Transonic flows through axial, multistage, transcritical organic rankine cycle (ORC) turbines are investigated by using a numerical solver including advanced multiparameter equations of state and a high-order discretization scheme. The working fluids in use are the refrigerants R134a and R245fa, classified as dense gases due to their complex molecules and relatively high molecular weight. Both inviscid and viscous numerical simulations are carried out to quantify the impact of dense gas effects and viscous effects on turbine performance. Both supercritical and subcritical inlet conditions are studied for the considered working fluids. In the former case, flow across the turbine is transcritical, since turbine output pressure is subcritical. Numerical results show that, due to dense gas effects characterizing the flow at supercritical inlet conditions, supercritical ORC turbines enable, for a given pressure ratio, a higher isentropic efficiency than subcritical turbines using the same working fluid. Moreover, for the selected operating conditions, R134a provides a better performance than R245fa.

References

1.
Schuster
,
A.
,
Karellas
,
S.
,
Kakaras
,
E.
, and
Spliethoff
,
H.
,
2009
, “
Energetic and Economic Investigation of Organic Rankine Cycle Applications
,”
Appl. Thermal Eng.
,
29
(
8–9
), pp.
1809
1817
.10.1016/j.applthermaleng.2008.08.016
2.
Shengjun
,
Z.
,
Huaixin
,
W.
, and
Tao
,
G.
,
2011
, “
Performance Comparison and Parametric Optimization of Subcritical Organic Rankine Cycle (ORC) and Transcritical Power Cycle System for Low-Temperature Geothermal Power Generation
,”
Appl. Energy
,
88
(
8
), pp.
2740
2754
.10.1016/j.apenergy.2011.02.034
3.
Drescher
,
U.
, and
Brüggemann
,
D.
,
2007
, “
Fluid Selection for the Organic Rankine Cycle (ORC) in Biomass Power and Heat Plants
,”
Appl. Thermal Eng.
,
27
(
1
), pp.
223
228
.10.1016/j.applthermaleng.2006.04.024
4.
Invernizzi
,
C.
,
Iora
,
P.
, and
Silva
,
P.
,
2007
, “
Bottoming Micro-Rankine Cycles for Micro-Gas Turbines
,”
Appl. Thermal Eng.
,
27
(
1
), pp.
100
110
.10.1016/j.applthermaleng.2006.05.003
5.
Karellas
,
S.
, and
Schuster
,
A.
,
2010
, “
Supercritical Fluid Parameters in Organic Rankine Cycle Applications
,”
Int. J. Thermodyn.
,
11
(
3
), pp.
101
108
.
6.
Chen
,
Y.
,
Lundqvist
,
P.
, and
Platel
,
P.
,
2005
, “
Theoretical Research of Carbon Dioxide Power Cycle Application in Automobile Industry to Reduce Vehicles Fuel Consumption
,”
Appl. Thermal Eng.
,
25
(
14–15
), pp.
2041
2053
.10.1016/j.applthermaleng.2005.02.001
7.
Chen
,
Y.
,
Lundqvist
,
P.
, Johansson, A., and
Platel
,
P.
,
2006
, “
A Comparative Study of the Carbon Dioxide Transcritical Power Cycle Compared With an Organic Rankine Cycle With R123 as Working Fluid in Waste Heat Recovery
,”
Appl. Thermal Eng.
,
26
(17–18), pp.
2142
2147
.10.1016/j.applthermaleng.2006.04.009
8.
Saleh
,
B.
,
Koglbauer
,
G.
,
Wendland
,
M.
, and
Fischer
,
J.
,
2007
, “
Working Fluids for Low-Temperature Organic Rankine Cycles
,”
Energy
,
32
(
7
), pp.
1210
1221
.10.1016/j.energy.2006.07.001
9.
Cramer
,
M.
, and
Kluwick
,
A.
,
1984
, “
On the Propagation of Waves Exhibiting Both Positive and Negative Nonlinearity
,”
J. Fluid Mech.
,
142
(
1
), pp.
9
37
.10.1017/S0022112084000975
10.
Hoffren
,
J.
,
Talonpoika
,
T.
,
Larjola
,
J.
, and
Siikoner
,
T.
,
2002
, “
Numerical Simulation of Real-Gas Flow in a Supersonic Turbine Nozzle Ring
,”
ASME J. Eng. Gas Turbines Power
,
124
(
2
), pp.
395
403
.10.1115/1.1423320
11.
Harinck
,
J.
,
Colonna
,
P.
,
Guardone
,
A.
, and
Rebay
,
S.
,
2010
, “
Influence of Thermodynamic Models in Two-Dimensional Flow Simulations of Turboexpanders
,”
ASME J. Turbomach.
,
132(1)
,
p
. 011001.10.1115/1.3192146
12.
Congedo
,
P. M.
,
Corre
,
C.
, and
Cinnella
,
P.
,
2011
, “
Numerical Investigation of Dense-Gas Effects in Turbomachinery
,”
Comput. Fluids
,
49
(
1
), pp.
290
301
.10.1016/j.compfluid.2011.06.012
13.
Rinaldi
,
E.
,
Buonocore
,
A.
,
Pecnik
,
R.
, and
Colonna
,
P.
,
2013
, “
Inviscid Stator/Rotor Interaction of a Single Stage High Expansion Ratio ORC Turbine
,” 2nd ASME International Seminar on ORC Power Systems, Rotterdam, Netherlands, October 7–8.
14.
Thompson
,
P.
,
1971
, “
A Fundamental Derivative in Gas Dynamics
,”
Phys. Fluids
,
14
(9), pp.
1843
1849
.10.1063/1.1693693
15.
Cinnella
,
P.
, and
Congedo
,
P. M.
,
2007
, “
Inviscid and Viscous Aerodynamics of Dense Gases
,”
J. Fluid Mech.
,
580
, pp.
179
217
.10.1017/S0022112007005290
16.
Setzmann
,
U.
, and
Wagner
,
W.
,
1989
, “
A New Method for Optimizing the Structure of Thermodynamic Correlation Equations
,”
Int. J. Thermophys.
,
10
(
6
), pp.
1103
1126
.10.1007/BF00500566
17.
Tillner-Roth
,
R.
, and
Dieter Baehr
,
H.
,
1994
, “
An International Standard Formulation for the Thermodynamic Properties of 1,1,1,2-Tetrafluoroethane (HFC-134a) for Temperatures From 170 K to 455 K and Pressures Up to 70 MPa
,”
J. Phys. Chem. Ref. Data
,
23
(
5
), pp.
657
730
.10.1063/1.555958
18.
Span
,
R.
, and
Wagner
,
W.
,
1996
, “
A New Equation of State for Carbon Dioxide Covering the Fluid Region From the Triple-Point Temperature to 1100 K at Pressures Up to 800 MPa
,”
J. Phys. Chem. Ref. Data
,
25
(6),
pp
. 1509–1596.10.1063/1.555991
19.
Span
,
R.
, and
Wagner
,
W.
,
2003
, “
Equations of State for Technical Applications. I. Simultaneously Optimized Functional Forms for Nonpolar and Polar Fluids
,”
Int. J. Thermophys.
,
24
(
1
), pp.
1
39
.10.1023/A:1022390430888
20.
Lemmon
,
E.
, and
Span
,
R.
,
2006
, “
Short Fundamental Equations of State for 20 Industrial Fluids
,”
J. Chem. Eng. Data
,
51
(
3
), pp.
785
850
.10.1021/je050186n
21.
Chung
,
T. H.
,
Lee
,
L. L.
, and
Starling
,
K. E.
,
1984
, “
Applications of Kinetic Gas Theories and Multiparameter Correlation for Prediction of Dilute Gas Viscosity and Thermal Conductivity
,”
Ind. Eng. Chem. Fund.
,
23
(
1
), pp.
8
13
.10.1021/i100013a002
22.
Chung
,
T. H.
,
Ajlan
,
M.
,
Lee
,
L. L.
, and
Starling
,
K. E.
,
1988
, “
Generalized Multiparameter Correlation for Nonpolar and Polar Fluid Transport Properties
,”
Ind. Eng. Chem. Res.
,
27
(
4
), pp.
671
679
.10.1021/ie00076a024
23.
Baldwin
,
B. S.
, and
Lomax
,
H.
,
1978
, “Thin-Layer Approximation and Algebraic Model for Separated Turbulent Flows,”
AIAA
Paper No. 78-257.10.2514/6.1978-257
24.
Spalart
,
P. R.
, and
Allmaras
,
S. R.
,
1992
, “
A One-Equation Turbulence Model for Aerodynamic Flows
,” 30th Aerospace Sciences Meeting & Exhibit, Reno, NV, January 6–9,
AIAA
Paper No. 92-0439.10.2514/6.1992-439
25.
Cinnella
,
P.
, and
Congedo
,
P.
,
2005
, “
Numerical Solver for Dense Gas Flows
,”
AIAA J.
,
43
(
11
), pp.
2458
2461
.10.2514/1.16335
26.
Jameson
,
A.
,
Schmidt
,
W.
, and
Turkel
,
E.
,
1981
, “
Numerical Solutions of the Euler Equations by Finite Volume Methods Using Runge Kutta Time Stepping Schemes
,”
AIAA
Paper No. 1981-1259.10.2514/6.1981-1259
27.
Rezgui
,
A.
,
Cinnella
,
P.
, and
Lerat
,
A.
,
2001
, “
Third-Order Accurate Finite Volume Schemes for Euler Computations on Curvilinear Meshes
,”
Comput. Fluids
,
30
(
7
), pp.
875
901
.10.1016/S0045-7930(01)00033-0
28.
Cinnella
,
P.
, and
Congedo
,
P.
,
2005
, “
Aerodynamic Performance of Transonic Bethe-Zal’dovich-Thompson Flows Past an Airfoil
,”
AIAA J.
,
43
(
2
), pp.
370
378
.10.2514/1.8627
29.
Roache
,
P. J.
,
1998
,
Verification and Validation in Computational Science and Engineering
,
Hermosa
,
Albuquerque
, NM.
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