How Does a Chiller Work? - Industrial Chiller System Working Principles
If your facility uses process fluids or heavy-duty machinery that generates heat, you’ll need an industrial chiller system to cool your processes and internal machine components. Understanding how an industrial chiller works and knowing the various types of chillers available will help you make the right choice for your cooling needs.
What Is a Chiller?
An industrial chiller is a refrigeration system used to lower the temperature of machinery, industrial spaces, and process fluids by removing heat from the system and transferring it somewhere else. Industrial chillers are essential for temperature regulation in several industrial processes such as injection molding, metal plating, oilfield production, and food processing.
Industrial chillers work based on the following principles of operation;
1. Phase Change
A liquid coolant undergoes a phase change into a gas when heated, and when the gaseous coolant is supercooled, it condenses back into a liquid.
2. Heat Flow
Heat energy always flows from an area of high concentration to an area of lower concentration.
3. Boiling Point
Reducing the pressure over a liquid decreases its boiling point and increasing the pressure increases its boiling point.
How Does a Chiller Work?
Chillers consist of four basic components; an evaporator, a compressor, a condenser, and an expansion unit. Every chiller system contains a refrigerant.
The process starts with a low-pressure refrigerant entering the evaporator. Inside the evaporator, the refrigerant is heated, causing it to undergo a phase change into a gas. The gaseous refrigerant goes into the compressor which increases its pressure.
The high-pressure refrigerant goes to the condenser which rejects the heat using cooling water from a cooling tower or air from the surroundings, condensing it into a high-pressure liquid. The condensed refrigerant then goes to the expansion unit which has a valve that acts as a metering device to limit the flow of refrigerant in the system.
Consequently, this lowers the pressure of the refrigerant and begins the cooling process again. The entire process is known as the refrigeration cycle.
Types of Industrial Chillers
The three main types of industrial chillers in use today are air-cooled chillers, water-cooled chillers, and absorbtion chillers. We will also briefly touch on cooling towers (an alternative or supplemental cooling system) and special chillers like glycol and centrifugal chillers.
Selecting the right chiller for your application will help you to save costs, reduce downtime, and improve operational efficiency.
Water-cooled chillers use water from an external cooling tower to reject heat from a gaseous refrigerant in the condenser before it undergoes a phase change into a liquid.
In place of the cooling water, air-cooled chillers use ambient air to reject heat from the refrigerant in the condenser.
Vapor Compressor Chillers
This type of chiller uses refrigerants to cool process fluids and spaces. A compressor is used as the driving force to pump refrigerant around the system.
Vapor Absorption Chillers
Vapor absorption chillers have no compressor in the unit. Rather, they use a heat source e.g., solar energy or waste heat to drive the coolant through the system.
How Does an Absorption Chiller Work?
The process starts with liquid coolant in an evaporator which turns it into gaseous form. The gaseous coolant is absorbed by a concentrated absorbent such as Lithium Bromide or Ammonia, provided by a generator. The diluted solution absorbs the coolant while the heat is being absorbed by the cooling water.
The diluted solution of coolant and absorbent flows through a heat exchanger to the generator where it is heated. The coolant vaporizes out of the solution, condenses, and is sent out for cooling again. The now-concentrated absorbent is recycled as well.
Glycol chillers are special types of chillers which use propylene glycol, an anti-freeze, in the system. They are widely used in food-grade applications such as in the production of alcohol and for brewery chilling systems.
How does a glycol chiller work?
The mode of operation of glycol chillers is the same as a standard chiller.
Centrifugal chillers consist of the usual evaporator, compressor, condenser, and expansion device set-up but with additional rotating impellers which compress the refrigerant and transport it around the system. They are particularly useful for medium to large scale cooling operations (from 150 – 6000 tons of refrigeration).
A cooling tower is a large heat exchanger unit which provides cooling water to remove heat from a coolant which has been used to cool machinery, process fluids, or buildings. When the cooling water meets with air, a small portion evaporates, lowering its temperature. This is known as “evaporative cooling.”
It’s common to find cooling towers conveniently situated near bodies of water such as lakes and rivers to ensure a constant supply of water for cooling. In many situations, you can pair a chiller and cooling tower together for more efficient industrial chilling.
Uses of Industrial Chillers
Industrial chiller systems can be used for cooling operations in diverse industries. Below are some of the most common applications:
Industrial chillers are used extensively in food production and processing operations which require a high degree of precision in temperature control. For instance, winery chillers are used for temperature control during the fermentation and storage of wine. Bakery chillers help with mixer cooling, potable water cooling, and cooling jacketed tanks of yeast that are all critical bakery components.
Temperature control is essential in metal finishing processes such as electroplating or electroless plating to remove the excess heat as they typically require very high temperatures (several hundred degrees) to bond the metals. Some industries use metal-finishing chillers to cool the anodizing liquid in a heat exchanger or use a glycol/water as a cooling medium to lower the temperature inside the tank.
Injection molding is a mass-production technique for creating plastic parts using an injection-molding machine, thermoplastic pellets, and a mold. The process and melt must be maintained within precise temperature limits to prevent problems such as cracks, warping, and internal stresses in the final product.
An injection molding chiller can supply a stream of supercooled fluid to cool the mold at an ideal rate to ensure optimum product quality.
In manufacturing plants which generate a lot of heat from the heavy-duty machinery they use, a chiller can help to prevent extremes of temperature in the offices and other working spaces. They also help save costs on purchasing separate HVAC systems for cooling.
Determining the Right Size of Chiller for Your Needs
Choosing an adequately-sized chiller is critical for efficient and cost-effective process, machinery, and space cooling. Cold Shot Chillers’ easy-to-use sizing tool can help you quickly determine your optimal chiller capacity, tonnage, and size.
Trust Cold Shot Chillers for All Your Chiller Needs!
With over three decades of expertise in manufacturing industrial chiller systems, Cold Shot Chillers provides cooling equipment and expertise for the most challenging process cooling needs.