Carbon black nano particle loaded lauric acid-based form-stable phase change material with enhanced thermal conductivity and photo-thermal conversion for thermal energy storage

We report significantly high enhancements in thermal conductivity and photo-thermal conversion for lauric acid-based phase change material (PCM), loaded with carbon black nano particles (CBNP). Addition of 25 wt % calcium carbonate powder to the PCM is found to arrest the material leakage during solid-liquid phase transition and the form-stable PCM showed superior thermal and mechanical properties. Thermal conductivity enhanced by ∼195% for the PCM loaded with 3.5 wt % of CBNP nano-inclusions, which is attributed to the development of interconnected percolation networks during solidification of the PCM. Superior volume filling capability and compressibility of CBNP nano-inclusions further augmented thermal conductivity enhancements in solid state. The micro-scale aggregation phenomena and the formation of quasi-2D percolation networks is observed in real time using timed stamped optical phase contrast video-microscopy. The ∼134% enhancement in photo-thermal conversion is attributed to the augmentation of extinction efficiency of the incident radiation due to multiple scattering from the micro-sized CBNP clusters, within the PCM host matrix. The excellent photo-thermal efficiency, high thermal conductivity, low cost and enhanced form-stability of the CBNP loaded PCMs at elevated temperature make them economically attractive choice for latent heat thermal energy storage applications. [Display omitted] •Enhanced thermal conductivity (TC) in PCM loaded with CBNP is observed.•TC enhanced by ∼195% for 3.5 wt % of CBNP loading.•Superior volume filling capability and compressibility of CBNP caused high TC.•Formation of quasi-2D percolation networks is seen in real time.•∼134% enhancement in photo-thermal conversion for 3.5 wt % CBNP loading.