Gallium–indium nanoparticles as phase change material additives for tunable thermal fluids

Abstract

One of the most critical limitations for high-power electronics today is thermal management and routing thermal energy efficiently away from thermally sensitive components. A potential solution to this problem is the integration of cooling channels in close proximity to thermally sensitive materials for increased heat removal efficiency. These channels typically use single phase fluids (liquid), dual phase fluids (vapor–liquid), or suspended organic/polymer phase change material particles in a fluid (PCM slurry). Expanding upon the latter, this work demonstrates the use of inorganic Ga–In alloy nanoparticles (NPs) suspended in a traditional thermal transport fluid to simultaneously (1) increase the overall thermal diffusivity of the fluid and (2) serve as a cyclable solid–liquid PCM slurry which provides a thermal sink that is definable over a wide range of relevant temperatures for power electronics. Herein, the relationship between particle size, composition, and volume fraction are explored as they relate to the PCM slurry optimum working temperature, total energy absorption, and rheological properties. A mere 0.10 volume fraction of Ga–In NPs is reported to increase the overall thermal conductivity by nearly 50% and can be optimized to melt at temperatures as low as −46 °C. Based on thermal measurements, it was observed that these nanoparticle systems lack the preference to form αGa and have a large thermal hysteresis due to exhibiting extreme undercooling, with crystallization temperatures near −130 °C, enabling opportunities within extreme environments such as space applications or low temperature imaging systems.