Phase Change Slurries: Next-Gen Cooling

Phase change slurries (PCS) are a class of advanced heat transfer fluids that exploit latent heat absorption during solid-to-liquid phase transitions of microencapsulated particles suspended in a carrier fluid.

How They Work

Micro-encapsulated phase change material (PCM) particles — typically paraffin wax or salt hydrates — are suspended in water or glycol. As the slurry absorbs heat, the PCM cores melt, storing energy as latent heat. This dramatically increases the effective heat capacity of the fluid without changing its bulk temperature.

Advantages

• 2–4× higher effective specific heat than water alone
• Near-isothermal heat absorption (temperature buffering)
• Compatible with existing pumped-loop infrastructure
• Reusable — PCM re-solidifies when cooled

Challenges

• Higher viscosity increases pumping power
• Capsule degradation over thermal cycling
• Narrow operating temperature window
• Cost and availability of microencapsulated PCM

Other Unique Cooling Phenomena

• Electrohydrodynamic (EHD) cooling – electric fields drive ionic wind for silent, no-moving-parts convection.
• Thermoelectric (Peltier) cooling – solid-state heat pumping below ambient.
• Jet impingement – high-velocity fluid jets targeted at hot spots.
• Spray cooling – thin-film evaporation for extreme heat fluxes (>100 W/cm²).

For a numerical study of channel geometry and slurry mixing, read how herringbone microchannels distribute heat through a phase-change slurry, with flow animation, schematics, and thermal-hydraulic trade-offs.