CFD simulation and thermodynamic analysis of energy separation in vortex tube using different inert gases at different inlet pressures and cold mass fractions

Abstract

In this paper, extensive three-dimensional CFD simulations of vortex tube (VT) are conducted with five inert gases, namely helium, neon, argon, nitrogen, and carbon dioxide, to understand the influence of different properties of these gases on the flow phenomena and thermal performance of VT at wide range of cold mass fractions and inlet pressures. Molecular weights and specific heat ratios of the gases are found to significantly influence the values of velocity and temperature distributions inside VT, although the nature of the flow remains unaffected for different gases. Both hot and cold temperature separations increase for higher specific heat ratio of the gas, while heating and cooling powers are more for higher constant pressure specific heat and higher temperature separations. Coefficient of performance of VT vary significantly with cold mass fraction and inlet pressure, but remain majorly unaffected for different gases. Exergy analysis shows that at VT outlets, physical exergy is very much smaller than kinetic exergy. Outlet kinetic exergy is lost to the surroundings, without producing any desired cooling or heating effect. Therefore, physical exergy efficiency of VT, which is limited to 5% only, is of more practical value.