Review of Ranque–Hilsch vortex tube experiments using air

This paper reviews the literature on Ranque–Hilsch vortex tube experiments using air as the working fluid. This is a simple device without any moving parts that uses vortex motion to separate a compressed gas flow into two streams of high and low temperature, respectively. After a brief introduction and background, the review focuses on the variables of interest and the important experimental results that have been obtained up to now. Another objective is to find curve-fitting equations using data from the literature which can provide a rough estimate of temperatures that are achieved, and which can be used in practice for preliminary vortex tube design. The review will conclude with comments on further directions that future studies on this device can take.