Household refrigeration units. Refrigeration device

Refrigeration is the process by which the room temperature is lowered below the outdoor temperature.

Air conditioning - this is the regulation of temperature and humidity in the room with the simultaneous implementation of air filtration, circulation and its partial replacement in the room.

Ventilation - it is the circulation and replacement of air in a room without changing its temperature. With the exception of special processes such as freezing fish, air is usually used as an intermediate heat transfer medium. Therefore, for the implementation of refrigeration, air conditioning and ventilation, fans and air ducts are used. The three processes mentioned above are closely related to each other and together provide a given microclimate for people, machines and cargo.

To reduce the temperature in cargo holds and in provisional storerooms during refrigeration, a cooling system is used, the operation of which is provided by a refrigeration machine. The selected heat is transferred to another body - a refrigerant at a low temperature. Air conditioning cooling is a similar process.

In the simplest schemes of refrigeration units, heat is transferred twice: first in the evaporator, where the refrigerant, which has a low temperature, takes heat from the cooled medium and reduces its temperature, then in the condenser, where the refrigerant is cooled, giving off heat to air or water. In the most common schemes of marine refrigeration plants (Fig. 1), a steam compression cycle is carried out. In the compressor, the vapor pressure of the refrigerant rises and its temperature rises accordingly.

Rice. 1. Scheme of a steam compressor refrigeration unit: 1 - evaporator; 2 - thermosensitive balloon; 3 - compressor; 4 - oil separator; 5 - capacitor; 6 - dryer; 7 - pipeline for oil; 8 - control valve; 9 - thermostatic valve.

This hot, pressurized steam is injected into the condenser, where, depending on the application conditions of the plant, the steam is cooled with air or water. Due to the fact that this process is carried out at elevated pressure, the steam is completely condensed. The liquid refrigerant is piped to a control valve which controls the liquid refrigerant supply to the evaporator where the pressure is kept low. The air from the refrigerated room or the conditioned air passes through the evaporator, causes the liquid refrigerant to boil, and itself, giving off heat, is cooled. The refrigerant supply to the evaporator must be adjusted so that all the liquid refrigerant in the evaporator is boiled off and the vapor is slightly superheated before it re-enters the compressor at low pressure for subsequent compression. Thus, the heat that has been transferred from the air to the evaporator is carried by the refrigerant through the system until it reaches the condenser, where it is transferred to the outside air or water. In installations where an air-cooled condenser is used, such as a small provisional refrigeration unit, ventilation must be provided to remove the heat generated in the condenser. For this purpose, water-cooled condensers are pumped with fresh or sea water. Fresh water is used in cases where other mechanisms of the engine room are cooled with fresh water, which is then cooled by sea water in a centralized water cooler. In this case, due to the higher temperature of the water cooling the condenser, the temperature of the water leaving the condenser will be higher than when the condenser is cooled directly by sea water.

Refrigerants and coolants. Cooling working fluids are divided mainly into primary - refrigerants and secondary - coolants.

The refrigerant under the influence of the compressor circulates through the condenser and evaporative system. The refrigerant must have certain properties that meet the requirements, such as boiling at low temperature and overpressure and condensing at a temperature close to sea water temperature and moderate pressure. The refrigerant must also be non-toxic, explosion-proof, non-flammable, non-corrosive. Some refrigerants have a low critical temperature, i.e. a temperature above which the refrigerant vapor does not condense. This is one of the disadvantages of refrigerants, in particular carbon dioxide, which has been used on ships for many years. Due to the low critical temperature of carbon dioxide, the operation of ships with carbon dioxide refrigeration plants in latitudes with high seawater temperatures was significantly hampered, and because of this, additional cooling condenser systems had to be used. In addition, the disadvantages of carbon dioxide include the very high pressure at which the system operates, which in turn leads to an increase in the mass of the machine as a whole. After carbon dioxide, methyl chloride and ammonia were widely used as refrigerants. Currently, methyl chloride is not used on ships due to its explosive nature. Ammonia still has some use today, but due to its high toxicity, special ventilation systems are required when using it. Modern refrigerants are fluorinated hydrocarbon compounds having various formulas, with the exception of the refrigerant R502 ( in accordance with the international standard (MS) HCO 817 - for the designation of refrigerants, the symbol of the refrigerant is used, which consists of the symbol R (refrigerant) and a defining number. In this regard, when translating, the designation of refrigerants R was introduced.), which is an azeotropic (fixed boiling point) mixture ( a specific mixture of different substances that has properties that are different from the properties of each substance separately.) refrigerants R22 and R115. These refrigerants are known as freons ( According to GOST 19212 - 73 (change 1), the name freon is established for freon), and each of them has a defining number.

The refrigerant R11 has a very low operating pressure, and to obtain a significant cooling effect, intensive circulation of the agent in the system is necessary. The advantage of this agent is especially evident when used in air conditioning installations, since relatively little power is required for air.

The first of the freons, after they were discovered and became available, freon R12 was widely used in practice. Its disadvantages include low (below atmospheric) boiling pressure, as a result of which, due to any leaks in the system, air and moisture are sucked into the system.

At present, the most common refrigerant is R22, which provides cooling at a sufficiently low temperature level at an excessive boiling pressure. This allows you to get some gain in the volume of the unit's compressor cylinders and other advantages. The volume described by the compressor piston operating on R22 freon is approximately 60% compared to the described volume of the compressor piston operating on R12 freon under the same conditions.

Approximately the same gain is obtained when using freon R502. In addition, due to the lower compressor discharge temperature, the likelihood of lube oil coking and failure of discharge valves is reduced.

All of these refrigerants are non-corrosive and can be used in hermetic and sealless compressors. To a lesser extent, the R502 refrigerant used in electric motors and compressors affects varnishes and plastic materials. At present, this promising refrigerant is still quite expensive and therefore has not been widely used.

Coolants are used in large air conditioning installations and in refrigeration plants that cool cargo. In this case, the refrigerant circulates through the evaporator, which is then sent to the room to be cooled. The refrigerant is used when the installation is large and branched, in order to eliminate the need to circulate in the system a large amount of expensive refrigerant, which has a very high penetrating power, i.e. it can penetrate through the slightest leaks, therefore it is very important to minimize the number of connections pipelines in the system. For air conditioning units, the usual coolant is fresh water, which may have the addition of a glycol solution.

The most common coolant in large refrigeration units is brine - an aqueous solution of calcium chloride, to which inhibitors are added to reduce corrosion.

The principle of operation of the refrigeration unit

To obtain artificial cold, technology uses the property of a liquid to change its boiling point depending on pressure.

To turn a liquid into vapor, a certain amount of heat must be applied to it. Conversely, the transformation of vapor into liquid (the process of condensation) occurs when heat is removed from the vapor.

The refrigeration unit consists of four main parts: a compressor, a condenser, a control valve and an air cooler (evaporator), connected in series by pipelines.

In this scheme, a refrigerant circulates in a closed circuit - a substance that can boil at low temperatures, depending on the vapor pressure in the air cooler. The lower this pressure, the lower the boiling point. The boiling process of the refrigerant is accompanied by the removal of heat from the environment in which the air cooler is located, as a result of which this environment is cooled.

The refrigerant vapor formed in the air cooler is sucked off by the compressor, compressed in it and forced into the condenser. During compression, the pressure and temperature of the refrigerant vapor rises. Thus, the compressor creates, on the one hand, a reduced pressure in the air cooler, which is necessary for the refrigerant to boil at a low temperature, and, on the other hand, an increased discharge pressure, at which the refrigerant can pass from the compressor to the condenser.

In the condenser, hot vapors of the refrigerant condense, i.e., they turn into a liquid. Condensation of vapors is carried out as a result of the removal of heat from them by the air cooling the condenser.

To obtain cold, it is necessary that the boiling (evaporation) temperature of the refrigerant be lower than the temperature of the cooled medium.

The AR-3 refrigeration unit is a single unit mounted on a frame with a heat-insulating wall separating the evaporative part (air cooler) from the rest of the equipment. The evaporative part enters into an opening made in the front wall of the cargo space. Outside air is sucked through the condenser by an axial fan into the engine room.

On the same shaft with the condenser fan, there is an air cooler fan that circulates air in the cargo space.

Thus, in the AR-3 refrigeration unit there are two independent air systems:
— cooled air circulation system in the cargo space (air from the floor of the cargo space is sucked in by the axial fan into the air cooler through the guide air duct, cooled and thrown out under the ceiling of the cargo space);
— condenser cooling system.

An axial fan located inside the engine room sucks air from the environment through the shutters of the front body panel, enters the condenser, cools it and is thrown out through the shutters installed on the side doors of the engine room.

To cool the carburetor engine, air is taken in through a special window in the front wall of the body and> thrown into the engine room. The heated air from the engine room exits through the side door shutters.

The control panel and all automation devices, as well as measuring devices, are located on the left (along the vehicle) side of the refrigeration unit and have free access.

Fuel is supplied to the carburetor engine from a tank fixed at the top of the unit.

The refrigeration unit is a closed hermetic system consisting of four main parts: an air cooler, a freon compressor, a condenser and a thermostatic expansion valve, connected in series by pipelines. This system is filled with freon-12 refrigerant, which continuously circulates in it, passing1 from one part to another.

The compressor sucks in the freon vapor formed during boiling from the air cooler 8, compresses them to the condensation pressure. Simultaneously with an increase in the pressure of the steam, their temperature also rises to 70-80 ° C. The heated freon vapor from the compressor is pumped through the pipeline into the condenser. Freon vapor condenses in the condenser, i.e., they turn into a liquid. Condensation of vapors is carried out as a result of deprivation from them. heat by air blowing over the outer surface of the condenser.

Liquid freon from the condenser enters the receiver (reserve tank). From the receiver, liquid freon is sent to the heat exchanger, where, passing through the coils, it is supercooled due to heat exchange with cold freon vapor moving towards from the air cooler. Then the liquid freon enters the filter-drier, where it is cleaned of moisture and contaminants with a moisture-absorbing substance - silica gel.

Rice. 2. Refrigeration
1 - control panel; 2 - instrument panel; 3 - block of fans; 4 - condenser; 5 - filter-drier; 9- heat exchanger; 10- heat-insulating wall; 1st engine UD-2; 15 - relay-regulator RR24-G; 16 - thermostatic pressor FV-6; 19 - electric motor A-51-2;

From the filter-drier, liquid freon is directed to a thermostatic expansion valve, which serves to regulate the amount of freon entering the air cooler (evaporator).

In the thermostatic valve, passing through a hole of small diameter, freon is throttled, that is, it sharply lowers its pressure. In this case, its pressure decreases from the condensation pressure to the evaporation pressure.

A decrease in pressure leads to a decrease in the temperature of freon. Freon in the form of a vapor-liquid mixture enters the air cooler through the liquid distributor, and the cycle is repeated.

Freon, flowing through the tubes of the air cooler at low pressure, boils intensively and, evaporating, passes from a liquid state to a vapor state.

The heat required for evaporation (latent heat of vaporization) is perceived by freon through the walls of the air cooler from the air of the cargo space blown by the fan through the finned surface of the air cooler.

Rice. 3. Scheme of air flows in the refrigeration unit: A - air flow for cooling the condenser; B - air flow for cooling the carburetor engine

Under these conditions, the air temperature of the cargo space decreases and the products in the cargo space cool down by transferring their heat to the colder air.

The thermostatic valve divides the freon system into two parts: the high pressure line (discharge or condensation pressure) - from the compressor discharge cavity to the thermostatic valve and the low pressure line (suction or evaporation pressure) - from the thermostatic valve to the compressor suction cavity.

From the air cooler, freon vapors are sucked off by the compressor through the suction pipeline and fed into the heat exchanger, where they, passing through the annulus, are overheated by liquid freon passing through the coil. Then the freon vapor enters the compressor, and the process of freon circulation in the refrigeration unit described below occurs in a closed cycle.

In the condenser, freon, turning from vapor into liquid, gives off heat to the blown air from the surrounding atmosphere, and in the air cooler, turning from liquid into vapor, absorbs the heat of the cargo space air, thereby lowering the temperature in the cargo space.

Thus, in the refrigeration unit, the refrigerant is circulated - freon-12, which itself is not consumed, and only the mechanical energy of the compressor driven by a carburetor or electric motor is expended to produce cold.

The power of a refrigeration unit is determined by the refrigeration capacity per hour of operation and is measured by the amount of heat (kilocalories per hour) that the refrigeration unit can take within an hour from the refrigerated medium, in this case from the refrigerator cargo space.

The compressor of the refrigeration unit is driven through a V-belt transmission by a carburetor engine, and when operating from an electrical network, by an electric motor.

From the compressor pulley, the movement is also transmitted by a V-belt to the DC generator and the fan shaft, which create air flows through the condenser and air cooler.

The temperature (from -15° to +4°С) in the cargo area of ​​the body is maintained automatically by means of a two-position thermostat TDDA.

When it is required to maintain a positive temperature in the cargo space of the body, the cooling capacity of the unit can be drastically reduced by means of a control valve on the suction line. In this case, the valve spool must be turned all the way clockwise.

The device, as well as the principle of operation of the refrigerator, is superficially studied in physics lessons, however, not every adult can imagine how the refrigerator works? Consideration and analysis of the main technical aspects will help in practice to extend the life and improve the performance of a household refrigerator.

Compression cooler device

The refrigerator device is best considered on the example of a compression sample, since such devices are most often used in everyday life:

1. - a device that pushes the refrigerant (gas) with the help of a piston, creating different pressures in different parts of the system;
2. Evaporator- a container into which the liquefied gas enters, absorbing heat from the refrigeration chamber;
3. Capacitor- a container in which the compressed gas gives off heat to the surrounding space;
4. expansion valve- a device that maintains the required pressure of the refrigerant;
5. refrigerant- a mixture of gases (freon is most often used), which, under the influence of the operation of the compressor, circulates in the system, taking and giving off heat in its different parts.

Refrigerator operation

The device of the refrigerator, as well as the principle of operation of a refrigerator with one chamber, can be understood by watching the corresponding video:

The most important aspect in understanding the operation of a compression apparatus is that it does not generate cold per se. Cold is caused by taking heat inside the device and sending it outside. Freon performs this function. Getting into the evaporator, which usually consists of aluminum tubes or plates soldered together, freon vapor absorbs heat.

You need to know: in old-style refrigerators, the evaporator housing is also the freezer housing. When defrosting this chamber, do not use sharp objects to remove ice, since all the freon will disappear through the pierced evaporator housing. A refrigerator without refrigerant becomes inoperative and is subject to costly repairs.

Further, under the influence of the compressor, freon vapor leaves the evaporator and passes into the condenser (a system of tubes that are located inside the walls and on the back of the unit). In the condenser, the refrigerant cools down, gradually becoming liquid. On the way to the evaporator, the gas mixture is dried in a filter-drier and also passes through a capillary tube. At the entrance to the evaporator, due to the increase in the inner diameter of the tube, the pressure drops and the gas becomes vaporous. The cycle is repeated until the required temperature is reached.

How does a compressor work?

With the help of a piston, the compressor distills the refrigerant from one pipe system to another, alternately changing the physical state of freon. When the refrigerant is supplied to the condenser, the compressor compresses it strongly, causing the freon to heat up. After going a long way through the labyrinth of condenser tubes, cooled freon enters the evaporator through an expanded tube. The sudden change in pressure cools the refrigerant rapidly. Now freon vapors are able to absorb a certain dose of heat and pass into the condenser tube system.

In household appliances, fully sealed compressor housings are used that do not allow the working gas mixture to pass through. For the purpose of tightness, the electric motor that drives the piston is also located inside the compressor housing. All rubbing parts inside the motor-compressor are lubricated with special oil.

The electrical circuit of the refrigerator can be useful for those who are ready for self-diagnosis and repair of the refrigerator:

The device and principle of operation of a two-chamber refrigerator

The device of a two-chamber refrigerator differs from a single-chamber one in that each compartment has its own evaporator. Unlike their predecessors, in two-chamber devices, both compartments are isolated from each other. In such devices, the freezer is usually located at the bottom, and the refrigeration part is at the top. The principle of operation of a two-chamber refrigerator is that the working gas mixture first cools the freezer evaporator to a certain sub-zero temperature. Only after that the freon passes into the evaporator of the refrigeration compartment. After the evaporator of the refrigerating chamber reaches a certain minus temperature, the thermostat is activated, which stops the operation of the motor.

In everyday life, two-chamber devices with one compressor are more often used. In units with two motors, the principle of operation of the refrigerator does not change significantly, just one compressor works for the freezer, the other for the refrigerator. It is generally accepted that the operation of a refrigerator with one compressor is more economical, but in reality this is not always the case. After all, in a device with two motors, you can turn off one of the cameras, in which there is no need. The operation of a two-chamber refrigerator with one compressor always involves the simultaneous cooling of both chambers.

Refrigerator and ambient temperature

The operating instructions for most household refrigerators indicate at what temperature it is best to operate it. The minimum allowable indicator is a temperature of +5 Celsius. Can the refrigerator work in cold conditions, especially in the cold? Consider possible problems:

• The thermostat is not working properly. Under normal conditions, the thermostat breaks the electrical circuit when the required temperature is reached. When the air inside warms up, the thermostat will close the electrical circuit again, and the motor will resume its operation. In conditions of sub-zero ambient temperature, the thermostat most likely will not turn on the compressor again, since the heat inside the chamber simply has nowhere to come from;
• Compressor difficult to start. In older devices, R12 and R22 refrigerants were most often used. For normal operation, refrigerant oils were used, which become too thick at temperatures below + 5 ° C, which means that the start and movement of the piston will be difficult;
• The appearance of the effect of "wet run". Since there is no heat in the refrigerator, the operation of the evaporator is disrupted. The vapor saturated with droplets enters the compressor. As a result of prolonged operation in such conditions, the entire mechanics of the motor will be damaged.

In simple words, a gentle attitude to the device will significantly extend its life.

The principle of operation of the absorption refrigerator

In the absorption apparatus, cooling is associated with the evaporation of the working mixture. Most often, this substance is ammonia. The movement of the refrigerant occurs as a result of the dissolution of ammonia in water. From the absorber, the ammonia solution enters the desorber, and then to the reflux condenser, in which the mixture is separated into its original components. In the condenser, the ammonia becomes liquid and is sent back to the evaporator.

Fluid movement is provided by jet pumps. In addition to water and ammonia, hydrogen or another inert gas is present in the system.

Most often, an absorption refrigerator is in demand where it is impossible to use a conventional compression analogue. In everyday life, such devices are rarely used, since they are relatively short-lived, and the refrigerant is a toxic substance.

Operation and rest mode of the compression refrigerator

Many users are interested in the question: how long should the refrigerator work? The only true criterion for the normal operation of a home appliance is a sufficient degree of freezing and cooling of food in it.

How long a refrigerator can work and how long it should rest is not spelled out in any instruction, however, there is the concept of “optimal working time ratio”. To calculate it, the duration of the working cycle is divided by the sum of the working and non-working cycle. So, for example, a refrigerator that has worked for 15 minutes with a further 25-minute rest will have a coefficient of 15/(15+25) = 0.37. The smaller this coefficient, the better the refrigerator works. If the result of the calculation is a number less than 0.2, then most likely the temperature in the refrigerator is incorrectly set. A coefficient greater than 0.6 means that the tightness of the unit is broken.

How does the No Frost refrigerator work?

In refrigerators with a no frost system (“no frost”), there is only one evaporator, which is hidden in the freezer behind a plastic wall. The cold from it is transferred using a fan, which is located behind the evaporator. Through the technological openings, cold air enters the freezer, and then into the refrigerator.

In contact with

A clear understanding of the device and the processes occurring inside the refrigeration unit helps to extend the life of the equipment. Understanding how a refrigerator works is easy. In any model, it consists in the formation of a cold environment by absorbing heat in the interior of the object and its subsequent removal outside the device.

You will learn everything about how refrigerators with different operating principles work from our article. We will tell you about the features of the device and the rules of operation associated with it. Our advice will help protect chillers from premature failure, and save you the need for repairs.

Refrigeration equipment is used in many areas of activity. It is impossible to do without it in everyday life and it is impossible to imagine the full-fledged work of production shops at enterprises, trading floors, catering establishments.

Depending on the intended purpose and field of application, several main types of devices are distinguished: absorption, vortex, thermoelectric and compressor.

The compressor type is the most common, so we will consider it in more detail in the next section. Now let's outline the main differences between all 4 designs.

Operation of absorption technology

Two substances circulate in the system of absorption type installations - refrigerant and absorbent. The functions of the refrigerant are usually performed by ammonia, less often by acetylene, methanol, freon, a solution of lithium bromide.

An absorbent is a liquid that has sufficient absorbency. It can be sulfuric acid, water, etc.

All operation of the equipment is based on the principle of absorption, which implies the absorption of one substance by another. The design consists of several leading units - an evaporator, an absorber, a condenser, control valves, a generator, a pump

The elements of the system are connected by tubes, with the help of which a single closed loop is formed. The chambers are cooled by thermal energy.

The process is carried out as follows:

• the refrigerant dissolved in the liquid enters the evaporator;
• ammonia vapor boiling at 33 degrees is released from the concentrated solution, cooling the object;
• the substance passes into the absorber, where it is again absorbed by the absorbent;
• the pump pumps the solution into a generator heated by a specific heat source;
• the substance boils and the released ammonia vapors go into the condenser;
• the refrigerant cools down and turns into a liquid;
• the working fluid passes through the control valve, is compressed and sent to the evaporator.

As a result, ammonia circulating in a closed circuit takes heat from the cooled chamber, entering the evaporator. And gives it to the external environment, being in the condenser. The cycles are played non-stop.

Since the unit cannot be turned off, it is not very economical and is characterized by increased energy consumption. If such equipment fails, it will most likely not be possible to repair it.

The dependence of absorption devices on voltage drops, current and other parameters of the electrical network is minimal. Compact dimensions make it easy to install them in any convenient area

There are no bulky moving and rubbing elements in the design of the devices, so they have a low noise level. The devices are relevant for buildings whose electrical network is subject to constant peak loads, and places where there is no constant power supply.

The principle of absorption is implemented in industrial refrigeration, small refrigerators for cars and offices. Sometimes it is found in individual household models that operate on natural gas.

The principle of operation of thermoelectric models

The decrease in temperature in the chamber of a thermoelectric refrigerator is achieved using a special system that pumps out heat according to the Peltier effect. It involves the absorption of heat in the area of ​​​​the connection of two different conductors at the time of passage of an electric current through it.

The design of the refrigerators consists of cube-shaped thermoelectric elements made of metals. They are connected by one electrical circuit. With the movement of current from one element to another, heat also moves.

The aluminum plate absorbs it from the internal compartment, and then transfers it to the cubic working parts, which, in turn, redirect to the stabilizer. There, thanks to the fan, it is thrown out. According to this principle, portable and bags with a cooling effect work.

In most models of thermoelectric refrigeration appliances, when switching the polarity of the power supply, you can get not only cold, but also heat - up to 60 degrees Celsius. This function is used for heating food

This equipment is used in camping, in the field of arranging cars, yachts and motor boats, often placed in cottages and other places where it is possible to provide the device with a 12 V power supply.

Thermoelectric products have a special emergency mechanism that turns them off in case of overheating of working parts or failure of the ventilation system.

The advantages of this method of operation include high reliability and a fairly low noise level during operation of the devices. Among the disadvantages are the high cost, sensitivity to external temperatures.

Features of equipment on vortex coolers

In devices of this category there is a compressor. It compresses the air, which is further expanded in the installed swirl cooler units. The object is cooled due to the sudden expansion of the compressed air.

Vortex devices are durable and safe: they do not need electricity, do not have moving parts, do not contain hazardous chemical compounds in the internal design system

The method of vortex coolers has not received wide distribution, but was limited only to test samples. This is due to high air consumption, very noisy operation and relatively low cooling capacity. Sometimes devices are used in industrial enterprises.

Overview of compressor technology

Compressor refrigerators are the most common type of equipment in everyday life. They are in almost every home - they do not consume too much energy and are safe to use. The most successful models of reliable manufacturers serve their owners for more than 10 years. Consider their structure and the principles by which they work.

Features of the internal device

A classic household refrigerator is a vertically oriented cabinet equipped with one or two doors. Its body is made of rigid sheet steel with a thickness of about 0.6 mm or durable plastic, which facilitates the weight of the supporting structure.

For high-quality sealing of the product, a paste with a high content of vinyl chloride resin is used. The surface is primed and covered with high-quality enamel from spray guns. In the production of internal metal compartments, the so-called stamping method is used, plastic cabinets are made using the vacuum forming method.

The doors of the appliance are made of steel sheets. A dense rubber seal is inserted along the edges, which does not allow outside air to pass through. In some modifications, magnetic shutters are built in.

A layer of thermal insulation is necessarily laid between the inner and outer walls of the product, which protects the chamber from heat trying to penetrate from the environment and prevents the loss of cold formed inside. Mineral or glass felt, expanded polystyrene, polyurethane foam are well suited for these purposes.

The interior space is traditionally divided into two functional areas: refrigeration and freezing.

According to the form of the layout, they distinguish:

• one-;
• two-;
• multi-chamber devices.

In a separate view are allocated, including two, three or four cameras.

Single chamber units are equipped with one door. In the upper part of the equipment there is a freezer compartment with its own door with a folding or opening mechanism, in the lower part there is a refrigeration compartment with height-adjustable shelves.

Lighting equipment with an LED or an ordinary incandescent lamp is installed in the cells in order to see what, in fact, is in the refrigerator.

Devices made according to the "side by side" type are much larger and wider than their counterparts. Both compartments in them occupy space along the entire height of the equipment. They are parallel to each other

In two-chamber units, the internal cabinets are insulated and each separated by its own door. The location of departments in them can be European and Asian. The first option involves the bottom layout of the freezer, the second - the top.

Components of the structure

Compressor-type refrigeration units do not produce cold. They cool an object by absorbing internal heat and transporting it outward.

The procedure for the formation of cold proceeds with the participation of the following nodes:

• coolant;
• capacitor;
• evaporative radiator;
• compressor apparatus;
• thermostatic valve.

The role of the refrigerant that fills the refrigerator system is played by various brands of freon - mixtures of gases with a high level of fluidity and rather low boiling / evaporation temperatures. The mixture moves in a closed circuit, transferring heat to different parts of the cycle.

In most cases, manufacturers use Freon 12 as a working element for home refrigeration machines. This colorless gas with a barely perceptible specific odor is not toxic to humans and does not affect the taste and properties of products stored in chambers.

Compressor- the central part of the design of any refrigerator. This is an inverter or linear unit that provokes forced circulation of gas in the system, forcing pressure. Simply put, it compresses freon vapors and makes them move in the right direction.

The equipment can be equipped with one or two compressors. Vibrations arising during operation are absorbed by the external or internal suspension. In models with a pair of compressors, a separate device is responsible for each chamber.

The classification of compressors provides for two subtypes:

1. Dynamic. Forces the refrigerant to move due to the force of the movement of the blades of a centrifugal or axial fan. It has a simple structure, but due to low efficiency and rapid wear under the action of torque, it is rarely used in household equipment.
2. Volume. It compresses the working fluid with the help of a special mechanical device, which is started by an electric motor. It happens piston and rotary. Basically, such compressors are installed in refrigerators.

piston apparatus presented in the form of an electric motor with a vertical shaft, enclosed in a solid metal casing. When the start relay connects power, it activates the crankshaft and the piston attached to it starts to move.

A system of opening and closing valves is connected to the work. As a result, freon vapors are drawn out of the evaporator and forced into the condenser.

If a piston compressor breaks down, repairs are possible only if specialized professional equipment is used. Any disassembly in a domestic environment is fraught with loss of tightness and the impossibility of further operation.

In rotary mechanisms, the required pressure is maintained by two rotors moving towards each other. Freon enters the upper pocket, located at the beginning of the shafts, is compressed and exits through the lower hole of a small diameter. To reduce friction, oil is introduced into the space between the shafts.

Capacitors are made in the form of a coil grill, which is fixed on the back or side wall of the equipment.

They have a different design, but they are always responsible for one task: cooling hot gas vapors to the specified temperature values ​​​​by condensing the substance and dissipating heat in the room. There are shield or ribbed-tubular.

The evaporator consists of a thin aluminum pipeline, brazed steel plates. It comes into contact with the internal compartments of the refrigerator, effectively removes the absorbed heat from the appliance and significantly lowers the temperature in the cabinets.

expansion valve is needed in order to maintain the pressure of the working fluid at a certain level. Large units of the unit are interconnected by a system of tubes forming a hermetic closed ring.

Work cycle sequence

The optimum temperature for long-term storage of provisions in compression devices is created during the work cycles carried out one after the other.

They proceed as follows:

• when the device is connected to the mains, a compressor is started, compressing freon vapor, synchronously increasing their pressure and temperature;
• under the force of excess pressure, the hot working fluid, which is in a gas aggregate state, enters the condenser tank;
• moving along a long metal tube, the steam releases the accumulated heat into the external environment, cools down smoothly to room temperature values ​​and turns into a liquid;
• the liquid working fluid passes through a filter-drier that absorbs excess moisture;
• the refrigerant penetrates through a narrow capillary tube, at the exit of which its pressure decreases;
• the substance cools down and transforms into a gas;
• cooled steam reaches the evaporator and, passing through its channels, takes heat from the internal compartments of the refrigeration unit;
• the temperature of the freon rises, and it goes back to the compressor.

In simple terms, how a compressor refrigerator works, the process looks like this: the compressor distills the refrigerant in a vicious circle. Freon, in turn, changes the state of aggregation thanks to special devices, collects heat inside and transfers it outside.

The operating cycle in the system is repeated until the temperature values ​​​​set by the system programs are reached, and resumes again when their increase is recorded

After cooling to the desired parameters, the thermostat stops the motor, opening the electrical circuit.

When the temperature in the chambers begins to rise, the contacts close again and the compressor motor is activated. That is why, during the operation of the refrigerator, the hum of the motor constantly appears, then again subsides.

There is nothing complicated in the operation of the equipment: it operates in automatic mode around the clock. The only thing that needs to be done the first time you turn it on and periodically adjust it during operation is to set the temperature regime that is optimal in specific circumstances.

The required temperature is set. In an electromechanical system, the values ​​​​are set by eye or taking into account the recommendations specified in the manufacturer's instructions. The type and amount of food stored in the refrigerator should be taken into account.

The regulator knob, as a rule, is a round mechanism with several divisions, or, in more modern and more expensive models, control can be carried out using a touch panel.

In order to assess the degree of freezing, experts advise first to put the regulator in the middle position, and after a while, if necessary, twist it to the right or left.

Each mark on such a pen corresponds to a certain temperature regime: the larger the division, the lower the temperature. The electronic unit allows you to set the temperature with a maximum accuracy of 1 degree using a rotary knob or buttons.

For example, set the freezer compartment to -14 degrees. All entered parameters will be displayed on the digital display.

To maximize the life of your home refrigerator, you should not only understand its structure, but also properly care for it. Lack of proper service and improper operation can lead to rapid wear of important parts and defective functioning.

You can avoid undesirable consequences by adhering to a number of rules:

1. Clean the condenser regularly from dirt, dust and cobwebs in models with an open metal grill on the back wall. To do this, you need to use an ordinary, slightly damp cloth or a vacuum cleaner with a small nozzle.
2. Install equipment correctly. Make sure that the distance between the condenser and the wall of the room is at least 10 cm. This measure will help ensure unhindered circulation of air masses.
3. Timely defrost, preventing the formation of an excessive layer of snow on the walls of the chambers. At the same time, to remove ice crusts, it is forbidden to use knives and other sharp objects that can easily damage and disable the evaporator.

It should also be borne in mind that the refrigerator should not be placed next to heating appliances and in places where direct contact with sunlight is possible. Excessive influence of external heat has a bad effect on the operation of the main components and the overall performance of the device.

For cleaning parts of the product made of stainless steel, only special products recommended by the manufacturer in the instructions for the device are suitable.

If you plan to move from place to place, it is best to transport the equipment in a truck with a high van, fixing it in a strictly upright position.

Thus, it is possible to prevent breakdowns, leakage of oil from the compressor, which enters directly into the refrigerant circuit.

Conclusions and useful video on the topic

Video #1 How the refrigeration unit works:

Video #2 Detailed explanation of the device of compression refrigerators:

Video #3 Information about the operation of absorption machines:

While refrigeration equipment is working properly, consumers are rarely interested in its device. However, this knowledge should not be neglected. They are very valuable because they allow you to quickly determine the cause of the breakdown and find the problem area, preventing serious malfunctions.

Please leave comments, post thematic photos, ask questions on the topic of the article in the block below. Tell us about how you figured out the device of your own refrigerator. Share how you put your knowledge about the design of a chiller into practice.

, and what processes occur during its operation. For the end consumer of refrigeration equipment, a person who needs artificial cold in his enterprise, whether it is the storage or freezing of products, air conditioning or , water, etc., it is not necessary to know and understand the theory of phase transformations in refrigeration equipment in detail. But basic knowledge in this area will help him in the right way. and supplier.

The refrigeration machine is designed to take heat (energy) from the cooled body. But according to the law of conservation of energy, heat will not disappear just like that, therefore, the energy taken must be transferred (given away).

Cooling process based on physicalheat absorption when boiling (evaporating) a liquid (liquid refrigerant).designed to suck gas from the evaporator and compress it, forcing it into the condenser. When compressing and heating refrigerant vapors, we give them energy (or heat), while cooling and expanding, we take away energy. This is the basic principle on which heat transfer occurs and the refrigeration plant operates. Refrigerants are used in refrigeration to transfer heat.

Refrigeration compressor 1 sucks off the gaseous refrigerant (freon) from (heat exchanger or air cooler) 3, compresses it and pumps it into 2 (air or water). In condenser 2, the refrigerant is condensed (cooled by air flow from a fan or water flow) and becomes liquid. From the condenser 2, the liquid refrigerant (freon) enters the receiver 4, where it accumulates. Alsothe receiver is necessary to constantly maintain the required level of refrigerant. The receiver is equipped with shut-off valves 19 at the inlet and outlet. From the receiver, the refrigerant enters the filter-drier 9, where the remaining moisture, impurities and contaminants are removed, then it passes through the sight glass with a humidity indicator 12, the solenoid valve 7 and is throttled by the thermostatic valve 17 into the evaporator 3.

The expansion valve is used to control the flow of refrigerant to the evaporator

In the evaporator, the refrigerant boils, taking heat from the object to be cooled. The refrigerant vapors from the evaporator through the filter on the suction line 11, where they are cleaned of contaminants, and the liquid separator 5 enter the compressor 1. Then the cycle of operation of the refrigeration machine is repeated.

Liquid separator 5 prevents liquid refrigerant from entering the compressor.

To ensure guaranteed oil return to the compressor crankcase, an oil separator 6 is installed at the compressor outlet. In this case, the oil enters the compressor through the shut-off valve 24, filter 10 and sight glass 13 through the oil return line.

Vibration isolators 25, 26 on the suction and discharge lines provide vibration damping during compressor operation and prevent their propagation along the refrigeration circuit.

The compressor is equipped with a crankcase heater 21 and two shut-off valves 20.

The crankcase heater 21 is necessary for evaporating the refrigerant from the oil, preventing the refrigerant from condensing in the compressor crankcase when it is stopped and maintaining the required oil temperature.

In semi-hermetic chillers that use an oil pump in the lubrication system, an oil pressure control switch 18 is used. This relay is designed to emergency shutdown of the compressor in the event of a decrease in oil pressure in the lubrication system.

If the unit is installed outdoors, it must be additionally equipped with a hydraulic condensing pressure regulator to ensure stable operation in winter conditions and maintain the required condensing pressure in the cold season.

High pressure switches 14 control the on/off of the condenser fans to maintain the required condensing pressure.

The low pressure switch 15 controls the on/off of the compressor.

The high and low pressure alarm switch 16 is designed for emergency shutdown of the compressor in case of low or high pressure.