Chillers are among the most important equipment in cooling that can be generally divided into two categories of compression chillers and absorption chillers.
In general, compression chillers use electrical energy and absorption chillers use thermal energy as the main source of cooling.
Absorption refrigeration technology is an excellent method for central air conditioning in installations that have additional boiler capacity and can provide the steam or hot water needed to operate the chiller.
Suction chillers easily provide capacities between 25 and 1200 tons of refrigeration. Of course, it should be noted that some Japanese manufacturers have succeeded in producing absorption chillers with a capacity of 5,000 tons.
In absorption systems, water is often used as a refrigerant.
The heat required for the operation of these chillers is supplied directly from natural gas or diesel.
Compression chillers use refrigerant gases such as freon in their heat transfer cycle and use a compressor to move and compress the gas;
In fact, compression chillers are the same as gas coolers on a much larger scale and with a much higher capacity;
In this type of chillers, the condensers are cooled by air or by air;
In chillers, water is used to transfer heat or cold, which moves inside the fan coils that are installed inside the environment;
That is, the water inside the outdoor chiller unit is heated or cooled and transferred to the indoor fan coil, causing the environment to cool or heat up;
Compression chillers are divided depending on the type of compressor:
A) Reciprocating compression chillers that have a reciprocating compressor or piston
B) Screw compression chillers that have a screw compressor
These types of chillers are very expensive due to the use of high capacity compressors with high propulsion devices and have a high cost of repairs and maintenance.
In a compression chiller, the gas is first compressed by a compressor.
This gas is then cooled to a condenser introduced by ambient water or air and liquefied.
This liquid enters the coolant (evaporator) through the expansion valve or capillary tube, which is at a lower pressure.
This reduction in pressure causes the liquid to evaporate, and the coolant, by taking its latent heat of evaporation from the environment, causes a cooling in the materials that are in contact with the cooling part.
The evaporating gas is then transferred to the compressor.
With the rapid passage of steam in the condenser vacuum, a liquid is formed due to the conversion of steam to water and the volume difference between steam and water.
Components of a compression refrigeration cycle
The components of a compression refrigeration cycle and how it works are as follows:
It sucks steam from the evaporator and raises its temperature and pressure to such an extent that it can be distilled with a normal distillation agent.
Hot or Discharge Line
The high-pressure, high-temperature spike is fed from the compressor outlet to the condenser.
Provides the heat exchange surface needed to transfer heat from the hot refrigerant vapor to the distillation agent.
Condensers are heat exchangers in which the heat of the refrigerant vapor is transferred to the distillation agent (for example, air or water) and as a result, the refrigerant vapor is first cooled to saturation temperature and then converted to liquid.
There are generally three types of condensers:
- Air Condenser (Cool Air)
- Water condenser (cold water): Two-pipe condensers, shell and coil, shell and pipe
- Evaporative condenser
In air condensers, air is used as the distillation agent, while in water condensers, the distillation agent is water refrigerant.
In evaporative condensers, both air and water are used.
In evaporative condensers, the temperature of the passing air increases slightly.
But the refrigerant distillation is mainly obtained from the evaporation of water sprayed on the condenser and the air is used to increase the evaporation rate by removing water vapor.
The air flow in air condensers may be in the form of natural flow (use of home refrigerators and freezers) and forced flow (air flow by fan or blower).
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