CORDIS - Forschungsergebnisse der EU

FREsnel for Solar Heat with New Receiver and Geometry

Final Report Summary - FRESH NRG (FREsnel for Solar Heat with New Receiver and Geometry)

Executive Summary:
FRESH NRG targeted efficiency of 60% at 250°C with a Linear Fresnel Collector (LFC) optimized for industrial use.
Our integrated approach designed, implemented and tested disruptive innovations in 4 key parts of the value chain.
Highly innovative sol-gel coatings targeted robustness, durability and performance (solar transmittance > 96%, solar absorptance > 95%, thermal emittance at 250°C < 7%).
To increase the annual yield, a LFC design with radically new geometry targeted differentiation of the width of the primary mirrors and concentration factor >90 to limit heat losses.
Ultra light mirror panels targeted safety, durability and solar reflectance > 93%.
Modular “plug-in” components (e.g. clip-on secondary mirrors) simplified transport and installation.
Laboratory and field tests of the new LFC and its key components included existing methods (e.g. EN12975) and methods that were revised or developed during the project duration (e.g. in IEA-SHC/SolarPaces Task 49).
A first-of-its-kind lean manufacturing system including receiver assembly and optimized processes to reduce cost and ensure mirror optical accuracy was prototyped and co-located to optimize cost reduction.
Integration packages for Mediterranean industrial applications included a new control logic to optimize energy output for industrial use.
A full blown polygeneration system in Jordan provided actual use of the new LFC for power generation, heating and cooling.
Besides the installation in Jordan, two other collector prototypes were installed and tested in Gambettola, Italy and in Freiburg, Germany, for a total of 3 different prototype installed and tested in different conditions.
A clear plan for the exploitation of the technical results included a highly multi-disciplinary approach.
Detailed bottom-up prospection of high-potential applications was analysed to drive industrial strategy towards a large economic impact.
Relevant key findings are being shared also with relevant stakeholders (e.g. the European Solar Thermal Technology Panel) and will be used with policymakers and industry regulators.
Knowledge dissemination promoted the innovative results of the project (e.g. comparison of test methods) to achieve a full scientific impact at EU level.

Project Context and Objectives:
Potential market size and environmental benefits make the use of solar heat in industrial applications a promising and vast area for future application of solar thermal systems. In Europe, the industrial and commercial sector account for about 28% of the overall energy consumption and 2/3 of this energy is used for heating applications . Task 33 of the IEA-SHC / Annex 4 of Solar Paces showed that in most industrial processes low and medium temperature is needed. More than 60% of the heat demand in the industry requires process heat with temperatures below 250°C. . Yet, despite this huge potential, many challenges need to be successfully overcome along the different steps of the value chain.
Specially designed collectors need to be developed for the temperature range from 100°C to 250°C. Concentration technologies used in CSP (Concentrated Solar Power) applications have a great potential, but the available components, collectors and systems are often not well-adapted to industrial settings, where installations of smaller size are usually required. Concentrating collectors developed so far for the 100-250°C temperature range show deficits by the lack of a dedicated manufacturing system, which is crucial to drive cost down and achieve market penetration. Finally, use above 100°C requires different application-specific system integration packages inclusive of adequate HTFs (Heat Transfer Fluids such as steam, thermal oil etc.), dedicated equipment (piping, valves, heat exchangers, storage systems etc.) and new integration concepts. An integrated approach is necessary to overcome these numerous challenges.

More specifically, the concept underlying the present project is to target the integrated development of a Fresnel collector, which will be specifically developed for the 100-250°C temperature range. The receiver and the collector design (especially primary and secondary reflectors) will be developed and optimized within the project, but also a cost-effective manufacturing will be implemented and the applicability will be assessed and integrated in the development.

The core objectives of FRESH NRG are outlined in the following nine S&T objectives.

1. Sol-Gel Anti Reflective Coating (ARC) for 96% solar transmittance for the receiver glass envelope
An advanced anti-reflective coating (ARC) will be developed for the glass envelope. Based on preliminary research, the new coating will have a close porosity structure. The addition of inert methyl groups in the coating will avoid the adsorption of water and contaminants in the porous surface and this will provide long-term durable coatings, as well as a sort of anti-soiling effect. As a result, the additional finishing layer on the glass which is now used to reach those properties will not be required anymore.

2. Sol-Gel selective coating for 95% solar absorptance and 7% emittance at 250°C for the absorber tube
Various multi-layer Sol-Gel coatings will be developed in small samples, tested and optimized thereafter. This will enable low manufacturing costs also for small batch production thus providing an alternative to current PVD solutions such as sputtering, which are not economically viable at low/intermediate volumes due to high investment requirements. An optimal coating solution will be identified and adapted to different metal substrates - such as aluminum and stainless steel - by means of additional intermediate layers, if necessary. Multiple solutions will be developed for different solar fluids and applications.

3. Optimized collector design to reach 67% efficiency at 250°C
A comparably high efficiency of 67% at an output operating temperature of 250°C shall be achieved for the collector (see section 1.2.1) by means of various innovations such as the new receiver and new primary and secondary mirror arrangement. This will constitute an improvement of 28% on the performance of Soltigua’s current Linear Fresnel collector which is 52% in the same conditions.

4. Engineering of modular “clip-on” secondary mirror and key “plug-in” components
This objective will enable the creation of an easy - to - use concentrating collector which can be installed easily and quickly with low skilled labour. This objective will be achieved by design of optimal ultra-light panels for primary mirrors, engineering of clip-on secondary mirror and other plug-in components, such as Soltigua’s patented receiver tube connections for facilitated assembly and longitudinal connections between primary mirror lines..

5. Lean manufacturing process for Sol-Gel coatings and receiver assembly
New prototypes of coating process lines will be developed to apply the new Sol-Gel coating processes (Anti Reflective and Selective) on full scale components. The selective coating line prototype will coat a metal tube up to 4-meters long with a uniform and industrial-type coating layer made of a Sol-Gel mixture. It will be the first line worldwide of its kind.
Furthermore, a simplified assembly method will be developed to connect the selectively coated metal tube and the glass envelope, in order to create a prototype receiver assembly line.

6. Engineering of scalable manufacturing process
The research on the manufacturing process will target scalability in order to move seamlessly from prototypes to industrial production.
Manufacturing of the new collector will follow a holistic approach across well defined phases. First of all, components will be developed and tested. Then, pre-production lots will be run to ensure that preliminary results can be implemented at an industrial level. Finally, production and control procedures will be implemented.

7. Improvement of the suitability of the new collector for industrial applications
The collector design criteria will be identified and optimized also by assessing information regarding possible installation sites and their respective demand profiles, temperature and pressure in selected Mediterranean areas such as Jordan and Italy. This investigation will cover integration solutions for different heat transfer fluids (thermal oil, steam etc.).
Furthermore, the installation process will be evaluated both before and after the actual installation related to the field test of the collector, in order to develop and evaluate hands on experience.

8. Test of receiver and complete collector in the 100-250°C temperature range
During the development phases detailed optical and thermal characterization of key components and of the whole collector will be carried out in the associated laboratories. Furthermore, a collector field of approx. 60 to 120 kWth will be installed and investigated under real operating conditions in Jordan.

9. Update of high impact plan for scientific and technical exploitation in the Mediterranean region
The high impact plan which is included in this proposal and which is described in Section 3.1 and 3.2 will be updated and integrated during the course of the project in order to include the main scientific and technical developments.
The plan does and will cover both dissemination of scientific results and industrial exploitation of technical achievements.

Project Results:
Please refer to attached file "Description of main S&T results_foregrounds.pdf"

Potential Impact:
Please refer to attached file "Potential impact and main dissemination activities and exploitation results.pdf"

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