The device and principle of operation of the refrigerator: two-chamber, absorption

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

Content:

  1. Compression Refrigerator Unit
  2. Refrigerator operation
  3. How does the compressor work?
  4. The device and principle of operation of the two-chamber refrigerator
  5. Refrigerator and ambient temperature
  6. The principle of operation of the absorption refrigerator
  7. Operating and resting mode of the compression refrigerator
  8. How does the No Frost refrigerator work?

Compression Refrigerator Unit

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

  1. Compressor - a device that pushes the refrigerant (gas) with a piston, creating different pressures in different parts of the system;
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  3. Evaporator - the tank into which the liquefied gas enters, absorbing heat from the refrigerator;
  4. Capacitor - a container in which compressed gas gives off heat to the surrounding space;
  5. Thermostatic expansion valve - a device supporting the necessary refrigerant pressure;
  6. Refrigerant - a mixture of gases (Freon is most often used), which, under the influence of compressor operation, circulates in the system, taking and giving off heat in its different areas.

Refrigerator operation

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

The most important aspect in understanding the operation of the compression apparatus is that it does not create cold as such. Cold occurs as a result of heat extraction inside the device and its sending out. This function is performed by freon. Once in an evaporator, which usually consists of aluminum tubes or plates welded together, freon vapor absorbs heat.

You need to know this: in old-style refrigerators, the evaporator case is also the case of the freezer. When defrosting this chamber, sharp objects must not be used to eliminate ice, since the entire freon will disappear through the punctured case of the evaporator. A refrigerator without a refrigerant becomes inoperative and requires expensive repairs.

Further, under the influence of the compressor, the 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, 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 inlet 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.

Read also:

  • What No Frost system?
  • How to remove bad breath from the refrigerator: https://sovetexpert.ru/kak-ubrat-zapax-iz-xolodilnika.html
  • What drip defrosting system? How is it different from No-Frost?
  • What is the average refrigerator power consumption? How much power does it wind?

How does the compressor work?

Using a piston, the compressor distills the refrigerant from one system of tubes to another, alternately changing the physical state of freon. When the refrigerant is supplied to the condenser, the compressor compresses it strongly, which makes freon heat up. Having traveled a long way through the labyrinth of condenser tubes, the cooled freon passes through the expanded tube into the evaporator. From a sudden change in pressure, the refrigerant cools quickly. Now freon vapors are able to absorb a certain dose of heat and go into the condenser tube system.

Compressor

In household appliances, completely sealed compressor housings are used that do not allow the working gas mixture to pass through. For the purpose of tightness, the electric motor, which 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:

Refrigerator circuit diagram

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

Two-chamber refrigerator

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. Indeed, in a device with two motors you can turn off one of the cameras, which is not needed. 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 a refrigerator work in cold conditions, especially in the cold? Consider the possible problems:

  • Incorrect operation of the thermostat. Under normal conditions, the thermostat breaks the electrical circuit when the required temperature is reached. When the air inside warms up, the thermostat again closes the electric circuit, and the motor resumes its work. In conditions of subzero 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;
  • Difficult start-up of the compressor. In older devices, R12 and R22 refrigerants were most often used. For normal operation, refrigerant oils were used, which at temperatures below + 5C become too thick, which means that starting and moving the piston will be difficult;
  • The occurrence of the effect of "wet running". Since there is no heat in the refrigerator, the operation of the evaporator is disrupted. Drop-saturated vapor enters the compressor. As a result of prolonged operation in such conditions, all the mechanics of the motor will be damaged.

In simple words, a sparing 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, such a 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 stripper, and then into the reflux condenser, in which the mixture is separated into the initial components. In the condenser, ammonia becomes liquid and is again sent to the evaporator.

Absorption refrigerator

Fluid transfer 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 analog. In everyday life, such devices are rarely used, since they are relatively short-lived, and the refrigerant is a toxic substance.

Operating and resting 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 the home appliance is a sufficient degree of freezing and cooling of the products in it.

How much the refrigerator can work, and how much it should rest is not spelled out in any instruction, however, there is the concept of an “optimal coefficient of working time”. To calculate it, the duration of the working cycle is divided by the sum of the working and non-working cycles. So, for example, a refrigerator that worked for 15 minutes with a further 25-minute rest will have a coefficient of 15 / (15 + 25) = 0.37. The lower this ratio, 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 integrity of the unit is impaired.

How does the No Frost refrigerator work?

In refrigerators with the no frost system (“without frost”) there is only one evaporator, which is hidden in the freezer behind a plastic wall. The cold from it is transmitted using a fan, which is located behind the evaporator. Through technological openings, cold air enters the freezer, and then into the refrigerator.

fridge no frost

To justify its name, the refrigerator has frost defrosting system. Several times a day, a timer is activated, activating the heating element located under the evaporator. The resulting liquid evaporates outside the refrigerator.

Just a few minutes spent studying the material may in the future benefit a simple layman because, knowing the device and the principle of operation, as well as the optimal operating conditions of the refrigerator, everyone can extend the life of the home keeper products.

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