Refrigeration device. Scheme and description of the operation of the refrigeration unit How the refrigeration unit works diagram

Information about the basic principles of the device of refrigeration equipment will help you to use its capabilities to the fullest, while maintaining its performance for a long time.

The device of the largest number of refrigeration machines is based on a compression refrigeration cycle, the main structural elements of which are - , and flow controller (thermal control valve or capillary tube) connected by pipelines and representing a closed system in which the compressor circulates the refrigerant (freon). In addition to providing circulation, the compressor maintains high pressure in the condenser (on the discharge line), about 20-23 atm.

Cooling in the refrigeration machine is provided by continuous circulation, boiling and condensation of the refrigerant in a closed system. The refrigerant boils at low pressure and low temperature. The vaporous refrigerant is sucked in by the compressor and fed into the condenser, the pressure of the refrigerant rises to 15-20 atm., and its temperature rises to 70-90?C.

Passing through the condenser, the hot vaporous refrigerant cools and condenses, i.e., passes into the liquid phase. The condenser can be either air-cooled or water-cooled, depending on the type of refrigeration system.

At the outlet of the condenser, the refrigerant is in a liquid state at high pressure. The dimensions of the condenser are chosen so that the gas is completely condensed inside the condenser. Therefore, the temperature of the liquid at the outlet of the condenser is somewhat lower than the condensation temperature. Subcooling in air-cooled condensers is typically around 4-7°C. At the same time, the condensation temperature is approximately 10–20°C higher than the atmospheric air temperature.

Then the refrigerant in the liquid phase at high temperature and pressure enters the flow regulator, where the pressure of the mixture decreases sharply - part of the liquid can evaporate, passing into the vapor phase. Thus, a mixture of vapor and liquid enters the evaporator. The liquid boils in the evaporator, taking heat from the surrounding air, and again goes into a vapor state.

The dimensions of the evaporator are chosen in such a way that the liquid in it completely evaporates. Therefore, the temperature of the steam at the outlet of the evaporator is higher than the boiling point - the so-called overheating of the refrigerant in the evaporator occurs. In this case, even the smallest droplets of refrigerant, and liquid does not enter the compressor.

It should be noted that if liquid refrigerant enters the compressor - the so-called hydraulic shock - valves and other parts of the compressor may be damaged and broken. For air-cooled condensers, the superheat value is 5-8?C. The superheated vapor exits the evaporator and the cycle restarts.

Thus, the refrigerant constantly circulates in a closed circuit, changing its state of aggregation from liquid to vapor and vice versa. Although there are many types of compression refrigeration machines, the basic cycle diagram is almost the same.

Let us describe the structure of individual units, assemblies and parts of refrigeration equipment:

UNIT

The refrigeration unit consists of the following main parts and assemblies: compressor, receiver, condenser, evaporator, expansion valve (TRV),.

Refrigeration units are produced on the basis of hermetic, shielded, semi-hermetic and stuffing box compressors. According to their design, the compressors used in refrigeration units are divided into two main categories: reciprocating and rotary, scroll, screw.

The fundamental difference between rotary, scroll and screw compressors from reciprocating ones is that the suction and compression of the refrigerant is carried out not due to the reciprocating movement of the pistons in the cylinders, but due to the rotational movement of the plates, spirals and screws.

AT sealed compressors, the electric motor and the compressor are located in a single hermetic housing. Such compressors are widely used in small and medium-sized refrigeration machines and in domestic air conditioners. The advantage of sealed units is their relatively low cost and lower noise level. The disadvantage is the impossibility of repairing the compressor even with minor damage, for example, if a valve fails.

In shielded compressors, the motor stator is taken out of the freon-oil environment. Units of this type are less sensitive to the presence of moisture in the refrigeration circuit and, importantly, allow all work on the installation and replacement of the compressor motor stator during its combustion to be carried out at the place of operation, without violating the tightness of the entire system.

AT semi-hermetic compressors, the electric motor and the compressor are located in a single collapsible housing. These compressors are produced in various capacities, which allows them to be used in medium and large capacity units. The advantage is the possibility of repair and reliability in operation, the disadvantage is the high price compared to hermetic compressors, increased noise and the need for maintenance.

AT stuffing boxes compressors, the electric motor is located outside. The compressor shaft through the seals is brought out of the housing and is driven by an electric motor using a belt drive. This design contributes to increased refrigerant leakage through the gland seals and requires regular maintenance.

Currently, units based on stuffing box compressors for commercial equipment are practically not produced. At the moment, there are no advantages in designs with gland compressors; the repair of such refrigeration machines is characterized by low reliability.

The condenser is a heat exchanger that transfers the thermal energy of the refrigerant to the environment. In refrigeration units for commercial equipment, air-cooled condensers are most often used. Compared with water-cooled condensers, they are more economical to operate and easier to operate.

The condenser can be mounted on the frame of the unit or be installed separately from it. The advantage of a remote condenser is that it is less demanding on the air temperature in the engine room and practically does not require additional ventilation in the engine room.

As a rule, the air condenser for refrigerators or freezers is installed outdoors. But, despite the advantage of a remote condenser, there are certain problems when operating a refrigeration unit in winter:

the possibility of damage to the compressor during start-up;
danger of liquid refrigerant entering the compressor;
freezing of the heat exchanger during prolonged operation;
reduction in cooling capacity.

To eliminate these causes, an additional automation kit is used: a pressure switch or an electric motor speed controller, a differential valve, a check valve and a condensation pressure regulator.

Receiver

Receiver - a reservoir used to collect liquid refrigerant in order to ensure its uniform flow to the thermostatic expansion valve and to the evaporator. In small freon machines, the receiver is designed to collect refrigerant during machine repairs, as well as to cool the gas and separate oil and moisture drops.

An evaporator is an apparatus in which a liquid refrigerant boils at low pressure, removing heat from the cooled objects (products). The lower the pressure maintained in the evaporator, the lower the boiling temperature of the refrigerant. The boiling point is usually maintained at 10-15°C below the air temperature in the chamber. The air temperature in the chamber depends on the type of product being cooled. The evaporator can be located directly in the refrigerated volume (chamber, cabinet) or located outside it.

In accordance with this purpose, evaporators for direct cooling of the medium and evaporators for cooling the intermediate coolant (water, brine, air, etc.) are distinguished. The design of the evaporator depends on the type of cooling medium, the required cooling capacity, and the properties of the refrigerant itself. As a rule, these are plate heat exchangers with copper or aluminum tubes and fins made of aluminium, copper or galvanized steel.

expansion valve

A thermostatic expansion valve (TRV) is installed in the discharge line before the evaporator and ensures that the evaporator is filled with liquid refrigerant within optimal limits. Too much refrigerant in the evaporator can cause liquid phase refrigerant to enter the compressor, resulting in compressor failure. The lack of refrigerant in the evaporator dramatically reduces the efficiency of the evaporator.

Drying cartridges are designed to clean the refrigerant circulating through the system of the refrigeration unit from mechanical particles and moisture. Often, drying cartridges are used to reduce the acidity of the environment inside the refrigeration unit system. Drying cartridges can be installed both on the discharge line and on the suction side.

AIR COOLER

Air cooler - a device for cooling the air inside the cooled volume. It consists of an evaporator and a fan(s). drives the cooled air through the evaporator and directs it to the cooled products.

MONOBLOCK

Monoblock refrigerating machine (monoblock) is designed to create artificial cold in commercial refrigeration equipment. A feature of the monoblock is that it does not require the installation of individual units at the place of operation, but is simply mounted on the refrigeration chamber. Unlike split systems, a monoblock has a lower cost with the same parameters.

This is a device for turning off and on the compressor in order to maintain a certain temperature in the refrigerated volume. Electronic thermostats are based on the principle of a thermocouple, where an electronic device - depending on the resistance of the temperature sensor - controls the running time of the compressor.

Electromechanical thermostats operate on the principle of expansion of a bellows bellows filled with refrigerant. When cooled, the pressure inside the bellows decreases, the bellows harmonica contracts and the contacts through which the compressor is powered open. When heated, everything happens in the reverse order.

REFRIGERANTS

Refrigerants are the working substances of steam refrigeration machines, with the help of which low temperatures are obtained.

Freon-12 (R-12) has the chemical formula CHF 2 C1 2 (difluorodichloromethane). It is a gaseous colorless substance with a slight specific odor, which begins to be felt when the volume content of its vapors in the air is over 20%. Freon-12 has good thermodynamic properties

Freon-22 (R-22) , or difluoromonochloromethane (CHF 2 C1), as well as freon-12, has good thermodynamic and operational properties. It has a lower boiling point and a higher heat of vaporization. The volumetric cooling capacity of Freon-22 is approximately 1.6 times greater than that of Freon-12.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Industrial refrigeration equipment has become very widespread in various industries. The main area of application of units and installations belonging to this class is the maintenance of certain temperature conditions necessary for long-term storage of a wide variety of goods, materials and substances. They are used for cooling liquids, as well as food products, chemical raw materials, process mixtures, etc.

Main characteristics of industrial refrigeration equipment

Used in industry, it is able to create 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 principle of a heat pump, transferring energy from a heat source to a heat sink. In the vast majority of cases, the role of the first is the environment, 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 that differs significantly 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 that acts as a refrigerant, where its pressure and temperature are increased. After that, the refrigerant enters the compressor unit, the most important parameters of which are compression and displacement. The condenser cools the heated refrigerant vapor, due to which the thermal energy is transferred to the environment. The evaporator is the component through which the medium to be cooled and the vaporized refrigerant pass.

Industrial refrigeration machines and installations are used to cool large enough volumes that are used by warehouses, vegetable warehouses, 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.)

Classification of industrial installations

All industrial refrigeration units are divided into compression and absorption. In the first case, the refrigeration equipment is a vapor condensation machine that compresses the refrigerant through 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 with a solid or liquid absorbent, from which the working substance is evaporated when heated due to a higher partial pressure. These units are continuously and intermittently operating, and the first type of units is divided into pumping and diffusion.

Compressor-type refrigeration equipment differs according to the compressor type 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 a larger amount of water in the process of operation and have significant dimensions and weight. They have a number of advantages compared to compressor refrigeration units, in particular, simple 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 amount of possible heat energy emissions is calculated. This heat can be used in 3 ways:
- to the environment. Heat transfer is carried out by means of an external compressor.
- in the production area. In this case, the released thermal energy allows you to save the financial resources needed 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. Particular attention should be paid to the maximum amount of heat release, as well as its dynamics during the production shift. In addition, it is important to take into account the hydraulic resistance index of the units 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, the following types of refrigeration equipment are most often used in industry:

. This type of units is used in meat, sausage, fish and bakery production.
cabinets and chambers of shock freezing. Equipment of this type is used in enterprises engaged in the production of fish, meat and vegetable products, as well as processing and storage of fruits, berries, etc.
food chillers. This type of refrigerating machines is excellent 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 piece, packaged and packaged goods in large quantities.

Cooling of various objects - food, water, other liquids, air, industrial gases, etc. to temperatures below ambient temperature occurs with the help of various types of refrigeration machines. The refrigeration machine, by and large, does not produce cold, it is only a kind of pump that transfers heat from less heated bodies to more heated ones. The cooling process is based on the constant repetition of the so-called. reverse thermodynamic or in other words refrigeration cycle. In the most common vapor-compression refrigeration cycle, heat transfer occurs during phase transformations of the refrigerant - its evaporation (boiling) and condensation due to the consumption of energy supplied from outside.

The main elements of the refrigeration machine, with the help of which its operating cycle is implemented, are:

compressor - an element of the refrigeration cycle, providing an increase in the pressure of the refrigerant and its circulation in the circuit of the refrigeration machine;
the throttling device (capillary tube, expansion valve) serves to regulate the amount of refrigerant entering the evaporator depending on the superheat on the evaporator.
evaporator (cooler) - a heat exchanger in which the refrigerant boils (with heat absorption) and the cooling process itself;
condenser - a heat exchanger in which, as a result of the phase transition of the refrigerant from a gaseous state to a liquid, the removed heat is discharged into the environment.

In this case, it is necessary to have other auxiliary elements in the refrigerating machine, such as electromagnetic (solenoid) valves, instrumentation, sight glasses, filter driers, etc. All elements are connected to each other in a sealed internal circuit using pipelines with thermal insulation. The refrigeration circuit is filled with refrigerant in the required quantity. The main energy characteristic of a refrigeration machine is the coefficient of performance, which is determined by the ratio of the amount of heat removed from the cooled source to the energy consumed.

Chillers, depending on the principles of operation and the refrigerant used, are of several types. The most common vapor compression, steam jet, absorption, air and thermoelectric.

refrigerant

Refrigerant is the working substance of the refrigeration cycle, the main characteristic of which is a low boiling point. As refrigerants, various hydrocarbon compounds are most often used, which may contain atoms of chlorine, fluorine or bromine. Also, the refrigerant can be ammonia, carbon dioxide, propane, etc. Rarely, air is used as a refrigerant. In total, about a hundred types of refrigerants are known, but they are manufactured industrially and are widely used in refrigeration, cryogenic engineering, air conditioning and other industries, only about 40. These are R12, R22, R134A, R407C, R404A, R410A, R717, R507 and others. The main area of application of refrigerants is the refrigeration and chemical industries. In addition, some freons are used as propellants in the manufacture of various aerosol products; foaming agents in the production of polyurethane and heat-insulating products; solvents; as well as substances that inhibit the combustion reaction, for fire extinguishing systems of various objects of increased danger - thermal and nuclear power plants, civilian ships, warships and submarines.

Expansion valve (TRV)

The thermostatic expansion valve (TRV) is one of the main components of refrigeration machines, and is known as the most common element for throttling and finely regulating the flow of refrigerant to the evaporator. The expansion valve uses a needle type valve adjacent to the poppet base as the refrigerant flow control valve. The amount and flow rate of the refrigerant is determined by the flow area of the expansion valve and depends on the temperature at the outlet of the evaporator. When the temperature of the refrigerant at the outlet of the evaporator changes, the pressure inside this system changes. When the pressure changes, the flow area of the expansion valve changes and, accordingly, the refrigerant flow changes.

The thermal system is filled at the factory with a precisely defined amount of the same refrigerant that is the working medium of this refrigeration machine. The task of the expansion valve is to throttle and regulate the refrigerant flow at the evaporator inlet in such a way that the cooling process takes place in it most efficiently. In this case, the refrigerant must completely go into a vapor state. This is necessary for the reliable operation of the compressor and the exclusion of its operation of the so-called. "wet" running (i.e. compressing the fluid). The thermal bulb is attached to the pipeline between the evaporator and the compressor, and at the attachment point it is necessary to ensure reliable thermal contact and thermal insulation from the effects of ambient temperature. Over the past 15-20 years, electronic expansion valves have become widespread in refrigeration technology. They differ in that they do not have a remote thermal system, and its role is played by a thermistor attached to the pipeline behind the evaporator, connected by a cable to a microprocessor controller, which in turn controls the electronic expansion valve and, in general, all the working processes of the refrigeration machine.

The solenoid valve is used for on-off control (“open-closed”) of the refrigerant supply to the evaporator of the refrigerating machine or for opening and closing certain sections of pipelines from an external signal. In the absence of power to the coil, the valve disc, under the influence of a special spring, keeps the solenoid valve closed. When power is applied, the core of the electromagnet, connected by a rod to the plate, overcomes the force of the spring, is drawn into the coil, thereby raising the plate and opening the flow area of the valve for supplying refrigerant.

The sight glass in the refrigeration machine is designed to determine:

state of the refrigerant;
the presence of moisture in the refrigerant, which is determined by the color of the indicator.

The sight glass is usually mounted in the pipeline at the outlet of the storage receiver. Structurally, the sight glass is a metal hermetic case with a transparent glass window. If, when the chiller is operating, liquid flows through the window with individual bubbles of vaporous refrigerant, this may indicate insufficient charging or other malfunctions in its functioning. A second sight glass can also be installed at the other end of the above pipeline, in close proximity to the flow controller, which can be a solenoid valve, an expansion valve or a capillary tube. The color of the indicator indicates the presence or absence of moisture in the refrigeration circuit.

The filter drier or zeolite cartridge is another important element of the refrigeration circuit. It is necessary to remove moisture and mechanical impurities from the refrigerant, thereby protecting the expansion valve from clogging. It is usually mounted with soldered or nipple connections directly into the pipeline between the condenser and the expansion valve (solenoid valve, capillary tube). Most often, it is structurally a piece of copper pipe with a diameter of 16 ... 30 and a length of 90 ... 170 mm, rolled up on both sides and with connecting pipes. Inside, two metal filter meshes are installed along the edges, between which a granular (1.5 ... 3.0 mm) adsorbent is located, usually a synthetic zeolite. This is the so-called. disposable filter drier, but there are reusable filter designs with a collapsible housing and threaded pipeline connections that require only an occasional replacement of the internal zeolite cartridge. Replacement of a one-time filter-drier or cartridge is necessary after each opening of the internal circuit of the refrigeration machine. There are unidirectional filters designed to work in "cold only" systems and bidirectional filters used in "heat-cold" units.

Receiver

Receiver - a sealed cylindrical storage tank of various capacities, made of steel sheet, and used to collect liquid refrigerant and its uniform supply to the flow regulator (TRV, capillary tube) and to the evaporator. There are receivers of both vertical and horizontal types. There are linear, drainage, circulation and protective receivers. The linear receiver is installed by means of solder joints in the pipeline between the condenser and the expansion valve and performs the following functions:

ensures continuous and uninterrupted operation of the refrigeration machine under various thermal loads;
is a hydraulic lock that prevents the ingress of refrigerant vapor into the expansion valve;
performs the function of oil and air separator;
frees the condenser tubes from liquid refrigerant.

Drainage receivers are used to collect and store the entire amount of charged refrigerant for the period of repair and service work associated with depressurization of the internal circuit of the refrigeration machine.

Circulation receivers are used in pump-circulation circuits for supplying liquid refrigerant to the evaporator to ensure continuous operation of the pump and are mounted in the pipeline after the evaporator at the point with the lowest elevation mark for free draining of liquid into it.

Protective receivers are designed for pumpless schemes for supplying freon to the evaporator; they are installed together with liquid separators in the suction pipeline between the evaporator and the compressor. They serve to protect the compressor from possible wet running.

A pressure regulator is an automatically controlled control valve used to reduce or maintain refrigerant pressure by changing the hydraulic resistance to the flow of liquid refrigerant passing through it. Structurally, it consists of three main elements: a control valve, its actuator and a measuring element. The actuator directly acts on the valve disc, changing or closing the flow area. The measuring element compares the current and set value of the refrigerant pressure and generates a control signal for the control valve actuator. In refrigeration, there are low pressure regulators, often called pressure switches. They control the boiling pressure in the evaporator and are installed in the suction pipe after the evaporator. High pressure regulators are called manocontrollers. They are most often used in air-cooled chillers to maintain the minimum required condensing pressure when the outside temperature drops during the transitional and cold seasons, thereby providing the so-called. winter regulation. The manocontroller is installed in the discharge pipeline between the compressor and the condenser.