What Is Aftercooling and Why Does It Matter?

Compressed air systems are required for a wide variety of industrial applications. They’re incredibly useful, but they also generate a lot of heat. Manufacturers and other industrial organizations need to find ways to dissipate this heat. Intercoolers and aftercoolers are some of the best options.

But how exactly do aftercoolers work? And how do you choose the right one?

Intercooling vs. Aftercooling

Both intercoolers and aftercoolers play a role in mitigating the heat output of compressed air systems. These terms are very similar and are sometimes used interchangeably, leading to confusion among amateurs, but they refer to two fundamentally different types of systems.

Intercoolers are heat exchangers designed to remove heat in the air that’s generated by an air compressor. These should generally restore the temperature of compressed air to levels similar to those in the immediate environment. They function similarly to an intake air cooling unit.

Aftercoolers are mechanical cooling units that utilize principles of heat exchange between two mediums (in many cases water and air). These units use a series of tubes to achieve the cooling process, pulling in ambient air to help remove moisture from the compressed air. 

Ultimately, they can attain temperatures between 5 and 20 degrees Fahrenheit.

Types of Aftercoolers

There are two primary types of aftercooling for compressed air systems.

Water cooled aftercoolers are sometimes called “shell and tube” heat exchangers, and as you might suspect, they use water as the primary cooling medium. In this system, compressed air passes through a sequence of tubes, all while cooling water surrounds the outside of the tubes, all within a shell (hence the “shell and tube” moniker). The heat generated by the compressed air is transferred to the water, ultimately reducing the temperature of the air.

Air cooled aftercoolers are sometimes called “fin and tube” heat exchangers, and they rely primarily on ambient air to cool compressed air. In most situations, typical surrounding air is much cooler than air generated in compressed air systems. When hot compressed air flows through the finned tubes in this system, ambient air is forced across the fins. Ultimately, the heat from the compressed air is transferred to the surrounding ambient air, thereby reducing the compressed air’s temperature.

Pros and Cons of Water Cooled Aftercoolers

There are several advantages associated with water cooled aftercoolers.

·       Better cooling efficiency. Overall, shell and tube heat exchangers have a much higher cooling efficiency. That’s primarily because water has a higher heat capacity than air, allowing water-based systems to absorb much more heat, given the same volume.

·       More compact design. Also, these types of aftercoolers have a much smaller footprint, allowing them to have a more compact design. This allows them to be installed in more locations and allows for more flexibility. It also preserves valuable floor space in industrial settings.

·       Consistent performance. Water cooled aftercoolers also have very consistent performance, as they are unaffected by changes in ambient air temperatures. This is especially important in environments with fluctuating air temperatures.

However, there are also some disadvantages.

·       Greater installation costs. These systems are impressive, but they’re also more expensive. They rely on water sources and have higher installation costs.

·       Greater maintenance costs. These systems also generally have greater maintenance costs, since the system’s complexity is somewhat higher.

·       Increased risk of water leakage. If the system fails, water can leak into the compressed air system. This contamination can have devastating effects.

Pros and Cons of Air Cooled Aftercoolers

So what are the advantages of air cooled aftercoolers?

·       Lower installation costs. Comparably, air cooled aftercoolers have lower installation costs. They aren’t dependent on water sources and can be installed almost anywhere.

·       Lower maintenance costs. These systems also have lower maintenance costs, as they’re simpler to maintain.

·       No risk of leakage or contamination. With an air cooled aftercooler, you’ll never have to worry about leakage or contamination.

·       Installation flexibility. You can install an air cooled aftercooler anywhere in your facility.

There are disadvantages here as well:

·       Less cooling efficiency. Air cooled systems have less cooling efficiency, as air has a lower heat capacity than water.

·       A bigger size. These systems also have a bigger footprint, forcing them to take up more floor space. This can impact the efficiency of your layout.

·       Dependency on ambient air temperature. Changes in the ambient temperature of your industrial setting can impact the effectiveness of your air cooled aftercoolers. This makes them less consistent, especially during seasonal changes.

So should you choose an aftercooler that’s air cooled or water cooled? That depends on many factors, including your cooling efficiency requirements, your susceptibility to water contamination, your available floor space, and your budget. Weigh your options carefully and work with a professional if you want the best possible results.