Enhancement of phase change materials by nanoparticles to improve battery thermal management for autonomous underwater vehicles

Battery thermal management (BTM) plays a significant role in the safety and reliability of autonomous underwater vehicles (AUV) at higher speeds. In this study, a nanoparticle/phase change material (nano-PCM) composite is proposed for the BTM of an AUV. The effects of nanoparticle loading percentage (φ = 5, 10, and 15%) and nanoparticle filling range (α = 30, 60, 90, and 120°) on the battery temperature and PCM melting were investigated numerically. Two criteria for the dimensionless temperature control performance (TCP) factor and dimensionless heat storage performance (HSP) factor were used to evaluate the influence of various variables on the BTM performance. The results show that increasing the nanoparticle loading percentage improves the effective thermal conductivity of the PCM but reduces the overall effective latent heat. An optimal nanoparticle filling range of α = 60° is recommended to accelerate the overall melting rate of the PCM. Compared with those of the pure PCM-based BTM, the TCP rate and TCP density are enhanced by 14.56% and 26.75%, respectively, at α = 60°. The HSP rate increases by 2.84% but the HSP density reduces by 11.85% at α = 60°. These findings can provide a reference for the accurate design of nano-PCM composites for the BTM of AUVs.