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.
Chen Yanan,Ge Sijia,Li Hong,Liu Ling,Hu Xueyan,Hu Peiying,Wu Xiaodong,Cui Sheng,Wang Jin
Aramid nanofiber (ANF) aerogels possess excellent flexibility and favorable mechanical properties. However, their limited infrared transmittance, relatively high thermal conductivity, and low flame retardancy significantly restrict their application in passive thermal management. In this study, a microphase separation strategy is employed to fabricate ANF@Al 2 O 3 composite aerogels, enabling a structural transition from a uniform-pore to a slit-pore morphology. Benefiting from the light regulation by the slit pore structure and the flame-retardant effect of Al 2 O 3 , the prepared ANF@Al 2 O 3 aerogels material have ultra-low thermal conductivity (as low as 30 mW/(m·K)), high infrared transmittance (near-infrared transmittance > 90%), and excellent fire resistance (enhanced combustion endurance), which is able to meet the various needs of passive heating in intelligent buildings. Under outdoor solar irradiation (29.3 °C, 677.6 W/m 2 ), the ANF@Al 2 O 3 composite aerogel achieves an internal temperature of 50.46 °C, achieving a relative heating enhancement of 72.22%. This study provides a strategy for designing high-performance composite aramid aerogels and holds great promise for mild thermal insulation applications with potential relevance to aerospace, energy-efficient buildings, and smart thermal management systems. Graphical
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