I have been working with a couple of overseas distributors lately who have projects involving vortex tubes that are tasked with cooling a chamber down to temperatures in the -10 to -20°C range. One of the projects was having some difficulty though. It seemed that in the beginning of the day, the vortex tube would function perfectly, but as the day wore on, the vortex tube would “stop working” as the customer would say.
We went back and forth a few times and I finally determined that the customer’s compressed air supply had a dew point that was higher than the -20°C output flow they were achieving in the beginning of the day. The mechanics of what was happening is that the vortex tube would cool an initial volume of compressed air and the moisture was condensing out of the airflow and lying inside the vortex tube body. When the subsequent “on” cycles would occur, that left over water would freeze up inside the vortex tube generator, eventually plugging it up.
And so the cycle after that point was reached would be one of freeze, plug up, thaw and freeze again. Not a very reliable way to go about the application. And so, in order for the customer to have a more reliable process, they had to dry their compressed air with a refrigerant type air dryer to drop that dew point before the compressed air entered the vortex tube. Once they did that, no more troubles.
Neal Raker, Application Engineer