Solar-thermal conversion investigation using surface partition method for a cavity receiver with helical pipe

To develop solar energy technology, the cavity receiver research is worth paying attention to. Instead of considering the cavity as a whole object, the surface of the cavity, exposed to solar radiation, is divided into five sections: the external front cover, the throat, the inner front cover, the pipe surface, and the bottom. Three critical parameters were investigated: the loops number n(loop), the distance from focus point to aperture center l(f)(-a), and the aperture diameter d(ap). Coupling Monte-Carlo Ray Tracing method, an optical simulation model was proposed, heat flux distributions and cavity absorption efficiencies were solved. The results showed that the optimum absorption efficiency achieved 87.44% at 6 loops and 184 mm aperture diameter. If the l(f-a) was less than -130 mm, the external front cover and bottom would risk the melting, while the heat flux of hot spots was higher than 1.3 x 10(6) W/m(2). The throat was damaged by large l(f-a) (130 mm) and small d(ap) (184 mm), since the heat flux was higher than 2.1 x 10(6) W/m(2). Summarily, this method can help to detect extremely high heat flux, to prevent hot melt phenomena, then to avoid safety risk of cavity receiver. (C) 2021 Elsevier Ltd. All rights reserved.