Exergy analysis of a hot cascade type Ranque-Hilsch vortex tube using turbulence model

•Exergy analysis of hot cascade type RHVT is performed numerically.•Acquired numerical results are in good agreement with experimental data.•Exergy destruction at hot exit increases with cold fraction.•Highest exergy efficiency of 42.69% is achieved at cold fraction of 0.24.•No secondary circulation is found in the second stage RHVT.

Ranque-Hilsch vortex tube (RHVT) is a simple device capable of splitting a compressed inlet gas stream into a cold and a hot outlet stream without any external source of energy supply. In hot cascade type RHVT the hot gas stream emerging out of the first stage vortex tube is supplied to the inlet of second stage vortex tube and thus producing higher heating effect. This paper presents results of a series of numerical simulation carried out using standard k–ε turbulence model focusing on exergy analysis on second stage of RHVT for different cold fractions. The results obtained from numerical simulations compare favorably with available experimental measurements, which demonstrate successful use of turbulence model for a cascade type RHVT.