The Different Types of Chillers for Industrial Use

Chiller systems are vital in several different types of industrial processes.  They provide essential cooling and temperature control, where excess heat accumulates and must be removed.  Common industrial settings where chillers are used include:

• Injection and blow molding
• Die casting
• Machine tooling
• Plastic industry
• Welding equipment
• Metal working, especially with cutting oils
• Pharmaceutical formulation processes
• Food and beverage
• Paper processing
• Cement manufacture
• X-ray diffraction
• Gas turbine power generation

In all these processes, and others, chillers provide the same necessary function – the removal of heat – to keep the processes themselves running properly and at peak efficiency, and in the case of indoor manufacturing, maintaining suitable air temperature conditions for the people occupying the interior space.  They are also frequently used to not only cool air, but also dehumidify it, especially in the case of interior applications.

There are several different types of chillers for industrial use.  Let’s take a look at them now – how they work, and the specific applications for which they are best suited.

Water-Cooled Chillers

Water cooled chillers are widely used in many of the industrial processes we’ve just listed.  They involve the use of an external cooling tower, which supplies water that cools the refrigerant in the condenser.  The chilled fluid gets pumped through whatever equipment needs to be cooled, whether it’s the mechanisms, the machinery, or the finished product. The cycle continues back outside where the excess heat collected by the fluid is dispelled, and the process can repeat.  

Chiller systems for industrial purposes can be centralized, i.e. one unit provides cooling for a number of processes; alternatively, they can be decentralized – each process has its own separate chiller system.  A combination of both centralized and decentralized systems is possible, usually in the case where some of the industrial processes have the same cooling requirements while others don’t.

Air-Cooled Chillers

Air-cooled chillers perform exactly the same function as their water-cooled counterparts – the only difference being the source of medium to collect heat from the desired area.  Rather than using water-humidified air to work with the condenser and evaporator, air-cooled chillers use the abundant supply of ambient air outside, sucking it into the system with large fans.  

Air-cooled chillers are typically a less common choice in industrial applications, usually for capacity reasons.  They tend to operate best at lower cooling volumes, which can negate their suitability in, for example, large-scale heat-producing industrial applications.  They can also be more energy intensive and therefore less efficient than water-cooled systems, due to the considerable electricity consumption from their fans and motors.  

The advantages of air-cooled chillers include a lower upfront installation cost due to the lack of necessity of the water cooling tower component.  They are also an excellent choice for portable or temporary installations, such as at a construction site, or some other type of non-permanent use, for the same reason.

Two other considerations which may limit the appropriateness of an air-cooled chiller system include:

Noise issues – the continuing use of high-powered fans can cause issues with noise, should the chiller unit be situated near human-occupied areas, such as residential or commercial buildings.  Complaints about their operating sound could arise.

Long-term cost – over their life-span, air-cooled chiller units tend to be more expensive to operate than water-cooled systems. Their overall service life may be shorter as well.

Evaporative Condensed Chiller

Evaporative condensed chiller systems sit somewhere between the typical water-cooled and air-cooled chiller units we are familiar with.  The net result is identical – the conversion of refrigerant from heated vapor to cooled liquid.  

There is no cooling tower with this type of system.  Rather, the conversion from vapor to liquid occurs by spraying water onto the tubing which holds the refrigerant, on its outside surface.  The net result is a reduction of steps – the spraying of the water is direct from the source, with no trip from a cooling tower.

Among their advantages: As noted, there are fewer components with an evaporative condensed chiller system.  Therefore installation and maintenance costs may prove lower. Being relatively compact, this can be beneficial where space restrictions exist, particularly in situations where there is no room for a cooling tower.

It should be noted that evaporative condenser chiller systems are best suited to dry, hot climate regions.  Colder northern climates, for example, may not be suitable for their use.  Exact site conditions and requirements should be thoroughly examined in advance of selecting this type of chiller system.

Vapor Compression Versus Vapor Absorption in Chiller Systems

There is another distinction in chiller systems – how the refrigerant is moved through the stages. There are two categories of chiller here:

Vapor Compression Chillers involve the use of a compressor pump to transport the refrigerant; it subsequently extracts the heat out of the process.  Both water-cooled and air-cooled chiller systems are examples of vapor compression-type units.

Vapor Absorption Compressors, by contrast, involve no compressor, but rather the use of an absorber – a heat source that is used to transport the refrigerant through the system. The heat source itself is heated by either water or steam. This technology has been around for many decades and is becoming more commonplace for compression systems in certain situations, such as locations with unreliable power, both in availability and cost, as well as cases where the noise from a compression unit is unacceptable.

Some Considerations When Selecting a Chiller System

Following are some distinctions between the two prevalent chiller systems – water-cooled and air-cooled.  Some or all of these factors should be taken into consideration when deciding on which is the most appropriate type:

Installed cost – we’ve mentioned that air-cooled chiller systems can be generally installed at a lower cost than water-cooled, due to the lack of need for a water cooling tower and the condenser pipes that keep the system circulating.

Overall lifetime cost – water-cooled systems tend to be less expensive. They consume less energy than the fans required in an air-cooled chiller system.  In general, air-cooled systems tend to have a shorter life span.  This, too should be taken into account at the design stage.

Maintenance requirements – water-cooled chiller units tend to have more components that require maintenance, mostly due to the ongoing flow of water through them.  This includes corrosion, mineral deposits, and scale buildup.  We’ve already mentioned, however, that on the whole, air-cooled chiller units do not typically last as long as water-cooled systems.

The size of the installation, and cooling requirements – air-cooled chiller systems tend to be on the smaller side, for cost reasons.  There is a lower upfront cost to installing them.  Larger-scale chiller installations are almost exclusively water-cooled, owing to their lower life-cycle cost.

Overall performance – on a square foot basis, water-cooled chiller systems provide superior cooling.  Some of this has to do with water’s superior heat-transferring properties over ambient air.  

Concluding Thoughts on the Differences Between Air-Cooled Vs Water-Cooled Chiller Systems

Clearly, all chiller units have one purpose – the removal of heat from whatever source is generating it in the most efficient way possible.  Water-cooled and air-cooled chiller systems make up almost the entire market.  Each has its place, and each comes with its own set of advantages and disadvantages.

In today’s world of ever greater focus on sustainability, energy consumption, and protecting the environment, any designer or engineer must factor all of the above with the specifics of their particular process and its location.  

Consulting with an expert in the field, which includes the manufacturers themselves, is an excellent first step in determining the appropriate chiller system for any given application.

We would be pleased to discuss your specific situation and requirements for heat removal via a chiller system. Contact us to learn more today.