Wolfgang Reinalter

Steffen Ulmer; Wolfgang Reinalter; Peter Heller; Eckhard Lüpfert; Diego Martı́nez

A flux mapping system able to measure the flux distribution of dish/Stirling systems in planes perpendicular to the optical axis was built and operated at the Plataforma Solar de Almeria (PSA). It uses the indirect measuring method with a water-cooled Lambertian target placed in the beam path and a CCD-camera mounted on the concentrator taking images of the brightness distribution of the focal spot. The calibration is made by calculating the total power coming from the dish and relating it to the integrated gray value over the whole measurement area. The system was successfully operated in a DISTAL II stretched membrane dish and in the new EURODISH in order to characterize their beams and improve the flux distribution on their receivers.Copyright

Wolfgang Reinalter; Steffen Ulmer; Peter Heller; Thorsten Rauch; Jean-Michel Gineste; Alain Ferriere; François Nepveu

The CNRS-Promes dish/Stirling system was erected in Jun. 2004 as the last of three country reference units built in the “Envirodish” project. It represents the latest development step of the EuroDish system with many improved components. With a measured peak of 11 kW electrical output power, it is also the best performing system so far. The measurement campaign to determine the optical and thermodynamic efficiency of the system is presented. The optical quality of the concentrator and the energy input to the power conversion unit was measured with a classical flux-mapping system using a Lambertian target and a charge coupled device camera system. An efficiency of the concentrator including the intercept losses of 74.4% could be defined for this particular system. For the thermodynamic analysis all the data necessary for a complete energy balance around the Stirling engine were measured or approximated by calculations. For the given ambient conditions during the tests, a Stirling engine efficiency of 39.4% could be measured. The overall efficiency for the conversion of solar to electric energy was 22.5%.

Steffen Ulmer; Peter Heller; Wolfgang Reinalter

A new short, yet highly accurate method for measuring the slope errors of parabolic dish concentrators has been developed. This method uses a flat target with colored stripes that is placed close to the focal plane and a digital camera located at an observation point on the optical axis at some distance from it. A specially developed image analysis algorithm detects the different colors in the images of the reflection of the target in the concentrator and assigns them their known position on the color target. This information, along with the geometric relationship between the components of the measurement setup and the theoretical parabolic shape of the concentrator, is used to calculate the normal vectors of the concentrator surface. From these normal vectors the radial and tangential slopes can be calculated and compared to the design values of the concentrator. The resulting slope errors not only give the total concentrator error for general characterization of the dish, but also indicate systematic errors in fabrication and mounting with high spatial resolution. In order to verify the quality of the results obtained, a ray-tracing code was developed that calculates the flux distribution on planes perpendicular to the optical axis. Measured slope errors of a DISTAL-2 dish concentrator are presented and the calculated flux distributions are compared to measured flux distributions. The comparison shows excellent agreement in the flux distribution on the absorber plane. This verifies the promising potential of this method for fast, highly precise measurement of imperfections in dish concentrator shape.

Martin Roeb; Jan-Peter Säck; Peter-Michael Rietbrock; Christoph Prahl; H. Schreiber; Martina Neises; L. de Oliveira; Daniela Graf; Miriam Ebert; Wolfgang Reinalter; M. Meyer-Grünefeldt; Christian Sattler; A. Lopez; Alfonso Vidal; A. Elsberg; Per Stobbe; Damien Jones; Andrew Steele; Souzana Lorentzou; Chrysoula Pagkoura; A. Zygogianni; C. Agrafiotis; Athanasios G. Konstandopoulos

Steffen Ulmer; Tobias März; Christoph Prahl; Wolfgang Reinalter; Boris Belhomme

Peter Heller; Wolfgang Reinalter; Diego Martinez Plaza

Steffen Ulmer; Wolfgang Reinalter; Peter Heller; Eckhard Lüpfert; Diego Martinez

Miriam Ebert; W. Arnold; Antonio L. Avila-Marin; T. Denk; Johannes Hertel; Andrea Jensch; Wolfgang Reinalter; A. Schlierbach; Ralf Uhlig

Thomas Keck; Wolfgang Schiel; Wolfgang Reinalter; Peter Heller; Schlaich Bergermann

L.F. Zarzalejo; Lourdes Ramírez; Rita X. Valenzuela; R. Bojo; Abel Paz-Gallardo; Marta Vasquez; J. Valero; Gines Garcia; Antonio Campos; A. Navarro; Jose Maria Vindel; Stefan Wilbert; Fabian Wolfertstetter; Wolfgang Reinalter; David Schüler; Bijan Nouri