Modification of the phase change transfer model for underwater vehicles: A molecular dynamics approach
Guohui Wang, Yanan Yang, Shuxin Wang, Hongwei Zhang, Yanhui Wang
Abstract
The thermophysical properties of phase change material (PCM) directly affect the performance of underwater vehicles. The accuracy of the phase change transfer model is an important index for evaluating the performance of PCM as well. In this paper, a molecular dynamics approach is proposed to obtain the thermophysical properties of PCM under different pressures. On such a basis, the modified models of “temperature-pressure-density,” “temperature-pressure-thermal conductivity” and “pressure-specific heat capacity” are established. By comparing the simulation results with the unmodified phase change transfer model and the laboratory experimental results, it can be seen that the modified phase change transfer model has higher accuracy. Furthermore, an ocean thermal energy conversion system for underwater vehicles is deployed in the South China Sea to test the utilization performance. By the contrast between the simulated calculation of the modified model and the sea trial results, it is found that the root mean square (RMS) of accumulator pressure between the simulation and sea trial is 0.2565, and the energy storage volume RMS is 1.6868. When the accumulator pressure reaches 205 bar, the time error is 0.58%, and the energy storage volume error is 3.16%. The results indicate that the modified model is effective in practical application.