Model construction and performance research of an equal-length multi-section asymmetric compound parabolic concentrator based on solar vacuum tube

Solar compound parabolic concentrator (CPC) has the features of not requiring real-time tracking, adjustable acceptance half-angle, and simultaneous collection of beam and diffuse radiation. However, conventional CPC reflectors suffer from high production and maintenance costs, poor substitutability and a low level of standardization in their application. Therefore, this research constructs a novel equal-length multi-section asymmetric CPC (MA-CPC) and investigates its geometric structure, light concentrating features, and photothermal conversion performance. It was found that MA-CPC optical efficiency and radiation collection can reach more than 90 % of A-CPC of the same specification, and the solar radiation gathered into the absorber has better uniformity than A-CPC. Subsequently, outdoor photothermal conversion experiments were synchronized. Under 10 m3/h fluid flow rate, the outlet temperature of MA-CPC collector system reached 332.9 K. The average thermal efficiency was 55.9 %, and the working condition of the system was stable. In addition, it was found that the vacuum tube also has high conversion capacity during the operation of the collector system, and the energy utilization of the fluid medium reaches more than 80 %, which is potentially promising for engineering applications.