posted on 2022-12-27, 17:05authored byHannah McPhee, Vikram Soni, Sepehr Saber, Mohammad Zargartalebi, Jason Riordon, Michael Holmes, Matthew Toews, David Sinton
Phase change materials that leverage the latent heat
of solid–liquid
transition have many applications in thermal energy transport and
storage. When employed as particles within a carrier fluid, the resulting
phase change slurries (PCSs) could outperform present-day single-phase
working fluidsprovided that viscous losses can be minimized.
This work investigates the rheological behavior of encapsulated and
nonencapsulated phase change slurries (PCSs) for applicability in
flowing thermal energy systems. The physical and thermal properties
of the PCS candidates, along with their rheological behavior, are
investigated below and above their phase transition points at shear
rates of 1–300 s–1, temperatures of 20–80
°C, and concentrations of 15–37.5 wt %. The effect of
shell robustness and melting on local shear thickening and global
shear thinning is discussed, followed by an analysis of the required
pumping power. A hysteresis analysis is performed to test the transient
response of the PCS under a range of shear rates. We assess the complex
viscoelastic behavior by employing oscillatory flow tests and by delineating
the flow indicesflow consistency index (K) and flow behavior index (n). We identify a viscosity
limit of 0.1 Pa·s for optimal thermal performance in high-flow
applications such as renewable geothermal energy.