Session: 08-01 Thermal Energy Conversion Techniques

Paper Number: 106769

106769 - Modeling and Optimization of a PCM-Based Ocean Thermal Energy Harvester for Powering Unmanned Underwater Vehicles 

As oceans cover over 70% of the planet’s surface, they represent a large reservoir of resources that remained vastly untapped. Nowadays, Unmanned Underwater Vehicles (UUVs) are becoming key technology for ocean exploration. Currently, UUVs rely mostly on bulky batteries which need to be recharged periodically and can take much space inside the vehicle that could be used to incorporate other mission critical electronic gadgets. The cost, environmental impact of those batteries could not be overlooked in case of an accident and at the end of the vehicles’ life, as many scientific gliders and floats used in the ocean are not retrieved at the end of their lifecycle. Ocean thermal gradient is a permanent and reliable energy source that can be used to power UUVs using phase change material (PCM)-based thermal engines. However, the main drawback of this technology is its low conversion efficiency. When using PCM-based thermal engines to power UUVs, there are different energy conversion stages, thermal-hydraulic, hydraulic-rotational, rotational-electrical, dependent of a wide variety of parameters. Thus, optimization of the overall energy conversion is still a challenge.

The goal of this study is to optimize a PCM-based ocean thermal energy harvesting system. For this purpose, we developed a computational model for a system consisting of a thermal engine, and hydraulic and electrical systems. This system is designed to provide the electrical power needed for the instruments aboard the underwater vehicle. This way, the whole UUV blends in the underwater environment and becomes self-powered. The whole model including thermal (PCM), hydraulic (working fluid, accumulator, pipes, valves), and electric (generator, electric load) systems is implemented in MATLAB-Simulink/Simscape environment. The preliminary results show good agreement with the experimental testing. We are working towards specifically increasing the energy conversion efficiencies between the different stages of energy conversion. This work will benefit engineers to develop in a short-time, efficient thermal energy harvesters for further novel applications.

Presenting Author: Habilou Ouro-Koura Rensselaer Polytechnic Institute

Presenting Author Biography: Habilou Ouro-Koura is a PhD candidate in Mechanical engineering at the Rensselaer Polytechnic Institute in Troy, NY. He is currently doing his fellowship work at the Pacific Northwest National Laboratory in Richland, WA. Habilou received his Bachelor of Science degree in 2018 at the University of Maryland Eastern Shore and Associate of Science degree from Montgomery College. His research interests include energy harvesting technologies such as kinetic and ocean thermal gradient for powering new technologies as wireless sensor nodes, Internet of Things (IoTs), and other marine applications.