The purge rate of a desiccant air dryer heatless refers to the volume of compressed air that is used for regeneration or purging purposes. In a desiccant air dryer heatless, the process involves two towers filled with desiccant material, typically activated alumina or silica gel. One tower is in the drying phase while the other is in the regeneration phase.

During the regeneration phase, a portion of the dried compressed air is used to remove the moisture from the desiccant material in the regeneration tower. This purging process releases the moisture-laden air, also known as purge air or regeneration air, to the atmosphere or a vent. The purge rate is the flow rate of this purge air, typically measured in cubic feet per minute (CFM) or liters per second (L/s).

The purge rate of a desiccant air dryer heatless depends on various factors, including the design of the dryer, the moisture load of the compressed air being treated, the desired dew point, and the efficiency of the desiccant material. Generally, the purge rate is expressed as a percentage of the total compressed air flow through the dryer.

To minimize the energy consumption associated with the purge air, desiccant air dryer heatless often utilize a technique called "pressure swing adsorption" (PSA). In PSA dryers, the regeneration and drying cycles are controlled by valves, allowing for more efficient use of the purge air. By optimizing the timing and duration of the cycles, the purge rate can be minimized, reducing energy costs.

It's important to note that the specific purge rate of a heatless desiccant dryer can vary depending on the manufacturer, model, and specifications of the dryer.