Expanded graphite nanoparticles-based eutectic phase change materials for enhancement of thermal efficiency of pin–fin heat sink arrangement

Abstract

This experimental work foresights the synthesis and characterization of the expanded graphite (EG) enhanced organic-organic eutectic PCM (EGePCM) with different weight percentages of the EG (ϕ = 1–5 %). In particular, the expanded graphite nanoparticles were exfoliated from the graphite flakes by acid protonation followed by extraction from the traditional co-precipitation synthesis. A series of EGePCM nanocomposites were fabricated through the homogeneous suspension of EG nanoparticles in the eutectic mixture (1:1) of organic PCM. The surface texture, physical morphology and chemical interaction of individual elements present inside the nanocomposites were thoroughly examined by FTIR, XRD, SEM, and FESEM. Conversely, the physical attributes, thermal stability, thermal degradation, and charging-discharging performance were also investigated. The EGePCM nanocomposite with 3 wt% of EG nanoparticles expresses a favourable increase of thermal conductivity by 232.24 %, with a nominal reduction in the latent heat storage capacity (176.5 J/g) of the PCM. In conjunction with the thermal attribute intensification, the incorporation of EG in nanocomposite reduces the supercooling degree to 9.16 °C with a phase change enthalpy of 174.8 J/g in cooling and 176.5 J/g in heating stage for 3 wt% of EG. A comprehensive experimental methodology was employed to investigate the thermal enactment features of different EGePCM nanocomposites inside a regular pin–fin arrangement imperilled with steady-state heat transfer. The effectiveness of the cooling rate was also encompassed under a variable range of heat flux (1.6–3.2 KW/m2) and EGePCM mixture (ϕ = 1–5 %). The heat transfer effectiveness was optimal at a mass fraction of 5 wt%, resulting in a 30 °C base temperature drop of the heat sink and a decrease in the charging-discharging duration of the nano PCM composite. This observation suggests an improvement in the thermal conductivity of the system with an incorporation of high thermal conductive EG nanoparticles. The enhanced thermal performance and notable thermal, physical and chemical stability facilitate the phase transition progression and render it highly advantageous for electronic or micro-electronic thermal cooling applications.