Review of the solar flux distribution in concentrated solar power: Non-uniform features, challenges, and solutions

Concentrated solar flux distribution in the concentrated solar power (CSP) systems is extremely non-uniform, which can lead to high local temperature and large temperature gradient in solar receivers that will cause great challenges for the safety and efficient operation of the system. This paper introduces the non-uniform flux features in four CSP technologies including the parabolic-trough collector, the linear Fresnel collector, the solar power tower, and the parabolic-dish collector. Challenges including degeneration of the materials, thermal stress and deformation, and overburning are summarized. The corresponding solutions proposed to tackle these challenges are emphatically reviewed, and a recommendation for the optimization of the solar collector is provided from this review, which is that the solar flux distribution and the heat transfer ability of the heat transfer fluid (HTF) should match with each other as well as possible. From this point of view, the existing solutions are classified into two groups. One is optimizing the heat transfer ability of the HTF to match with the flux distribution, which is called the passive approach. The other is homogenizing the flux distribution to match with the heat transfer ability of the HTF, which is called the active approach. This review can help to have a better understanding of the non-uniform solar flux features in CSPs, and provide guidance for solving the corresponding challenges.