A coaxial evacuated solar tube has been analyzed. The tube is included in a small-scale concentrated solar power (CSP) system, which runs a cogeneration Stirling engine unit. The engine provides electricity and at the same time generates hot water for heating and sanitary purposes, by cooling down the compression cylinder. The present work is focused on the thermodynamic characterization for a forced-flow in the coaxial evacuated tube, which can heat thermal oil up to 300 °C, when coupled with a parabolic trough collector. The single coaxial tube is 2 m long, it has one glass penetration, it is provided with a glass–metal seal and it has an absorber tube in the focal point with a diameter of 12 mm. A model based on heat transfer analysis coupled with fluid dynamic is presented and discussed. The model is then used to investigate spatial temperature profiles and thermal behaviors for the whole solar collector. It improves previous works in the field of concentrating solar collectors and covers the research in small-size concentrating system using thermal oil as heat transfer fluid.

References

References
1.
“DiGeSPo.edu: What is Digespo?,” Digespo Project
,
2012
, http://www.digespo.eu
2.
Glembin
,
J.
,
Rockendorf
,
G.
, and
Scheuren
,
J.
,
2010
, “
Internal Thermal Coupling in Direct-Flow Coaxial Vacuum Tube Collectors
,”
Sol. Energy
,
84
(
7
), pp.
1137
1146
.10.1016/j.solener.2010.03.018
3.
Kim
,
J. T.
,
Ahn
,
H. T.
,
Han
,
H.
,
Kim
,
H. T.
, and
Chun
,
W.
,
2007
, “
The Performance Simulation of All-Glass Vacuum Tubes With Coaxial Fluid Conduit
,”
Int. Commun. Heat Mass Transfer
,
34
(
5
), pp.
587
597
.10.1016/j.icheatmasstransfer.2007.01.012
4.
Han
,
H.
,
Kim
,
J. T.
,
Ahn
,
H. T.
, and
Lee
,
S. J.
,
2008
, “
A Three Dimensional Performance Analysis of All-Glass Vacuum Tubes With Coaxial Fluid Conduit
,”
Int. Commun. Heat Mass Transfer
,
35
(
5
),
589
596
.10.1016/j.icheatmasstransfer.2007.11.006
5.
Forristall
,
R.
,
2003
, “
Heat Transfer Analysis and Modelling of a Parabolic Trough Solar Receiver Implemented in Engineering Equation Solver
,” National Renewable Energy Laboratory, Golden, CO,
Technical Report No. NREL/TP-550-34169
, available at: http://www.nrel.gov/csp/troughnet/pdfs/34169.pdf
6.
Price
,
H.
,
Forristall
,
R.
,
Wendelin
,
T.
,
Lewandowski
,
A.
,
Moss
,
T.
, and
Gummo
,
C.
,
2006
, “
Field Survey of Parabolic Trough Receiver Thermal Performance
,”
Proceedings of ASME International Solar Energy Conference
(ISEC2006),
Denver, USA
, July 8–13,
ASME
Paper No. ISEC2006-99167.10.1115/ISEC2006-99167
7.
Burkholder
,
F.
, and
Kutscher
,
C.
,
2009
, “
Heat-Loss Testing of Schott's 2008 PTR70 Parabolic Trough Receiver
,” National Renewable Energy Laboratory, Golden, CO,
Technical Report No. NREL/TP-550-45633
.
8.
Gnielinski
,
V.
,
1976
, “
New Equations for Heat and Mass Transfer in Turbulent Pipe and Channel Flow
,”
Int. Chem. Eng.
,
16
(
2
), pp.
359
363
.
9.
Ratzel
,
A.
,
Hickox
,
C.
, and
Gartling
,
D.
,
1979
, “
Techniques for Reducing Thermal Conduction and Natural Convection Heat Losses in Annular Receiver Geometries
,”
ASME J. Heat Transfer
,
101
(
1
), pp.
108
113
.10.1115/1.3450899
10.
Bejan
,
A.
,
1995
,
Convection Heat Transfer
,
John Wiley and Sons
,
New York
.
11.
Incropera
,
F.
, and
DeWitt
,
D.
,
2007
,
Fundamentals of Heat and Mass Transfer
,
John Wiley and Sons
,
New York
.
12.
Solutia
,
2010
, “
Therminol 66 Fluid Proprieties
,”
Information Bulletin
, Group Provoc T.B.S 10-7 12/98 E, available at: http://twt.mpei.ac.ru/TTHB/HEDH/HTF-66.PDF.
13.
Mientkewitz
,
G.
,
Hesse
,
S.
, and
Schaffrath
,
W.
,
2011
, “
Definition of the Evacuated Solar Tube
,” Deliverable D2.3, Digespo Project, FP7-Energy-2009-1.
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