Researchers from the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University have proposed a novel design for wave energy harvesting that could potentially enhance the efficiency and stability of ocean wave energy conversion. The team, led by Chongwei Zhang and including Zhenyu Ding, Lifen Chen, and Dezhi Ning, has developed a system called the ‘sloshing wave energy converter (S-WEC)’ that utilizes internal liquid sloshing to capture wave energy. Their findings were published in the journal Applied Energy.
The S-WEC design features a liquid tank with built-in buoys. When the tank is oscillated by external forces such as ocean waves, the internal liquid begins to slosh, and the mechanical energy of these sloshing waves can be absorbed by a power take-off (PTO) system attached to the buoys. To study the dynamics of this system, the researchers established a fully-nonlinear numerical model based on the boundary element method. They also developed a motion decoupling algorithm to solve the complex interactions between the sloshing waves and the floating buoys within the tank. Additionally, an artificial damping model was introduced to account for the viscous effects of the sloshing liquid.
To validate their mathematical and numerical methodologies, the researchers conducted physical experiments on a scaled S-WEC model. Through spectrum analyses of the buoy and sloshing liquid motion histories, they identified the natural frequencies of the S-WEC system. By comparing these findings with experimental measurements, they were able to determine the viscous damping strength. The study also explored the effects of PTO damping on the power generation characteristics of the S-WEC, revealing that an optimal PTO damping can be found for each excitation frequency to maximize power generation and conversion efficiency.
For practical engineering design, the researchers proposed a method based on diagram analyses to determine a constant PTO damping. They also investigated how the geometry of the buoy affects the power generation characteristics of the S-WEC. The study suggests that the S-WEC design could offer several advantages for ocean wave energy harvesting, including enhanced survivability, reduced metal corrosion and fouling organism inhibition, and improved power generation stability and efficiency.
In the context of the energy industry, the S-WEC design presents a promising technical solution for capturing wave energy more effectively and reliably. By optimizing the PTO damping and buoy geometry, this system could contribute to more efficient and stable wave energy conversion, potentially making wave energy a more viable and competitive source of renewable power.
This article is based on research available at arXiv.