Solar Thermal Energy Utilization: German Studies on Technology and Application

530 Pages·1991·13.331 MB·English

by  G. Lensch, P. Lippert, W. Rudolph (auth.), Dr.-Ing. Manfred Becker, Dr. rer. nat. Karl-Heinz Funken, Dipl.-Ing. Gernot Schneider (eds.)

DEUTSCHE FORSCHUNGSANSTALTFÜR
LUFT- UND RAUMFAHRT E.v. (DLR)
SOLARTHERMALENERGY
UTILIZATION
German Studies on Technology and Application
Volume 5:
Final Reports 1989
Editors: M. Becker, K.-H. Funken, G. Schneider
Springer-Verlag Berlin Heidelberg New York
London Paris Tokyo Hongkong Barcelona 1991
Dr.-Ing. Manfred Becker
Dr. rer. nat. Karl-Heinz Funken
Dipl.-Ing. Gemüt Schneider
Deutsche Forschungsanstalt für Luft-und Raumfahrt e.v. (DLR),
Hauptabteilung Energietechnik, Köln
ISBN 978-3-540-53269-9 ISBN 978-3-642-52342-7 (eBook)
DOI 10.1007/978-3-642-52342-7
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© Springer-Verlag Berlin Heidelberg 1991
The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of
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therefore free for general use.
2362/3020-543210
P r e f ace
The German R+D program "Solares Testzentrum Almeria" (SOTA)
provides the scientific basis for the realization of advanced
solar technologies including facility modifications, component
tests and new lines of development. One of the working
packages, WP 300, addresses the "Scientific Support" by the
performance of preparatory studies, exploratory laboratory
activities and qualified expertise. Universities, Research
Institutes and Company R+D Entities in Germany are enabled to
treat the following aspects:
* Meteorological, system and cost investigations,
Development of important components as concentrator,
receiver, storage,
Utilization of solar energy for process heat and chemical
reactions.
In 1989 the studies concentrated on the deve10pment of compo
nents. The reports of the activities were finalized recently
and collected in the present volume. The final reports were
printed as received. The achieved results and the views ex
pressed within the reports were under the responsibility of
the authors.
As organizers of these solar thermal activities and as editors
of tbe corresponding final reports, we would like to thank
BMFT and KFA-BEO for the farsighted funding (grant no.
0328823A) and the research groups for their engagement and
consultations. We would also like to thank Ms S. Preusser and
Ms U. Rachow, who among many others contributed to the reali
zation of this collection.
Cologne, December 1990
M. Becker, K.-H. Funken, G. Schneider
v
C 0 n t e n t s
Receivers
Investigation and Selection of Materials Resistant to 1
Temperatures and Radiation to Construct a Metallicl
Ceramic Secondary Concentrator as weIl as Measurements
at Premodels
G. Lensch, P. Lippert, W. Rudolph,
N.U. - Tech GmbH
Investigations of Hard Coating and Heat Mirrors for 59
Simultaneous Energy Conservation in a Photovoltaicl
Solarthermic Hybrid System or for Use in a Secondary
Reflector
R. Anton, G. Lensch, W. Rudolph, R. Ueth
N.U. - Tech GmbH
Optimization of Terminal Concentrators 109
U. Schöffel, R. Sizmann,
Ludwig-Maximilians-Universität München
Receivers
200 kW Stirling Engine for SSP Module; 147
Solar Stirling Receiver with Heat Storage
System Analysis
H. Michel,
MAN Technologie AG
The Construction of a Volumetrie Receiver with 273
a Staggered Structure
R. Pitz-Paal, J. Morhenne, M. Fiebig,
Ruhr-Universität Bochum
Analysis of Convective Heat Transfer in Volumetrie 309
Receivers Built of Porous Media
J. Morhenne, R. Pitz-Paal,
Ruhr-Universität Bochum
VI
Solar Chemistry
Thermochemical H2 - Production with Sulfur-Iodine 335
Process and Solar Energy Adaptation
K.F. Knoche,
RWTH Aachen
The Use of Thermal Solar Energy to Treat 413
Waste Materials
H. Effelsberg, B. Barbknecht
Gesellschaft für Systemtechnik mbH (GST)
Solar Thermal Energy Cycle Based on Sulfur and 483
Sulfide Oxidizing Bacteria
c.c. Bärtels, H. Tributsch
Hahn-Meitner-Institut
VII
Investigation and Selection of
Materials Resistant to Temperatures and Radiation to
Construct a Metallic/Ceramic Secondary Concentrator
as weil as Measurements at Premoclels
w.
G. Lensch, P. Lippert, Rudolph,
N.U. - Tech GmbH
1
Zusammenfassung
Sie beinhaltet zum einen die Fortsetzung und abschließende Bewertung der
Materialuntersuchungen zum Bau eines Sckundärkonzentrators (feil I Vertragsnr.
5-370-4355), zum anderen werden der Bau mehrerer Vormodelle zu den mög
lichen Konzentratorformen und Meßergebnisse zu diesen Modellen vorgestellt, wo
bei unter Berücksichtigung der aufwendigen Fertigung der harten Spiegelbasis
materialien zur Kostenersparnis Iinearisierte Formen untersucht wurden, mit und
ohne Teilbereich mit keramikähnlichen optischen Eigenschaften (Glanzkarton).
Polierte Keramik in unbeschiehteter Form ist nur bedingt einsetzbar, da sie bei
nahezu senkrechtem Strahlungseinfall einen direkten Reflexionsgrad von ca 9% zeigt
(A12T iOs). Die 27T-Reflexion dagegen kann für weiße, reine Keramik über 90%
liegen (Hartporzellan). Erst durch Beschichtungen lassen sich die Werte für die
direkte Reflexion deutlich erhöhen, wobei die Oberflächenbeschaffenheit eine we
sentliche Rolle spielt. Eine Beschichtung von TiN auf Glas erzielt Werte über
90%, jedoch ist diese Schicht nicht über das gesamte Sonnenspektrum einsetzbar.
Außerdem ist die Schicht oxidationsgefährdet, eine zusätzliche Goldschicht wäre
möglicherweise ein Schutz dagegen.
Bei den Modellen ( CPC, Trumpet ) wurde die Intensitätsverteilung in einigen
Schnitten in der Austrittsapcrtur aufgenommen, zum Teil bei unterschiedlichen
Einfallswinkeln. Daraus wurde die Verstärkung innerhalb der Schnitte und der Fluß
im Vergleich zum Zustand ohne Konzcntrator ermittelt. Durch den Einsatz einc.<;
"keramikvergleichbaren" Halsbereichs im Trumpet ist eine Reduzierung des Fluß
verhältnisses gegenüber dem Modell, das nur mit Spiegelfolie belegt ist,
festzustellen.
Summary
On the one hand it containes the continuation and finally assessment of material
examinations to construct a sccondary concentrator (part I eontract no. 5-370-
4355), on the other hand some premodels for the possibJe form of conccntrators
and measurement results for this models are presented. Taking into account the
costly production of the hard ceramic materials we tcsted Iinearized forms with and
without zones with optical properties similar to ceramic.
3
Polished ceramic in uncoated form is partly useable, because it shows a specular
refleetion o[ about 9% with near normal incidence. But the 27r-reflection for
white ceramic might be higher than 90%.
Only coatings increase the value of specular reflection clearly if the surface
roughness is very smal!. With a coating of TiN on glass values higher than 90%
are reachable, but this layer is not universal useable for the whole spectrum of
sunlight. Besides this the eoating has risk of oxidation. An additional gold coating
might be a possible protection against it.
At the models (CPC, Trumpet) pictures o[ the intensity distribution in the exit
aperture have been taken, partly with different angle of incidence. The
intensification along some perpendicular lines and the flux In relation with and
without a concentrator have been taken from this. With using of a ceramic-similar
material next to the receiver area in a Trumpet model we found areduction of
the flux ratio compared with the model, only covered with mirror foi!.
Concept of the study
The way of testing the materials and models was as folIows:
In addition to the last experiment<; we selected further materials and qualities.
Besides this the form and modifications of the concentrator were established.
The measurement arrangements were lightly modified or new built (measure
me nt of models).
Preparation of the sampIes. The necessary parts for the models were cut and
assembled afterwards. Ordering of different materials.
Measuring of all sampIes with the modified measuring assembly.
Measurements at the models.
Evaluation and reporting.
4
Contents
1. Introduction
2. Investigation of materials
2.1 Test devices and principles of measurement
2.2 Sampies
2.3 Material results
3. Models far secondary coneentratar
3.1 Description of concentratars
3.2 Models
3.3 Test device and measurement
3.4 Results
4. Conclusion
5. Nomenclature
6. References
7. Supplement
5