What is a chiller and how does it work. How an air-cooled chiller works

According to the principle of operation and obtaining cold, chillers can be divided into two types: vapor compression and absorption. The scope of both types of refrigeration machines is similar. Both types are mainly used for the production of coolant (coolant) for the needs of air conditioning, industrial refrigeration, ventilation or technology. In addition, chillers can also be used to heat the coolant for heating and ventilation needs. At the same time, steam-compression-type units are used for heating much less frequently than absorption ones due to their low efficiency at negative ambient temperatures. In this article, vapor compression type chillers will be considered.

Principle of operation.

The main elements of a vapor compression chiller are a compressor, an evaporator, a condenser, and a throttling device. The removal of heat energy in a vapor-compression refrigeration machine occurs due to a change in the state of aggregation of the substance (refrigerant). As a rule, refrigerants are fluorine- and chlorine-containing derivatives of saturated hydrocarbons (mainly methane and ethane). The refrigeration machine works according to the following principle: the compressor pumps the gaseous refrigerant into the condenser (see the diagram in Fig. 1), where, as a result of high pressure and heat removal, the gaseous freon condenses. Further, when the liquid refrigerant passes through the throttling device, its pressure drops, while part of the liquid is converted into vapor. This process is accompanied by a decrease in its temperature. Then the vapor-liquid mixture enters the evaporator, where it boils and finally turns into steam. The evaporator is an intermediate freon/water heat exchanger in which heat is transferred from the refrigerant to the liquid to be cooled. Then the liquid of the required temperature is supplied through the hydraulic circuit to consumers - fan coil units, ventilation installations etc.

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Chiller classification.

Vapor compression chillers can be classified:

by type of condenser cooling;

air-cooled condenser;
water-cooled condenser;

by execution:

for installation outside buildings;
for installation inside buildings;

for others design features, for example:

with free cooling system (freecooling);
with centrifugal condenser cooling fan;
by type of compressor, etc.

Condenser cooling method:

air cooled chillers;
water-cooled chillers (water-cooled).

To chillers outdoor installation include air-cooled monoblock chillers, which are usually installed on the roof of buildings or on special sites next to the buildings served. Also, chillers with a remote evaporator can be attributed to outdoor chillers.

To chillers indoor installation relate:

chillers with remote condenser(capacitorless);
water-cooled chillers (water-to-water chillers);
air-cooled chillers with centrifugal fan.

Chillers of internal installation are located in special rooms - machine rooms. Due to the ease of installation, ease of operation and price, air-cooled monoblock chillers are most widely used.

Monobloc air-cooled chillers

Monoblock chillers with are widely used in central air conditioning systems with supply units and in chiller-fan coil systems. Monoblocks have two modifications:

with axial fans;
With centrifugal fans(for installation inside buildings).

Chillers with axial fans(Fig. 2) are units mounted on a frame in a single housing and installed on the roof of buildings or nearby on a prepared site. The heat is released in environment.

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Water or aqueous glycol solutions are used as a heat carrier for operation. refrigeration machine during the cold season. If the requirements of the project do not allow the use of glycols, then an intermediate heat exchanger is built into the system (Fig. 3). With this scheme, the temperature parameters of the glycol solution in the chiller must be 2ºС lower than the calculated temperature in the consumer circuit. For example, in order to ensure the temperature parameters of water in the intermediate heat exchanger outlet / inlet: 7/12ºC, it is necessary to obtain a glycol solution at the outlet of the chiller with a temperature of 5ºC.

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In addition, when using an intermediate heat exchanger, it is possible to operate the chiller at negative ambient temperatures. The main advantages of air-cooled monoblock chillers are ease of installation, ease of maintenance, complete readiness of the units for operation (charged with refrigerant and oil), relatively low price. To the number additional benefits monoblocks can be attributed wide opportunities when placed due to the unlimited length of the coolant routes and the height difference between the chiller and consumers. Chillers modular design also have undeniable advantages:

minimum delivery time due to stock availability;
cost savings - the system is put into operation in parts as needed;
variability - by combining modules of different capacities, we obtain a refrigerating machine of the required power (diagram Fig. 4);
energy savings - the system operates at the same power level, which in this moment required by consumers by enabling/disabling individual modules.

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Chillers with centrifugal fans(Fig. 5) are intended for installation in premises: basements, attics, office special premises. The main difference from chillers with axial fans is the presence of high pressure centrifugal fan/s. Through a network of air ducts, the fan blows air, which cools the condenser and then is removed to the outside, and the heat is discharged into the environment.

Advantage of chillers with centrifugal fans:

long service life due to the location in a heated room.

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Air is taken from the room, blowing can be organized through air ducts in one of three directions (Fig. 6)

Hydromodule. The circulation of the coolant (water, glycol solution) between the chiller and consumers (fan coil units) is provided by a hydronic module ( pumping station) (Fig. 7, a), Hydromodule includes circulation pump, expansion tank, stop valves, storage tank (buffer tank), control and protection system.

The storage tank (Fig. 4, b) is necessary to increase the capacity of the coolant in the system. The buffer tank reduces the number of compressor starts and pumping equipment thereby extending the life of the chiller. The buffer tank may not be part of the hydronic module and may be supplied separately.

Chillers with a remote condenser (condenserless) (Fig. 8)

A chiller with a remote condenser is a unit in which all the main elements: a compressor, an evaporator, a throttling device are installed on the same frame in a single housing. At the same time, the chiller itself is designed for indoor installation, and the air-cooled condenser is designed for outdoor use and is installed outside.

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The main advantages of chillers with a remote condenser:

the possibility of year-round operation using water;
ease of maintenance at any time of the year;
high efficiency due to the absence of a glycol circuit and intermediate heat exchangers;
long service life due to location in a heated room;
the possibility of using a capacitor in a low-noise or explosion-proof version.

It is quite difficult to understand everything that is in the world. And to be a professional in all areas of science and technology is almost impossible. However, on duty, for educational purposes, or simply to increase our own awareness, we need to quickly get the maximum information about some device or process, in an easy and accessible form for non-professionals. For these purposes, there are so-called "dummies" manuals, that is, for those who need to quickly understand what is at stake and how it works. Let's analyze a similar instruction and consider the principle of operation of a chiller (for dummies).

What it is

Chiller (or in another way) is a unit for creating artificial cold and transfer it to the appropriate coolant. The role of such, as a rule, is ordinary water, less often - brines (solutions of salts in water). The etymology of the word refers to English language, to the verb to chill (English) - cool, and the noun chiller (English) formed from it - cooler. The refrigerator can be two different types. There is a vapor compression and absorption chiller. The principle of operation of each of them is significantly different.

Cool always

The main task of any refrigeration unit- obtaining cold in artificial conditions, that is, where it cannot be done due to nature (free-cooling). It is clear that in winter, with a deep minus on the street, it will not be difficult. But what to do in the summer, when the ambient temperature is much higher than we need? This is where a chiller comes in. Its principle of operation is based on the use of special media created by certain substances (refrigerants). They have the ability to take heat from another medium (that is, cool it) during boiling, transfer and release it into another medium during condensation. During the operation of the refrigeration cycle, such refrigerants change their phase (aggregate) state from liquid to gaseous and vice versa.

Heat exchangers

Any refrigeration machine can be conditionally divided into two zones: low and high pressure. Regardless of the type, in any chiller there will always be two heat exchangers: the evaporator - in the zone low pressure and the condenser - in the high pressure zone. Without these two components of the system, the chiller will not be able to operate. The principle of operation of such heat exchangers is based on thermal conductivity (conduction), that is, the transfer of heat from one medium to another through a wall separating these two media. The evaporator of the refrigeration machine returns the generated cold to the system to the consumer, and the condenser either dumps the removed heat into the environment or sends it to recovery (heating the first stage of hot water supply, heated floors, etc.).

How does it work

Consider a standard vapor compression chiller. The principle of operation of such a refrigeration machine is theoretically based on the Compressor increases the pressure of the gas, while simultaneously raising its temperature. hot gas under high pressure is fed into the condenser, where it participates in the process of heat exchange with another medium of lower temperature. As a rule, it is either water (brine) or air. Here, the gas condenses into a liquid, during which excess heat is released, given to the coolant and thus removed from the consumer. Further, the liquid enters the throttling device, where the pressure in the system decreases with a corresponding temperature drop. After that, the partially boiled liquid enters directly into the evaporator, which is also an important part of the chiller-fan coil system. The principle of operation of an evaporator is similar to that of a condenser. Here, heat exchange takes place between the coolant (which carries the cold into the fan coil unit) and the refrigerant, which begins to boil and at the same time takes heat from another medium. After the evaporator, the gas enters the compressor and the cycle repeats.

absorption chiller

The operation of the compressor in the vapor compression cycle requires a significant amount of electricity. However, there is already equipment available to avoid these expenses. Consider the principle of operation of an absorption chiller. Instead of a compressor, an absorbent-based pressurization system using an external heat source is used. Hot steam can serve as such a source, hot water, or thermal energy from the combustion of gas or other fuel. This energy is used to rectify or evaporate the absorbent, during which the pressure of the refrigerant rises and it is fed into the condenser. Further, the cycle works similarly to the vapor compression cycle, and after the evaporator, the gaseous refrigerant is fed to the heat exchanger-absorber, where it is mixed with the absorbent. As an absorbent, ammonia is used (in water-ammonia chillers) or (lithium bromide ABCM).

Chiller-fancoil system

The principle of operation is based on the preparation of air in special heat exchangers, closers, fan coil units (from the words fan (English) - fan and coil- coil), which are installed in the air ducts before its direct distribution to the serviced premises. The advantages of such systems over central air conditioning is that in each room it is possible to maintain different air parameters (temperature, humidity, mobility), depending on the purpose of the room and calculation heat balance. And although the air air handling unit sometimes passed through closers for it final processing, that is, just like in the "chiller-fan coil" system, the principle of operation of the described systems is noticeably different.

The chiller is a refrigeration machine that is designed to cool the coolant, such as water and glycol solution.

The operation of the chiller is carried out thanks to the vapor-compression refrigeration cycle, which is also used in simple air conditioners. This means that the chiller contains all four main elements of any refrigeration equipment:

compressor;
capacitor;
evaporator;
freon flow controller.

Due to a wide range of power and versatility, chillers are used in everyday life, industry (cooling of industrial equipment, raw materials, equipment), warehouses, sports (cooling skating rinks, and ice rinks) and public buildings (air conditioning) of any size.

Chiller working principle:

So, the chiller consists of the following elements: a compressor and a condenser, as well as an evaporator. The main task The evaporator is the removal of heat from the object that is being cooled. It is for this purpose that refrigerant and water are passed through the chiller. When the refrigerant boils, it takes energy from the liquid. As a result, water or other coolant is cooled, and the refrigerant itself is heated and takes on a gaseous state.

The next stage is the transition of the gaseous refrigerant to the compressor, where the hot vapor is compressed with heating to a temperature of 80-90 ºС and in the condenser it passes into liquid state.

The principle of operation of the chiller of different types:

Absorption chiller type It has main feature work - the use of water vapor as a refrigerant, the temperature of which is up to 130 ºС, and is supplied under a pressure of 1 bar. The main advantage of these units is the absence of moving parts, as well as increased reliability in operation.

Chillers of vapor compression type- the most common refrigeration machines that operate on the basis of a compression cycle. The principle of operation of this type of chiller is a continuous cycle of circulation, evaporation, and condensation of the heat transfer medium.

Air cooled chiller installed outside the building outdoors. The heat exchanger is cooled by air driven by axial fans. The principle of operation of a water-cooled chiller is that a refrigeration machine is used to cool the condenser of a refrigeration machine. intermediate coolant, which is cooled in cooling towers, as well as dry coolers.

Chiller with remote condenser operates on the basis of a water condenser, is located indoors and is connected by a system of freon pipelines to an outdoor installation.

Chiller, what is it and what is it for? How does it differ from air conditioners, and what is its principle of operation? If you are faced with a choice or service issue climatic equipment These things are worth knowing about.

Many people think that a chiller is just a big air conditioner. But such an opinion is fundamentally wrong. Such refrigeration equipment has its own differences and features. In this publication, we will tell you what types of such refrigeration machines are and how they differ.

Chiller: what is it and how does it work

Chillers (eng. Chiller - refrigerator, refrigerator) - devices for providing cooling or heating in industrial scale. They are often used in factories, to provide a microclimate in shopping centers, residential buildings, office buildings.

This climatic equipment can be compared with the outdoor unit of the air conditioner, to which it is connected a large number of internal. Fan coil units act as them, therefore such a system is called "" the principle of operation of the chiller is such that any combination of them can be connected to it.

As in a conventional air conditioner, the production of heat or cold occurs through cycles of evaporation and condensation of the refrigerant. But unlike split systems, it circulates only in the device itself.

Working cycle

The main elements of the chiller are:

Compressor;
Capacitor;
Evaporator;
Heat exchanger.

The compressor compresses the freon, increasing its pressure so much that it turns into a liquid state. At the same time, its temperature rises significantly.

Getting into the condenser, freon gives off heat to air or water. It cools down and passes into the evaporator.

The evaporator has a control valve that controls the amount of refrigerant. Freon expands and passes into a gaseous state. At the same time, its temperature drops.

In this state, it passes into the heat exchanger, where it cools the water in the line. Cold water enters the fan coil units, thereby ensuring their operation.

In the case when the chiller is working for heating, the process is the same, but the circulation is reversed.

Example of work (values are given for clarity)

Before entering the compressor, freon has a temperature of 0 degrees. After compression and transition to the liquid phase, it rises to +60.
Passing through the condenser, the refrigerant is cooled down to +30 °С.
In the evaporator, freon goes into a state of gas, its temperature drops to -15 degrees.
Flowing through the heat exchanger, it heats up from water to 0 °C.
The cycle repeats again.

Chiller Indoor Unit Installation (Video)

Advantages and disadvantages of chillers

By their purpose, chillers are similar to multi-zone or multi-split systems. They are also designed to provide a microclimate in several rooms and large volumes. But they have a number of fundamental differences.

How an air-cooled chiller works

Chillers with air-cooled condenser are the most common. They are often seen on the roofs of large buildings. The principle of operation of an air-cooled chiller is based on the heat exchange between freon and atmospheric air.

There are two types of such equipment:

With a remote, external condenser;
With built-in, internal capacitor.

In the first case, the condenser unit is located at a distance from the main unit and is connected to it by a line through which freon circulates. Such installations are more expensive, but more convenient to maintain - the indoor unit can be installed indoors.

Working principle of water cooled chiller

Water-cooled chillers use water as the medium for extracting or discharging thermal energy. It can be a pond, river, pool or any body of water. In them, the condenser is located separately from the main unit and is immersed in water.

To create at home comfortable conditions In summer, we aim to cool the air in our home by installing air conditioners. When it is necessary to lower the temperature in 2 or 3 rooms, we install the same number of coolers or split systems. But what if you need to keep cool in a large private house, and even with two or three floors? For such purposes, instead of air conditioners, a chiller-fan coil climate system is used. What it is and how it works will be discussed in this article.

The modern chiller-fan coil system is designed to maintain the temperature regime inside the entire building all year round. That is, the system can provide both cooling and heating. air environment. At the same time, the temperature in the rooms can be regulated in accordance with the wishes of the homeowner. AT summer time the main role here is played by the cooling device - the chiller. Its task is to generate cold and supply it inside the building using pipelines with a coolant, which plays the role of a coolant in winter.

As a coolant, as a rule, ordinary purified water acts, less often - non-freezing substance - ethylene glycol. The latter, in terms of its heat capacity, is not inferior to water, which is why it is successfully used instead of it both in the cold supply system and in heating. Further, through the pipes, low-temperature water enters another heat exchange unit - a fan coil unit installed in each room. In its heat exchanger, the water heats up, transferring its cold to the room air, after which it returns back to the chiller.

In fact, the main elements of the chiller-fan coil system resemble the parts of an air conditioner, - outdoor unit(chiller), indoor unit (fan coil) and refrigerant pipes connecting them. Only instead of freon, water flows through the pipes, and there can be as many indoor units as you like, it depends on the cooling capacity of the chiller.

Since the operation of the chiller depends on the need for cold, and it is not constant, there is a capacity in the intermediate hydraulic module of the circuit - an accumulator for the coolant, and an expansion tank is connected to the supply pipeline to compensate for the thermal expansion of water. The need for a coolant transfer pump is obvious, as shown in the diagram.

Connection of chiller and fan coils via hydraulic module

As mentioned above, this climate system refers to air and in winter time can work for space heating, only the refrigerant that cools the air becomes a heat carrier and is heated by the boiler plant. Due to this, such schemes are used to maintain the microclimate in buildings of large shopping centers, cinemas and other buildings with large dimensions.

Types of chillers

I must say that freon is still present in the system and it is located inside the refrigeration machine. That is, the principle of operation of a chiller, like an air conditioner, is to transfer heat by a working fluid (freon) from one medium to another. In our case, the heat is taken away by the chiller evaporator from the water heated in the fan coil unit and transferred to the surrounding air or again to the water, which serves as a kind of intermediary - the cooler of the condensing unit.

Recall that freon is a gas that passes under standard conditions into a liquid state of aggregation. This property uses a chiller device, where freon evaporates in a heat exchanger - an evaporator. This happens due to the selection of energy for vaporization from the water heated in fan coil units. As a result, the latter again goes into the building to cool the air, and the freon injected by the compressor enters the second heat exchanger - the condenser, where it is cooled and returns to the liquid state again.

The condensation process in the second heat exchanger most often occurs under the influence of the external environment, this principle uses an air-cooled chiller. For achievement high efficiency During the process, the air is driven through several radiators at once with the help of axial fans that provide the required flow rate.

In the climate systems of large buildings, water-cooled chillers are often used, whose principle of operation is not much different from air unit. Only here, for freon condensation, another type of heat exchanger is installed, in which water circulates, it serves as a cooler instead of air.

The principle of operation of a water-cooled unit

The result is more expensive and complex scheme with an additional water cooling circuit, but the cooling capacity of such a system is higher than that of an air system. The complexity and high cost arise due to the fact that the water cooling the condenser itself also needs to be cooled, but now with the help of air, and this requires additional installation– cooling tower (drycooler). It functions simply: water passes through several radiators, each of which has an axial fan. great performance, driving through it a powerful stream of air.

The principle of operation of the fan coil

Having understood the operation of the chiller, let's move on to considering what a fan coil is. This is a device that provides the process of heat exchange inside each room. Its task is to maintain the temperature of the air at a given level; for this purpose, the unit is equipped with the necessary instruments and automation equipment.

It operates in the same way as the drycooler: through aluminum radiator, within which water circulates, axial fan air flow is driven. After passing through the fins of the heat exchanger, it gives thermal energy water, and he cools himself and returns to the room. Working scheme fan coil is shown in the figure below.

1 - connection panel electrical equipment; 2 – unit body in ceiling version; 3 – fan; 4 - heat exchanger made of aluminum or copper; 5 - bath for condensate; 6 - air valve with filter; connecting pipe and condensate pump.

Since the operation of fan coil units in the summer is associated with a large flow of cooled air masses, the design of the unit provides for a special container for the accumulation of condensate and a small pump that pumps it into the sewer. In addition to the ceiling version of the fan coil unit shown in the diagram, there are duct and wall models devices.

Unlike the heating system, the connection of the chiller with fan coil units is carried out by pipelines covered with thermal insulation, otherwise the efficiency of the entire system will significantly decrease.

The area of any dwelling or public building divided into climatic zones with different temperature regime. For this reason, each zone must be served by one or a group of fan coil units with the same automation settings. The total number of fan coil units is determined by calculation at the stage of developing the scheme.

It should be noted that one cannot do without the correct calculation and design of the system, since all of the listed equipment has a very decent cost. The price of a mistake is too high, since an incorrectly selected chiller for cooling water or a fan coil unit in a particular room will not be able to provide the required microclimate, and it will be very expensive to redo everything over again.

Conclusion

Chiller-fan coil systems are different effective work and saving energy resources, for the production of 3 kW of cold, approximately 1 kW of electricity is needed. But designing, purchasing equipment, as well as installing and maintaining fan coil units and a chiller require considerable investments.

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