Resumo:
The main objective of this thesis was to develop a mathematical modeling of a Parabolic
Cylindrical Collector System integrated to an Organic Rankine Cycle with Thermal Storage
as an option to generate electricity of both low and medium capacity, friendly to the
environment and that is able to respond to the intermittence of the renewable energy
sources, as is the case of solar energy. Matlab was used as the computational tool to
develop the mathematical models.
Different heat transfer fluids (Water, Donwtherm A, Donwthwer Q e Syltherm 800) and
working fluids (R-245fa, R-141b and R-123) were analyzed in order to determine the
influence of these on the use of thermal energy, the electricity generated by the system and
on the behavior of the turbine. In addition, the preliminary design of a radial turbine for the
Rankine Organic Cycle was developed for three work fluids. For this, a mathematical
model of the turbine was elaborated in Matlab, for different operating conditions. The onedimensional model is useful for determining the geometric and design parameters; it also
represents the basis for developing the 3D analysis of the turbine using the program
CFX-ANSYS. The 3D analysis of the turbine aims to analyze the pressure, velocity and
temperature profiles of each of the geometries obtained for each working fluid, besides
allowing to determine the behavior of the turbine at the design point and out this point.
Conditions from which the analysis of the integrated behavior of the system proposed in
this thesis is developed.From the analysis of the integrated behavior of a Parabolic Cylindrical Collector operating
with an Organic Rankine Cycle and Thermal Storage of Two Tanks, it was possible to
determine for the conditions and parameters defined in this thesis that a pair of tanks with a
diameter of 4 m, height of 4,55 m and using the Downtherm A as the system fluid, ensures
generation of approximately 7,4 kWe over a period of 3 hours 26 min. In addition, it was
determined that for the analyzed day, the Parabolic Cylinder Collector system contributes
with 63,6 % of the energy supplied to the Organic Rankine Cycle system, while the storage
system contributes with 36,4 %.
The approach of the 3D design of the radial turbine presented in this thesis, allowed to
determine that the efficiency of the turbine changes as a function of the operating condition
and the working fluid. These results show that for the analysis of Organic Rankine Cycle
behavior, it is important to determine the efficiency value for the analyzed condition, and
should not be defined as a constant value.
