Hybrid NiFe2O4-NiCO4O4 nanoparticles-based eutectic phase change materials for enhancement of thermal efficiency of pin-fin heat sink arrangement

This work reports the synthesis and characterization of hybrid nanoparticles-based phase change material (HNbPCM) along with a practical approach in the pin-fin heat sink system. In particular, the hybrids of Nickel cobaltite (NiCO4O4) - Nickel ferrite (NiFe2O4) nanoparticles (NiCo−NiFe) were synthesized by traditional sol–gel method. The (HNbPCM) composites were then prepared by suspending the nanoparticles in paraffin wax (PW) and polyethylene glycol-6000 (PEG−6000) eutectic organic PCMs with various weight fractions (ϕ=1%–5%). The surface texture, physical and chemical interaction of hybrid nanoparticles and its dispersion in the HNbPCM composites were comprehensively analyzed. The cyclic thermal stability, thermal conductivity, and charging and discharging of characteristics of the developed nano-composites were also confirmed by transient hot-wire apparatus, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC). A nanoparticles concentration of 3wt% in the HNbPCM shows a promising enhancement in the thermophysical properties. The thermal conductivity of HNbPCM was improved by 304.4% by adding hybrid NiCo-NiFe nanoparticles with ϕ=5%. In addition to thermal conductivity augmentation, nanoparticles enriched HNbPCM altered the phase transition process and eliminated super-cooling by maintaining the high latent heat capacity of 188.95J/g in the melting phase and 189.70J/g in crystallization phase. A systematic experimental framework of thermal performance characteristics for HNbPCM composite in rectangular pin-fin heat sink subjected to steady state heat transfer for effective and reliable cooling was also studied. The cooling of heat sinks was under testimony at different power inputs, volume fractions and modes of heat transfer in two distinct case studies with and without PCM. A volume fraction of 3wt% shown the best thermal performance with a heat transfer enhancement up to 3.2kW/m2 with 18°C temperature reduction in operational time, specific heat capacity, and thermal conducting ability. An improved thermal performance shows considerable thermal and chemical stability, which can expedite the transition process and makes it a desirable prospect for superior thermal energy storage (TES) applications.