A numerical comparison of the thermal performances of nano-PCM heat sinks with Fe3O4, MgO, ZnO and xGNP nanoparticles: Key role of increased thermal conductivity

• PCM with heat sink is used for electronic cooling, for its high heat absorption feature during phase transition. • Although PCMs have high heat storage capacity, they have low thermal conductivity. • Thermal conductivity of a PCM can be improved by addition of nanoparticles. • Adding nanoparticles improved the melting rate and thermal conductivity of Nano based PCM. • The highest thermal conductivity, at high PCM temperatures, was obtained by using the nanoparticle with the highest volumetric heat capacity and t h e l o w e s t d i a m e t e r . A Nano-PCM heat sink model for electronic device cooling was numerically analyzed. RT-35HC was selected as the PCM. Nano-PCMs were created by using different types of nanoparticles, such as Fe 3 O 4 , MgO, ZnO and xGNP, added into the PCM at volume fractions of 0.02, 0.04 and 0.06. Nano-PCM heat sinks were numerically simulated in ANSYS under heat fluxes of 3, 4 and 5 kW/m 2 . Enthalpy-porosity technique was used and UDFs were set in ANSYS for altering the Nano-PCM’s thermal conductivity and dynamic viscosity. Results indicate that, by nanoparticles addition, PCM’s melting time and heat sink temperature decreased. The reduction in melting time of Nano-PCM were 6.19 %, 10.8 %, and 14.56 % for v o l u m e f r a c t i o n s 0.02, 0.04, and 0.06 for Fe 3 O 4 , respectively, relative to PCM only. Initially, the best thermal conductivity was obtained with utilization of xGNP (15 nm), however, with rising temperature over time, thermal conductivity of Nano-PCM with Fe 3 O 4, (10 nm) became the highest. The findings suggest that the lowest base temperature was attained by using Fe 3 O 4 , which has the optimum thermal and physical properties, in a 0.02 vol fraction. A detailed and comparative evaluation was provided by addressing various nanoparticles or different sizes of the same nanoparticle for Nano-PCM heat sink.