I recently had a customer e-mail me with this inquiry. Following is our discussion:
We have a small vortex (3208) and a set of generators, the one that is pre-installed in the Vortex Tube (8GR) and a few more:
2GR, 4GR, 2GC, 4GC, 8GC
Maybe you could tell me the effect of these generators on the cold flow.
My main application is to refrigerate tools during machining or cool ultrasonic transducers during continuous operation. My compressed air source is 6.5 BARG. Using the Vortex Tube as it comes, after closing the hot flow and opening it a revolution, I can reduce the temperature from 22ºC (room temperature) to -6ºC (measured in the cold air flow at the output). How do I use the flow generators?
Thank you for your question concerning the generators which are interchangeable on the Vortex Tube. The purpose of the various sizes and types is explained as follows:
GC vs. GR designation: The GC type generators are designed to achieve maximum temperature drop for applications which may need an airflow which is below 0 degrees F. It is unusual that an industrial cooling application would need air this cold, but some scientific and other similar academic pursuits do need air flows that cold. The thing you give up when you try to achieve low cold temperature is the flow. Flow and temperature drop are inversely related to one another with a vortex tube’s function.
The GR type generators are used for temperatures down to zero degrees F. So, these would be the more prominently used generators for industrial applications. We usually will set up a Vortex Tube in a cooling application to have about 50 degree F temperature drop and can still preserve 80% of the total flow for cold flow applications. This is what we refer to as maximum refrigeration settings.
As for the numbers on each generator (2, 4 or 8) this is the indication of the amount of air volume consumed by the Vortex Tube when this specific generator is installed. The flow rate is indicated in SCFM with 100 PSIG inlet working pressure. So an 8 SCFM @ 100 PSIG flow rate is what is determined by an 8-GR or 8-GC generator. Small Vortex Tubes are available in flows of 2, 4 or 8 SCFM.
Basically, the larger your flow rate, the more cooling power you can generate. Think of the cold air as ice. Think of 8 SCFM as a 55 gallon drum of ice and a 2 SCFM as a 5 gallon bucket of ice. Both have the same temperature, but the 55 gallon size has potential to do more work to cool down a larger heat load.
Creating a spot of heat with a torch or an electric heating element is not hard to do with common tools found in a manufacturing environment. Creating a spot of cold air for similar situations is a very tough thing to do in the same situation. A Vortex Tube is a handy and convenient tool to allow for the spot cooling or small chamber cooling applications.
Neal Raker, Application Engineer