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Water-cooled and air-cooled chillers

Chiller refers to a machine that removes heat from a specific fluid flow (refrigerant) through a thermodynamic cycle (vapor condensation or absorption). Then this flow is used for cooling water by circulating in a heat exchanger. In fact, the chiller takes heat from an environment and transfers it to another environment. So, the chiller can be considered as a type of energy pump whose output product is cold water.

چیلر صنعتی آب خنک و هوا خنک

Application of water-cooled and air-cooled industrial chillers

Industrial chillers are one of the most important cooling and cooling equipment in industrial buildings and factories. The cold water produced in the chiller can be used to cool the interior of any building with the help of fan coils or air conditioners, or it can be used in industrial machines and various production processes that require cooling.


Application of chiller in industrial equipment

The cold water produced by the chiller is used in many industrial processes that require a cooling process, including the cooling of production line mechanisms and machines, in a wide range of different industries. Examples of these industries are: plastics, injection and casting, metalworking, welding, machine tools, petrochemicals, pharmaceuticals, healthcare, food production and preservation, fish farming, paper and cement, road construction, etc.


Chiller is basically used to produce cold water, but in a certain temperature range. For example, if the required water temperature is higher than the wet temperature of the environment, a cooling tower should be used, and if it is higher than the dry temperature of the environment, a dry cooler should be used to reduce the desired water flow temperature; Because, firstly, the price and electricity consumption of the chiller is higher compared to the mentioned systems, and secondly, the working range of the compressor (Envelope) does not allow any temperature to be obtained with the help of the chiller. Therefore, the chiller is used to produce cold water from -40 to 3 degrees Celsius more than the wet temperature of the environment, and special compressors and refrigerants are defined for this temperature range.

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All kinds of industrial chillers

Chillers are generally divided into two general categories based on the type of work cycle that performs the refrigeration or cooling process:

  • Compression chiller
  • Absorption chiller

For a better understanding of chillers and a correct understanding of the function and application of each of them, we will examine the basis of each one separately.

Steam compression chiller

The basis of vapor compression chiller is the circulation of fluid called refrigerant in the vapor compression refrigeration (Carnot) cycle and it is formed based on four main components including: Compressor, Condenser, Expansion valve and Evaporator. take So that the refrigerant vapor is condensed by the compressor and after increasing the pressure and temperature, it enters the condenser to remove the heat. In this way, its temperature is reduced and it becomes a liquid by losing more heat. Then it passes through the expansion valve and with the sudden pressure drop, a small amount of it evaporates.

As a result, the resulting mixture of liquid and steam enters the evaporator at a lower temperature and evaporates completely by absorbing the heat of water or air. In this way, after completing the cooling process in the evaporator, the refrigerant vapor returns to the compressor.

Types of compression chillers

Types of compression chillers based on compressor type:

Depending on several criteria, such as: the required refrigeration capacity, the climatic conditions of the project site, the type of refrigerant used, the use of the project, etc., the right compressor is selected for the chiller.

Types of compression chillers based on the type of condenser:

According to the required refrigeration capacity, the climatic conditions of the project site, the costs of energy consumption and service and maintenance of the device and other factors, how the process of heat removal in the condenser is predicted, which types are:

چیلر آب خنک صنعتی

Water cooled compression chiller

In water-cooled compression chillers, the condenser (shell and tube exchanger) is cooled by exchanging energy with water. So that the hot refrigerant coming out of the compressor enters the condenser shell and the water flow with the appropriate temperature (produced by the cooling tower) is passed through the pipes.

Water-cooled compression chiller and water-cooled condenser

Evaporatively condensing chiller: In evaporative condensing chillers, the condenser (coil) is cooled through the evaporative cooling process. So that the hot refrigerant coming out of the compressor enters the condenser coil tubes and the water is sprayed on the tubes by nozzles and evaporates due to receiving heat energy.

Evaporative condenser in evaporative compression chiller

Air cooled compression chiller

In air-cooled compression chillers, the condenser (finned coil) is cooled by exchanging energy with the air. So that the hot refrigerant coming out of the compressor enters the finned pipes of the condenser coil and the ambient air is passed over the pipes by the built-in blower or suction fans.

Air-cooled compression chillers can be designed and produced in two ways: Packaged and Split. As in the double fabric type, the chiller condenser is made in a separate unit. While in the integrated type, all the accessories of the chiller are installed in one unit.

Absorption industrial chiller

The basis of absorption chiller work is the absorption refrigeration cycle, in which the basis of the cooling process is similar to the steam condensation cycle. with the difference that the components including the absorber, pump and generator have been replaced by the compressor, and in addition to the refrigerant (water), another fluid is also used as an absorber (lithium bromide). (Previously, water was used as an absorbent fluid and ammonia was used as a refrigerant.)

In the absorption chiller, the refrigerant and the absorbent fluid form a liquid solution that flows through the pump to the generator due to heat rejection in the absorber. By absorbing heat in the generator, the refrigerant evaporates and separates from the solution. In this way, on the one hand, the refrigerant vapor goes to the condenser, and on the other hand, the absorbent fluid remaining in the generator returns to the absorber. In the rest of the way, the process is similar to the vapor compression cycle, and after transferring energy in the evaporator, the refrigerant vapor enters the absorber again and dissolves in the absorbent fluid.

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Types of absorption chillers

Single effect absorption chiller: Those absorption chillers that have only one generator in their refrigeration cycle and are defined in three different categories based on the heat source of the generator:

Hot water: with a temperature of less than 100 degrees Celsius (about 95 degrees Celsius)

Hot water: with a temperature greater than 100 degrees Celsius

Low pressure steam: with a pressure of less than 15 psi

Double-effect absorption chiller: those absorption chillers that have two high temperature and low temperature generators. In such a way that the dilute solution coming out of the absorber is pumped towards the high temperature generator and due to the contact with the hot pipes that passed through the generator, the refrigerant in it evaporates and leaves the generator. The remaining solution in the generator, which now has a medium concentration, enters the low temperature generator in parallel with the resulting refrigerant vapor. As the refrigerant vapor passes through the generator tubes and the incoming solution becomes completely concentrated due to contact with these tubes, which have a higher temperature. In this way, after energy transfer and temperature reduction, the refrigerant vapor enters the condenser and the thick solution obtained in the low temperature generator returns to the absorber. In addition, the steam separated from the solution together with the cooled steam is condensed in the condenser and flows to the evaporator. According to the type of heat source of the generator, these types of chillers are divided into two categories:

High pressure steam: with a pressure between 110 and 120 psi

Direct flame: by burning city gas or diesel

Double effect absorption chiller

Diagram of refrigeration cycle of absorption chiller with two effects

Comparison of compression chiller and absorption chiller

The choice of compression or absorption chiller can be affected by the required refrigeration capacity, the climatic conditions of the project location and energy consumption costs. But today, regardless of these factors and with a more complete evaluation, compression and absorption chillers can be compared from other angles:

Coefficient of performance (COP): The chiller’s coefficient of performance actually indicates its energy consumption efficiency. As the ratio of the heat received in the evaporator to the total energy consumed in the consumers (compressor, air condenser, cooling tower, pump and generator) is defined as the energy efficiency ratio or the performance coefficient. The performance factor based on the same conditions (standard ventilation conditions) can be achieved up to 3.5 in air compression chillers and up to 6 in water compression chillers. Meanwhile, the performance coefficient of absorption chillers in the best case (double effect absorption chillers) will be 1.4.

Dimensions and weight of the device: with the addition of generator, absorber and other peripheral equipment, the dimensions of absorption chillers are almost twice that of compression chillers of the same capacity and require more space for installation in the engine room. In addition, due to the greater weight of these chillers, more resistant infrastructure and chassis should be provided for placing absorption chillers.

چیلر تزریق پلاستیک

Purchase cost and initial investment: The cost of purchasing single-effect absorption chillers is about 50%, and double-effect absorption chillers (direct flame) are nearly twice the cost of purchasing compression chillers of the same capacity.

Service and maintenance cost: The service and maintenance costs of absorption chillers are much higher compared to compression chillers due to the presence of more, larger and more sensitive equipment. Especially since the negative pressure in the absorption chiller system requires more sensitivity and accuracy to prevent leakage and oxygen entry.

Water consumption: Due to the presence of absorbers in absorption chillers, the need for cooling water to remove heat is more than water compression chillers with the same capacity, and this means more water consumption and the need to use pumps and cooling towers. It is also bigger.

Energy consumption: burning fossil fuels to provide the heat source of the generator in absorption chillers, in addition to releasing more pollutants in the environment, imposes a significant cost on the system. Meanwhile, the power consumption of compression chillers can be significantly optimized by using intelligent control systems. For this reason, in total, the current cost of absorption chillers, which in addition to energy consumption, includes water consumption and service and maintenance costs, is estimated to be higher compared to compression chillers.

The sound level of the device operation: the amount of noise produced by absorption chillers (except for the direct flame type) is lower than compression chillers due to the presence of fewer moving and mechanical parts.

Climatic conditions: Due to the requirement of a cooling tower in absorption chillers, it is not possible to use this system in humid areas. Because the basis of the work of cooling towers is evaporative cooling and the presence of air close to saturated conditions cannot be suitable for their cooling mechanism. While with the help of air compression chillers, it is easy to meet the existing refrigeration needs even in completely humid air conditions.

Buying all kinds of chillers

Water-cooled and air-cooled chillers can have many different functions according to the customer’s needs. Based on this, we recommend that you click on the link to contact us and get in touch with the company’s sales experts to get technical advice regarding the purchase of chillers and price inquiries.

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