Abstract
The long-term mission capacity of battery-powered underwater vehicles is quite limited, which necessitates the development of underwater vehicles that utilise ocean thermal engines (OTEng) to capture renewable energy. The literature indicates that OTEng based on solid-liquid phase-change materials (PCM) is the optimum solution; however, the energy capture performance of OTEng strongly affects the motion and power supply of the thermal underwater vehicle, and thus, improving their energy capture performance is critical. In this study, a new OTEng with an enhanced heat transfer structure based on PCM was designed by employing copper foam and filling fluid. An experimental platform for the performance study of OTEng was established, and a corresponding evaluation method was introduced. Comparative experiments on its performance, including the phase-transition time, volume of oil input and output, and amount of energy captured under various scenarios, were carried out. The results were analysed, and it was concluded that (1) the designed OTEng enhanced the heat transfer ability up to 58.3% in the melting process and 21.4% in the solidification process when the temperature difference was 10 degrees C; (2) filling liquid with 0.3 MPa system pressure was the optimal choice during the solidification process; (3) increasing the system pressure or ambient temperature during the melting process could improve the captured energy or average power in one cycle, respectively.
NSTL
Elsevier