How the refrigerator works: principle of operation of the main types of refrigerators

Different types of refrigerators

A clear understanding of the device and the processes occurring inside the refrigeration unit helps to extend the life of the equipment. It’s easy to understand how the refrigerator works. It consists of the formation of a cold environment by absorbing heat in the internal part of the object and its subsequent removal outside the device.

You will learn all about how refrigerators with different operating principles work from this article. We will talk about the features of the device and related operating rules. Our tips will help protect your unit from premature breakdowns and save you the trouble of repairing them.

Depending on the intended purpose and scope, there are several main types of devices: 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 types.

The operation of absorption technology

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

The absorbent is a liquid that has sufficient absorption capacity. It can be sulfuric acid, water, etc.

Elements of the system are connected by tubes, with the help of which a single closed cycle / loop is formed. The cooling of the chambers happens due to thermal energy.

The process is as follows:

  • a refrigerant dissolved in a liquid penetrates the evaporator;
  • ammonia vapors boiling at 33 degrees C are 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 special heat source;
  • the substance boils and the ammonia vapors released go into the condenser;
  • the refrigerant cools and transforms into a liquid;
  • the working fluid passes through the control valve, is compressed and sent to the evaporator.

As a result, the ammonia circulating in a closed circuit takes heat from the cooled chamber and enters the evaporator, and gives it out into the environment, being in the capacitor. This process runs non-stop.

Since the unit cannot be turned off, it has an increased energy consumption. If such equipment fails, you will most likely fail repairing it.

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

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

The principle of operation of thermoelectric models

The temperature reduction in the chamber of the thermoelectric refrigerator is achieved using a special system that pumps heat. It implies the absorption of heat in the area of ​​the connection of two different conductors at the time of passage of electric current through it.

The design of refrigerators consists of thermoelectric elements in the form of a cube made of metal. They are combined by one electrical circuit. Along with the movement of current from one element to another, heat moves as well.

The aluminum plate absorbs it from the inner compartment, and then transfers it to the cubic working parts, which, in turn, perform a redirection to the stabilizer. There it is lead out of the chamber, thanks to the fan. Portable mini-refrigerators and bags with a cooling effect work according to this principle, too.

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

Thermoelectric units are provided with a special emergency mechanism which turns them off in case of overheating of working parts or a failure of the ventilation system.

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

Features of vortex systems

In devices of this category there is a compressor. It compresses the air, which further expands in the installed units of the vortex coolers. The object cools due to a sharp expansion of compressed air.

The vortex cooler method did not succeed in being widely used, and was limited only to test samples. This is explained by high air consumption, very noisy operation and relatively low cooling capacity. Sometimes such devices are used in industrial enterprises.

Compressor units overview

Compressor refrigerators are the most common type of household equipment. They are in almost every home – they do not consume too much energy resources and are safe to operate. The most successful models of reliable manufacturers have been serving 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 or durable plastic that facilitates the weight of the supporting structure.

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

Between the inner and outer wall of the unit, a thermal insulation layer is necessarily laid, which protects the chamber from heat trying to penetrate in there from the environment, and prevents the loss of cold formed inside. Mineral or glass felt, polystyrene foam, polyurethane foam are well suited for these purposes.

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

According to the layout, they distinguish:

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

Side-by-Side units, including two, three or four cameras, are a separate option.

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, and in the lower part there is a refrigeration section with shelves adjustable in height.

Lighting equipment with an LED or an ordinary incandescent lamp is installed in the chambers in order to see what there is in the refrigerator.

In two-chamber units, the internal cabinets are isolated and separated by their own doors. The location of compartments can be European and Asian. The first option involves the lower layout of the freezer, the second – the upper.

Constituent structural elements

Compressor-type refrigeration units do not produce cold. They cool the object by absorbing internal heat and redirecting it outside.

The procedure for the formation of cold happens with the help of:

  • cooling agent;
  • capacitor;
  • evaporative radiator;
  • compressor unit;
  • thermostatic valve.

The refrigerant used to fill the refrigerator system is called freon – a mixture of gases with a high level of fluidity and fairly low boiling / evaporation temperatures. 

A compressor is 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 by pumping pressure. Simply put, a refrigerator compressor compresses the freon vapor and makes them move in the right direction.

The equipment can have 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.

There are two subtypes of compressor classification:

  • Dynamic. Forces the refrigerant to move due to the force of movement of the blades of a centrifugal or axial fan. It has a simple structure, but is rarely used due to low efficiency and rapid wear.
  • Volume. It compresses the working fluid using a special mechanical device that is started by an electric motor. It happens piston and rotary. Such compressors are installed in most refrigerators.

The piston unit is presented in the form of an electric motor with a vertical shaft enclosed in a one-piece metal casing. When the start relay connects power, it activates the crankshaft, and the piston mounted on it starts to move.

A system of opening and closing valves is connected. As a result, freon vapors are pulled from the evaporator and pumped into the condenser.

In rotor mechanisms, the necessary 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 added into the space between the shafts.

Capacitors are made in the form of a grid-coil, which is fixed to the rear or side wall of the refrigerator.

They have a different design, but they are always responsible for one thing: cooling hot gas vapors to preset temperatures by condensing the substance and dissipating heat in the room.

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

The optimum temperature for long-term storage of food in compressor devices is created during work cycles that are carried out one after another.

They proceed as follows:

  • when the device is connected to the mains, a compressor starts compressing the freon pairs, simultaneously increasing their pressure and temperature;
  • under the force of excess pressure, a hot working fluid in a gas state of aggregation enters the capacitor;
  • moving along a long metal tube, steam releases the accumulated heat into the environment, cools down to room temperature ​​and turns into a liquid;
  • a liquid fluid passes through a filter drier that absorbs excess moisture;
  • the refrigerant penetrates through a narrow capillary tube, at the outlet of which its pressure decreases;
  • the substance cools and is converted into gas;
  • chilled steam gets to the evaporator and, passing through its channels, takes heat from the internal compartments of the refrigeration unit;
  • freon temperature rises, and it goes to the compressor again.

In other words, the process looks like this: the compressor distills the refrigerant in a never-ending circle. Freon, in turn, changes the state of aggregation due to special devices, collects heat inside and transfers it outside.

After cooling to the desired parameters, the temperature controller stops the motor, breaking the electrical circuit.

When the temperature in the chambers begins to rise, the contacts close again, and the compressor motor is activated by a protective start-up relay. That is why, during the operation of the refrigerator, the hum of the motor constantly appears and then disappears again.

Recommendations for proper use and care

There is nothing complicated in the operation of the equipment: it operates automatically around the clock. The only thing that needs to be done the first time you turn it on and when you periodically adjust it during operation is to establish the optimum temperature regime.

The desired temperature is set by the thermostat. In an electromechanical system, values ​​are set by eye or in accordance with the recommendations specified in the manufacturer’s instructions. In this case, the type and quantity of products 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 the touch panel.

To maximize the life of a home refrigerator, you should not only understand its principle of operation, but also take care of it. Lack of proper service and improper operation can lead to rapid wear of important parts and malfunctioning.

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

  • Regularly clean the condenser from dirt, dust and cobwebs in models with an open metal grill on the rear wall. To do this, use an ordinary slightly moistened rag or vacuum cleaner with a small nozzle.
  • Correctly install the refrigerator. Ensure that the distance between the condenser and the wall of the room is not less than 10 cm / 4 inches. This measure will help ensure unhindered circulation of air masses.
  • Defrost it in a timely manner, preventing the formation of an excessive layer of snow and ice on the walls of the chambers. On the other hand, it is forbidden to use knives and other sharp objects to eliminate ice crusts 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 it will constantly and for a long time be in direct contact with sunlight. Excessive influence of external heat adversely affects the operation of the main components and the overall performance of the device.

If you plan to transport it from place to place, it is best to transport the equipment in a high truck or van, fixing it in a vertical position only.

That way you can prevent breakdowns, oil leakage from the compressor entering directly into the circulation circuit of the cooling agent.

While refrigeration equipment is working properly, consumers are rarely interested in its way of work and in how to take care of it. However, this knowledge should not be neglected. It is a very valuable information because it allows you to quickly determine the cause of the breakdown and find the problem cause, preventing serious malfunctions.