New hybrid suspension of MEPCM/GO particles with enhanced dispersion stability and thermo-physical properties

A new type of hybrid suspension comprising microencapsulated phase change material (MEPCM) spheres and graphene oxide (GO) nanoplatelets is proposed. The dispersion stability of the MEPCM/GO suspension was guaranteed by precisely adjusting the density of the MEPCM particles, which had n-heptadecane as the core and hexanediol diacrylate polymer as the shell. The MEPCM particles with excellent monodispersity were fabricated successfully using a co-flowing microfluidic method. The micromorphology of the hybrid MEPCM/GO suspension, measured using a transmission electron microscope, showed that the MEPCM particles and GO nanoplatelets were dispersed uniformly in the base fluid without aggregation. The high dispersity and stability of the hybrid MEPCM/GO suspension provide basic conditions for regulating its thermo-physical properties. Thermal conductivity, specific heat capacity, and viscosity were measured using a laser-flash analysis device, a differential scanning calorimeter, and a rotational rheometer, respectively. The effects of the concentrations of the MEPCM particles and GO nanoplates were investigated. Results showed that enhanced thermal conductivity and specific heat capacity were achieved for the hybrid MEPCM/GO suspension. This advantage of the hybrid suspension became increasingly obvious as the MEPCM and GO concentrations increased. The viscosity of the hybrid MEPCM/GO suspension changed only slightly with the GO concentration, whereas it increased with the MEPCM concentration, and thus showed a relatively good rheological property. The proposed hybrid MEPCM/GO suspension with enhanced thermo-physical properties possesses immense potential for use as a novel working fluid for high-efficiency heat transfer.