Development and assessment of ceria-propylene glycol nanofluid as an alternative to propylene glycol for cooling applications

Spherical, crystalline ceria nanoparticles of 18-25 nm were synthesized from cerium nitrate precursor. The dispersion of as-synthesized ceria nanoparticles in propylene glycol was achieved through extended probe ultrasonication for 14 h, leading to ceria-propylene glycol nanofluids. The influence of nanoparticle concentration (0-1 vol.%) and temperature on viscosity and thermal conductivity of ceria-propylene glycol nanofluids were investigated. Our data indicate that the higher thermal conductivity enhancement at elevated temperatures (18.8% at 80 °C for 1 vol.% nanofluid) can be attributed to the particle clustering and Brownian-motion induced microconvection. Ceria nanoparticles interact with propylene glycol leading to disturbance in hydrogen bonding network prevalent in propylene glycol. This resulted in lower viscosity of 0.5 vol.% and 1 vol.% ceria-propylene glycol nanofluids than propylene glycol over a wide range of temperatures. The heat absorption by ceria-propylene glycol nanofluids under transient, natural convective heat transfer conditions increased with ceria nanoparticle concentration. Hence ceria-propylene glycol nanofluids are suitable for cooling applications.