Thermophysical properties analysis of graphene-added phase change materials and evaluation of enhanced heat transfer effect in underwater thermal vehicles

•The basic principle of ocean thermal energy utilization in the underwater vehicle is revealed.•An enhanced heat transfer method of PCM for underwater vehicles is proposed.•The change rules of thermophysical properties of added graphene PCM have been analyzed by molecular dynamics.•The optimal addition ratio of graphene for enhancing the heat transfer capability of underwater vehicles is proposed.