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Research Papers: Gas Turbines: Microturbines and Small Turbomachinery

# Influence of Molecular Complexity on Nozzle Design for an Organic Vapor Wind Tunnel

[+] Author and Article Information
Alberto Guardone

Assistant Professor
Dipartimento di Ingegneria Aerospaziale,
Politecnico di Milano,
Milano,20156, Italy
e-mail: alberto.guardone@polimi.it

Andrea Spinelli

Research Fellow
e-mail: andrea.spinelli@polimi.it

Vincenzo Dossena

Associate Professor
e-mail: vincenzo.dossena@polimi.it
Dipartimento di Energia,
Politecnico di Milano,
Milano, 20156, Italy

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received February 29, 2012; final manuscript received November 7, 2012; published online March 18, 2013. Assoc. Editor: Joost J. Brasz.

J. Eng. Gas Turbines Power 135(4), 042307 (Mar 18, 2013) (6 pages) Paper No: GTP-12-1059; doi: 10.1115/1.4023117 History: Received February 29, 2012; Revised November 07, 2012

## Abstract

A novel blow-down wind tunnel is currently being commissioned at the Politecnico di Milano, Italy, to investigate real-gas behavior of organic fluids operating at subsonic-supersonic speed in the proximity of the liquid-vapor critical point and the saturation curve. The working fluid is expanded from a high-pressure reservoir, where it is kept at controlled super-heated or super-critical conditions, into a low-pressure reservoir, where the vapor is condensed and pumped back into the high-pressure reservoir. Expansion to supersonic speeds occurs through a converging-diverging Laval nozzle. Siloxane fluid MDM (octamethyltrisiloxane-$C8H24O2Si3$) is to be tested during the first experimental trials. A standard method of characteristics is used here to assess the influence of the molecular complexity of the working fluid on the design of the supersonic portion of the nozzle by considering different fluids at the same real-gas operating conditions, including linear and cyclic siloxanes, refrigerant R245fa, toluene, and ammonia. The thermodynamic properties of these fluids are described by state-of-the-art thermodynamic models. The nozzle length and exit area are found to increase with increasing molecular complexity due to the nonideal dependence of the speed of sound on density along isentropic expansion of organic fluids.

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## References

Gaia, M., and Duvia, A., 2002, “ORC Plants for Power Production From Biomass From 0.4 MWel to 15 MWel: Technology, Efficiency, Practical Experiences and Economy,” Proceedings of the 7th Holzenergie Synposium, ETH Zurich, Switzerland, October 18.
Bini, R., and Manciana, E., 1996, “Organic Rankine Cycle Turbogenerators for Combined Heat and Power Production From Biomass,” Proceedings of the 3rd Munich Discussion Meeting, Energy Conversion from Biomass Fuels, Current Trends and Future System, Munich, Germany, October 22–23.
Angelino, G., Gaia, M., and Macchi, E., 1984, “A Review of Italian Activity in the Field of Organic Rankine Cycles,” Proceedings of the International VDI Seminar, Zurich, Switzerland, September 10–12, VDI Verlag, Berlin, Vol. 539.
Schuster, A., Karellas, S., Kakaras, E., and Spliethoff, H., 2009, “Energetic and Economic Investigation of Organic Rankine Cycle Applications,” Appl. Therm. Eng., 29(8–9), pp. 1809–1817.
Duvia, A., and Tavolo, S., 2008, “Application of ORC Units in the Pellet Production Field: Technical-Economic Considerations and Overview of the Operational Results of an ORC Plant in the Industry Installed in Madau (Germany),” Turboden s.r.l., Brescia, Italy, Technical Report No. 08A03210.
Colonna, P., and Rebay, S., 2004, “Numerical Simulation of Dense Gas Flows on Unstructured Grids With an Implicit High Resolution Upwind Euler Solver,” Int. J. Numer. Methods Fluids, 46(7), pp. 735–765.
Guardone, A., 2007, “Three-Dimensional Shock Tube Flows of Dense Gases,” J. Fluid Mech., 583, pp. 423–442.
Cinnella, P., and Congedo, P. M., 2007, “Inviscid and Viscous Aerodynamics of Dense Gases,” J. Fluid Mech., 580, pp. 179–217.
Colonna, P., Harinck, J., Rebay, S., and Guardone, A., 2008, “Real-Gas Effects in Organic Rankine Cycle Turbine Nozzles,” J. Propul. Power, 24, pp. 282–294.
Hoffren, J., Talonpoika, T., Larjola, J., and Siikonen, T., 2002, “Numerical Simulation of Real-Gas Flow in a Supersonic Turbine Nozzle Ring,” ASME J. Eng. Gas Turbines Power, 124, pp. 395–403.
Harinck, J., Guardone, A., and Colonna, P., 2009, “The Influence of Molecular Complexity on Expanding Flows of Ideal and Dense Gases,” Phys. Fluids, 21, p. 086101.
Spinelli, A., Dossena, V., Gaetani, P., Osnaghi, C., and Colombo, D., 2010, “Design of a Test Rig for Organic Vapours,” Proceedings of the ASME Turbo Expo, Glasgow, UK, June 14–18, ASME Paper No. GT2010-22959.
Colonna, P., Guardone, A., and Nannan, R., 2007, “Siloxanes: A New Class of Candidate Bethe-Zel'dovich-Thompson Fluids,” Phys. Fluids, 19(8), p. 086102.
Thompson, P. A., 1971, “A Fundamental Derivative in Gas Dynamics,” Phys. Fluids, 14(9), pp. 1843–1849.
Cramer, M. S., 1989, “Negative Nonlinearity in Selected Fluorocarbons,” Phys. Fluids, 1(11), pp. 1894–1897.
Kluwick, A., 2004, “Internal Flows of Dense Gases,” Acta Mech., 169, pp. 123–143.
Colonna, P., and Guardone, A., 2006, “Molecular Interpretation of Nonclassical Gasdynamics of Dense Vapors Under the van der Waals Model,” Phys. Fluids, 18(5), p. 056101.
Zucrow, M. H., and Hoffman, J. D., 1977, Gas Dynamics: Multidimensional Flow, Vol. 2, Wiley, New York.
Sauer, R., 1947, “General Characteristics of the Flow Through Nozzles at Near Critical Speeds,” National Advisory Committee for Aeronautics, Report No. NACA-TM-1147.
Span, R., 2000, Multiparameter Equations of State—An Accurate Source of Thermodynamic Property Data, Springer-Verlag, Berlin.
Colonna, P., Nannan, N., Guardone, A., and Lemmon, E. W., 2006, “Multiparameter Equations of State for Selected Siloxanes,” Fluid Phase Equilib., 244, pp. 193–211.
Guardone, A., 2010, “Real-Gas Effects in Supercritical Carbon Dioxide Gasdynamic Nozzles,” Proceedings of the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT 2010), Antalya, Turkey, July 19–21.
Colonna, P., and van der Stelt, T. P., 2004, “FluidProp: A Program for the Estimation of Thermo Physical Properties of Fluids,” Energy Technology Section, Delft University of Technology, Delft, The Netherlands, http://www.FluidProp.com

## Figures

Fig. 1

Reference nozzle expansion process in the T-s plane for siloxane fluid MDM. Left: case initial and final state point 6 and 7. Right: expansion states superimposed to the iso-Γ lines.

Fig. 5

Nozzle geometry for fluids of different molecular complexity for TT,6/Tc=0.975, PT,6/Pc=0.78, and β=PT,6/P7=25. Left: geometry of the divergent section. Right: detail of the exit section.

Fig. 4

Mach number (a), pressure (b), temperature number (c), and Γ (d) profiles for design case in Table 1, using the real and the ideal gas models. The solid lines refer to the nozzle wall and the dash-dotted lines refer to the nozzle axis of symmetry.

Fig. 3

Mach number (a), pressure (b), temperature (c), and fundamental derivative (d) fields for the design case in Table 1, using both the real gas (SW, top) and ideal gas (PIG, bottom) models

Fig. 2

Sketch of the TROVA test rig. State points are also indicated.

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