Receiver with light-trapping nanostructured coating: A possible way to achieve high-efficiency solar thermal conversion for the next-generation concentrating solar power

To improve the receiver's solar-thermal conversion efficiency at high temperature for the next-generation concentrating solar power (CSP), a receiver with the light-trapping nanostructured coating is proposed herein. However, for the CSP plant with the light-trapping nanostructure coated receiver, the scale of the heliostat field is on the order of meters (∼10m), the solar receiver tube on the order of millimeters (∼10 mm), and the light-trapping coating on the order of nanometers (∼100 nm). The whole system spans nine orders of magnitude, which makes it extremely complicated and difficult to evaluate the receiver's optical and thermal performance. To solve this problem, a multi-scale model is proposed by combining Monte Carol Ray tracing method (MCRT), finite difference time domain (FDTD) method, and finite volume method (FVM). Then, the influences of three typical light-trapping nanostructured coatings, including pyramid nanostructure, moth-eye nanostructure, and cone nanostructure, on the receiver's optical-thermal performance are studied. Among these three typical nanostructures, the cone nanostructure can maximize the receiver's optical-thermal performance, with a receiver efficiency more than 88%, which is higher than that of the commercial Pyromark2500 coating by 6–10% points. The study demonstrates that the receiver with light-trapping nanostructured coatings can achieve high receiver efficiency for the next-generation CSP.