Abstract:
A comparative analysis is drawn on the energetic responses numerically simulated for Brasov, Romania location, delivered by
two mono-axial pseudo-equatorial STCs (solar thermal collectors): a flat plate STC and a STC with heat pipes; the two systems
are destined for future implementation on Transilvania University Campus. Accordingly, two tracking programs are considered
for the diurnal motion: a) of 1h constant duration steps, for school courses interval (September-June) and b) 1-step program for
the summer vacation (July-August). For September-June two contradictory requirements meet: 1. a small diurnal angular stroke is
needed to protect the mechanical structure of the tracked STC and 2. A large diurnal angular stroke is needed to receive an
important amount of the available global solar radiation. The optimized annual tracking law along with the correspondent
energetic responses and the STCs temperature variation are attained by numerically simulation. The STCs efficiencies, tracking
efficiencies and stagnation temperatures are compared on ideal clear and estimated cloudy sky conditions. The results indicate that
the tracking law for September-June consisting of: (annual) elevation angle γ* = 30° and 1h constant step program for the diurnal
motion covering β* = 90(β* = +45… β* = -45) delivers approximately with 20% higher energetic gain than the fix tilted STC
and also ensures safe mechanical tracking; for the school summer holiday: an (annual) elevation angle γ* = 30°, 1-step tracking
program covering β* = 120 (β* = +60… β* = -60) for the flat plate STC and β* = 150 (β* = +75…β* = -75) for the STC
with heat pipes, ensure the necessary safe thermal and tracking conditions.