Stainless steel plate perforated by concentrated sunlight. Source: DLR
The DLR High-Flux Solar Furnace in Cologne-Porz generates highly concentrated sunlight for irradiation experiments. Its heliostat and concentrator mirrors bundle natural sunlight up to 5000 times and direct it into an experimental chamber. When the concentrated radiation hits solid or liquid materials at the experimental setup, for example ceramic particles or a redox material in a reactor, the radiation generates temperatures of up to 1500 degrees Celsius. The high concentration turns simple sunlight into a CO2-free energy source with an energy density comparable to coal, oil and gas.
The Solar Furnace building also houses a High-Flux Solar Simulator for experiments with artificial concentrated sunlight. It can be used around the clock and is therefore particularly suitable for long-term experiments and sequential irradiations under constant conditions, for example component tests at certification level.
Research focus of the Solar Furnace and Solar Simulator:
When the Solar Furnace building was constructed in 1994, great emphasis was placed on the energy efficiency of the building. Further information about the Solar Furnace as a low-energy laboratory building can be found here [Link].
Functionality and equipment
Solar Furnace
A flat mirror (heliostat) bundles the impinging sunlight to a concentrator consisting of 159 mirrors, which are arranged in a honeycomb pattern. They condense the radiation even further and direct the light off the axis of the impinging light to the experimental set-up in the building. By means of a shutter, the staff of the solar oven can regulate the incoming radiation, to avoid overheating for example. The arrangement of the heliostat, concentrator and laboratory in the so-called "off-axis geometry" offers the advantage that there is no shade partially covering the incoming radiation in experimental set-ups.
The building of the High-Flux Solar Furnace in Cologne. Credit: DLR
The staff of the Solar Furnace adapt the experimental setup to the desired experiments using special tools and components. From a measuring room located right next to the experiment room, they monitor and control the experiments during irradiation. Power and radiation density measurement systems developed at DLR determine the irradiated power and its distribution over a target area; pyrometers and an infrared camera are used for non-contact measurement of high temperatures.
High-Flux Solar Simulator
The Xenon-High-Flux Solar Simulator consists of 10 elliptical reflectors with Xenon short-arc lamps. The reflectors are aligned in a way, so that their short-wave radiation with a total power of about 25 kilowatts impinges on a target area at a distance of 3 meters. The energy reaches a power density of up to 4 megawatts per square meter here.
Examples
Solar cement production: SolPart project
The fossil fuels used in cement production so far, contribute significantly to the global CO2 balance of industrial processes. In the Solar Furnace, DLR scientists have successfully demonstrated that concentrated sunlight is a suitable alternative to fossil energy sources.
Reactor for solar calcination of cement raw meal in the High-Flux Solar Simulator Cologne. Image: DLR
Further information on the SolPart project:
Solar melting of aluminium scrap
Further information on the Solam Project:
Solar production of "green" hydrogen: Hydrosol project
The CO2-free production of hydrogen is of central global importance for the future energy supply, either for direct use or as a prerequisite for the production of synthetic fuels.
In 2004, the Cologne Solar Furnace succeeded for the first time in producing hydrogen from concentrated sunlight, water and CO2 under laboratory conditions.
Splitting water into hydrogen and oxygen in a closed thermochemical cycle using solar energy - and without carbon dioxide emissions at temperatures below 1200 degrees Celsius without loss of the chemicals used. Image: DLR
Photocell test for Venus Express. Credit: DLR
Component tests under vacuum for the European space industry
For about 20 years now, we have been carrying out component tests under vacuum for several companies in the European space industry. The most important factors here are the even distribution of radiation on the test body as well as reliable and exact measurement technology. Components of the satellites Bepi Colombo, Venus Express or Solar Orbiter were solar tested in the Cologne Solar Furnace before their operation in space.
Solar production of building material made of "lunar sand"
As part of the Regolight project, we have developed a 3D printing process to produce solid building blocks from lunar dust that are suitable for the construction of protective domes on the moon. Concentrated solar radiation provides the energy for a sintering process that sinters volcanic dust (which is similar to the dust on the moon) within 30 minutes.
Further examples of irradiation experiments in the Solar Furnace: