Concentrating the solar energy is a well-known technique for increasing the working temperatures of solar collectors while maintaining high conversion efficiencies. In the industrial and residential sectors medium temperature solar collectors (80-250°C) are gaining more and more interest for power production and absorption cycle applications. In the present paper the attention is focused on the design and testing of a solar collector where a high performance evacuated tube is coupled with a Compound Parabolic Concentrator. The design of the solar mirror is carried out by imposing a series of constraints related to a broad acceptance angle (about 30°), reduced mirror height, possibility to employ a displaced tubular receiver. The mirror surface was tested in laboratory with a ray tracing approach. The complete CPC collector was finally tested under real outdoor operating conditions according to the Standard EN 12975-2. In such a way the instantaneous efficiency of the collector has been evaluated. The main findings are related to the effects of the concentration ratio and truncated height on the collector efficiency; they also highlight some limits and possible corrections to be employed when the results of the Outdoor steady state test method are applied in daily simulations of the collector behavior.

Development and testing of a compound parabolic collector for large acceptance angle thermal applications

Fossa, Marco;
2017

Abstract

Concentrating the solar energy is a well-known technique for increasing the working temperatures of solar collectors while maintaining high conversion efficiencies. In the industrial and residential sectors medium temperature solar collectors (80-250°C) are gaining more and more interest for power production and absorption cycle applications. In the present paper the attention is focused on the design and testing of a solar collector where a high performance evacuated tube is coupled with a Compound Parabolic Concentrator. The design of the solar mirror is carried out by imposing a series of constraints related to a broad acceptance angle (about 30°), reduced mirror height, possibility to employ a displaced tubular receiver. The mirror surface was tested in laboratory with a ray tracing approach. The complete CPC collector was finally tested under real outdoor operating conditions according to the Standard EN 12975-2. In such a way the instantaneous efficiency of the collector has been evaluated. The main findings are related to the effects of the concentration ratio and truncated height on the collector efficiency; they also highlight some limits and possible corrections to be employed when the results of the Outdoor steady state test method are applied in daily simulations of the collector behavior.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/885879
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