Discover How to Use Heat Recovery to Cut Your Energy Costs

In industrial operations, compressed air plays a vital role across a range of manufacturing processes. As air undergoes compression, its moisture content rises significantly. Air compressor manufacturers use intercoolers and aftercoolers to remove much of the water from the air stream to address this. Still, the coolers alone do not remove enough moisture for some applications, and an external dryer, particularly heat of compression (HOC) dryers, become critical.

Since air compressors are such a good heat source, many operators find benefits in recovering that heat and turning it into energy savings for their facility. To do this, your compressed air system will need a compressor paired with a dryer. There are many types of compressed air dryers available to remove moisture from the air, but it is important to make sure that if you decide to go down this path that great care is taken in planning your system. Often the selection would include both your compressor and heat of compression dryer.
 

Unlocking Energy Efficiency Through Heat Recovery

Air compressors generate a considerable amount of waste heat during operation. With the right system design, thermal energy can be recovered and repurposed, significantly reducing facility energy demands. A heat recovery strategy typically involves coupling a centrifugal or rotary screw compressor with an appropriate dryer system.

When designed properly, this setup not only improves air quality and moisture control but also cuts down on the facility’s heating or energy costs. However, successful integration demands careful equipment selection, including the compatibility between the air compressor and the drying technology used.

What are Heat of Compression (HOC) Dryers?

Among the available dryer options, HOC desiccant dryers offer a high-efficiency solution for facilities running continuous-duty compressors.  These HOC dryers use a process called adsorption to remove water from the air. A hygroscopic material, or desiccant, is used to remove the water, which clings to its surface. However, over time, the desiccant becomes saturated with water and must be regenerated or dried. 

During its normal operation, the centrifugal air compressor creates heat. Instead of consuming additional energy for this regeneration process, HOC dryers harness the heat from the compressor discharge. This high-temperature air is redirected through the saturated desiccant bed, evaporating the moisture and restoring the desiccant’s drying capacity. By using the system’s thermal output, HOC dryers eliminate the need for external heating sources, dramatically improving system energy efficiency.
 

Key Considerations for System Integration

Before implementing an HOC dryer, engineers must evaluate:

• Compressor Type – HOC systems pair best with oil-free centrifugal or rotary screw compressors that operate at steady loads.
• Required Dew Point – Assess whether the application demands a consistent -40°F/-40°C pressure dew point or lower.
• Flow Rate and Load Profile – Ensure that the compressor's duty cycle aligns with the regeneration requirements of the dryer.
• Ambient and Discharge Temperatures – Proper performance depends on the availability of sufficient discharge heat.

These factors directly affect dryer performance and energy recovery potential. A misalignment in system design can lead to reduced efficiency or drying performance below spec.

The Importance of Understanding Your System Set-up

Before deciding to add an HOC dryer to your plant’s system, there are important factors such as the type of air compressor installed and the level of dryness that needs to be achieved.

To better understand HOC dryers and find out if it’s the right solution for you, check out our Hidden Costs of HOC Air Dryers in Centrifugal Compressor Operation white paper.