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SolarPACES-Technical Guideline for SiHTF

Guideline for the use of silicone-based high-temperature fluids in solar thermal power plants

In recent years, a significant increase of the maximal operating temperature of silicone-based heat transfer fluids (SiHTF) in concentrating solar thermal systems has been achieved.
DLR scientists and their industrial partners demonstrated the advantages of silicone fluids as heat transfer fluids in parabolic trough systems in various international projects. They proved that the use of silicone fluids can reduce the costs and risks of heat transport in solar power plants significantly. The results from the projects show that silicone fluids are an advantageous alternative to other established heat transfer fluids in technical and economic terms.
Under the umbrella of the SolarPACES network (Solar Power & Chemical Energy Systems) and the International Energy Agency IEA, an international group of researchers and experts with special expertise in the area of high temperature applications developed a guideline for the use of silicone-based high temperature fluids in solar thermal power plants. The "SolarPACES-Technical Guideline for SiHTF" (Silicone-Based Heat Transfer Fluids) was published in February 2021. On 75 pages, the document provides a comprehensive overview of existing standards and suitable new methods for determining the material properties of silicone fluids in use at temperatures up to 450 °C. It supports power plant construction companies and operators in using silicone-based heat transfer fluids in parabolic trough power plants.
The aim of the "SolarPACES SiHTF Standard" project is to develop an international standard that makes the findings and recommendations of the previous guideline binding.

The project is carried out under the following conditions:

1. The HTF expert group continues its successful collaboration from the SiHTF guideline and uses the know-how to develop a standard for "silicone-based heat transfer fluids in line-focusing concentrating solar power".
2. Already the guideline will have a positive effect among international CSP stakeholders and promote the acceptance of SiHTF technology. International feedback from external experts on this guideline paper is desired for the preparation of the standards. The results of the exchange between experts from research and practice should flow into the development of the standards.

Internationally valid standards should serve users as a reliable basis for the design and economic calculation of line-focusing parabolic trough plants. This will ultimately increase the acceptance of the new type of heat carrier in international projects and improve the bankability of the projects.