A chiller is a machine that removes heat from a liquid coolant using a refrigeration cycle, delivering precise temperature control to equipment, processes and industrial environments. Industrial chillers are widely used across manufacturing, food processing, pharmaceuticals, data centres and chemical processing: anywhere that consistent temperature control is critical to product quality and operational efficiency.

Understanding the different types of chillers (such as the difference between process chillers and HVAC chillers) helps businesses specify the right equipment for their application.

 

Types of Chillers and Their Mechanisms

Air-Cooled Chillers

Air cooled chillers use air that is passed through the condenser by the use of fans to extract heat from the condenser.

Water-Cooled Chillers

Water cooled chillers use a secondary water circuit that is pumped through the condenser to remove heat from the condenser.

Now let’s look at the vapour compression cycle...

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  1. The chiller pumps water, or water / glycol solution to the process application where heat is extracted from the application into the cooling fluid that then returns to the chiller. The chiller has a refrigerant circuit that consists of four main components: evaporator, compressor, condenser, and thermostatic expansion valve (TEV).
  2. The evaporator is a heat exchange device that absorbs the heat from the cooling fluid into the refrigerant and causes the refrigerant to evaporate and become superheated vapour.
  3. This superheated vapour at low evaporating pressure is then compressed by the compressor into superheated vapour at a higher condensing pressure.
  4. It then enters the condenser, rejects the heat at high pressure, whilst desuperheating and condensing into a high-pressure liquid. The condenser is another heat exchange device and the rejected heat from the refrigerant is absorbed by the air (air cooled chiller) or water (water cooled chiller) that passes through the condenser.
  5. Expansion of the refrigerant then takes place at the thermostatic expansion valve and the high-pressure liquid lowers to an evaporating pressure liquid and enters the evaporator completing the cycle.
  6. Through this process, the cooling fluid is continually cooled and returned to the process application at the required temperature set point due to the correct staging of the compressor and modulation of cooling across the condenser.
How does a chiller work? The 4-step refrigeration cycle explained

Chillers operate using a refrigeration cycle, consisting of 4 key steps:

  1. Compression: The compressor raises the refrigerant gas’s pressure and temperature, initiating the cooling process.
  2. Condensation: The high-pressure gas moves to the condenser, where it releases heat through a heat transfer process and turns into a high-pressure liquid. During this phase, the refrigerant condensing temperature is a critical factor in determining the efficiency of the heat exchange.
  3. Expansion: The liquid refrigerant then passes through the expansion valve, causing a drop in pressure and temperature.
  4. Evaporation: This low-pressure liquid enters the evaporator, absorbing heat from the surroundings and converting back into a low-pressure gas. The cycle then repeats.

Key Components of Chillers

Compressor: The heart of the chiller, it compresses the refrigerant, increasing its pressure and temperature.

Condenser: This component allows the high-pressure gas to release heat and condense into a high-pressure liquid. The refrigerant condensing temperature is crucial here for efficient heat transfer.

Expansion Valve: It reduces the pressure of the liquid refrigerant, causing it to cool down.

Evaporator: Here, the refrigerant absorbs heat from the process water or air, cooling it down before returning to the compressor to repeat the cycle.

Benefits of Using Chillers

Energy Efficiency: Modern industrial chillers are highly energy efficient, with variable speed drives and advanced controls delivering significant reductions in operational costs across a range of cooling capacity requirements.

Consistency and Reliability: A well-specified process chiller delivers consistent, reliable cooling, which is critical for industrial operations requiring precise temperature control throughout the production cycle.

Flexibility: Chillers come in various sizes and configurations, making them adaptable to different needs and environments.

Longevity: With proper maintenance, chillers can have a long operational life, providing reliable cooling for many years.

 

Applications of Chillers in Industry

 Industrial chillers are required across a wide range of industrial process applications, such as manufacturing, pharmaceuticals, food processing, chemical processing, laser cooling, data centres and medical imaging equipment to name a few. In each case, the process chiller acts as a heat exchanger between the industrial process and the environment, removing excess heat to maintain consistent process temperatures and protect product quality. For instance, in plastic manufacturing, process chillers rapidly cool injected, blown, extruded or stamped plastic to ensure dimensional accuracy and cycle time efficiency.