Numerical analysis of flow and thermal patterns in a double-pipe Ranque-Hilsch vortex tube: Influence of cooling a hot-tube

Thermal efficiency and performance of a counter-flow vortex tube can be improved by cooling the main or hot-tube of the vortex tube. The present work investigates the effect of cooling (by water) a hot-tube on flow and thermal patterns (temperature separation) using a three-dimensional steady state model of turbulent swirling air flow inside vortex tube. The Computational Fluid Dynamics (CFD) was verified by comparing the present data with previous data reported in literature. In this work, the effects of performance parameters like length to diameter ratio (L/D) and number of nozzle intakes (N) on thermal separation of vortex tube within cooled hot-tube are also investigated numerically. The numerical data indicate that the cooling the hot-tube helps in increasing the cold air temperature difference, ΔTc, and improving isentropic efficiency of the system. The vortex tube with cooling water possesses higher cold air temperature differences and efficiencies than the one without cooling water by 6.3-10.3% and 5.8-10.6%, respectively. The highest temperature differences and efficiencies are belonging to the vortex tube with a cooled hot-tube at N = 4 and L/D = 47.5, and the lowest are belong to the vortex tube without a cooled hot-tube at N = 1 and L/D = 42.5.