Effect of orientation of a CPC with concentric tube on efficiency

In this paper, we present a comparative study of two compound parabolic concentrators with a concentric tube as absorber positioned longitudinally in the North-South and East-West directions. The analysis includes the design, modeling, construction, experimentation and validation of the concentrators. It was defined as an object of study a CPC with 24.3 degrees of acceptance and 2.22 of geometric concentration, with a length of 2 m. The absorber tube has an outside diameter of 0.04 m. Later a mathematical model and a simulator for the thermal analysis of the CPC were elaborated. In order to carry out the experimentation, two pieces of equipment were formed by 4 CPC cavities implementing the same construction method. It was necessary to set up a test bench to position both collectors respectively in the N-S and E-W direction. Based on the experimental results it was possible to adjust the simulator to obtain an average difference of +/- 0.15 degrees C for N-S and +/- 0.21 degrees C for E-W. The results show that on average, the CPC with an E-W orientation has an optical efficiency of 57.5%, while the N-S position reaches 51.3%. The coefficient of heat losses is higher for the CPC E-W than the N-S position, with -21.54 and -10.44 respectively. (C) 2017 Elsevier Ltd. All rights reserved.