Publications Search Results

Now showing 1 - 10 of 35
  • Publication
    Wertstromgerechte Produktgestaltung mittels Simulation absichern
    ( 2021)
    Riedel, O.
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    Scholtz, O.
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    Marrenbach, D.
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    Hornung, T.
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    Mack, J.
    Die Methodik, Produkt und Produktionssystem wertstromgerecht aufeinander abzustimmen, wird anhand eines Demonstrationsprodukts am Fraunhofer IAO beispielhaft vorgestellt. Hierbei werden in einer frühen Phase der Produktentwicklung der Wertstrom simuliert und die Lieferfähigkeit analysiert. In Anlehnung an ein reales Industrieprodukt werden das lieferzeitbestimmende Teil standardisiert und die Variantenanzahl von 128 auf 2 verringert. Mit dieser wertstromgerechten Produktgestaltung können die Anforderungen an die Lieferfähigkeit erfüllt werden.
  • Publication
    Flexjet project, sustainable jet fuel from flexible waste biomass
    ( 2019)
    Hornung, A.
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    Ouadi, M.
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    Galileu Speranza, L.
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    Apfelbacher, A.
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    Hornung, T.
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    Hofmann, M.
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    Hygate, J.
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    Hilditch, P.
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    Lima, S.
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    Lieftink, D.
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    Capaccioli, S.
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    Grassi, A.
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    Contin, A.
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    Righi, S.
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    Marazza, D.
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    Quaranta, M.
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    Vogli, L.
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    Macrelli, S.
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    Blakey, S.G.
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    Lewis, C.
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    Valk, M.
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    Tuck, C.
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    Langley, M.
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    Ott, T.
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    Winkel, M.
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    Bastos, J.
    flexJET project will build a pre-commercial demonstration plant for the production of advanced sustainable aviation biofuel (SAF) from waste vegetable oil and organic solid waste biomass, successfully demonstrating the ""Sustainable Aviation through Biofuel Refining"" (SABR) process for the refining biodiesel from organic waste oils combined with Thermo-Catalytic Reforming (TCR®) combined with hydrogen separation through pressure swing adsorption (PSA)) to produce SAF, a fully equivalent jet fuel blend (in compliant with ASTM D7566 Standards). This project will deliver respective environmental and social sustainability mapping of SAF production and it will validate its a comprehensive exploitation. The consortium brings together some of the most renowned scientific departments, applied research institutions, key industrial companies in the renewable energy sector, particularly in terms of bioenergy studies and the development of relevant projects in Europe. Partners are from 5 different European countries. From 2018 until 2022, this conjoined effort will make use of the precious assistance of respected industry experts to advise and guide the project.
  • Publication
    Technical specification IEC TS 62989:2018
    ( 2018)
    Arndt, T.
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    Askins, S.
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    Bengoechea, J.
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    Carter, S.
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    Dominguez, C.
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    Herrero, R.
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    Hornung, T.
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    Kasai, H.
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    Kogler, R.
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    Leutz, R.
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    Miller, D.
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    Nitz, P.
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    Scott, S.
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    Victoria, M.
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    Voarino, P.
    The first edition of the Technical Specification (TS) on Primary Optics for Concentrator Photovoltaic (CPV) Systems, IEC TS 62989:2018, has been published by the International Electrotechnical Commission (IEC), on March 8th, 2018. TS 62989 covers aspects related to the primary optics including: product identification, optical characteristics, mechanical characteristics, materials, (design) geometry, and visual appearance. This paper focuses on the key aspects of the norm, including optical performance, in order to promote the awareness and use of the standard. We describe the three methods intended to measure the key optical characteristics of the primary elements, i.e. focal spot size and optical efficiency, by using the encircled energy. The three methods are using different light sources, optical components and receiver sensors, but yielded very similar results in a round robin test. This justifies the continued use of all three methods. The use of a website (opticstests.pbworks.com) for documentation of discussions and references was novel to the standard development. The website proved to be useful for the introduction of new members of the group. The website helped to keep track of changes to the document as well as the required actions of the project team.
  • Publication
    An end of service life assessment of PMMA lenses from veteran concentrator photovoltaic systems
    ( 2017)
    Miller, D.C.
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    Khonkar, H.I.
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    Herrero, R.
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    Anton, I.
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    Johnson, D.K.
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    Hornung, T.
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    Schmid-Schirling, T.
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    Vinzant, T.B.
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    Deutch, S.
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    To, B.
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    Sala, G.
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    Kurtz, S.R.
    The optical performance of poly(methyl methacrylate) lenses from veteran concentrator photovoltaic modules was examined after the end of their service life. Lenses from the Martin-Marietta and Intersol module designs were examined from the ""Solar Village"" site near Riyadh, Saudi Arabia, as well as the Phoenix Sky Harbor airport, followed by the Arizona Public Service Solar Test and Research (APS-STaR) center in Tempe, Arizona. The various lens specimens were deployed for 20, 27, and 22 years, respectively. Optical characterizations included lens efficiency (Solar Simulator instrument), material transmittance and haze (of coupons cut from veteran lenses, then measured again after their faceted back surface was polished, and then measured again after the incident front surface was polished), and direct transmittance (as a function of detector's acceptance angle, using the Very Low Angular Beam Spread (""VLABS"") instrument). Lens efficiency measurements compared the central region to the entire lens, also using hot and cold mirror measurements to diagnose differences in performance. A series of subsequent characterizations was performed because a decrease in performance of greater than 10% was observed for some of the veteran lenses. The optimal focal distance of the lenses was quantified using the Solar Simulator, and then correlated to lens curvature using a recently developed measurement technique. Surface roughness was examined using atomic force microscopy and scanning electron microscopy. Facet geometry (tip and valley radius) was quantified on cross-sectioned specimens. Molecular weight was compared between the incident and faceted surfaces of the lenses.
  • Publication
    Slope-deviation measurement of Fresnel-shaped mold surfaces
    ( 2016)
    Kiefel, P.
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    Hornung, T.
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    Nitz, P.
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    Reinecke, H.
    Molds are used to dictate their shape to other materials in embossing or filling processes. In optics fabrication especially, the exact surface slope of the polymer replica is of high relevance. The quality control of molds is challenging: non-invasive, optical metrologies struggle with shiny surfaces that minimize the scattering of light. In addition, the inspection of complex shaped molds with a stepped optical surface can be difficult. In response, the authors show a backward ray-tracing approach combined with fringe-reflection technique to determine the slopes of a Fresnel-shaped mold surface with topography features in the magnitude order of a quarter millimeter. The error is kept small by stitching together several measurements with different sample rotations.
  • Publication
    Specularity of concentrator mirrors for CPV measured with VLABS
    ( 2015)
    Schmid, T.
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    Heimsath, A.
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    Hornung, T.
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    Nitz, P.
    We investigate the specular reflectance properties of four different mirror samples suitable for massmanufacturing of CPV primary concentrators. The laboratory setup VLABS and its data evaluation procedure to calculate specular reflectance are introduced. We present measurement results of specular reflectance with a very high angular resolution around the specular direction making it possible to compare different mirror materials to a high degree of accuracy for arbitrary acceptance angles. It is shown that the specular reflectance can be significantly lower than hemispherical reflectance due to surface scattering. For a CPV system with 1° acceptance angle the loss of radiant flux due to surface scattering amounts to a maximum of 8% relative for the investigated samples.
  • Publication
    CPV module with fresnel lens primary optics and homogenizing secondary optics
    ( 2015)
    Wiesenfarth, M.
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    Dörsam, T.
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    Eltermann, F.
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    Hornung, T.
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    Siefer, G.
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    Steiner, M.
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    Riesen, S. van
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    Neubauer, M.
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    Boos, A.
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    Wanka, S.
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    Gombert, A.
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    Bett, A.W.
    In this work CPV modules based on Fresnel lenses and using refractive secondary optical elements (SOEs) are investigated. Pure silicone as well as glass SOEs glued on top of the solar cells are explored in prototype modules. They are differently manufactured in respect to how the secondary optics was assembled. For example, units with secondary silicone optics directly casted to solar cells are manufactured. For a design of glued glass optics and Fresnel lenses, the thermal design and optimum cell-lens distance are analyzed. Moreover, the long term stability has been intensively tested by accelerated aging tests and outdoor experiments. Here, the focus was on the used silicone material and the adhesion of the silicone to the glass interface.
  • Publication
    Silicone on glass fresnel lenses
    ( 2015)
    Hornung, T.
  • Publication
    Concentrator optics for photovoltaic systems
    ( 2015)
    Gombert, A.
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    Minano, J.C.
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    Benitez, P.
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    Hornung, T.
    An overview of the fundamentals, the optimization strategies, and specific optical designs of concentrators for concentrated photovoltaic (CPV) systems is given. Several designs of secondary optical element (SOE) were compared with respect to their CAP and the achievable photocurrent densities. When using silicone on glass (SOG) Fresnel lens primary optical element (POE), special attention has to be given to the temperature effects of this POE type. It is shown how these effects can be minimized. Concentrator optics for CPV modules are lowest-cost high-volume optical elements. This puts very strong constraints on the parameter space of theoretically feasible optical designs. The field of concentrator optics for CPV is still emerging and it is only recent that very important feedback from the operation of CPV modules in high volumes can be gained. Many possible design variants the most promising will be selected and incorporated in the next generation CPV module designs.
  • Publication
    FLATCON® CPV-module with 36.7% efficiency equipped with four-junction solar cells
    ( 2015)
    Steiner, M.
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    Bösch, A.
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    Dilger, A.
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    Dimroth, F.
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    Dörsam, T.
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    Muller, M.
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    Hornung, T.
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    Siefer, G.
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    Wiesenfarth, M.
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    Bett, A.W.
    In this paper we present the application of high efficiency four-junction solar cells using SOITEC bonding technology under a Fresnel lens optic and in a FLATCON®-type CPV module. We demonstrate very high performance. The measurement of a sub-module, consisting of a four-junction solar cell adjusted under a single Fresnel lens, showed an efficiency of 38.9%. An 829.6 cm2 sized FLATCON®-type CPV module yielded in an efficiency of 35.0% and 36.7% at CSOC and CSTC, respectively. Thus, both, the sub-module and the CPV module showed record values, which prove the usefulness of high efficiency four-junction solar cells in CPV applications.