posted on 2023-05-09, 15:04authored bySuyeon Kim, Seongeun Kang, Joohyung Lee
Colloidal suspensions of thermally conductive particles
in a carrier
fluid are considered promising heat transfer fluids for various thermal
energy transfer applications, such as transportation, plants, electronics,
and renewable energy systems. The thermal conductivity (k) of the particle-suspended fluids can be improved substantially
by increasing the concentration of conductive particles above a “thermal
percolation threshold,” which is limited because of the vitrification
of the resulting fluid at the high particle loadings. In this study,
eutectic Ga–In liquid metal (LM) was employed as a soft high-k filler dispersed as microdroplets at high loadings in
paraffin oil (as a carrier fluid) to produce an emulsion-type heat
transfer fluid with the combined advantages of high thermal conductivity
and high fluidity. Two types of the LM-in-oil emulsions, which were
produced via the probe-sonication and rotor–stator homogenization
(RSH) methods, demonstrated significant improvements in k, i.e., Δk ∼409 and ∼261%, respectively,
at the maximum investigated LM loading of 50 vol % (∼89 wt
%), attributed to the enhanced heat transport via high-k LM fillers above the percolation threshold. Despite the high filler
loading, the RSH-produced emulsion retained remarkably high fluidity,
with a relatively low viscosity increase and no yield stress, demonstrating
its potential as a circulatable heat transfer fluid.