H2020 NEXTOWER Project - Results
Ceramic solar receiver
- Innovative ceramic for high-temperature open volumetric receivers based on all-SiC honeycomb design by VPS for more durability to oxidation
- Better ceramics for high-temperature receivers - with extended durability (20-25 years) vs thermal fatigue and thermal shock
- Superior thermal properties and reliability
All-SiC ceramics receivers optimized for oxidation:
- - Porosity of 30% in the cup
- - Porosity of 43% in the square part
- - Strenght of 100MPa
- Innovative ceramic for high-temperature open volumetric receivers based on more flexible multuparts Si-SiC- 3D printed design for higher toughness, higher thermal conductivity and more open design
- Optimized joining technique with proven scalability based on two steps methodology (Si coat on SiSiC disk and Mo-Wrap joining)
Si-Sic ceramic lattices for solar receivers optimized for higher toughness and thermal conductivity:
- - Performance:higher aitr temperature by same radiation and flow
- - Lifetime:25 years with an inlet air flow at 900oC at concentrated solar flux density of about 2MW/m2 and maximum thermal gradient of 70oC/cm
- Intefacial cracking of the receiver made of three pieces avoided
Coating and surface treatments to improve thermomechanical properties and emissivity:
- For increased thermal conductivity and thermal schock resistance: introduction by CVI of highly thermal conductive aluminium nitride (AIN)
For reduced emissivity:
- - innovative metal-oxide coating by sol-gel-deposition
- - engineering surface roughness by micropatterning
- - engineering surface coatings filled with nanocavity by plasmonic technology based on nanoparticles
Increased thermal conductivity and durability of porous SiC receivers and reduction of their emissivity (in order of magnitude of about 20%) to boost performance at higher temperatures (900oC)
A proposal of amendment to the current standard on thermal di?usivity determination with the Laser Flash Method (LFA) has been dra?ed and submitted to the ISO Standardization Body. The objective is to propose to employ a single standard and only the LFA method to characterize the whole thermal behaviour of the ceramic materials under investigation, in terms of thermal di?usivity, speci?c heat and thermal conductivity.
A correct evaluation of the speci?c heat by means of the LFA has been demonstrated by comparison with the results achieved by the standard DSC technique. In this way, the acceptance and utilisation by the market of the developed solutions can be favoured.
Thermal storage architecture and materials
Liquid lead as heat transfer fluid as technology transfer from nuclear fission to CSP of high-temperature lead-based thermal fluid
Because of the higher stability and continuity of the heat supply ensured by the lead storage, the solar heat collected can be used also as high-temperature process heat, significatively extending the range of possible applications of concentrated solar thermal plants.
Corrosion resistant alumina forming steels: innovative FeCrAl-alloys with better performance than reference commercial ones (good corrosion resistance in liquid lead at 750o, minor oxidation, self-healing properties) used for the construction of steel piping and plates of the CSP full-scale demo.
- Raw material reduction: partial substitution of chrome through both composition (lowering Cr by replacement of 4% Al) and by increased performance (increasing oxidation resistance) as compared to standard stainless steels and Ni superalloys
- Liquid lead applications up to 750o enabled, thus achieving increased thermal e?ciency of CSP plants
Optimized robotic GMAW welding procedures and SAW Strip Cladding to be used with NEXTOWER innovative alloy at high temperature strength of the welds: defect free coatings on NiFeCr high temperature resistant steels (no liquation cracks, nor solidification cracks).
Greater repeatability and faster execution of the welding process compared to a semi-automatic procedure.
Up to 100kW demo pilot plant including:
- The improved open volumetric receiver
- An innovative single-tank thermocline indirect thermal energy store (TES) system using liquid lead as heat storage medium installed and tested at Plataforma Solar de Almeria
- Compact and efficient thermal energy storage system based on a liquid heat storage medium
- Flexible plant operation and dispatchable production
- Ease of integration with high-temperature power cycles using compressed gases or supercritical fluids as working media