Purpose and types of refrigerators - methods of obtaining cold. Household refrigerators: classification, modern range of compression refrigerators. Refrigerators depending on the number of chambers
The operation of refrigerators is based on artificial heat removal from interior space into the environment.
I. By the method of transferring heat from the refrigerator to the environment. Household refrigerators are subdivided into:
Compression (K);
Absorption-diffusion (A);
Thermoelectric (TE);
Magnetic (M).
In compression and absorption-diffusion refrigerators, heat from the refrigeration cabinet is removed to the environment using a special working substance - a refrigerant (in compression refrigerators - freon gas , in absorption-diffusion - a solution of ammonia with hydrogen), which, as it circulates through the closed system of the refrigeration unit, changes its state of aggregation, passing from a liquid state to a gaseous state and back to a liquid state.
The process of transition from liquid to gaseous state (evaporation or boiling process) takes place inside the refrigerator and is accompanied by heat absorption.
In compression refrigerators, the movement of refrigerant (freon - 12, less often freon - 22, another name for freon - 12, 22) is caused by the operation of the electric motor and compressor (a complex unit designed to compress and increase the temperature of refrigerant vapors).
The pressurized refrigerant caused by the operation of the electric motor enters the compressor where it is compressed and heated. The heated vapors enter the condenser, the temperature of which is below the temperature of the refrigerant. Condensation occurs in the condenser due to the temperature difference (vapor to liquid). The refrigerant then enters the evaporator through a narrow capillary tube. Since the channels of the evaporator are much larger than the diameter of the capillary tube, there is a drop in pressure and boiling of the refrigerant. The refrigerant turns into vapor and absorbs heat in the refrigerating chamber and the temperature decreases. Then the vaporous freon is sucked from the evaporator by the compressor and the whole cycle is repeated. The condenser is cooled with ambient air.
The design of the refrigerating chamber of compression refrigerators allows you to create different temperature conditions in individual places. In a conventional refrigerating chamber, the temperature is maintained from +2 to + 10 o C, in some types -0 o C, in the freezer compartment from -6 to -24 o C (quick freezing), in the low-temperature compartment, pre-frozen products are stored.
[In foreign-made compression refrigerators there may be additional temperature compartments ("wine cellar", ice maker, etc.). ]
Defrosting refrigerators can be carried out in the usual way or using special systems (No-Frost, Frost-Free, etc.).
Devices with the No-Frost system defrost automatically due to the fact that the air is distributed throughout the refrigerator using special fans. However, this system creates:
1) increased noise level and constant air circulation;
2) dries food.
In refrigerators with a “crying” evaporator, the latter is located in the refrigerating chamber. When the compressor is running, freezing occurs, and when it stops, thawing occurs due to the heat generated by the products. Moisture is removed through special channels.
Refrigerators with the Frost-Free system use both a “crying” evaporator and a No-Frost system.
Range of compression refrigerators:
1) domestic - Stinol-205 (107; 110) - Novolipetsk Metallurgical Plant; Atlant - 355-0 (151-01); Nord - 233 (226; 234) - Belarus and Ukraine.
2) foreign - Bosch KGS 3202; Siemens KGE 3501; Indesit GC 2322 W; Ariston - 216; Sharp RFSJ-55; Samsung SR-V-43.
In absorption-diffusion refrigerators, unlike compression refrigerators, there is no electric motor with a compressor, so the device works silently. The movement of the refrigerant (ammonia solution with hydrogen) is carried out by heating (electric, gas, etc.).
The cooling of the chamber is achieved, as in compression refrigerators, due to the absorption of heat from it by boiling liquid ammonia in the evaporator.
In the freezer compartment of such refrigerators, the temperature is maintained at about -5 o C.
Absorption refrigerators are small in size, operate silently, consume little electricity, and are relatively cheap.
The assortment is represented by devices of domestic production (Hoarfrost, Morozko), as well as foreign firms - Whirpool, Electrolux, etc.
Getting cold in thermoelectric refrigerators is based on the Peltier effect; also refrigerators do not have a refrigerant. The Peltier effect lies in the fact that when direct current flows through dissimilar semiconductors (i.e., materials with different conductivity - exp: selenium with bismuth, tellurium with antimony), a temperature difference is created at their junctions (connections); one semiconductor heats up (it is located outside the refrigerator), and the other is cooled by the same amount (it is located inside the refrigerator).
The temperature inside the refrigerator is up to +5 o C.
Thermoelectric refrigerators consume a lot of electricity and are expensive. They are mainly used as car refrigerators.
Assortment: Seagull, Voronezh, Tiny, etc.
II. Climatic design:
1) (up to 40 о С) refrigerators for a temperate climate (U);
2) (up to 45 ° C) for tropical (T).
III. By the number of refrigerating chambers:
Single chamber;
Two-chamber;
Three-chamber;
Multi-chamber.
IV. By temperature regime in the low-temperature compartment:
1) up to -6 o C;
2) from -6 to -12 about C;
3) from -12 to -18 about C;
4) from -18 to -24 o C.
V. At the place of installation:
1) floor-standing in the form of a cabinet (W);
2) floor in the form of a table (C);
3) built-in desktop (H);
4) block-built (B);
5) portable.
Vi. According to the group of difficulty - from 0 to 5.
Vii. By the level of comfort:
1) refrigerators with ordinary comfort;
2) with increased comfort (automatic defrosting; automatic door closing (if not closed at an angle of up to 10 °), light indication of the operating mode, a device for cooling and dispensing drinks, computer control and control system, timer clock, sound alarm open door and etc.).
VIII. By the internal volume of the chamber:
In the labeling of refrigerators, the total volume in liters is indicated by numbers through a fraction, the numerator is the total volume, the denominator is the volume of the low-temperature regime.
IX. By materials of manufacture: metal, plastic, etc.
X. By the nature of the coating and finishing.
XI. By model: model number - two digits, modification number - a digit separated by a hyphen).
Refrigerators are marked with:
1) brand - Stinol;
2) a group of complexity (0-5);
3) serial number of the model (two digits);
4) the serial number of the modification (digit separated by a hyphen);
5) type of refrigeration device (compression);
6) the number of cameras;
7) total volume;
8) the nature of the installation (floor-standing in the form of a cabinet);
9) standard number;
10) temperature in the lower temperature compartment.
In foreign models of refrigerators, the level of energy consumption is indicated, which is reflected in the letters: A, B and C - very economical, D - economical, E, F and G - with high energy consumption.
Classification refrigeration units is carried out taking into account the scope, principle of operation, design, the number of chambers, etc., which requires a different approach during the repair of refrigerators.
The most diverse models of refrigerators and freezers, both domestic and foreign, are subdivided into household and industrial ones according to the scope of their application.
Types and types of household refrigerators
All household refrigerators are manufactured in accordance with GOST 16317-87 and technical requirements EU.
According to the principle of action and obtaining cold, they are:
- compressor,
- absorption,
- thermoelectric,
- steam jet.
Currently, most household refrigerators (both domestic and imported) are made of the compressor type.
The advantage of compressor refrigerators lies in their economical production, safety and reliability in operation. Besides refrigerator repair this type is quite simple and inexpensive.
The use of freon or isobutane as a refrigerant in compressor refrigeration units is also an advantage over absorption refrigerators, which use an ammonia refrigerant. Due to the negative impact on human health and the environment, absorption refrigerators are almost never produced.
Household refrigerators, designed for storing and / or freezing food, are divided into two types by their design:
- cupboard,
- table.
By the number of cameras:
- single chamber,
- two-chamber,
- three-chambered.
Single-chamber refrigerators can be with or without a low-temperature compartment (NTO). The temperature in the NTO happens:
- not higher than -6? C (marking - one asterisk);
- not higher than -12? C (two asterisks);
- not higher than -18? C (three stars).
Freezers have a designation (special marking) on \u200b\u200bthe door - one large asterisk and three small ones.
Freezer types
Freezers are of two types by design: horizontal and vertical.
Horizontal freezers, rectangular in shape and opening from the top, are quite spacious. They are economical, with good thermal insulation, which allows them to remain cold for a long time in the event of a power outage.
The vertical structure of the freezer is designed as a cabinet with drawers and shelves. Such models are both small-sized (65 cm high), and two-meter, or in combination with side by side refrigerators.
The class of installation that characterizes the main function of the freezer - the freezing time and the duration of preservation of products, is indicated by the number of stars:
- in a freezer with one star, food can be stored at t? -12? C (up to 7 days);
- with two asterisks - at t? -12? C (up to 30 days);
- with three asterisks - at t? -18? C (up to 90 days);
- with four asterisks - at t? below -18 ° C (6-12 months).
Freezers are available with mechanical and electrical control. The panels house temperature controls and various colored indicators.
Freezers have different defrosting modes: manual, automatic, No Frost system.
Like refrigerators, freezers are categorized according to their ability to function normally at various maximum ambient temperatures. To do this, they are indicated by the corresponding letters:
- N, SN - not higher than +32? C;
- ST- not higher than +38? C;
- T- not higher than +43? C.
There are differences in the operational parameters of refrigeration units, such as:
- the total volume of the refrigerating chamber;
- useful volume;
- the total area of \u200b\u200bthe shelves of the chamber, NTO and door panel.
Classification of household refrigerators
Modern household refrigerators and freezers are sophisticated household appliances that operate in specific conditions - in residential (kitchen) premises, therefore high requirements are imposed on them: functioning in automatic mode; minimum noise level; high level reliability; complete operational safety; possibly small overall dimensions with a certain useful capacity, low cost and low operating costs.
By the type of refrigeration machine, household refrigerators are compressor-cooled (cooled by a compressor refrigeration machine), absorption (cooled by an absorption refrigeration machine) and semiconductor (cooled by semiconductor batteries), and freezers - compressor and absorption.
Compressor refrigerators make up a significant share in the range of household refrigeration equipment - over 90%.
By the method of installation, refrigerators are divided into floor-standing, wall-mounted and built-in ones.
Floor-standing refrigerators, installed on the floor of the premises, are the most widespread type of refrigerators both in our country and abroad. Among them are models made in the form of a table; their height is the same as kitchen tables - 850 mm, and on top there is a serving surface made of a special type of plastic for placing kitchen utensils and products. Wall-mounted refrigerators suspended from the wall of the room do not take up floor space, which is important for small apartments
Built-in refrigerators - devices included in the design furniture block and enclosed in a common shell with him. The unit can be a kitchen or living room, such as a sideboard and a bar.
According to climatic design, refrigerators are divided into U and T designs. The first refrigerators are intended for operation in regions with a temperate climate, i.e. in an area where the average of the annual absolute maximum air temperature does not exceed 40 ° C, and the average of the minima is below 45 ° C. Products of version U, operated in residential premises, must provide the required parameters at an ambient temperature of 10 to 35 ° C GOST 16317-70 "Household electric refrigerators" provides for a narrower range of climatic factors: 16-32 ° C. Usually, for products of version Y, the upper limit value is taken equal to 40 ° C.
Refrigerators of T version are used in regions with a tropical climate, which include the Near and Middle East, India, Indonesia, Vietnam, a significant part of Africa and Latin America, Cuba, the southeast and far west of the United States and several other areas. In Russia, tropical refrigerators are manufactured for export to these countries. For products of execution T, operated in residential premises, the limiting and operating values \u200b\u200bof ambient temperatures coincide: from 10 to 45 ° C; International Organization for Standardization (ISO) and CMEA set temperature Range from 18 to 43 ° C. Tropical refrigerators are subject to increased requirements with regard to the materials used, protective coatings, grounding, cabinet sealing and automation partitions.
Functionally, there are refrigerators for storing fresh food and fresh and frozen food. Appliances for storing fresh food do not have a low temperature compartment. They are produced in small quantities in some countries. The possibility of storing frozen products is provided only if the temperature in the low-temperature compartment is maintained at a temperature not higher than - 6 ° C; the lower the temperature in the compartment, the longer the shelf life.
In accordance with international and domestic standards, refrigerators are divided into three categories: for short-term (several days) storage of frozen foods - the temperature is not higher than - 6 ° C; for medium-term storage (up to two weeks) - temperature not higher than - 12 ° С; for long-term storage (up to three months) - the temperature is not higher than - 18 ° С. Refrigerators are labeled with one, two or three stars accordingly. Models with two and three stars are referred to as two temperature models. Asterisks are not used in the USA, Canada and Australia. According to the standards of these countries, two-temperature refrigerators must provide a temperature in the low-temperature compartment no higher than - 15 ° C.
By design, two-temperature refrigerators are single-chamber, two-chamber and multi-chamber. In two-chambers there is a heat-insulating partition between the low-temperature and positive compartments; each compartment has a separate door. Multi-compartment refrigerators have several (at least three) chambers with separate doors for storing various products.
Air circulation in the chambers can be carried out naturally or with the help of a fan, or in combination: in a low-temperature chamber forcibly, and in a positive one - naturally.
Refrigerators with natural circulation air in the chamber can have one (conventional design) or two evaporators (design with a "weeping" evaporator).
In models with natural air circulation, the low-temperature chamber is located at the top; in refrigerators with forced circulation, it can also be placed below or next to the positive one.
Refrigerators also differ in the method of defrosting the evaporator: they use manual defrosting, semi-automatic and automatic (partially or completely). In the first method, the consumer himself determines the moment of the beginning and end of the process, and also manually removes the melt water. With semi-automatic - the consumer determines only the beginning of defrosting, the end of the process is automatic; melt water is removed manually or automatically via drainage system... Defrosting is automatic if the process is controlled and the defrost water is removed without the participation of the consumer.
Partially automatic defrosting is the automatic defrosting of one of the two cooling surfaces. For example, the evaporator in the positive compartment is defrosting automatically in every cycle, and the evaporator in the low temperature compartment is defrosting manually every few months. Fully automatic defrosting is the automatic defrosting of all cooling surfaces.
The defrosting process can be fully automated only in refrigerators with forced air circulation; in other designs, use automatic system thawing (due to its frequent triggering) would damage the frozen food.
There are three methods of heating the evaporator during defrosting: with ambient air; hot steam of freon supplied by the compressor to the evaporator, bypassing the condenser; electric heater. For manual defrosting, natural heating with ambient air is applied, for semi-automatic and partially automatic - all three types of heating. In the case of partially automatic defrosting, natural heating of the evaporator occurs during the non-working part of each cycle. With fully automatic defrosting, intensive heating of the evaporator is used with hot freon steam or an electric heater.
The adopted cooling system, i.e. the presence of one or two evaporators, natural or forced air circulation, largely determines the operational and design features refrigerators. Therefore, later in this chapter, we will discuss (as the main types) refrigerators with one evaporator, including two-temperature, two-evaporator refrigerators, and refrigerators with forced air circulation.
According to GOST 16317-87, household refrigerators are subdivided according to the method of obtaining cold into:
compression (K); absorption (A);
by the method of installation on:
floor cabinet type (W); apolle table type (C);
by the number of cameras on:
single-chamber; two-chamber (D); three-chamber (T).
In two chamber refrigerators there is a heat-insulating partition between the NTO and the plus compartment.
According to their ability to work at maximum ambient temperatures, refrigerators are divided into classes:
UHL - not higher than 32 0 С;
T - not higher than 43 0 С.
Refrigerating appliance chambers are subdivided into:
a chamber for storing fresh vegetables and fruits;
a refrigerating chamber for cooling and storing chilled products;
a low-temperature chamber for storing frozen products (NTC);
freezer for freezing and storing frozen foods (MK);
a versatile chamber for storing food in a fresh, chilled or frozen state.
Single-chamber refrigerators are divided into:
by the availability of NTO on:
single chamber with NTO;
single-chamber without NTO;
by temperature in NTO for:
with a temperature not higher than -6 0 С;
with a temperature not higher than -12 0 С;
with a temperature not higher than -18 0 С.
The temperature in the NTO is not higher than - 6 0 С provides short-term storage for several days, not higher than - 12 0 С for two weeks and not higher than - 18 0 С for three months.
Types of refrigeration units according to the principle of operation:
- Compression
- Absorption
- Thermoelectric
- With vortex coolers
The device and principle of operation of the compression refrigerator
The theoretical basis on which the principle of operation of refrigerators is built is the second law of thermodynamics. The cooling working medium (refrigerant) in refrigerators performs the so-called reverse Carnot cycle. In this case, the main contribution to the transfer of heat is made by a change in the thermodynamic state of the refrigerant not in the Carnot cycle, but in phase transitions - evaporation and condensation of the refrigerant. In principle, it is possible to use only the Carnot cycle in the refrigeration cycle, but at the same time, in order to achieve a high cooling capacity, either a compressor that creates a very high pressure or a very large heat exchange area in the cooling and heating heat exchangers is required.
The main components of the refrigerator are:
- a compressor that creates the required pressure difference;
- an evaporator that takes heat from the inner volume of the refrigerator;
- a condenser that gives off heat to the environment;
- thermostatic expansion valve that maintains the pressure difference due to the throttling of the refrigerant;
- refrigerant - a substance that transfers heat from the evaporator to the condenser.
The compressor sucks in the refrigerant in the form of vapor from the evaporator, compresses it (while the temperature of the refrigerant rises) and pumps it into the condenser, where the refrigerant condenses into a liquid giving off the heat of condensation to external environment.
Domestic refrigerators use hermetic piston motor-compressors. In these compressors, the motor is located inside the compressor housing to prevent refrigerant from leaking through the shaft seal. To absorb vibrations, an elastic suspension of the motor-compressor is used. The suspension of the motor-compressor can be external, when the entire housing of the motor-compressor is suspended on springs, or internal, when only the compressor motor is suspended inside the housing.
In modern household refrigerators, external suspension is not used, since it absorbs compressor vibrations worse, and which is also noisier. To lubricate the rubbing parts of the compressor and the electric motor, special refrigerating oils are used, which have a low pour point. Oil and refrigerant dissolve well in each other.
In the condenser, the refrigerant heated as a result of compression cools down, giving off heat to the external environment, and at the same time it condenses, that is, it turns into a liquid that enters the capillary.
In household refrigerators, finned-tube condensers are most often used; steel wire or steel perforated sheet is used as fins. Heat removal from condensers is usually natural - due to convection and heat radiation; in high-performance and industrial refrigerators, forced cooling of the condenser with fan air or water is used.
The liquid refrigerant under pressure enters the evaporator through a throttling hole (capillary or thermoregulated expansion valve), where, due to a sharp decrease in pressure, the liquid evaporates. In this case, the refrigerant removes heat from the inner walls of the evaporator, the heat taken is spent on the boiling heat of the liquid, due to which the refrigeration space of the refrigerator is cooled, where the evaporator is located.
Evaporators of household refrigerators are most often sheet-tube, welded from a pair of aluminum sheets with internal channels for the passage of the refrigerant. The evaporator of the freezer is often the body of the freezer, while the evaporator of the refrigeration compartment (in refrigerators with two evaporators) is located on the back of the compartment.
Thus, in the condenser, the refrigerant under the influence of high pressure condenses and turns into a liquid state, releasing heat, and in the evaporator, under the influence of low pressure, it boils and turns into a gaseous state, absorbing heat.
The thermostatic expansion valve is required to create the required pressure differential between the condenser and the evaporator at which the heat transfer cycle takes place. It allows you to correctly (most completely) fill the internal volume of the evaporator with boiling refrigerant. The flow area of \u200b\u200bthe valve changes as the heat flux in the evaporator decreases; as the temperature in the cold chamber decreases, the flow rate of the circulating refrigerant decreases.
In household refrigerators, a capillary is most often used instead of a thermoregulated expansion valve. It does not change its cross section, but throttles a certain amount of refrigerant, which depends on the pressure at the inlet and outlet of the capillary, its diameter, length and type of refrigerant.
The purity of the refrigerant is important: water and impurities can clog the capillary or damage the compressor. Impurities can form as a result of corrosion of the inner walls of the refrigerator pipelines, and moisture can get in when filling the refrigerator, or penetrate through leaks (especially in refrigerators with an open compressor). Therefore, when charging, tightness is carefully observed; before charging with refrigerant, the circulation circuit is evacuated. Each refrigerator has a filter drier that is installed in front of the capillary.
Typically, a simple counter-flow heat exchanger is also used to reduce the temperature of the liquid refrigerant from the condenser before it enters the evaporator. As a result, the already cooled liquid refrigerant enters the evaporator, which is then further cooled in the evaporator, while the refrigerant from the evaporator is heated before entering the compressor and condenser. This improves the thermal efficiency and performance of the refrigerator and prevents liquid refrigerant from entering the compressor.
Refrigerator circuit
1 - Motor-compressor.
2 - Discharge tube.
3 - Condenser (or capacitor).
4 - Filter drier.
5 - Capillary tube
6 - Evaporator of the refrigerating chamber.
7 - Freezer evaporator.
8 - Return pipeline.
How an absorption refrigerator works
Just like in a compression refrigerator, in an absorption refrigerator, the working chamber is cooled due to the evaporation of a refrigerant (most often ammonia). Unlike a compression refrigerator, refrigerant is circulated by dissolving (absorbing) it in a liquid, usually water. Up to 1000 units can be dissolved in one unit of water volume. volume of ammonia. Saturated ammonia solution from the absorber enters the generator (stripper), and then into the reflux condenser, where it is decomposed into ammonia and water. Gaseous ammonia is liquefied in the condenser and again enters the evaporator, and the water purified from ammonia enters the absorber.
A variety of devices such as jet pumps can be used to circulate water through the system, eliminating the need for moving parts. A gas inert to the system components, for example hydrogen, is also added to the refrigerator system. In this case, the pressure in the entire system is almost the same, and the evaporation of the refrigerant occurs due to a change in the partial pressure.
In addition to ammonia and water, other vapors of substances can be used - for example, a solution of lithium bromide, acetylene and acetone. The advantages of absorption refrigerators are quiet operation, no moving mechanical parts, the ability to work from heating by direct fuel combustion, the disadvantages are poor specific indicators of cooling capacity per unit volume, sensitivity to position in space, as well as fragility: the pipelines of such a refrigerator are relatively quickly clogged with corrosion products. In addition, the refrigeration unit contains toxic ammonia and flammable hydrogen. Such refrigerators are practically not used in modern apartments, but are common in places where there is no round-the-clock access to electricity: for example, in mobile homes, where they run on electricity in parking lots in campsites, and on the way they work from burning natural gas. In addition, absorption units are often used in industrial refrigerators in cases where it is more profitable to use the energy of combustion of gas, rather than electricity. They are most efficiently used in industry in conjunction with cogeneration units, which makes it possible to utilize excess heat and increase efficiency. In this case, we are talking about the so-called trigeneration. In addition, absorption machines allow the use of waste heat.
The principle of operation of a thermoelectric refrigerator
The operation of a thermoelectric refrigerator is based on the Peltier Effect - when, when current passes through the contact of two dissimilar conductors in the direction of the contact potential difference, thermal energy is transferred so that one of these “dissimilar” conductors is cooled, and the second is heated due to thermal energy from the first and electrical energy of the passed electric current. A refrigerator based on Peltier elements is silent, reliable and durable, but it has not received wide distribution due to the high cost of cooling thermoelectric elements. Another disadvantage is the dependence of the refrigerating capacity on the ambient temperature. However, cooler bags, small car refrigerators and coolers drinking water often made with cooling from Peltier elements.
The principle of operation of the refrigerator on vortex coolers
Cooling is carried out by expanding the air pre-compressed by the compressor in blocks of special vortex coolers. It did not become widespread due to the high noise level, the need to supply compressed (up to 10-20 atm) air and its very large flow rate, low efficiency. Advantages - safety (since no electricity is used and there are no moving mechanical parts or dangerous chemical compounds in construction) durability, reliability.
Household electrical appliances for storing refrigerated and frozen food include refrigerators and freezers. Domestic refrigerators are designed for storing fresh and frozen food and cooking in small quantities food ice.
Refrigerators used for freezing food and their long-term storage are called freezers. These devices can be used for making edible ice, cooling and dispensing drinks, quick freezing food products in order to reduce their losses, for freezing and storing frozen ready-to-eat meals, semi-finished products, vegetable mixtures, etc.
Refrigerator classification:
By appointment: refrigerators, freezers, refrigerator-freezers.
By installation method: floor-standing cabinet type, floor-standing table type, built-in.
By the number of chambers: 1, 2 and 3 chambers.
By the degree of comfort: ordinary and superior.
By the method of defrosting the evaporator: refrigerators with a natural evaporator tap, semi-automatic and automatic.
In terms of temperature: in the low-temperature compartment (NTO) not higher than -6 ° C, products can be stored for no more than a week; with a temperature not higher than 12 ° C, frozen foods can be stored from two weeks to a month; with a temperature not higher than 18 ° С, from 3 months of storage to a year; freezer.
According to the method of obtaining cold, refrigerators are divided into compression, absorption, thermoelectric.
1) Compression refrigeratorsoccupy 90% of the refrigerator market. There are one-, two-, and multi-chamber. Such refrigerators are produced in combination, such as refrigerators-freezers. In a compression refrigerator, the refrigerant is:
a) freon 12 ("Sviyaga") freezer temperature -6 ° C;
b) freon-701, the temperature is -12-18 ° С in the freezer.
They have a large freezer volume, the volume of the cold chamber is 120-450 dm 3, they do not consume a large number of energy.
Ergonomic properties- ease of use, degree of comfort, the strength of shelves, pallets, dimensions, light and sound alarms matter.
Aesthetic properties of the refrigerator- this is color scheme, proportionality of the refrigerator cabinet shapes, arrangement of chambers, expressiveness of brand names.
The range of refrigerators entering the trade includes a large number of models of different designs, different manufacturers: Atlanta (Belarus), Stinol, Nord, Biryusa (Russia), Arston (Italy), etc.
2) Absorption refrigerators- the refrigerant is ammonia, which is heated by electric current or gas.
Absorption refrigerators are simple in design, silent, but have disadvantages: small amounts of food storage, high energy consumption. The capacity is 80-300 dm3. The assortment is represented by domestic models "Frost", "Morozko", as well as more expensive imported "Electrolux" (Sweden), etc.
Negative feature - no thermostat, no time relay, consume a lot of energy.
3) Thermoelectric refrigerators- there is no refrigerant. Its role is played by electricity... They are more secure. Heat is removed and removed to the outside by a thermopile. The refrigerator does not freeze, it cools. The temperature is from + 3 to + 8c. The range of Russian-made refrigerators includes such brands as "Chaika", "Voronezh", "Krokha", etc.
Quality requirements.
Refrigerators in terms of technical and operational indicators must comply with the requirements of the standard. Household refrigerators must provide the required temperature in the refrigerator compartment and low-temperature compartment. The noise level should not exceed 45dB at a distance of 1 m from the case. Refrigerators should be stored in a packed form in closed rooms with natural ventilation at a relative humidity of no higher than 80%.
Refrigerators are transported in the working position (vertically), securely fastened in order to exclude possible shocks and movements inside the vehicle.
They have a warranty period of 2-3 years.
