it enters other compartments. The air balance between the freezer and the main compartment is controlled by a damper. It is located in the channel connecting the compartments and operates under the control of a separate regulator.

WHERE DOES THE HEAT GO?

The heated freon from the evaporator is fed into the compressor, where it is compressed by a piston and it heats up strongly, according to the laws of thermodynamics. Electrical energy from the network passes in the motor windings into mechanical energy, and then in the piston chamber into thermal energy. The conservation laws are fulfilled flawlessly. It is easy to remove excess heat from red-hot freon, it is hotter than room air and cools when passing through a condenser - a grate protruding outward on the back of the refrigerator.

In "advanced" models of refrigerators, air is blown through the condenser by a separate fan. The heat from the condenser can be used to evaporate the water from the drip tray that flows into it during defrosting. Thus, the moisture returns to where it came from - to the atmosphere surrounding the refrigerator. The freon cooled in the condenser returns to the refrigeration circuit, where the compressor creates a vacuum, and the gas expands, reaching very low temperatures. The cycle is repeated. The task of development engineers is to correctly calculate the volume and shape of the refrigerator chambers, the power of the devices so that the efficiency of the system is maximum. Modern refrigerators in this regard are brought to the ideal.

The article is specially written in simple words so that an ordinary owner of any household refrigerator could understand the device of this technique.

Additional Information

It is difficult to imagine a modern apartment without a refrigerator. Everyone knows that the refrigerator keeps the cold inside, so the food stored in it does not spoil for a long time. How is the refrigerator arranged?

There are 4 main components in the refrigerator:

1. refrigerant- a substance that goes in a circle and transfers heat. Freon gas is used as a refrigerant.

2. Compressor- a motor that works on the principle of a pump and drives the refrigerant in a circle.

3. Capacitor- through it, heat escapes to the outside, into the environment. The condenser is a grate on the back of the refrigerator.

4. Evaporator- it draws heat from the refrigerator. Usually the evaporator is the inside wall of the refrigerator.

The main parts of a household refrigerator:
1 - evaporator, 2 - condenser, 3 - filter dryer, 4 - capillary, 5 - compressor

The compressor draws the refrigerant from the evaporator. The refrigerant is currently in a state of vapor. The compressor pressurizes it into the condenser. The refrigerant is compressed under pressure, that is, it changes from a gaseous state to a liquid state. At the same time, its temperature rises. Hot gas, passing through the pipes of the condenser, gives off heat to the surrounding space and, as a result, cools down to room temperature.

The refrigerant then enters the evaporator through a very narrow opening (capillary). Its pressure decreases sharply, and due to this, the refrigerant evaporates - it boils, turning into steam. At the same time, it cools down a lot. As a result, it takes away heat from the walls of the evaporator, and the evaporator, in turn, cools the interior of the refrigerator and the products contained in it.

Thus, the refrigerant works in a cycle: in the condenser, under the influence of high pressure, it condenses and passes into a liquid state, highlighting heat, and in the evaporator under the influence of low pressure boils and passes into a gaseous state, absorbing warm.

Scheme of operation of a compression refrigerator
1 - condenser, 2 - capillary, 3 - evaporator, 4 - compressor

The refrigerator must have a thermostat, with which the cooling temperature of the refrigerator compartment is set. When this temperature is reached, the thermostat opens the electrical circuit and the compressor stops.

After a while, the temperature in the refrigerator starts to rise again (due to environmental influences). Then the contacts of the thermostat close and the electric motor of the motor-compressor starts with the help of a protective start relay. The whole cycle is repeated from the beginning until the temperature in the refrigerator again drops to the desired value.

That's why we hear how the refrigerator starts "rumbling" from time to time, and then calms down again - this is the compressor motor turning on and off.

In the refrigerant circuit in the very first figure, you probably noticed one more link - a filter drier. It is needed to clean and dry the refrigerant that passes through it. The filter drier is a cylinder filled with a substance that absorbs moisture (silica gel or zeolite).

So, the refrigerator is designed in such a way that it does not cool air in the chamber picks up heat from it and releases it to the environment. This is provided by the pressure difference in the condenser and evaporator of the refrigerator. The refrigerant flows from a high pressure area where it liquefies (condenses) to a low pressure area where the pressure of the refrigerant is reduced and it turns into a vapor (evaporates).

This article uses materials from secureforms.danfoss.com and

In single-chamber devices, the cooling of the chamber is carried out from the main evaporator, which is located at the top of the refrigerator. The cooled air from the evaporator comes down and lowers the temperature in the refrigerator compartment. In order to avoid a sharp drop in temperature, a pan with small holes is located under the main evaporator through which the cooled air from the evaporator enters the refrigerator compartment. By opening and closing these holes, we can change the temperature in the refrigerator compartment. From the course of physics, we know that cold air always comes down, and therefore in single-chamber refrigerators, the freezer is always on top.

Simplified electrical circuit of the refrigerator

The refrigeration unit in a single-chamber device operates according to the following scheme: the compressor pumps out refrigerant vapors from the evaporator and pumps them into the condenser, where they are cooled, condensed and eventually transferred to the liquid phase. Further, this liquid enters the evaporator through the filter-drier and capillary tubes, where it boils and begins to take thermal energy from the surface of the evaporator, that is, cooling the contents of the refrigerator. The refrigerant boils off and turns into vapor while passing through the evaporator, which is pumped out by the compressor in the same way. The algorithm repeats cyclically until the temperature on the surface of the evaporator reaches the set temperature, after which the thermostat switches off the compressor.

Refrigerator diagram working principle

Under the influence of external climatic influences, the temperature in the freezer increases, and the thermostat switches the compressor back on. Working according to this scheme, a constant temperature is kept inside the refrigerator. To prevent the formation of condensate on the surface of the pipeline system, a capillary tube is installed along its entire length. During operation, the capillary tube heats up, thereby heating the suction line. In modern models, the capillary tube is located inside the suction pipeline.

The two-chamber device, unlike the single-chamber brother, has two separate evaporators for the refrigerator and freezer, separated by a heat-insulating partition.

Simplified electrical circuit of the refrigerator (two-chamber)

The principle of operation of the two-chamber is as follows: the refrigerant pumped by the compressor, through the capillary tube, enters the evaporator of the freezer, where, boiling up and evaporating, the process of cooling the surface of the evaporator begins. Until the freezer evaporator freezes to minus values, the refrigerant in the refrigerator compartment will not enter the other evaporator.

As soon as the evaporator in the freezer freezes, the liquid refrigerant will begin to flow into the evaporator of the refrigerating chamber, lowering its temperature to minus 14 ° C, after which the thermostat will turn off the compressor. And the compressor will turn on automatically after heating the evaporator to a certain temperature.

The compressor is the heart of any refrigerator or freezer. If there are problems with it, then the refrigerator will definitely not work. The average consumer has a question. Is it possible to test it at home? It turns out that it is not only possible, but also necessary. The main thing is that for this you have the necessary knowledge and direct hands.

The circuitry principle of operation of the thermostat is considered and described, as well as options for replacing a burned-out temperature controller with its simple home-made counterparts.

There is one significant drawback in the principles of compressor operation discussed above - the compressor operates at full capacity, and even though it is periodically turned off by a thermal relay, the total energy consumption is much higher than that of inverter compressors

The principle of operation of an inverter type compressor is as follows: When power is supplied, the refrigerator quickly reaches the set cooling temperature, and then the required temperature is maintained by smoothly changing the compressor power, while the inverter compressor does not turn off, but only reduces the number of compressor cycles per unit time, and the temperature inside the refrigerator compartment is kept constant.

Troubleshooting is a serious matter, but any radio amateur is able to make simple repairs with his own hands, and even replace some failed nodes with alternative amateur radio designs.

Sometimes it happens that when you go to the refrigerator early in the morning, you realize that you forgot to close its door tightly in the evening. The refrigerator defrosted overnight, and some products for the prevention of poisoning are best sent to the trash can. To avoid this, I propose to assemble an audible alarm, and after a while the device itself will remind you that the door is open. Of course, this function is already built into some new models of refrigerators, but old budget models that work perfectly need to be upgraded by installing this detector circuit as an option.

In many models of modern refrigerators, the doors open on the right side. But from time to time there are situations in which it is required to change this principle and rehang the refrigerator doors to the opposite side.

The lack of lighting in the refrigerator brings a lot of inconvenience, especially at night. Old refrigeration devices used typical low-power incandescent lamps, their only drawback was heat generation. In modern kitchen appliances, along with classic incandescent lamps, fluorescent and LED lamps are used. These types of lamps are much more energy efficient and generate cold white light, and most importantly, they hardly heat up. But even they have to be periodically replaced with new ones, and in order to do this correctly, you should read this article.

All cooling systems of modern refrigerators can be divided into three classes: static cooling, No Frost system and dynamic cooling. It is these three groups that are the basis of any refrigeration device.

Static cooling

Another name for this system is "Direct Cool". The principle of operation is the following. When the compressor is running, the temperature in the chamber is reduced due to the removal of heat by the evaporator, which is located in the rear wall of the housing. The temperature of the back wall is low and all the moisture begins to condense and freeze on it. When the temperature drops to the user-selected level, the compressor is switched off. After some time, frozen drops of moisture on the wall begin to melt and drain through a special hole into a container located outside the refrigerator. When the temperature increases to the maximum values ​​​​set by the thermostat settings and the compressor starts again and everything repeats in the same sequence. The temperature in the freezer is always in the negative range due to the design features and the area of ​​the evaporator.

Defrost in refrigeration devices with a static cooling system is called manual. Under defrosting, we understand only the process of defrosting the freezer, since due to the constant negative temperature, moisture constantly freezes on the walls of the freezer. In the refrigerator compartment, defrosting is carried out automatically.

The disadvantage of such a cooling system is the lack of uniform cooling throughout the volume. The cooling rate in static systems is the lowest. The advantage is the maximum preservation of moisture products.

Cooling No Frost

The system can work without defrosting all the time until it breaks. The principle of its operation is as follows - since the evaporator in such refrigerators is open, the air in the chamber is in contact with it. No Frost cooling is based on forced air circulation in the refrigerator compartment through the evaporator. While the compressor is running, the air is blown by the fan through the evaporator, which takes heat and has a sufficiently low temperature. All the moisture that is in the air instantly freezes on the evaporator itself. Due to this, ice does not occur. When the compressor turns off when it reaches the set temperature, the moisture on the evaporator melts itself and is discharged through a special drainage channel. A similar process takes place in the freezer.

Together with this system, the concept of a multi-flow cooling system Air Flow or Multi Air Flow is used. It cannot be separated into its own cooling system, since this circulation system only increases the cooling efficiency. The advantage of No Frost systems is the excellent cooling efficiency. Since the distributed air flow forms the same temperature in any part of the refrigerating chamber.

Of the disadvantages, products in such refrigerators partially lose their moisture and it is desirable to store them in containers.

Dynamic cooling

In fact, this is an improved static system, but with certain improvements, in the form of a chamber fan. The principle of operation is the same as in the case of static cooling. A fan provides forced air circulation in the chamber.

This system combines the advantages of static and No Frost systems, providing the best conditions for food storage.

Modern refrigerator designs use combinations of cooling systems, which is why they cannot be considered as one specific system. For example, Electrolux produces refrigerators with the Frost Free system. But in the original, this is a combination of a static system in the refrigerator and No Frost in the freezer.

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These records on refrigerators are presented for you from our own outlined material based on the technical literature read by domestic authors, as well as from personal practice for repairing home refrigerators.

Getting cold - in refrigerators

Any body that has a higher temperature than the environment is able to cool naturally. That is, heat from a more heated body is transferred to the environment, while the temperature of the body itself will decrease.

To cool the body to a temperature below the environment, you will need a method of artificial cooling with the expenditure of a certain amount of energy.

For this method of artificial cooling, there are special machines that take heat from the cooled object and transfer it to a warmer environment. The principle of heat transfer in this way is called the artificial method of obtaining cold, according to which all refrigerators work.

Cooling in refrigerators occurs as a result of the boiling of the refrigerant, circulating forcibly, in a closed refrigerator system. Such a refrigerant, or as it is also called refrigerant, - is usually freon.

Refrigerators \ refrigerators \ distinguish between two types:

• absorption;
• compression.

As we know, compression types of refrigerators have received wider application, where the refrigerant circulation is forced, due to the operation of the motor-compressor.

refrigerator Atlant

According to the photograph of the Atlant refrigerator, this refrigerator can be characterized as follows:

The compression refrigerator by its design is of a closed type with one motor-compressor, ensuring complete sealing of the refrigeration unit.

The refrigerator compartment is located in the upper compartment of the refrigerator. The freezer is located in the lower compartment. The lower compartment of the freezer consists of three drawers for freezing food. The upper compartment of the refrigerator compartment consists of six shelves for storing food in a chilled state.

For absorption types of refrigerators, the circulation of the refrigerant occurs under the influence of the heating element \heater\, or where the refrigerant circulates in a different way, under the influence of another heat source.

And the third way to obtain artificial cold is the thermoelectric method, where the work of transferring heat from a cooled object to a warmer environment is carried out due to the movement, flow of electrons. That is, in this example, cooling occurs due to the flow of electric current. As you know, this method of obtaining artificial cold is not used in household, home refrigerators.

Compression type refrigerators

As mentioned above, the principle of operation of compression types of refrigerators is the operation of a motor-compressor, due to which the refrigerant is pumped and circulated in a closed refrigerator system.

The system consists of:

• condenser \ coil \;
• control valve;
• evaporator

and compressor. The operation of the compressor is driven by an electric motor, hence the name "motor-compressor".

This diagram of the refrigeration unit \ fig. 1 \ is comparable, for example, with the Atlant two-chamber refrigerator and the fundamental principle of operation itself is no different from single-chamber refrigerators with one motor-compressor.

Figure 2 shows a diagram of a refrigeration unit with one motor-compressor, consisting of:

1. motor - compressor;
2. thermal circuit;
3. condenser \ coil \;
4. zeolite filter;
5. capillary tube of small section;
6. refrigerator evaporator;
7. freezer evaporator;
8. injection tube.

The principle of operation of a compression type refrigerator is as follows:

The heated refrigerant under the pressure of the piston in the cylinder is supplied through the discharge pipeline to the condenser. At elevated pressure, the refrigerant passes from a gaseous state to a liquid state, while giving off heat to the environment. Further, when the refrigerant passes through the valve, a sharp drop in pressure is created in the evaporator, the refrigerant boils at low pressure. The very process of liquid passing through the valve into the evaporator is called throttling.

The evaporator, as you understand, is located in the wall of the freezer. When the refrigerant boils in the evaporator, heat is removed from the environment, that is, the freezer. The refrigerant vapor from the evaporator is sucked by the compressor and then the compressed refrigerant in the cylinder is supplied under pressure to the condenser.

Repetitive cycles of refrigerant circulation in a closed refrigerator system occur again and again. That is, the refrigerant circulating during the operation of the refrigerator takes heat from the freezer through the evaporator and gives off heat through the condenser to the environment.

The electrical energy that is expended when cooling the freezer depends on the work performed by the motor-compressor. Chillers \refrigerators\ are determined by their cooling capacity, which takes into account the amount of heat \kcal\ that the evaporator is able to take away within one hour.

The cooling capacity of the same refrigerator will be different, depending on the ambient temperature itself, therefore, it is not recommended to install refrigerators near the heating system \batteries, pipes\.

The evaluation of the cooling capacity of different types of refrigerators is determined by measuring the temperature of the refrigerant in the corresponding places of the refrigerator. Temperature measurements include places such as:

• the temperature of the suction vapors of the refrigerant;
• condensation temperature;
• boiling point of the refrigerant in the evaporator;
• subcooling temperature, liquid refrigerant in front of expansion valve.

Temperatures have a significant effect on cooling capacity:

• boiling of the refrigerant in the evaporator;
• refrigerant condensation.

To determine the cooling capacity, the following "standard" temperature conditions are adopted for:

• the boiling point of the refrigerant in the evaporator is minus fifteen degrees Celsius;
• condensation temperature - minus thirty degrees Celsius;
• the temperature of the suction vapors of the refrigerant is fifteen degrees Celsius;
• liquid refrigerant temperature in front of the control valve - thirty-two degrees Celsius.

Compression-type chillers in their design are of closed and open types, differing in the location of the compressor and electric motor, as well as the presence of detachable connections.

For open types, in chillers, the electric motor and compressor are installed separately, where the compressor crankshaft is driven by the electric motor through a belt drive. In these refrigerators of this type, the refrigerant leakage occurs at the sealing points, that is, the seals remain the main refrigerant leakage point.

The piping connections between the evaporator, condenser and compressor are detachable. In places of such connections, refrigerant leakage is also not excluded.

In refrigerators of a closed type, in particular, this applies to most of all modifications of household, home refrigerators, there are no detachable connections. That is, here the entire system is tightly welded and soldered, refrigerant leakage is almost impossible. In this example, refrigerant leakage may occur due to any mechanical damage with the formation of microcracks.

For closed-type refrigerators or as they are also called sealed refrigeration units, the complexity of the repair lies in the impossibility of disassembling, replacing parts, for example, the same motor-compressor. A similar repair in this topic will be given later.

Refrigerator refrigerants

Among the main parameters of the refrigerant \ refrigerant \ is its boiling point. The relationship is as follows - the lower the temperature of the cooled object / freezer is required to be lowered, the lower the boiling point of the refrigerant should be.

• The refrigerant is selected not only taking into account its boiling, the refrigerant must also be:
• not poisonous;
• non-flammable;
• explosion-proof;
• with low pressure for condensation.

Typically, such a refrigerant used in home refrigerators is - freon 12.

freon - 12

Freon 12 is a heavy colorless gas, not poisonous. A slight specific smell of gas is felt with a large leak, if the concentration of gas in the air is more than 20%. The boiling point of this gas is almost minus 30 degrees Celsius, the solidification temperature is minus 155 degrees Celsius.

Other refrigerants used in refrigeration machines include:

• freon -11;
• freon - 13;
• freon - 22.

Freon-12, like other refrigerants, is fluid in its properties, capable of penetrating into the smallest microcracks, metal pores. This gas can also corrode varnish coatings. Special lacquers are used as insulation for the motor windings \hermetic unit\.

When repairing, it should be borne in mind that this gas washes away rust well from the inner surface of the entire system - accordingly, the parts must be clean. Liquid freon, when it comes into contact with the skin, can cause frostbite on the surface of the skin; freon does not have any irritating effect on the respiratory system.

Evaporation of gas does not affect the taste of stored food and does not change the structure of any food stored in the refrigerator. The rubbing parts of the motor-compressor are thoroughly lubricated during the repair process; special refrigeration oils are used for this purpose.

Corrosion of the internal surfaces of the metal is caused by the so-called aging of the oil - its oxidation, the ingress of atmospheric oxygen into the composition of a special refrigerator oil. Therefore, before application, the oil is thoroughly dried and special antioxidant additives are added to the oil.

Corrosion in the composition of freon can subsequently cause blockage of small flow sections that are present in the circulation system. Lubricating oil for such purposes is used brand HF 12-16. The solubility of the lubricating oil in freon should also be taken into account, the oil contains paraffin, which subsequently can also cause blockage of small flow sections in the refrigerator system. This brand of lubricating oil is used in closed-type refrigeration compressors using freon-12 in the system, that is, it can be used in modern home refrigerators.

The principle of operation and device of the refrigerator

Home refrigerators have two food storage chambers:

• refrigeration;
• freezing

chambers \ departments \. If the products have a long shelf life in frozen form, special home refrigerators are used for this purpose. For products stored simply chilled \in the refrigerator compartment\, the temperature ranges from 2 to 8 degrees Celsius.

Periodic shutdown of the refrigerator is carried out due to the operation of the thermostat, \\ cyclical operation\ and does not affect the conditions of freezing, food storage.

At the request of the owner, by manually adjusting the thermostat, slight temperature changes in the refrigerator chamber are carried out. Also, with the help of a thermostat, its settings, the necessary lower temperature is provided depending on the ambient temperature \ warm room, cool room \.

refrigerator thermostat

Names such as refrigerator thermostat and refrigerator thermostat are exactly the same in their purpose.

The thermal protection relay of the refrigerator is designed to protect the windings:

• stator;
• rotor

electric motor from sudden voltage surges, current overloads.

refrigerator compressor motor

The motor - compressor of closed-type refrigeration machines is tightly welded in a metal casing, like other parts of the refrigeration system as a whole.

The heat-protective relay \start-protective relay\ has a detachable connection with the motor-compressor of the refrigerator and, in the event of a malfunction, the heat-protective relay must be replaced.

start - protective relay refrigerator Atlant

Differences between the names: "start-protective relay and heat-protective relay" - there is no difference.

Why did you choose a closed-type compression unit for home refrigerators? This design of home refrigerators allows you to virtually eliminate the leakage of the working fluid - freon. That is, the manufacturer, when producing refrigerators, pays special attention to the manufacture of permanent connections in the circulating system.

In turn, these types of refrigerators provide economical energy consumption. At an ambient air temperature of 25 degrees Celsius, the consumption of electricity consumed is up to 1.2 kilowatts per hour.

The capacity of the refrigerator compartment is determined geometrically, that is, it is measured either in cubic decimeters or in liters. According to the norms, based on one kilogram of products, there are 6-8 liters of the refrigerator chamber. In terms of capacity, home refrigerators usually do not exceed 400 liters.

Based on the number of people in the family, when purchasing a refrigerator, the following options for choosing refrigerators are convenient:

• for a family of two people, the capacity of the refrigerator chamber is selected for 100 - 160 liters;
• for a family of three, the capacity is selected for 160 - 200 liters;
• out of four people, the amount of a family adheres to a capacity of 240 to 300 liters;
• more than four people chamber capacity is up to 400 liters.

For better heat dissipation by the evaporator, it is more expedient to install shelves in the form of a metal grill in refrigerators. Shelves made in this way allow you to evenly distribute the temperature in the refrigerator.

On the door, from the side of the freezer in refrigerators, a push-button light switch is installed. When the refrigerator door is opened, the contacts close and the refrigerator chamber is illuminated by an electric bulb.

For storing frozen food in large quantities, refrigerators with a larger freezer compartment are provided. For the freezer \storage of frozen food\, you can use the following calculation - for half a kilogram of frozen food, there is one liter of capacity \freezer\.

The snow cover in the chamber is formed from air condensate entering when the door is opened, as well as in the presence of insufficient sealing when the refrigerator door is closed. The resulting snow coat must be systematically removed, since such formation impairs the removal of heat from the chamber by the evaporator.

Usually, earlier in the design of the refrigerator, a tray was provided to collect melted water during defrosting. Currently, refrigerators are being manufactured, where in the freezer itself there is a hole for draining water formed as a result of condensate. Water flowing into the hole then simply evaporates. The owners of refrigerators, when they are defrosted \ removing frost, snow coats \, turn off the refrigerator and with the doors open, an effective complete defrosting occurs. Also, in some designs of refrigerators, heating elements \heating elements\ are provided for the defrosting process. That is, both semi-automatic and automatic defrosting of the chamber occurs when the motor-compressor is turned off with the participation of a thermostat.

Automatic defrosting occurs automatically, periodically after a certain time and without the participation of the owner. The water, in this example, is led out through a tube from the chamber, where it is then evaporated.

Home refrigerators - and their types

The methods of generating artificial cold in refrigerators are different and depend on the type of refrigerator. As already mentioned, refrigerators are divided into:

• compression;
• absorption;
• thermoelectric \semiconductor\.

absorption refrigerator Ezetil Absorber A – 4000

thermoelectric refrigerator Tropi Cool Classik

According to their purpose, refrigerators are divided into:

• two-chamber;
• single-chamber;
• low temperature.

Single-chamber refrigerators are used to store food in a chilled state.

Two-chamber refrigerators are used for storage of both frozen and chilled products.

Low-temperature refrigerators are used for freezing, as well as for storing frozen foods.

low-temperature refrigerator XNT-200

Refrigerators are also available in their design:

• wall;
• embedded;
• desktop;
• floor.

built-in refrigerator

Low-temperature refrigerators are usually produced in the form of a chest, the lid / door / of such a refrigerator is located on top.

Single-chamber floor \ in the form of a cabinet \ refrigerators have a more common use in home life.

Refrigerators of small sizes, the so-called “table cabinets”, are also convenient for their operation.

In the acquisition, in the choice of refrigerators, of course, everything depends on the desire of the buyer himself. For example, combined floor refrigerators can be combined with a kitchen cabinet.

To order, the refrigerating cabinet can be made combined \ combined \ with a sideboard. The finishing of these refrigerated cabinets is carried out in color with combined furniture.

Wall-mounted refrigerators have double doors, in their design they resemble a small wall-mounted cabinet.

refrigerated cabinet \ wall, desktop \ Liebherr FKv 503 Premium

Built-in refrigerators are the least common. To cool the condenser, the refrigeration unit in the built-in cabinet is placed taking into account the provision of air circulation.

In desktop refrigerators, cooling occurs usually by thermoelectric method.

Two-chamber refrigerators consist of two food storage chambers - a cooling chamber and a freezer chamber.

Low-temperature refrigerators, or as they are also called "freezers", are used for long-term storage of food in a frozen state.

In the following topics, you will get acquainted with a detailed description of the repair of refrigerators and their electrical circuits.

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