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In this numerical study, exergy analysis of a Ranque-Hilsch vortex twbe (RHVT) has been investigated. The threedimensional ( $3 \mathrm{D}$ ) computational fluid dynamic (CFD) model which is used in this study is a steady axisymmetric model that employs two turbulence models (standard k- $\varepsilon$ and standard $k$ - $-\omega$ ) to perform the computation procedure of results. All of these computations are based on the second-order numerical schemes. The curves of exergy performance such as inlet exergy, exergy of cold and hot outlet, lost exergy and exergy efficiency have been achieved for the present vortex tube. These curves have been validated with the experimental data and have shown good agreement. In this paper, variation of exergy in the cold and hot exit has been predicted as a function of cold mass fraction and the behaviors of obtained curves have been discussed. In addition, variation of temperature and pressure in the cold and hot exhaust has been presented as a function of cold mass fraction. More ever the comparison between two turbulence model results has been obtained in different fields such as exergy, pressure and temperature.
exergy analysis, ranque-hilsch vortex tube (RHVT), three-dimensional (3D), computational fluid dynamic (CFD) model, turbulence models
[1] G. J. Ranque, Experiments on expansion in a vortex with simultaneous exhaust of hot air and cold air, Le Journal de Physique et le Radium, vol. 4, pp. 112-114, 1933.
[2] R. Hilsch, The use of expansion of gases in a centrifugal field as a cooling process, Rev. Sci. Instrum, vol. 18, pp. 108-113, 1947.
[3] S. E. Rafice and M. Rahimi, Experimental study and threedimensional ( 3D) computational fluid dynamics (CFD) analysis on the effect of the convergence ratio, pressure inlet and number of nozzle intake on vortex tube performanceValidation and CFD optimization, Energy, vol. 63, pp. 195-204, 2013.
[4] B. K. Ahlborn and J.M. Gordon, The vortex tube as a classic thermodynamic refrigeration cycle, Journal of Applied Physics, vol. 88, pp. 3645-3653, 2000.
[5] K. Stephan, S. Lin, M. Durst, F. Huang, D. Seher, An investigation of energy separation in a vortex tube, Int. J. Heat Mass Transfer, vol. 26, pp. 341-348, 1983.
[6] S. E. Rafiee, M. M. Sadeghiazad, Three-dimensional and Experimental investigation on the effect of cone length of throttle valve on thermal performance of a vortex tube using $\mathbf{k}-\varepsilon$ turbulence model, Applied Thermal Engineering, vol. 66 pp. 65-74, 2014.
[7] H. M. Skye, G. F. Nellis, S. A. Klein, Comparison of CFD analysis to empirical data in a commercial vortex tube, Int. J. Refrig, vol. 29, pp. 71-80, 2006.
[8] N. Pourmahmoud, A. Hassanzadeh, S. E. Rafiee, M. Rahimi, Three Dimensional Numerical Investigation of Effect of Convergent Nozzles on the Energy Separation in a Vortex Tube, International Journal of Heat and Technology, vol. 30(2), pp. 133-140, 2012.
[9] S. E. Rafiee, M. Rahimi, N. Pourmahmoud, Threedimensional numerical investigation on a commercial vortex tube based on an experimental model- Part I: Optimization of the working tube radius, International Journal of Heat and Technology, vol. 31(1), pp. 49-56, 2013.
[10] N. Pourmahmoud, S. E. Rafiee, M. Rahimi, A. Hasanzadeh, Numerical energy separation analysis on the commercial Ranque-Hilsch vortex tube on basis of application of different gases, Scientia Iranica, vol. 20(5), pp. 1528-1537, 2013.
[11] H. S. Chang, Experimental and Numerical Studies in a Vortex Tube. Journal of Mechanical Science and Technology Vol 20(3), pp. 418-425, 2006.
[12] M. Ameri, B. Behnia, The study of key design parameters effects on the vortex tube performance, Journal of Thermal Science, vol. 18(4), pp. 370-376, 2010.
[13] Eisma and S. Promvonge, Numerical investigations of the thermal separation in a Ranque-Hilsch vortex tube. Int J Heat Mass Transfer, vol( 50 ), pp. 821-32, 2007.
[14] A. B. Agrawal, V. Shrivastava, Retrofitting of vapour compression refrigeration trainer by an eco-friendly refrigerant, Indian J. Sci. Technol, vol. 3(4), 2010.
[15] B. Jayaraman, P. Senthil Kumar. Design, optimization and performance analysis of orifice pulse tube cryogenic refrigerators. Indian J. Sci. Technol, vol. 3(4), 2010.
[16] V. Kirmaci, Optimization of counter flow Ranque-Hilsch vortex tube performance using Taguchi method. International Journal of Refrigeration, vol. 32, pp. 1487-1494, 2009.
[17] K. Dincer, A. Avci, S. Baskaya, A. Berber, Experimental investigation and exergy analysis of the performance of a counter flow Ranque-Hilsch vortex tube with regard to nozzle cross-section areas. Int. J. Refrig, vol. 33, pp. 954-962, 2010.
[18] I. Ceylan, M. Aktas, H. Dogan, Energy and exergy analysis of timber dryer assisted heat pump, Applied Thermal Engineering, vol. 27, pp. 216-222, 2007.
[19] V. Kirmaci, Exergy analysis and performance of a counter flow Ranque-Hilsch vortex tube having various nozzle numbers at different inlet pressures of oxygen and air. International Journal of Refrigeration, vol. 32, pp. 1626-1633, 2009.
[20] O. Ozgener, A. Hepbasli, A review on the energy and exergy analysis of solar assisted heat pump systems. Renewable and Sustainable Energy Reviews, vol. 11, pp. 482-496, 2007.
[21] R. Saidur, M.A. Sattar, H.H. Masjuki, H. Abdessalam, B.S. Shahruan, Energy and exergy analysis at the utility and commercial sectors of Malaysia, Energy Policy, vol. 35, pp. 1956-1966, 2007.
[22] H. Esen, M. Inalli, M. Esen, K. Pihtili, Energy and exergy analysis of a ground-coupled heat pump system with two horizontal ground heat exchangers, Building and Environment, vol. 42, pp. 3606-3615, 2007.
[23] E.Lorenzini, M.Spiga, Aspetti fluidodinamici della separazione isotopica mediante tubi a vortice di Hilsch Ingegneria, n. 5-6, pp. 121-126 (maggio-giugno 1982 ).
[24] E.K. Akpinar, A. Hepbasli, A comparative study on exergetic assessment of two ground-source (geothermal) heat pump systems for residential applications, Building and Environment, vol. 42, pp. 2004-2013, 2007.
[25] T.J. Kotas, The Exergy Method of Thermal Plant Analysis, Anchor Brendon Ltd, Tiptree, Essex, 1985.
[26]. K. Dincer, S. Baskaya, Assessment of plug angle effect on exergy efficiency of counter flow Ranque-Hilsch vortex tubes with the exergy analysis method, Journal of the Faculty of Engineering and Architecture of Gazi University, vol. 24, pp. 533-538, 2009.
[27] Exair Corporation. Vortex tubes and spot cooling products. Available at [http://www.exair.com]
[28] S. Eiamsa-ard, P. Promvonge, Review of Ranque-Hilsch effects in vortex tubes, Renewable and Sustainable Energy Reviews, vol. 12, pp. 1822-1842, 2007.