Thermal diffusivity measurement of Au nanofluids of very low concentration by using photoflash technique

• New technique was developed to measure thermal diffusivity of liquid.
• It was designed for small volume liquids of low concentration.
• It is suitable for 0.1 mL Au nanofluids in the range of 1.11–3.18 mg/L.
• Thermal diffusivity was found to increase with concentration.
• Smaller nanoparticles also contributed to higher fluid’s thermal diffusivity.

In this paper, the application of photoflash technique to measuring the thermal diffusivity of gold nanofluids of very low concentration at room temperature was presented. The nanofluid samples were prepared from the pulse laser ablation procedure. The thermal diffusivity was obtained by fitting the theoretical temperature signal to the experimental data, and it was found to increase linearly from 1.47 × 10−3 cm2 s−1 to 1.68 × 10−3 cm2 s−1 as the concentration increased from 1.11 mg/L to 3.18 mg/L. The increase in thermal diffusivity in these multidispersed nanofluids was attributed to the higher nanoparticle concentration as well as to the increasing presence of the smaller size nanoparticles.