FAQ: Types of Compressed Air Dryers – Refrigerant and Regenerative Desiccant

Why Use Refrigerated Dryers

Industrial or commercial facilities that use air-operated machinery or tools, must have an efficient compressed air dryer to remove any water vapor from the compressed air and prevent condensation from interfering with sensitive machinery or producing condensation which can rust and damage the machine.

Refrigerated compressed air dryers are used because of their low initial cost, operating cost, and maintenance cost. Even though they may have a limited dew point capability when compared to other compressed air dryer systems, such as chemical dryers, refrigerated dryers are less susceptible to damage by oil in the air stream, through filtration is usually still recommended.

Different Types of Refrigerated Dryers

Refrigerated dryers are a good choice for many facilities that need high-performing air dryers in extreme working conditions, such as low-pressure or high-pressure environments.

Because they are energy efficient and can remove most moisture from the air without using any compressed air in the process, refrigerated dryers are a top choice among facilities that do not produce water-sensitive products.

Non-Cycling Refrigerated Dryers

Non-cycling dryers are cost effective and can efficiently remove most moisture from compressed air systems by using a two-stage heat exchanger system to keep dew points stable and consistent. Non-cycling refrigerated dryers are valued because they have minimal dew point swings and their refrigerant compressor operates all the time, unlike cycling dryers.

However, non-cycling refrigerated dryers do not save energy at partial and zero air flow, so they are best for systems that run regularly.

Cycling dryers are the most common refrigerated compressed air dryer. Also called thermal mass dryers, these refrigerated dryers have a three-stage heater exchanger system. They use a refrigerant, either a liquid or a solid, to cool the air passage in the heat exchanger.

These dryers are used when system conditions are frequently less than full load, because cycling dryers save energy during partial air flow and zero air flow conditions. These units turn off once they have reached the desired temperature and turn back on if the temperature rises above that.

This system makes cycling refrigerated dryers the most efficient compressed air dryers available. However, cycling refrigerated dryers are much more liable to dew point swings and are bulkier than their non-cycling counterparts.

Regenerative Desiccant Refrigerated Dryers

Regenerative desiccant refrigerated dryers use a desiccant, which is a drying agent, to adsorb or condensate moisture within the air stream. These dryers are used in mobile, remote, and hazardous conditions because heatless desiccant refrigerated dryers can be designed to operate by pressurized air or gas.

Desiccant dryers are also used because of their low cost of operation and the dew points they can achieve. However, desiccant refrigerated dryers are less popular than other types of refrigerated dryers because they have a relatively pricier initial cost. They require more maintenance than other types of dryers and the desiccant bed needs to be replaced regularly. Usually, desiccant dryers require purge air.

When you shop for the right compressed air dryer for your situation, keep these pros and cons of refrigerated dryers in mind so you can make a smart, informed purchase!