The dairy plant uses a one-stage refrigeration unit.
1 - compressor; 2 - capacitor; 3 - evaporators; 4 - receiver;
5 - liquid separator; 6 - oil separator; 7 - solenoid valve;
9 - filter drier; 10 - filter; 11 - filter on the suction line; 12 - sight glass with humidity indicator; 13 - sight glass;
14 - high pressure switch; 15 - low pressure switch; 16 - high and low pressure alarm relay; 17 - thermostatic valve; 18 - oil pressure control relay; 19 - receiver shut-off valve; 20 - compressor shut-off valve; 21 - crankcase heater; 25, 26 - vibration isolators.
Figure 4 - Scheme of the refrigeration unit
The cooling process is based on the physical phenomenon of heat absorption during boiling (evaporation) of a liquid (liquid refrigerant). The compressor of the refrigeration machine is designed to suck gas out of the evaporator and compress it, pump it into the condenser. When compressing and heating refrigerant vapors, we give them energy (or heat), while cooling and expanding, we take energy. This is the basic principle on the basis of which heat transfer takes place and the refrigeration plant operates. Refrigeration equipment uses refrigerants to transfer heat.
The refrigeration compressor (1) sucks in gaseous refrigerant from the evaporators (3), compresses it and pumps it into the condenser (2) (air or water). In the condenser (2), the refrigerant condenses and turns into a liquid state. From the condenser (2) the liquid refrigerant enters the receiver (4), where it accumulates. Also, the 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 moisture residues, impurities and impurities are removed, then it passes through a sight glass with a humidity indicator (12), a solenoid valve (7) and throttled by a thermostatic valve (17) into the evaporator ( 3).
The thermostatic expansion valve is used to regulate the refrigerant supply to the evaporator.
In the evaporator, the refrigerant boils, taking heat from the refrigeration object. Refrigerant vapors from the evaporator through the filter on the suction line (11), where they are cleaned from impurities, and the liquid separator (5) enters the compressor (1). Then the cycle of the chiller is repeated.
A liquid separator (5) prevents liquid refrigerant from entering the compressor.
To ensure a guaranteed return of oil to the compressor crankcase, an oil separator (6) is installed at the compressor outlet. In this case, the oil through the shut-off valve (24), filter (10) and sight glass (13) enters the compressor through the oil return line.
Vibration isolators (25), (26) on the suction and discharge lines provide damping of vibrations 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 to evaporate the refrigerant from the oil, prevent condensation of the refrigerant in the compressor crankcase when the compressor is at rest and maintain the required oil temperature.
Refrigeration machines with semi-hermetic reciprocating compressors, which use an oil pump in the lubrication system, use an oil pressure monitor (18). This relay is designed for 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.
The high pressure switch (14) controls 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 intended for emergency shutdown of the compressor in case of low or high pressure.
The machine method is the most common way of obtaining cold by changing the state of aggregation of the working substance, boiling it at low temperatures, with the removal of the necessary heat of vaporization from the cooled body or medium.
One of the conditions for the effective operation of commercial refrigeration equipment is the use of refrigerants with good thermodynamic, thermophysical, physicochemical, physiological and ozone-safe properties as working substances. Cost and availability are also important. Refrigerating agents must not be poisonous, cause suffocation and irritation of the mucous membranes of the eyes, nose and respiratory tract of a person.
Distinguish between natural and artificial refrigerants. Natural refrigerants include: ammonia (R717), air (R729), water (R718), carbon dioxide (R744), etc., artificial refrigerants - freons (mixtures of various freons).
There are currently three types of hydrofluorocarbon refrigerants:
chlorofluorocarbons (CFCs) with high ozone depletion potential. For example: R12, R13, R502, R503;
hydrochlorofluorocarbons (HCFCs), which contain hydrogen atoms, resulting in a shorter lifetime of these refrigerants in the atmosphere compared to CFCs, such as R22;
hydrofluorocarbons (HFCs), which do not contain chlorine. They do not deplete the ozone layer of the Earth and have a short lifetime in the atmosphere. For example: R134A, R404A.
In this regard, the problem of using natural substances as refrigerants, and first of all ammonia, is most urgent now for manufacturers of refrigeration equipment. In Russia, the need for cold for stationary refrigerators is mainly provided by ammonia refrigeration units, since ammonia does not destroy the ozone layer, does not directly affect the global thermal effect, has excellent thermodynamic properties, has a high heat transfer coefficient during boiling and condensation, and production availability.
The negative properties of ammonia include toxicity, fire and explosion hazard, and a strong unpleasant odor. Any accident with ammonia has serious consequences.
Compression refrigeration machines are mainly used in trade, which consist of the following main components: a compressor, an air-cooled condenser, a thermostatic expansion valve (TRV) and an evaporator. The refrigerating machine, in addition to the listed main parts, has automatic devices, filters, dryers, heat exchangers, etc.
The compressor is the most complex and important part of the refrigeration machine. It serves for suction of refrigerant vapors from the evaporator, compression and discharge into the condenser. The main indicator of the compressor's operation is its refrigerating capacity (the amount of heat that the refrigerating machine receives per unit of time from the cooled medium).
An air-cooled condenser is a heat exchanger in which the vaporous refrigerant coming from the compressor is converted into a liquid. This process takes place when the refrigerant gives off heat to the external environment.
An evaporator is a heat exchanger that removes heat from the medium to be cooled.
The thermostatic expansion valve is used to automatically supply the required amount of refrigerant to the evaporator. It controls and maintains the set temperature of the refrigerant vapor at the outlet from the evaporator.
Automation devices provide starting, stopping the refrigerating machine, protecting it from overloads, maintaining a given temperature regime in the cooled environment, optimal filling of the refrigerant evaporator, timely thawing of the snow coat from the evaporators.
The pressure switch automatically maintains the set pressure in the suction line by turning the compressor on and off.
Receiver - a reservoir that collects liquid refrigerant in order to ensure its uniform flow to the expansion valve and to the evaporator. The filter is used to remove mechanical impurities. The dehumidifier is designed to absorb moisture from the refrigerant when filling the system with it and during machine operation. The heat exchanger serves to superheat the refrigerant vapors from the evaporator to the compressor and subcool the refrigerant from the condenser to the expansion valve.
The principle of the refrigerating machine is as follows.
1. In the evaporator installed in the cooling volume, the liquid refrigerant boils at low pressure and temperature due to the extraction of heat from the environment.
2. From the evaporator, refrigerant vapors pass through the heat exchanger and the steam filter, then they are sucked off by the compressor, compressed and in the superheated state are pumped into the condenser, while the temperature and pressure increase.
3. In the air-cooled condenser, they condense; turn into liquid.
4. Liquid refrigerant flows down the condenser pipes and accumulates in the receiver, from where it passes under pressure through the liquid filter and heat exchanger.
5. The purified freon, passing through the narrow opening of the expansion valve, is throttled, sprayed and, with a sharp drop in temperature and pressure, enters the evaporator.
The cycle is repeated. Circulating in such a closed circle, the refrigerant alternately changes its state of aggregation, i.e., there is an abrupt transition of the refrigerant from a liquid to a gaseous state and vice versa.
Currently, commercial refrigeration equipment uses various refrigeration systems: built-in, remote and centralized.
Heat inflows into storerooms from refrigeration units built into the equipment lead to a decrease in turnover and an increase in unforeseen costs, including:
uncomfortable conditions for buyers are created (high air temperature in the trading floor and high noise level, unpleasant odors);
uncomfortable conditions for sellers and service personnel lead to a decrease in the quality of service, the image of the enterprise falls and the turnover decreases;
the service life of built-in refrigeration units is 2 ... 3 times lower than when using external cooling systems, and 4 ... 6 times lower than when using central units;
frequent equipment failures occur;
there are additional costs for air conditioning and energy consumption.
The external refrigeration supply is a refrigeration system based on autonomous condensing units located in the engine room and isolated from the commercial premises. Moreover, each unit can provide cold to several consumers.
One of the most important conditions for the effective development of trade enterprises is the use of centralized refrigeration systems, which are several parallel-connected compressors on a single frame with additional equipment. Each central unit is equipped with a microprocessor control unit that regulates the cooling capacity of the unit and ensures the uniform operation of each compressor and condenser.
The main advantages of using a centralized refrigeration system are as follows:
central units are compact and take up much less space;
significant energy savings are achieved, since large compressors have a higher efficiency;
for large supermarkets, a centralized refrigeration system is more economically profitable than the traditional refrigeration option; turnover increases;
high reliability is provided due to the use of several compressors;
in case of failure of one or several compressors, the remaining compressors will maintain the required temperature to prevent product loss until the malfunction is eliminated;
In order to navigate when the kitchen equipment fails, many housewives are forced to understand the principle of operation of many devices, such as: an electric stove, microwave oven, refrigerator and others. The main function of the refrigerator compartment is to keep nutritious food fresh, so it has to work constantly, and the services of a repair specialist cannot be used instantly. Understanding how a refrigerator works will help save financial and time resources, and many malfunctions can be fixed by hand.
The interior of the refrigerator
Everyone knows how a refrigerator works, in simple words - this equipment freezes and cools a wide variety of products, allowing them to avoid spoilage for some time.
At the same time, not everyone knows certain features of this device: what the refrigerator consists of, where does the cold come from in the inner plane of the chamber, how it is created by the refrigerator and why the device turns off from time to time.
To understand these issues, it is necessary to consider in detail the principle of the refrigerator.... To begin with, we note that cold air masses do not arise by themselves: the air temperature decreases inside the chamber during the operation of the unit.
This refrigeration equipment includes several main parts:
- refrigerant;
- evaporator;
- capacitor;
- compressor.
The compressor is the heart of any refrigeration system... This element is responsible for the circulation of the refrigerant through a large number of special tubes, some of which are located at the back of the refrigerator. The rest of the parts are camouflaged in the inside of the camera under the panel.
During operation, the compressor, like any motor, is exposed to significant heating, so it needs some time to cool down. So that this unit does not lose its performance due to overheating, a relay is built into it, which opens the electrical circuit at certain temperature indicators.
The tubes located on the outer surface of refrigeration equipment are a condenser. It is designed to release heat energy to the outside. The compressor, while pumping the refrigerant, sends it inside the condenser by means of high pressure. As a result, a substance with a gaseous structure (isobutane or freon) becomes liquid and begins to heat up. Excess heat is then dissipated in the room so that the refrigerant is cooled naturally. It is for this reason that it is forbidden to install heating devices next to refrigerators.
The owners, who know about the principle of operation of the refrigerator, try to arrange for their “kitchen assistant” the most optimal conditions for cooling the condenser and compressor. This allows you to extend its life..
To obtain cold in the inner chamber, there is another part of the pipe system, into which the liquefied gaseous substance is sent after the condenser - it is called the evaporator. This element is separated from the condenser by a drying filter and a capillary. The principle of cooling inside the chamber:
- Once in the evaporator, freon begins to boil and expand, again transforming into gas. In this case, heat energy is absorbed.
- The tubes in the chamber cool not only the air masses of the unit, but also cool themselves.
- The refrigerant is then sent back to the compressor and the cycle is repeated.
In order to prevent nutritious foods from freezing inside the refrigerator, a thermostat is built into the equipment. A special scale makes it possible to set the required degree of cooling, and after reaching the required values, the equipment automatically turns off.
Single and double chamber models
The air-cooling unit in each refrigerator has a common design principle. However, there are still differences in the functioning of different equipment. They are based on the peculiarities of the movement of the refrigerant in refrigerators with one or a pair of chambers.
The scheme, which was presented just above, is typical for single-chamber models. Regardless of the location of the evaporator, the principle of operation will be the same... However, if the freezer is located under or above the cooling compartment, then an additional compressor is required for stable and full operation of the refrigerator. For a freezer, the principle of operation will be the same.
The refrigeration compartment, in which the temperature does not fall below zero, starts only after the freezer has cooled sufficiently and turned off. Just at this moment, the refrigerant from the freezing system is sent to the chambers with a positive temperature, and the evaporation / condensation cycle is already at a lower level, therefore it is impossible to say exactly how long the refrigeration equipment needs to work before it turns off automatically. It all depends on the setting of the thermostat and the volume of the freezer chamber.
Fast freezing function
This function is typical for two-compartment refrigerators. In this mode, the refrigerator can work continuously for a long time. Fast freezing is intended for effective freezing of products in large volumes..
After activating the option, special LED indicators on the panel will light up, indicating that the compressor is running. Here it is necessary to take into account the fact that the operation of the unit will not be stopped automatically, and too long operation of the refrigerator can negatively affect its condition.
After manual shutdown of the unit, the indicators themselves will go out, and the compressor drive will shut down.
Modern refrigerators are equipped with a wide variety of functions. And today, housewives are aware of the existence of the automatic defrosting function. Non-freezing and drip refrigeration systems have made human life much easier, but the principle of the refrigerator has remained the same.
Industrial refrigeration equipment became very widespread in the most diverse spheres of production. The main area of \u200b\u200bapplication of units and installations belonging to this class is the maintenance of certain temperature regimes necessary for long-term storage of a wide variety of goods, materials and substances. They are used to cool liquids, as well as food products, chemical raw materials, process mixtures, etc.
Main characteristics of industrial refrigeration equipment
Used in industry, it is capable of creating operating temperatures from -150 to + 10C. Units belonging to this class are adapted to work in rather harsh conditions and have a high degree of reliability of components.
Industrial refrigeration machines operate on the heat pump principle, transferring energy from a heat sink to a heat sink. In the overwhelming majority of cases, the environment is the first, and the refrigerant is the receiving object. The latter belongs to the class of substances that are capable of boiling at a pressure of 1 atm, and a temperature significantly different from that of the external environment.
Industrial refrigeration equipment consists of 8 main components:
- compressor;
- evaporator;
- flow regulator;
- fan;
- solenoid valve;
- reversing valve;
The condenser sucks in vapors of a substance acting as a refrigerant, where its pressure and temperature are increased. After that, the refrigerant enters the compressor block, the most important parameters of which are compression and displacement. The condenser cools the heated refrigerant vapors, thereby transferring thermal energy to the environment. The evaporator is the component through which the medium to be cooled and the refrigerant vapor flows.
Industrial refrigeration machines and installations are used for cooling large enough volumes, which are used by warehouses, vegetable depots, freezing lines, freezing tunnels, as well as large and complex air conditioning systems. In particular, such refrigeration equipment most often used for industrial needs in food processing shops (meat, poultry, fish, milk, etc.)
Industrial plant classification
All industrial refrigeration units are divided into compression and absorption. In the first case, the refrigeration equipment is a steam condensing machine that compresses the refrigerant by means of compressor or turbo compressor units. Such systems use freon or ammonia as the most effective substances in terms of temperature absorption.
Absorption plants condense a vaporous refrigerant using a solid or liquid absorbent substance, from which the working substance is evaporated when heated due to a higher partial pressure. These units are continuously and periodically operating, with the first type of units being divided into pumping and diffusion units.
Compressor-type refrigeration equipment differs by the type of compressor design into open, semi-hermetic and hermetic units. Depending on the method of cooling the condensing unit, the machines are equipped with water or air cooling systems. Absorption units use more water during operation and have significant dimensions and weight. They have a number of advantages compared to compressor refrigeration units, in particular, simplicity of design, higher reliability of components, as well as the ability to use inexpensive heat sources and quiet operation.
Depending on the capacity of industrial refrigeration equipment, the value of possible emissions of thermal energy is calculated. This heat can be used in 3 ways:
- into the environment. Heat transfer is carried out by means of an external compressor.
- to the production area. In this case, the released thermal energy allows you to save financial resources required for heating.
- energy recovery. The released heat is transferred to the place where it is most needed.
The main types of industrial refrigeration equipment
When choosing industrial refrigeration equipment, it is necessary to focus on the main technical parameters of the proposed models. Special attention should be paid to the maximum amount of heat generation, as well as its dynamics during the production shift. In addition, it is important to take into account the hydraulic resistance of the components and components of the system. It is necessary to determine the direction of heat removal, as well as to decide on the possibility of duplicating the entire refrigeration system.
To date, refrigeration equipment of the following types is most often used in industry:
- ... This type of machine is used in meat, sausage, fish and bakery industries.
- blast freezer cabinets and chambers. Equipment of this type is used in enterprises engaged in the production of fish, cape and vegetable products, as well as in the processing and storage of fruits, berries, etc.
- food chillers. This type of refrigeration machine is perfect for cooling various liquids and certain categories of food products;
- chillers for cooling plastics. Such units are used for cooling raw polymers and finished products.
- liquid separators and receivers and collectors;
- freezing tunnels. This type of equipment is used for freezing bulk, prepackaged and packaged goods in large quantities.
A clear understanding of the device and the processes taking place inside the refrigeration unit helps to extend the life of the equipment. It is not difficult to understand how the refrigerator works. 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 all about how refrigerators with different operating principles work from our article. We will tell you about the features of the device and related operating rules. Our advice will help protect chillers from premature breakdowns and save you the trouble of repairing.
Refrigeration equipment is used in many fields of activity. One cannot do without it in everyday life and it is impossible to imagine the full-fledged work of production workshops at enterprises, trading floors, catering establishments.
Depending on the purpose and field of application, 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. For now, let's outline the main differences between all 4 designs.
Functioning of absorption technology
In the system of absorption-type installations, two substances circulate - a refrigerant and an absorbent. The functions of a 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.
All equipment operation is based on the principle of absorption, which implies the absorption of one substance by another. The design consists of several leading units - evaporator, absorber, condenser, control valves, generator, pump
The elements of the system are connected by pipes, 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;
- from the concentrated solution, ammonia vapors boiling at 33 degrees are released, 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 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 loop takes heat from the cooled chamber and enters the evaporator. And gives it to the external environment, being in the condenser. The loops 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 them easy to install in any convenient location
There are no bulky moving and rubbing elements in the design of the devices, therefore they have a low noise level. The devices are relevant for buildings, the electrical network of which is subject to constant peak loads, and places where there is no constant power supply.
The absorption principle is implemented in industrial refrigeration plants, small refrigerators for cars and offices. It is sometimes found in individual household models that run on natural gas.
The principle of operation of thermoelectric models
Reducing the temperature in the chamber of a thermoelectric refrigerator is achieved using a special system that pumps out heat according to the Peltier effect. It implies the absorption of heat in the area where two different conductors are connected at the moment an electric current passes through it.
The design of refrigerators consists of cube-shaped thermoelectric elements made of metals. They are united by one electrical circuit. Together with the movement of current from one element to another, heat also moves.
The aluminum plate absorbs it from the inner compartment and then transfers it to the cubic work pieces, which in turn redirect to the stabilizer. There, thanks to the fan, it is thrown out. This is how portable and cooling bags work.
In most models of thermoelectric refrigeration devices, when switching the polarity of the power supply, you can receive not only cold, but also heat - up to 60 degrees Celsius. This function is used to heat food
This equipment is used in camping, in the field of arranging cars, yachts and motor boats, it is often installed in summer cottages and other places where it is possible to provide the device with a power supply with a voltage of 12 V.
In thermoelectric products, a special emergency mechanism is provided 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 the operation of the devices. Among the shortcomings - high cost, sensitivity to external temperatures.
Features of equipment on vortex coolers
A compressor is included in this category. It compresses air, which is further expanded in installed vortex 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 elements, do not contain hazardous chemical compounds in the internal system of the structure
The vortex cooler method was not widely used, but limited itself to test samples. This is due to high air consumption, very noisy operation and relatively low cooling capacity. Sometimes the devices are used in industrial plants.
Compressor technology overview
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 from reliable manufacturers have served their owners for over 10 years. Let's 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 rough steel sheet with a thickness of about 0.6 mm or durable plastic, which lightens 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 external air to pass through. Some modifications incorporate magnetic closures
Between the inner and outer wall of the product, a layer of thermal insulation must be placed, which protects the camera from heat that tries to penetrate from the environment, and prevent the loss of the cold formed inside. Mineral or glass felt, expanded polystyrene, polyurethane foam are well suited for these purposes.
The internal space is traditionally subdivided into two functional areas: refrigerating and freezing.
By the form of the layout, they are distinguished:
- one-;
- two-;
- multi-chamber devices.
A separate view includes 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 shelves adjustable in height.
In the chambers, lighting equipment is installed with an LED or an ordinary incandescent lamp in order to see what, in fact, lies in the refrigerator.
Devices made on the "side by side" type are much larger and wider than their counterparts. Both compartments occupy the entire height of the equipment. They are parallel to each other
In double-chamber units, the inner cabinets are insulated and each separated by its own door. The location of departments in them can be European and Asian. The first option assumes the lower layout of the freezer, the second - the upper one.
Component structural elements
Compressor refrigeration units do not produce cold. They cool the object by absorbing internal heat and sending it out.
The cold formation procedure involves the following nodes:
- cooling agent;
- capacitor;
- evaporative radiator;
- compressor apparatus;
- thermostatic valve.
Various brands of freon act as a refrigerant, which is used to fill the refrigerator system - mixtures of gases with a high level of fluidity and rather low boiling / evaporation points. The mixture moves in a closed loop, transferring heat to various 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 smell is not toxic to humans and does not affect the taste and properties of products stored in chambers.
Compressor - the central part of the structure of any refrigerator. This is an inverter or linear unit that provokes forced gas circulation in the system, building up 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. Vibration generated during operation is absorbed by an external or internal suspension. In models with a pair of compressors, a separate device is responsible for each chamber.
Compressors are classified into two subtypes:
- 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 due to its low efficiency and rapid wear under the influence of torque, it is rarely used in household equipment.
- Volume... Compresses the working fluid using a special mechanical device that is started by an electric motor. It is 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 one-piece 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 work. As a result, freon vapors are drawn from the evaporator and pumped into the condenser.
In the event of a piston compressor breakdown, repair is possible only with the use of specialized professional equipment. 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, compresses and exits through the lower hole of a small diameter. To reduce friction, oil is injected into the space between the shafts.
Capacitors are made in the form of a coil lattice, 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 preset temperature values \u200b\u200bby condensing the substance and dissipating heat in the room. They are shield or ribbed-tubular.
The evaporator consists of a thin aluminum pipe, welded steel plates. It contacts the inner compartments of the refrigerator, effectively removes the absorbed heat from the device and significantly lowers the temperature in the cabinets
Thermostatic expansion valve is needed in order to maintain the pressure of the working fluid at a certain level. Large units of the unit are connected to each other by a system of pipes that form a sealed closed ring.
Duty cycle sequence
The optimum temperature for long-term storage of provisions in compression devices is created during working cycles, carried out one after another.
They proceed as follows:
- when the device is connected to the mains, the compressor starts, compressing the freon vapors, simultaneously increasing their pressure and temperature;
- under the force of the action of excess pressure, the hot working fluid, which is in the gaseous aggregate state, enters the condenser tank;
- moving along a long metal tube, the steam releases the accumulated heat into the external environment, gradually cools down to room temperature values \u200b\u200band turns into a liquid;
- the liquid working fluid passes through a filter dryer that absorbs excess moisture;
- the refrigerant penetrates through a narrow capillary tube, at the outlet of which its pressure decreases;
- the substance cools down and turns into gas;
- cooled steam reaches the evaporator and, passing through its channels, takes heat from the internal compartments of the refrigeration unit;
- the freon temperature rises, and it is again sent to the compressor.
If we talk in simple words about how a compressor refrigerator works, the process looks like this: the compressor distills the refrigerant in a closed circle. Freon, in turn, changes its state of aggregation thanks to special devices, collects heat inside and transfers it outside.
The working cycle in the system repeats until the temperature values \u200b\u200bset by the system programs are reached, and resumes again when their increase is recorded
After cooling to the required parameters, the thermostat stops the motor, opening the electrical circuit.
When the temperature in the chambers starts 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 and then again dies down.
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 at the first start-up and periodically adjusted during operation is to set the optimal temperature regime for specific circumstances.
The desired temperature is set. In an electromechanical system, the values \u200b\u200bare set by eye or taking into account the recommendations specified in the manufacturer's instructions. When doing this, take into account the type and quantity of food stored in the refrigerator.
The knob of the regulator is usually a round mechanism with several divisions, or, in more modern and more expensive models, control can be carried out using the touch panel.
In order to assess the degree of freezing, experts advise at first to put the regulator in the middle position, and after a while, if necessary, turn it to the right or left.
Each mark on such a handle 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 the 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 a home refrigerator, you should not only understand its device, but also take good 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:
- 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 attachment.
- Install the technique correctly... Make sure that the distance between the condenser and the wall of the room is at least 10 cm. This will help to ensure unhindered circulation of air masses.
- Defrost in timeavoiding 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 devices and in places where direct contact with sunlight is possible. Excessive influence of external heat adversely affects the operation of the main components and the overall performance of the device.
Only special products recommended by the manufacturer in the instructions for the device are suitable for cleaning stainless steel fragments of a product.
If you plan to transport from place to place, it is best to transport the equipment in a truck with a tall van, fixing it in a strictly vertical 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 on the operation of absorption machines:
As long as the 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 locate the problem area, preventing serious malfunctions.
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