Oriented thermal conductive and dimensionally stable phase change composite for hot-side thermal management of thermoelectric coolers

This paper reports a novel high-performance phase change composite (PCC) featuring anisotropic high heat conduction ability and dimensionally stable properties for the hot-side thermal management of thermoelectric coolers. This composite is developed by employing paraffin as the phase change material and expanded graphite/phase change polymer (EG/PCP) binary networks as the supporting skeleton. The obtained paraffin/EG/PCP composite demonstrates an axial thermal conductivity of 2.62–6.11 W·m −1 ·K −1 and an even higher radial conductivity of 2.93–12.99 W·m −1 ·K −1 because the graphite sheets in the EG are aligned along the radial direction. The axial size of the composite presents a dimensionless increment of less than 0.0179 when the temperature increases from 25 to 80 °C, whereas the value for the radial size is 0.00284. The latent heat of the as-prepared composite reaches a relatively high level (128–175 kJ·kg −1 ) when the paraffin content is only 50–70 wt% because PCP in the composite also presents heat storage capability. Application of this composite in a thermoelectric cooling system for hot-side passive thermal management leads to a 1.55 °C decrease in the minimum temperature of the cold side compared to using bare substrates on the hot side. The running period of the composite integrated-system with a coefficient of performance (COP) higher than 0.2 is more than twice length compared to the running period of the system with bare substrates. This study sheds light on the development of PCCs with good comprehensive properties, which are promising for use in the thermoelectric field.