A refrigerated compressed air dryer is a type of compressed-air dryer that is used to eliminate moisture from compressed air. Compressed air often contains moisture that comes from the air sucked by the compressor.Such water and oil can damage the compressed air piping system, and for this reason you need acompressed compressed-air dryer.
Key Takeaways
- The volume of compressed air as measured in CFM (Cfm)
- The air pressure entering the compressed air dryer measured in PSI
- The temperature of the compressed air
Why a refrigerated compressed air dryer?
Refrigerated air dryers are among the most used types of air dryers for compressors. They come in a simple design and require minimal upkeep. Additionally, they are more economical than other types of compressed air dryers.
A refrigeration dryer should be the standard choice if you need a compressor dryer that does not require specific features, such as very low dewpoint. As said before, refrigerated air dryers do not require special upkeep, and as long as you get a quality one and have installed in the right way, you will be in the set-and-forget mode for a very long time. There is a takeaway here. It is necessary to have the compressed-air dryer appropriately installed for it to work efficiently and prolong the life span of your compressor and air tools. So, what is the right way to mount a compressed-air dryer? Do not worry; we will look into that shortly. But before we go into how to mount the compressor compressed-air dryer, we need to understand what a compressed-air dryer for a compressor is and how it works.
How does refrigeration dryer works?
As the name goes, a refrigeration dryer works by cooling compressed air. Warm wet air enters the dryer, where it gets cooled down to 3 degrees Celsius for moisture (water vapour) in the air to condense into water. The condensed water is then trapped using a water trap and removed from the compressed-air system. The cold air is then entered into room temperature. The remaining air is now free from moisture (dry air) of any kind since the water has been trapped out. The cooling effect happens in the same way that your cooler or refrigerator would work. Liquid refrigerant goes through an evaporator and is evaporated to cool down the warm air from the compressor. This process happens in a separate circuit.
As the compressed air gets cooled down, the refrigerant becomes warm. Thus, to cool the refrigerant down once again, it is compressed by a small compressor in the condenser. The evaporator, which is the place where the refrigerant cools down warm compressed air, is found at the top part of the compressed-air dryer. In most cases, you will see a cooling fan close to the condenser.
Types of refrigerated compressed air dryers
There are two types of refrigerated air dryers; cycling and non-cycling air dryers. A cycling compressed-air dryer is beneficial in the sense that it increases or decreases the cooling capacity according to compressed air demand. This makes it more energy-efficient and economical. On the other hand, the non-cycling compressed-air dryer is the most used one because it requires less upkeep and is extremely dependable.
What to evaluate when buying one?
There are some essential factors to keep in mind when shopping for a refrigeration dryer. Here are some of the key points:
The maximum pressure:
You have to guarantee that the maximum pressure of your refrigeration dryer is the same or slightly higher than the maximum pressure of your compressor.
Maximum airflow:
The maximum rate of airflow through your compressed air dryer must be higher than what is delivered by your compressor. Going for a too-small compressed-air dryer will cause massive pressure drop over the dryer, due to this reason it is necessary to adjust the pressure on your compressor higher to compensate for the pressure drop. This would mean incurring high expenses in energy bills. Additionally, the dryer may not be in a position to reach the required dewpoint.
Inlet temperature:
The compressed-air dryer comes with a specified inlet temperature that you have to take a keen interest in. If you go above the recommended temperature, some parts of the compressed-air dryer may be damaged all the entire system will fail and for this reason not achieve the desired dewpoint. Some compressors come with an aftercooler installed in their system.
In this case, the compressed air will be somewhere around 40 degrees Celsius. Without an installed aftercooler, the compressed air can be as high as 80 degrees Celsius and above. It is necessary to check the temperature of compressed air, leaving your compressor. If it is scorching, then users can go for some special high inlet temperature dryers found in the market. These are specifically designed to work in such hot air conditions.
Maximum outside temperature:
Do it is necessary to work with your compressed-air dryer in hot conditions? The chances are that your compressed-air dryer will overheat and power down. It is necessary to find out the maximum temperature that your compressor can work in and buy a compressed-air dryer that can handle such temperature ranges.
Compressed-air dryer Upkeep and Setup
For setup and upkeep of your compressed-air dryer, always check your user manual for guidelines. Every make and model of a refrigeration dryer has its specific needs and instructions. Nevertheless, there are general things that users can keep in mind when it comes to installing and maintain a refrigeration dryer. Here are some of the aspects to focus on:
Mount the compressed-air dryer in a cold room that is free of any kind of dirt and dust. You also require a drain to get rid of the water. The standard power requirement for the setup of a compressed-air dryer is between 115 and 230 volts.
The most common breakdown or compressed-air dryer failure is overheating. When the condenser in the refrigerant circuit catches dirt and dust, or when the room temperature is too high, the dryer fails to get rid of the heat. It, for this reason, trips on its over-pressure switch.
Upkeep
It is necessary to clean the condenser once in a while to get rid of the accumulated dirt. In the process, operators should take caution because the fins (seen as small plates) are very sensitive and can be damaged easily. The right way to eliminate the dirt is by using a steel brush to scrape off all the dust gently. Users can also buy some special condenser combs to clean and straighten the fins. Cleaning the fins eliminate dirt and prevents accumulations that would cause overheating of the compressed-air dryer.
Another compressed-air dryer breakdown is being too cold. If the compressed air dryer is used to dry air below 0 degrees Celsius, the water removed from the air freezes to form ice particles in the piping. If the problem is not taken care of fast enough, the entire piping system in the compressed-air dryer becomes completely blocked.
Sometimes this breakdown is experienced when the compressed-air dryer is set at a very low point, and sometimes it can happen when the refrigerant circuit is experiencing problems. In both cases, it is necessary to repair the compressed-air dryer as fast as possible to avoid further damage and complications.
How to Mount a Refrigeration Compressed-air dryer
Well, you now know what a compressed-air dryer is and how to keep it in shape. The next step would be installing the compressed air dryer in the right to guarantee that it operates efficiently. This guide will help you through the process of installing a refrigeration dryer complete with its filters.
One best practice when installing a refrigeration dryer is ensuring that you have a multiple feeding into pre-filters with two air dryers. This process will cause a thermal overload in one of the air dryers. For instance, the filters that experience the least pressure drop (one that has the cleanest filter element) will allow more air to pass through. In case the air dryers are not the same brand or model, you may experience different pressure drops. This means that one compressed-air dryer will experience higher pressure of compressed air, representing a thermal load, than the other one. The situation can lead to dryers experiencing dewpoint and mechanical instability, causing the compressed-air dryer to trip put and compressed air getting wetter. With multiple feeds into the pre-filter, this problem is alleviated.
Frequently Asked Questions
What is the difference between a pre-filter and an after-filter?
A pre-filter sits before the dryer and removes bulk moisture and coarse particles; an after-filter sits after the dryer and polishes remaining fine impurities.
How do I choose a refrigerated versus an adsorption dryer?
Refrigerated dryers are economical down to about +3°C dew point. Desiccant dryers are needed for lower dew points or critical, oil-free applications.
What root causes high dew point in a refrigerated air dryer?
Overloading, high inlet temperature, a faulty condenser, or a blocked drain can all raise the dew point.
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