Question

Why ultrasonication is used to prepare nanofluids?

Answer 1

Nanofluids of CuO and Al2O3with 0.25%, 0.5%, 0.75% and 1.0% (by wt.) of nanoparticles are prepared using probe sonication process. In the preparation of nanofluid probe sonication process is used in which the probe of sonicator is directly inserted into the mixture of nanoparticles and base fluid of distilled water, and energy is transferred in the form of ultrasonic waves to the fluid mixture and disperse the nanoparticle agglomerations and the fluid is thoroughly mixed and homogenised.

The properties viz., pH value, TDS and conductivity are tested before use and after use in a heat transfer appliance named Natural circulation loop operated at various temperatures. The temperature effects on the properties of the nanofluid in the heat transfer appliance are studied. The nanofluid prepared by CuO nanofluid has less affected by temperature than the Al2O3 nanofluid. Due to this, the CuO nanoparticles less settled than the Al2O3nanoparticlesin nanofluid and hence showed good thermal performance in the heat transfer appliance operated at various temperatures.

Nanofluid samples are prepared by adjusting pH value less than seven and were used in the heat transfer device. The effect of temperature on the properties are tested. Separate nanofluid samples were prepared without adjusting the pH values. Such a samples have the pH value above seven. The properties were tested and analysed for the effect of pH on properties of the fluid.