| dc.description.abstract | Recently, the oceans have been seen as a promising source of renewable
energy. Theoretically, the oceans could offer enough energy to supply the entire world
demand. Among the technologies available for energy conversion from the oceans,
the Oscillating Water Column (OWC) type devices stand out, which are characterized
by a chamber, in which the water oscillates inside in a movement similar to a piston.
This movement moves the air to a chimney, where a turbine is attached. The passage
of air through the turbine promotes the conversion into mechanical energy. In the
present work, the study of the performance of a 1:15 scale OWC type converter was
performed using a three-dimensional computational fluid dynamics model. The
analysis was based on the Constructal Design Method. In this approach, energy is the
quantity that flows through the system, whose purpose is the maximum rate of
conversion of wave energy into mechanical energy. Three degrees of freedom were
used: the ratio of height to length of the hydropneumatic chamber (H1/L), the ratio of
the height of the chimney to its diameter (H2/d), and the ratio of the width of the
hydropneumatic chamber to the width of the wave tank (W/Z). The effect of different
combinations between degrees of freedom for a typical wave of the southern region of
the Brazilian coast was investigated. Conversion efficiency was used as a performance
parameter. Computational modeling of the system was performed, using
computational fluid dynamics software based on the finite volume method (FVM), using
the Volume of Fluid (VoF) modeling for the interface between the gas and liquid
phases. In a first analysis, it was observed that the height of the chimney always has
a positive effect on the efficiency of the system. However, only workable values were
selected for this degree of freedom, limiting the subsequent analyzes to two degrees
of freedom, H1/L and W/Z. Through a Design Experiment of the Central Composite
Project type, different combinations of degrees of freedom were simulated, allowing
the construction of Response Surfaces and correlations for the efficiency of the system
depending on the degrees of freedom width and height of the chamber, as well as the
optimization of the system based on the Response Surfaces. In the tests carried out,
the efficiency of the OWC device varied from 1.48% to 19.32% in the worst and best
case, respectively. | en |
