Energy response of a mono-axis tracked solar thermal collector with vacuum tubes

Abstract

. Looking towards a sustainable future, Transilvania University of Brasov develops many projects on diverse renewable energy conversion systems; this paper presents a solar tracked solar thermal collector (STC) system, designed for a future implementation on Transilvania University campus. The specific requirement is that the STC system has to be configured to keep a zero energy response during the summer holydays (when the energy consumption is null). The proposed solution describes a mono-axial solar tracking system designed to perform an annual step wise tracking program to capture the most of the available solar energy using a solar thermal collector (STC) with vacuum tubes. The tracking program represents an optimised step tracking law developed in dependence with the diurnal movement of the sun. Numerical simulations are done for one year interval, for Brasov Romania geographic site, to evaluate the daily variations of: the pseudo-equatorial solar angles (γ, β); the pseudo-equatorial tracking angles (γ*, β*); the incidence angle; the available beam solar radiation (B) and the beam received solar radiation by the STC system (B*). The energy response of the tracked STC, for Brasov, Romania, is evaluated considering both clear sky and cloudy sky conditions, while neglecting the diffuse radiation effect.