A composite phase change material thermal buffer based on porous metal foam and low-melting-temperature metal alloy

摘要

Composite phase change materials consisting of a high-latent-heat phase change material (PCM) embedded in a high-thermal-conductivity matrix are desirable for thermally buffering pulsed heat loads via rapid absorption and release of thermal energy at a constant temperature. This paper reports a composite PCM thermal buffer consisting of a Field's metal PCM having high volumetric latent heat (315 MT/m~3) embedded in a copper (Cu) matrix having high intrinsic thermal conductivity [384 W/(mK)]. We demonstrate thermal buffer samples fabricated with Cu volume fractions from 0.05 to 0.2 and sample thicknesses ranging between 1 mm and 4 mm. Experiments coupled with finite element method simulations were used to determine the figures of merit (FOMs), cooling capacity η_(eff), energy density E_(eff), effective thermal conductivity k_(eff), and the buffering time constant τ. The cooling capacity was measured to be as high as η_(eff) = 72 ± 4 kJ/(m~2 · K~(1/2) · s~(1/2)) for the 1.45 mm thick thermal buffer sample having a Cu volume fraction of 0.13, significantly higher than theoretical values for aluminum-paraffin composites [45 kJ/(m~2 · K~(1/2) · s~(1/2))] or pure paraffin wax [8 kJ/(m~2 · K~(1/2) · s~(1/2))]. Our work develops design guidelines for high-FOM thermal buffer devices for pulsed heat load thermal management.