Dynamic simulation and exergetic analysis of a solar thermal collector installation

Abstract

Solar collectors are active solar devices which help reducing the energy consumption in buildings. In this paper, a real installation of solar collectors is analysed under different collector array configurations. Also, both energetic and exergetic analyses have been developed, for both general balance and specific variables. To apply these analyses, a TRNSYS dynamic model has been built and validated with experimental data obtained in the real installation. The values of the representative variables have been examined in different points of the installation, resulting in a description of the installation operation and parameters influencing the exergetic efficiency. Although parallel connections of the collectors are commonly used, in this work, simulations and experiments have been carried out with both parallel and series connections. As a result, no significant differences regarding the array configurations have been found. The values of the exergetic efficiency of the collectors are always very low (within 1% and 4.6%), no matter the configuration nor the irradiance. Its maximum value was reached after about 5 h of operation, for all configurations. The values obtained for the whole installation are in the range of 20–50% for the energetic efficiency, whereas the exergetic efficiency is always lower than 1.5%.