Effect of cavity surface material on the concentrated solar flux distribution for an impinging receiver

- A ray-tracing model of a cavity receiver-dish system has been developed.
- Five cavity surface materials/coatings and their combinations have been studied.
- For single cavity surface material design, high absorptivity material is superior.
- The radiative boundary condition can be tailored by using multi-coating on surfaces.

In this paper, the effects of cavity surface materials on the radiative flux distribution of solar cavity receivers have been studied with the help of a ray-tracing methodology. Three metallic substrate materials (Inconel 600, austenitic stainless steel 253 MA and Kanthal APM) and two coating materials (Pyromark® 2500 coating and YSZ TBC coating) were selected as the candidate cavity surface materials. The results show that the flux distribution and the total optical efficiency are much more sensitive to the absorptivity on the cylindrical surface than on the bottom. By using high absorptivity coating on the cylindrical surface and low absorptivity coating on the bottom, the radiative flux on the bottom can be controlled at a low level, and it can help to reduce the cavity length for an impinging receiver with jets on the cylindrical surface. Furthermore, the radiative flux distribution on the cylindrical surface can also be tailored to meet various design requirements by applying different coating designs on the cylindrical surface.