Typical receiver designs and their roles
Receivers are where concentrated sunlight becomes useful thermal energy. Different receiver types match different concentrator geometries and temperature requirements. Common receiver types include tubular (absorber) receivers, cavity receivers, and receiver tubes with heat transfer fluids.
Main receiver types:
- Tubular receivers: Often used with parabolic troughs, these are glass-covered metal tubes (receiver tubes) with an absorber coating that captures sunlight and transfers heat to a working fluid (oil, water/steam, or molten salt).
- Cavity receivers: Used on tower systems, cavity receivers have an enclosed space that minimizes radiative heat loss at very high temperatures. The concentrated beam enters the cavity and heats an absorber surface or fluid inside.
- Direct molten salt receivers: In some towers, molten salt flows directly through the receiver and is heated to high temperatures for storage and power generation.
- Volumetric receivers: Typically used with dish systems and some tower designs, these use porous or foam materials that allow air or gas to flow through and pick up heat, enabling very high-temperature operations.
Receiver selection depends on:
- Temperature needs: Higher operating temperatures require robust materials and cavity designs to reduce losses.
- Working fluid: Choices include thermal oils (lower temperature), steam/water, molten salts (for storage), or gases for direct Brayton cycles.
- Optical concentration level: Higher concentration demands receivers that can withstand intense flux and manage thermal stresses.
Design considerations also include thermal losses (radiation, convection), absorber coatings, maintenance accessibility, and compatibility with storage systems. Proper receiver design is critical to system efficiency: it determines how effectively concentrated sunlight becomes usable heat and how well the system integrates with turbines or industrial processes.