This paper presents a study aimed at evaluating the use of siloxanes as the working fluid of a small-capacity (10kWe) ORC turbogenerator based on the “high-speed technology” concept, combining the turbine, the pump, and the electrical generator on one shaft, whereby the whole assembly is hermetically sealed, and the bearings are lubricated by the working fluid. The effects of adopting different siloxane working fluids on the thermodynamic cycle configuration, power output, and on the turbine and component design are studied by means of simulations. Toluene is included into the analysis as a reference fluid in order to make comparisons between siloxanes and a suitable low molecular weight hydrocarbon. The most influential working fluid parameters are the critical temperature and pressure, molecular complexity and weight, and, related to them, the condensation pressure, density and specific enthalpy over the expansion, which affect the optimal design of the turbine. The fluid thermal stability is also extremely relevant in the considered applications. Exhaust gas heat recovery from a 120 kW diesel engine is considered in this study. The highest power output, 13.1 kW, is achieved with toluene as the working fluid, while, among siloxanes, D4 provides the best simulated performance, namely 10.9 kW. The high molecular weight of siloxanes is beneficial in low power capacity applications, because it leads to larger turbines with larger blade heights at the turbine rotor outlet, and lower rotational speed if compares, for instance, to toluene.

References

References
1.
Larjola
,
J.
,
1995
, “
Electricity From Industrial Waste Heat Using High-Speed Organic Rankine Cycle
,”
Int. J. Prod. Econ.
,
41
, pp.
227
235
.10.1016/0925-5273(94)00098-0
2.
Larjola
,
J.
,
1988
, “
ORC Power Plant Based on High Speed Technology
,”
Conference on High Speed Technology
,
Lappeenranta, Finland
,
August 21–24
, pp.
63
77
.
3.
Larjola
,
J.
,
2011
, “
Organic Rankine Cycle (ORC) Based Waste Heat/Waste Fuel Recovery Systems for Small CHP Applications
,”
Small- and Micro-Combined Heat and Power (CHP) Systems, Advanced Design, Performance, Materials and Applications
,
Robert
Beith
, ed.,
Woodhead Publishing Limited
,
Cambridge
, UK, p.
528
.
4.
Angelino
,
G.
,
Gaia
,
M.
, and
Macchi
,
E.
,
1984
, “
A Review of Italian Activity in the Field of Organic Rankine Cycles
,”
VDI Berichte—Proceedings of the International VDI Seminar
, Vol.
539
, VDI Verlag, Düsseldorf, Germany, pp.
465
482
.
5.
Liu
,
B.-T.
,
Chien
,
K.-H.
, and
Wang
,
C.-C.
,
2004
, “
Effect of Working Fluids on Organic Rankine Cycle for Waste Heat Recovery
,”
Energy
,
29
, pp.
1207
1217
.10.1016/j.energy.2004.01.004
6.
Macchi
,
E.
,
1977
, “
Design Criteria for Turbines Operating With Fluids Having a Low Speed of Sound
,”
Lecture Series 100, on Closed Cycle Gas Turbines, Von Karman Institute for Fluid Dynamics
,
May 1977
.
7.
Angelino
,
G.
, and
Invernizzi
,
C.
,
1993
, “
Cyclic Methylsiloxanes as Working Fluids for Space Power Cycles
,”
ASME J. Sol. Energy Eng.
,
115
, pp.
130
137
.10.1115/1.2930039
8.
Angelino
,
G.
, and
Colonna
,
P.
,
1998
, “
Multicomponent Working Fluids for Organic Rankine Cycles (ORCs)
,”
Energy
,
23
, pp.
449
463
.10.1016/S0360-5442(98)00009-7
9.
Colonna
,
P.
,
Nannan
,
N. R.
,
Guardone
,
A.
, and
Lemmon
,
E. W.
,
2006
, “
Multiparameter Equations of State for Selected Siloxanes
,”
Fluid Phase Equilibria
,
244
, pp.
193
211
.10.1016/j.fluid.2006.04.015
10.
Colonna
,
P.
,
Nannan
,
N. R.
, and
Guardone
,
A.
,
2008
, “
Multiparameter Equations of State for Siloxanes: [(CH3)3-Si-O1/2]2-[O-Si-(CH3)2]i = 1,.,3, and [O-Si-(CH3)2]6
,”
Fluid Phase Equilibria
,
263
, pp.
115
130
.10.1016/j.fluid.2007.10.001
11.
Colonna
,
P.
,
1991
, “
Fluidi Silossanici per Cicli di Potenza Spaziali (Siloxane Fluids for Space Power Cycles)
,” Master's thesis,
Politecnico di Milano
,
Milano
.
12.
Invernizzi
,
C.
,
Iora
,
P.
, and
Silva
,
P.
,
2007
, “
Bottoming Micro-Rankine Cycles for Micro-Gas Turbines
,”
Appl. Thermal Eng.
,
27
, pp.
100
110
.10.1016/j.applthermaleng.2006.05.003
13.
Angelino
,
G.
, and
Colonna
,
P.
,
2000
, “
Organic Rankine Cycles (ORCs) for Energy Recovery of Molten Carbonate Fuel Cells
,”
35th Intersociety Energy Conversion Engineering Conference
,
Las Vegas, NV
, July 24–28.
14.
Angelino
,
G.
, and
Colonna
,
P.
,
2000
, “
Air Cooled Siloxane Bottoming Cycle for Molten Carbonate Fuel Cells
,”
Fuel Cell Seminar
,
Portland, OR, October 30–November 2
, pp.
667
670
.
15.
Fernández
,
F. J.
,
Prieto
,
M. M.
, and
Suárez
,
I.
,
2011
, “
Thermodynamic Analysis of High-Temperature Regenerative Organic Rankine Cycles Using Siloxanes as Working Fluids
,”
Energy
,
36
, pp.
5239
5249
.10.1016/j.energy.2011.06.028
16.
Lemmon
,
E. W.
, and
Span
,
R.
,
2006
, “
Short Fundamental Equations of State for 20 Industrial Fluids,
J. Chem. Eng. Data
,
51
, pp.
785
850
.10.1021/je050186n
17.
Jokinen
,
T.
,
Larjola
,
J.
, and
Mikhaltsev
,
I.
,
1998
, “
Power Unit for Research Submersible
,”
Elecship 98; International Conference on Electric Ship
,
Istanbul
,
September 1
, pp.
114
118
.
18.
van Buijtenen
,
J. P.
,
2009
, “
The Tri-O-Gen Organic Rankine Cycle: Development and Perspectives
,”
Power Engineer: Journal of the IDGTE (The Institution of Diesel and Gas Turbine Engineers)
,
13
(1)
.
19.
Bronicki
,
L.
,
1988
, “
Experience With High Speed Organic Rankine Cycle Turbomachinery
,”
Conference on High Speed Technology
,
Lappeenranta, Finland
, August 21–24, pp.
47
61
.
20.
van Buijtenen
,
J. P.
,
Larjola
,
J.
,
Turunen-Saaresti
,
T.
,
Honkatukia
,
J.
,
Esa
,
H.
,
Backman
,
J.
, and
Reunanen
,
A.
,
2003
, “
Design and Validation of a New High Expansion Ratio Radial Turbine for ORC Application
,”
5th European Conference on Turbomachinery
,
Prague, Czech Republic
,
March 17–22
.
21.
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
.10.1115/1.1423320
22.
Harinck
,
J.
,
Turunen-Saaresti
,
T.
,
Colonna
,
P.
,
Rebay
,
S.
, and
van Buijtenen
,
J. P.
,
2010
, “
Computational Study of a High-Expansion Ratio Radial Organic Rankine Cycle Turbine Stator
,”
ASME J. Eng. Gas Turbines Power
,
132
, pp.
1
6
.10.1115/1.3204505
23.
Heinimö
,
J.
,
van Buijtenen
,
J. P.
,
Backman
,
J.
,
Ojaniemi
,
A.
, and
Malinen
,
H.
,
2004
, “
High-Speed ORC Technology For Distributed Electricity Production
,”
2nd World Conference on Biomass for Electricity, Industry and Climate Protection
,
Rome, Italy
,
May 10–14
.
24.
Lemmon
,
E. W.
,
Huber
,
M. L.
, and
McLinden
,
M. O.
,
2010
, Reference Fluid Thermodynamic and Transport Properties (REFPROP), Version 9.0,
National Institute of Standards and Technology
.
25.
Colonna
,
P.
,
1996
, “
Fluidi di Lavoro Multi Componenti Per Cicli Termodinamici di Potenza (Multicomponent Working Fluids for Power Cycles)
,” Ph.D. thesis,
Politecnico di Milano
,
Milano
.
26.
Balje
,
O. E.
,
1981
,
Turbomachines. A Guide to Design, Selection and Theory
,
John Wiley and Sons
,
New York
.
27.
Rohlik
,
H.
,
1972
, “
Radial Inflow Turbines
,”
Turbine Design and Application
,
A. J.
Glassman
, ed., Vol.
1–3
,
NASA
, pp.
388
.
28.
Drescher
,
U.
, and
Brüggemann
,
D.
,
2007
, “
Fluid Selection for the Organic Rankine Cycle (ORC) in Biomass Power and Heat Plants
,”
Appl. Thermal Eng.
,
27
, pp.
223
228
.10.1016/j.applthermaleng.2006.04.024
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