Radiantly versatile – In Cologne, DLR has a unique facility in Germany for irradiation tests with natural and artificial sunlight in the form of the High-Flux Solar Furnace and Solar Simulator. The high concentration transforms simple sunlight into a CO2-free energy source with a comparably high energy density as coal, oil and gas.
High-Flux Solar Furnace
For the experiments in the solar furnace, a plane mirror (heliostat) concentrates the incident sunlight into a concentrator consisting of 159 hexagonal mirrors. These are arranged in a honeycomb pattern on a vertical square surface. The concentrator further condenses the radiation and directs it to the experiment setup in the building.
If the radiation, which is concentrated up to 5,000 times, hits solid or liquid materials there, for example ceramic particles or a redox material in a reactor, temperatures of up to 1,800 degrees Celsius are generated. By means of an aperture, the incident concentrated radiation can be regulated to prevent overheating, for example. The arrangement of heliostat, concentrator and laboratory space in the so-called "off-axis geometry" offers the advantage that the experimental setups do not partially shade the incident radiation.
The building of the High-Flux Solar Furnace in Cologne
In good weather conditions, the heliostat reflects the incident sunlight to a concentrator, which further compresses the radiation and directs it to the experiment setup inside the building.
When the High-Flux Solar Furnace building was constructed in 1994, great emphasis was placed on its building energy efficiency. Info about the High-Flux Solar Furnace as a low-energy laboratory building can be found on the following page:
High-Flux Solar Simulator
The solar furnace building also houses a High-Flux Solar Simulator for experiments with artificially concentrated sunlight. It is ready for use around the clock and therefore particularly suitable for long-term experiments as well as experiments with sequential irradiations under always the same conditions. Here, for example, component tests at certification level are also possible.
The xenon high-flux solar simulator consists of ten elliptical reflectors with xenon short-arc lamps. The reflectors are aligned so that their short-wave radiation with a total power of about 25 kilowatts impinges on a target area at a distance of three meters. The energy concentrated in this way achieves a power density of up to four megawatts per square meter here.
Research focus of High-Flux Solar Furnace and Solar Simulator
Solar production of hydrogen and synthesis gas
Green hydrogen and its derivatives are of central importance for a CO2-neutral energy supply. Synthesis gas is urgently needed as a starting product of synthetic fuels for the switch to sustainable aviation.
In 2004, the Cologne High-Flux Solar Furnace succeeded for the first time in producing hydrogen from concentrated sunlight, water and CO2 under laboratory conditions.
Since then, this and other processes for storing solar energy in chemical energy carriers have been further developed. The tests take place in the High-Flux Solar Furnace and Solar Simulator in Cologne and in DLR's Synlight solar simulator in Jülich.
Use of concentrated solar energy for industrial processes
In order to reduce CO2 emissions or bring them close to zero in the long term, industrial companies are required to convert their processes from fossil fuels to renewable energy sources. DLR scientists have successfully demonstrated in various projects in the High-Flux Solar Furnace and Solar Simulator that concentrated sunlight is suitable for replacing fossil energy sources in industrial processes.
Solar irradiation of components for use in space
In the High-Flux Solar Furnace and Solar Simulator, it is possible to irradiate space components under vacuum conditions. The most important factors here are the uniform distribution of the radiation on the test body and a reliable and precise measurement technique. Components of the Bepi Colombo, Venus Express or Solar Orbiter satellites were solar tested in the Cologne High-Flux Solar Furnace before their deployment in space.
As part of the Regolight project, the High-Flux Solar Furnace team has developed a 3D printing process to produce solid building blocks from lunar dust suitable for building protective domes on the moon. Concentrated solar radiation provides the energy for a sintering process that sinter volcanic dust (which is similar to dust on the moon) into solid building blocks within 30 minutes.
