21 June 2022

The team of scientists in the HiTRec3D research project used an innovative absorber to achieve up to 8 per cent higher efficiency than before.

"We have achieved our goals", says a pleased project manager Jakob Herrmann from Kraftanlagen Energies & Services. Together with experts from three partners - Exentis Technology, Vitesco Technologies and the German Aerospace Center (DLR) - two innovative absorber designs and the necessary manufacturing processes for solar thermal tower power plants were developed over the last three and a half years. The team of scientists then tested the new absorbers at the DLR research institute "Synlight" in Jülich. The result is striking. The innovative absorbers enable efficiency increases of up to 8 percentage points. When building a solar thermal power plant in future, smaller heliostat fields could be constructed for the same output. The heliostat fields usually incur high costs. The results are therefore significant in both technical and economic terms.

The solar absorber - the heart of the project

A solar receiver uses solar irradiation to generate heat that is used to produce power. Here, sunlight is focused by a heliostat field onto a receiver, which is composed of many individual absorbers. The HiTRec3D science team tested two different material variants for the open volumetric receiver: a network of needle-like pins made of ceramic, and also a honeycomb-like structure made of metal strips. The special feature of the ceramic HiTRec3D absorber is that the needle-like pins become finer and finer towards the top. This geometry allows the radiation to penetrate particularly deep into the absorber. Inside, this heats the ambient air drawn in to up to 800 degrees Celsius. The heat energy at a high temperature level can be "parked" very efficiently in a corresponding thermal storage system. It is needed to drive turbines with steam around the clock, which produce power with the help of generators.

Two different material variants were tested in the Synlight test stand: a net made of ceramic pins, and also a honeycomb-like structure made of metal strips.
© Kraftanlagen Energies & Services GmbH

Two different material variants were tested in the Synlight test stand: a net made of ceramic pins, and also a honeycomb-like structure made of metal strips.

New manufacturing processes such as 3D printing make new design possible

New technical possibilities, such as the production of particularly delicate components using 3D printing, have enabled the team to make the best possible use of the volumetric effect. In the Jülich solar power plant, which uses state-of-the-art absorbers, efficiencies of around 71 per cent have been achieved so far when heating air. "The evaluations of the measurements and simulations of our new absorbers have shown that the ceramic design has an efficiency that is around 8 percentage points higher than the current state of the art", reports Peter Schwarzbözl from DLR. "The efficiency of the metal foil design is around 6 percentage points higher than before. Work is underway to also achieve this 6 per cent in the module composite." In addition to the component design, the high thermal conductivity of the two materials also contributes to the good values.

"Commercialisation possible in one to two years"

The project also holds economic opportunities due to the new absorber material and design as well as innovative manufacturing processes. DLR has already had the technology patented internationally. The research group considers the metal strip design to be most relevant to the market at first: "I expect that the first commercialisation will be possible in one to two years", Jakob Herrmann estimates. As far as the ceramic absorber variant is concerned, the initial hurdle is greater. For this, the systems technology - in contrast to the metallic variant, which is based on the catalytic converter technology used in the automotive industry - has to be set up completely from scratch. Project manager Jakob Herrmann is satisfied: "We have a two-stage market introduction option, so to speak: The metallic absorber can be produced in the near future and installed in solar thermal power plants. The ceramic variant, on the other hand, is 2 percentage points more efficient. But for this, the production chains must first be established with the plant and component manufacturers." (nd/it)

Contact

Jakob Herrmann

Kraftanlagen Energies & Services GmbH
KPVT | Technologieentwicklung
80339 München


www.kraftanlagen.com/en
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