Effects of cadmium doping on thermo-physical properties of ZnO nanoparticles and nanofluids for heat transfer applications

The most common method of improving the thermal performance of the conventional fluids is adding the solid particles to the base fluid. This even though increases the thermal conductivity, but in turn increases the viscosity and the risk of sedimentation. Hence alternative methods are required to enhance the thermal performance of the base fluids. One such promising method is doping. In this regard, in this work it is aimed to study the effects of cadmium doping ZnO nanoparticles, which were then analyzed using X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX), and Scanning Electron Microscopy (SEM). Their elemental composition was determined using SEM. XRD was utilized to ascertain the average size of the crystallite. All particles were found to be spherical and the average particle size ranged from 17 to 20 nm. Their thermal features were determined for various temperatures (20°C–60°C) and concentrations (0.1%–0.3%). Outcomes depict that at the highest concentration of the doped ZnO NPs, the thermal conductivity (TC) of the cadmium doped ZnO NFs for the concentration of 0.05% has enhanced by 42% than the base fluid. The TC of the Cadmium doped NFs was also found to be 7% higher than the TC of pure ZnO NFs. Density and viscosity has showed an increasing trend with the rise in the loading of the nanoparticles(NPs) whereas the specific heat has decreased. Doped nanofluids outperformed the ZnO nanofluids in their properties.