Elliott Cycle Refrigerated
Compressed Air Dryers

Air-Options
dryers utilize the Elliott refrigeration cycle. This is a highly reliable process that uses tap water, compressed air and the heat of compression, which the compressor generates. Compressed air is channeled from the “cool” end of the heat exchanger to the air jet and discharged into the coolant cavity. A perpendicular needle of tap water is introduced into the expanding air jet. This has the effect of atomizing the water into micro-droplets. Some of the micro-droplets evaporate and, in doing so, the temperature of the discharge is cooled.

To improve the evaporation process, a portion of the compressed air is directed to a dropping orifice and allowed to expand to match the coolant cavity pressure. As the air expands it’s temperature and water vapor content lowers. The air then flows through a re-heater, which raises the temperature. The re-heated air, which now has a low relative humidity, is introduced into the water/air discharge. The introduction of this "dry" air aids in the evaporation of the micro-droplets and forces a lower discharge temperature.

The dryer body consists of a tube-in-shell heat exchanger with a built-in water separator. Hot, moist air from the compressor head is introduced into the air input where it flows through the exchanger tubes. A cooled vapor cloud, discharged from the Elliott cycle refrigerator, is introduced into the coolant cavity. The cloud then flows through the heat exchanger, where it cools the outside of the exchanger tubes, and out the coolant discharge. When the hot, moist air comes in contact with the inside of the cooled exchanger tubes, the water vapor condenses onto the inside walls of the tubes. The condensed water runs down the inside of the tubes along with the air flow and drips into the water reservoir. The dried air flows around the lower end of the air baffle, through the coalescing filter, and out the dried air output.

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