Synthesis and Heat Transfer Performance of Phase Change Microcapsule Enhanced Thermal Fluids

Abstract

Polyalphaolefins (PAOs) are widely implemented for electronics cooling, but suffer from a low thermal conductivity of about 0.14 W/mK. However, adding thermally conductive, phase-change-material (PCM) particles to a PAO can significantly improve the fluid thermal properties. In this paper, PCM microcapsules and silver-coated PCM microcapsules were synthesized using the emulsion polymerization method and the thermal performance of PCM fluids was studied in a microchannel heat sink and compared with that of the pure PAO. A test loop was designed and fabricated to evaluate the synthesized PCM fluids and it was found that fluid with uncoated PCM microcapsules has a 36% higher heat transfer coefficient than that of the pure PAO. Additionally, the heat transfer coefficient of PCM fluids with silver-coated PCM microcapsules was also 27% higher than that of pure PAO, but lower than that of fluids with uncoated PCM microcapsules. The thermal resistance of the uncoated PCM fluid was about 20% lower than that of the pure PAO fluid at the same pumping power, despite the PCM fluid's higher viscosity. Pumping tests were run for several hours and showed no evidence of particle accumulation or settling within the heat transfer loop.