Geometric Analysis through the Constructal Design of a Sea Wave Energy Converter with Several Coupled Hydropneumatic Chambers Considering the Oscillating Water Column Operating Principle

Abstract

The work presents a numerical study of a wave energy converter (WEC) device based on the oscillating water column (OWC) operating principle with a variation of one to five coupled chambers. The main objective is to evaluate the influence of the geometry and the number of coupled chambers to maximize the available hydropneumatic power converted in the energy extraction process. The results were analyzed using the data obtained for hydropneumatic power, pressure, mass flow rate, and the calculated performance indicator’s hydropneumatic power. The Constructal Design method associated with the Exhaustive Search optimization method was used to maximize the performance indicator and determine the optimized geometric configurations. The degrees of freedom analyzed were the ratios between the height and length of the hydropneumatic chambers. A wave tank represents the computational domain. The OWC device is positioned inside it, subject to the regular incident waves. Conservation equations of mass and momentum and one equation for the transport of the water volume fraction are solved with the finite volume method (FVM). The multiphase model volume of fluid (VOF) is used to tackle the water–air mixture. The analysis of the results took place by evaluating the performance indicator in each chamber separately and determining the accumulated power, which represents the sum of all the powers calculated in all chambers. The turbine was ignored, i.e., only the duct without it was analyzed. It was found that, among the cases examined, the device with five coupled chambers converts more energy than others and that there is an inflection point in the performance indicator, hydropneumatic power, as the value of the degree of freedom increases, characterizing a decrease in the value of the performance indicator. With the results of the hydropneumatic power, pressure, and mass flow rate, it was possible to determine a range of geometry values that maximizes the energy conversion, taking into account the cases of one to five coupled chambers and the individual influence of each one.

Study of the Geometry of an Oscillating Water Column Device with Five Chambers Coupled under Regular Waves through the Constructal Design Method

“…Different parameters can define the characteristics of a regular wave. These characteristics can be seen in [17,24].…”

“…The studies conducted in this research are original and complement the research developed in [17], presenting an analysis of the influence of coupling five hydropneumatic chambers in an OWC device and how this coupling affects the available power in the system, thereby contributing to the state of the art.…”

“…Finally, Lima et al [17] conducted a study to assess the increase in coupled chambers and their influence on the accumulated hydropneumatic power. In total, devices containing from one to five coupled chambers were evaluated, and it was observed that devices with five coupled chambers exhibit higher accumulated power values than others, even with a decrease in hydropneumatic power in chambers farther from the initial wave structure interaction.…”

“…When determini the channel's length, it is essential to take the wave length into account. These dimensio are recommended and presented by Lima et al [17]. Additional features are required to delineate the two-dimensional geometry of t OWC device, encompassing the heights of the hydropneumatic chambers (Hn), the su mersion depth of the device (Hdepth), the elevations of the turbine ducts (Hj), the lengths the ducts (lj), the lengths of the chambers (Ln), and the thicknesses of the columns dividi the devices (en).…”

Multi-Objective Constructal Design for Quadrilateral Heat Generation Body with Vein-Shaped High Thermal Conductivity Channel

“…The constructal theory [ 27 , 28 , 29 ] optimizes problems by following the idea that the structure of things develops in the direction of better internal flow performance, which provides a new method for traditional thermodynamic optimization problems. Constructal theory proved to be fully interdisciplinary and versatile, it can be used in heat transfer problems [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], fluid flow problems [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ], solar cell [ 44 ], and stiffened plates [ 45 ] designs.…”