Numerical analysis of energy separation in Ranque-Hilsch vortex tube with gaseous hydrogen using real gas model

Ranque-Hilsch vortex tube (RHVT) is a simple device with energy separation effect. It has potential to precool gaseous hydrogen in the multi-stage liquefaction process in situations where a device of high reliability is required or high-pressure gas is readily available. In the present work, CFD analysis using the real gas model has been carried out to investigate energy separation performance in RHVT with gaseous hydrogen from cryogenic temperature to ambient temperature. The predicted temperature separation at both cold and hot exits are found to satisfactorily accord with the experimental data from literature. Streamline structure at cryogenic inlet temperature is carefully compared with that at ambient temperature. Accordingly, energy separation mechanism is concluded from two kinds of streamline structures existing in RHVT with inlet gas temperature ranging from 50 K to 294 K. Additionally, the influences of inlet temperature and mass flow rates on energy separation are investigated. To find a more accurate measurement criteria of energy separation in RVHT, the specific cooling power separation is defined to evaluate the cooling capacity of instead of cold exit temperature alone.