The Ranque-Hilsch Vortex Tube is a device that separates a stream of gas (or liqiud) into hot and cold components. It has no moving parts and at first glance seems to violate the laws of thermodynamics.
You will measure the temperatures of the hot and cold streams as a function of diaphram size and as a function of the input pressure. Use your data to calculate the thermodynamic efficiency. Compare the performance of a "home-built" vortex tube and a commercial tube.