Materials that withstand intense solar flux
Receivers in high-temperature concentrators must tolerate extreme heat, thermal cycling, oxidation, and high radiant flux. Material choice depends on the maximum operating temperature, the heat transfer medium, and cost considerations.
Common receiver material classes:
- High-temperature alloys: stainless steels and nickel-based superalloys are used for moderate to high temperatures and offer good mechanical strength.
- Refractory metals: molybdenum, tungsten, and tantalum are used where very high melting points and thermal stability are required, though they are more expensive and heavy.
- Ceramic and composite materials: advanced ceramics and ceramic matrix composites resist oxidation and thermal shock at very high temperatures and are used in special applications.
- Coatings and absorbers: selective coatings (black chrome, black nickel, or specialized cermet coatings) increase absorptance while reducing emissivity to limit radiative losses.
Design trade-offs:
- Thermal conductivity versus corrosion resistance: metals conduct heat well but can corrode; ceramics resist heat but may be brittle.
- Cost and manufacturability: high-performance alloys and ceramics add cost and complexity to fabrication.
- Maintenance and repairability: metallic receivers are easier to repair, while ceramic parts may require full replacement.
Receivers are paired with appropriate insulation, cooling systems, and flow channels for heat transfer fluids like molten salts, oils, or pressurized gases. Material selection is a critical part of reliable, efficient concentrator design.