Fabrication, Characterization, and Simulation of Paraffin / Kaolin / Carbon Nanotube Composite Phase Change Materials for Shell-and-Tube Thermal Energy Storage Unit

In this work, shape-stabilized composite phase change materials (SSPCMs) were fabricated using paraffin (PA) as the phase change medium, kaolin as the supporting framework, and multi-walled carbon nanotubes (MWCNT) as thermal conductivity enhancers.Five SSPCMs specimens with MWCNT mass fractions of 0%, 2.5%, 5%, 7.5% and 10% were prepared at a constant kaolin-to-PA mass ratio of 3:7.The microstructure, chemical compatibility, thermal conductivity, specific heat capacity and latent heat were comprehensively characterized.The layered and porous structure of kaolin and MWCNT enabled favorable encapsulation of PA, and only physical interactions occurred among components, guaranteeing superior chemical stability.With the increase of MWCNT content, the specific heat capacity and latent heat gradually decreased, whereas thermal conductivity exhibited a monotonic increase.The SSPCM with 10% MWCNT possessed a thermal conductivity of 1.88 W/m•K, which was 5 times higher than that of pure PA.Numerical investigation on a finned latent heat thermal energy storage (LHTES) device indicated that MWCNT incorporation effectively reduced thermal energy storage duration and elevated energy storage efficiency.