Home Useful tips Water cooling chiller operating principle. Chiller-fan coil system - what it is and how it works. Warm and cold flows

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Water cooling chiller operating principle. Chiller-fan coil system - what it is and how it works. Warm and cold flows

The multi-zone chiller-fan coil climate system is designed to create comfortable conditions inside the building large area. It works constantly - it supplies cold in the summer, and heat in the winter, warming the air to the set temperature. It’s worth getting to know her device, don’t you agree?

The article we propose describes in detail the design and components of the climate system. Methods for connecting equipment are given and discussed in detail. We will tell you how this thermoregulation system works and functions.

The role of the cooling device is assigned to the chiller - an external unit that produces and supplies cold through pipelines with water or ethylene glycol circulating through them. This is what distinguishes it from other split systems, where freon is pumped in as a coolant.

For the movement and transmission of freon, a refrigerant, expensive copper pipes. Here, water pipes with thermal insulation cope well with this task. Its operation is not affected by the outside air temperature, while split systems with freon lose their functionality already at -10⁰. The internal heat exchange unit is a fan coil.

It receives liquid at a low temperature, then transfers the cold into the room air, and the heated liquid is returned back to the chiller. Fan coil units are installed in all rooms. Each of them works according to an individual program.

Main elements of the system - pumping station‚ chiller‚ fan coil. The fan coil can be installed at a great distance from the chiller. It all depends on how much power the pump has. The number of fan coil units is proportional to the chiller power

Typically, such systems are used in hypermarkets, shopping malls, structures built underground, and hotels. Sometimes they are used as heating. Then heated water is supplied to the fan coils through the second circuit or the system is switched to the heating boiler.

System design

According to the design, chiller-fan coil systems can be 2-pipe or 4-pipe. Depending on the type of installation, devices are distinguished between wall-mounted, floor-mounted, and built-in.

The system is evaluated according to the following basic parameters:

chiller power or cooling capacity;
fan coil performance;
efficiency of air mass movement;
length of highways.

The last parameter depends on the strength of the pumping unit and the quality of pipe insulation.

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A chiller is a refrigeration machine designed to cool a coolant (water, glycol solution, etc.).

The operation of the chiller is based on a vapor-compression refrigeration cycle, similar to that used in conventional air conditioners. That is, the chiller includes all four main elements of any refrigeration machine: compressor, condenser, evaporator and flow regulator.

Figure 1 shows an outdoor chiller with an air-cooled condenser. All elements of the refrigeration machine are assembled in a single housing, which is mounted on a rigid frame.

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Warm and cold flows On the opposite side of the chiller there are inlet and outlet water pipes: the chiller receives water from the building warm water

, and the cold flow returns back. The concepts of “warm” and “cold” are very relative. In fact, when the chiller is operating, both flows are cold: their temperature is about 10°C.

However, the temperature of the warm flow is higher. Both temperatures are adjustable and can vary, but there are two standard temperature schedules: 7/12 and 10/15. In the first case, the temperature of the cold flow is +7°C, and the warm flow is +12°C. In the second case, +10°C and +15°C, respectively.

Water cooling

Cooling of the water in the chiller is carried out in an evaporator-heat exchanger, in which the working substance of the refrigeration machine (refrigerant or, for short, refrigerant or freon) evaporates due to the heat received from the water. Thus, the water gives up its energy to the refrigerant, due to which it is cooled. But where does the refrigerant come from?

Refrigerant circuit

Next, the temperature is reset in the condenser: the refrigerant flowing through the tubes is blown by outside air. At the same time, the refrigerant changes its state of aggregation: it passes from a gaseous state to a liquid one.

However, the refrigerant pressure remained high. The cooled high-pressure refrigerant passes through the control valve, where it expands. The refrigerant pressure drops sharply.

This process is reminiscent of supplying a breathing mixture to a scuba diver: from a cylinder where the gas is stored under high pressure, it goes to a person who breathes a mixture with normal atmospheric pressure. At the same time, the temperature of the respiratory mixture decreases noticeably.

Likewise, the refrigerant after the control valve loses not only pressure, but also temperature. Thus, its temperature drops to just a few degrees. It can now cool the water flow of the building's refrigeration system. This happens in the evaporator. The refrigerant then flows back into the compressor and the cycle is completed.

Heatsink

Thus, a special working substance - refrigerant - circulates in the chiller. Its purpose is to cool the water and the energy obtained from the water and transfer it to environment. Both processes of energy transfer are realized in heat exchangers (heat exchangers).
As we already know, water is cooled in the evaporator: here the refrigerant receives the thermal energy of the water. And the release of heat into the environment occurs in the second heat exchanger - in the condenser.

The condenser is the only place where the refrigerant comes into contact with the environment: the tubes through which the refrigerant passes are blown by outside air. At the same time, the hot refrigerant cools down, that is, gives up its energy, and the street air heats up.

You can easily verify this by passing your hand over the top of the chiller or even just by walking up to the outdoor unit of a conventional air conditioner. The temperature of the air blowing from there is noticeably higher than the ambient temperature.

So, the heat that is released by people, equipment, lighting, as well as the heat that enters the premises due to solar radiation, is transmitted to the water circulating through the pipes. In the evaporator of a refrigeration machine, water transfers this heat to the refrigerant. And in the condenser of the refrigeration machine, this same heat comes out.

The compressor is the heart of the refrigeration machine

The compressor is the heart of the chiller. Thus, Hitachi Samurai series chillers use the latest screw compressors (see Figure 2). Compressors are the most energy-consuming elements of a chiller, so optimizing their energy consumption is one of the main tasks.

Figure 2. Layout of a twin-screw compressor in Hitachi Samurai series chillers:
1. Highly reliable HITACHI two-pole electric motor
2. Built-in oil separator (cyclone type oil separator)
3. Sight glass for monitoring oil level
4. Oil heater
5. High precision twin screw rotors
6. Suction filter

Thanks to the small number of moving parts, the compressor is high degree reliability, low level noise and low vibration levels. In addition, these compressors use continuous cooling capacity control technology to perfectly adapt to the load by precisely controlling the chilled water temperature, eliminating the need for expensive inverters.

Heat discharge to outside

Figure 3. Condenser fans in Hitachi chillers

Heat is removed to the environment in a condenser - a heat exchanger through which the refrigerant moves and outside air. In this case, the movement of the refrigerant, as we already know, is provided by the compressor.

The air movement is carried out by the condenser fan. On general view of the chiller (see Fig. 1), 6 cylindrical elements are visible from above - it is in them that the fans are installed, ensuring air movement through the condenser. Air is drawn in from the sides of the chiller, passes through the condensers, is heated, and then is expelled vertically upward.

Condenser fans are the second largest energy consumers in chillers, so their design and profiling also receives a lot of attention.

In particular, Hitachi uses new two-blade fans (see Figure 3), which reduce noise compared to a four-blade propeller. This increases the static pressure of the air flow and, at the same time, significantly reduces the power consumed by the electric motor.

Work "for heat"

Many chillers can also work in reverse refrigeration cycle, generating heat instead of cold. This is akin to the reverse operating mode of air conditioners - the “heat” operating mode. In this case, the chiller condenser plays the role of an evaporator and takes heat from the environment, and in the evaporator (which has now become a condenser) the heat is transferred to the coolant. By the way, in this case it is more appropriate to call the coolant coolant.

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

What it is

A chiller (or in another way) is a unit for creating artificial cold and transferring it to the appropriate coolant. As a rule, this role is played by ordinary water, less often by 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) derived from it - cooler. The refrigeration machine can be two different types. There are vapor compression and absorption chillers. The operating principle of each of them is significantly different.

Always cool

The main task of any refrigeration unit is to obtain cold in artificial conditions, that is, where this cannot be done due to nature (free cooling). It is clear that in winter, with deep minus temperatures outside, it will not be difficult. But what to do in the summer, when the ambient temperature is much higher than what we need? This is where a chiller comes to the rescue. Its operating principle is based on the use of special environments created by certain substances (refrigerants). They have the ability to take heat from another environment (that is, cool it) during boiling, transfer and release it into another environment during condensation. During 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 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 is in the high pressure zone. Without these two system components, the chiller will not be able to operate. The operating principle of such heat exchangers is based on thermal conductivity (conduction), that is, the transfer of heat from one medium to another through the wall separating these two media. The evaporator of the refrigeration machine releases the generated cold into the system to the consumer, and the condenser either discharges the rejected heat into the environment or sends it for recovery (heating the first stage of DHW, heated floors, etc.).

How does it work

Let's consider a standard vapor compression chiller. The operating principle of such a refrigeration machine is theoretically based on the compressor increasing the pressure of the gas, at the same time raising its temperature. Hot gas under high pressure is supplied to the condenser, where it participates in the process of heat exchange with another medium at a lower temperature. Typically, this is either water (brine) or air. Here the gas condenses into a liquid, during which excess heat is released, transferred to the coolant and thus removed from the consumer. Next, the liquid enters the throttling device, where the pressure in the system decreases with a corresponding temperature drop. After this, the partially boiled liquid goes directly to the evaporator, which is also an important part of the chiller-fan coil system. The operating principle of an evaporator is similar to a condenser. Here, heat exchange occurs between the coolant (which carries the cold into the fan coil) 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

Operating a compressor in the vapor compression cycle requires significant energy consumption. However, equipment already exists that allows you to avoid these expenses. Let's look at the operating principle of an absorption chiller. Instead of a compressor, a pressure boosting system is used here based on an absorbent substance using a heat source supplied from outside. This source can be hot steam, hot water, or thermal energy from burning gas or other fuel. This energy is used for rectification or evaporation of the absorbent, during which the pressure of the refrigerant increases and it is supplied to the condenser. Next, the cycle operates similarly to a vapor compression cycle, and after the evaporator, the gaseous refrigerant is supplied to the heat exchanger-absorber, where it is mixed with the absorbent. Ammonia is used as an absorbent (in water-ammonia chillers) or (lithium bromide ABHM).

Chiller-fan coil system

The principle of operation is based on air preparation in special heat exchangers-closers, fan coils (from the words fan - 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 each room can be maintained different parameters air (temperature, humidity, mobility), depending on the purpose of the room and the calculation of the heat balance. And although the air is air handling unit sometimes it is passed through closers for its final processing, that is, just as in the “chiller-fan coil” system, the operating principle of the described systems is noticeably different.

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

The chiller operates thanks to a 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 regulator.

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

Chiller operating 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 an object that is being cooled. This is why refrigerant and water are passed through the chiller. When the refrigerant boils, it takes energy away from the liquid. As a result, water or other coolant is cooled, and the refrigerant itself heats up and takes on gaseous state.

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

The operating principle of different types of chiller:

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 elements, as well as increased reliability in operation.

Vapor compression chillers- the most common refrigeration machines that operate on the basis of a compression cycle. The operating principle of this type of chiller is a continuous cycle of circulation, evaporation, and condensation of the heat transfer substance.

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

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

Chiller, what is it and what is it for? How is it different from air conditioners, and what is its operating principle? If you are faced with the issue of choosing or servicing air conditioning equipment, these things are worth knowing about.

Many people think that a chiller is just a big air conditioner. But this 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 there are and how they differ.

Chiller: what is it and how does it work

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

This climate control equipment can be compared to the outdoor unit of an air conditioner, to which it is connected a large number of internal. They are fan coils, which is why this system is called “The principle of operation of the chiller is such that any combinations thereof can be connected to it.

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

Duty 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 increases significantly.

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

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

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

In the case when the chiller operates for heating, the process is the same, but the circulation occurs in the reverse order.

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 to +30 °C.
In the evaporator, freon turns into a gas, its temperature drops to -15 degrees.
Flowing through the heat exchanger, it is heated from water to 0 ° C.
The cycle repeats again.

Installing the indoor unit of the chiller (Video)

Advantages and disadvantages of chillers

In terms of 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 does an air cooled chiller work?

Air-cooled refrigeration machines are the most common. They can often be seen on the roofs of large buildings. The operating principle of an air-cooled chiller is based on 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 capacitor 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 a medium for extracting or discharging thermal energy. This could be a pond, river, pool or any body of water. In them, the capacitor is located separately from the main unit and is immersed in water.