Investigations Into Energy Separation Model And Numerical Simulation Of The Vortex Tube

The vortex tube is a device which separates standard compressed air into two parts simultaneously, one hotter than the inlet temperature and the other cooler. The vortex tube is now more and more widespread availability for scientific research, industry and other many realms, which is simple, is highly reliable and compact, has no moving parts and low cost, as well as that it has many practical functions of refrigeration, heating, separation, creation of vacuum.In spite of the potential usefulness and simple geometry of the vortex tube, its real physical processes and energy separation effect are far from being fully understood. Since the invention of the vortex tube, the vortex tube and theoretical value of coherent energy separation as well as its potential applications have been being focused by more and more experts.Entropy model of irreversible process and thermodynamic model of energy separation were derived by the usage of thermodynamic first law and thermodynamic second law, according to the special characteristic of air inside the vortex tube. Qualitative analyses and quantitative calculation concerning about technical work and irreversible loss produced during the process of energy separation by the method of entropy theory. As a result, various thermodynamic parameters as the function of cold air fraction were obtained.The mathematical model of internal movement process was deduced on the basis of flow patterns inside the vortex tube. The expressions of pressure and temperature were derived from the change of flow field. The results show that the distributions of temperature and pressure are mainly dependent on velocity distribution, which have direct relation with the cold air fraction, inlet pressure and geometrical parameters. The perfect numerical method which is suited to vortex tube's numerical simulation was determined according to the characteristic of strong swirl flow inside the tube. Energy separation of vortex tube was simulated by usage of this numerical method. Flow patterns and temperature (total, static and dynamic) distributions was obtained and analyzed in detail. In order to validate the numerical results, comparisons between the numerical predictions and the experimental results were conducted, and satisfactory agreements were observed. The results indicate that the gained flow field and temperature distributions can reflect essential phenomenon of energy separation happened inside the vortex tube, which proves the rationality of the used numerical method further.