Fabrication of Zn1-XCuXO nanoparticles and investigation of their effect on the thermal conductivity of nanofluids

The main purpose of this research is to investigate the effect of doped nanoparticles on the thermal conductivity of nanofluids. ZnO, CuO, and Zn1-XCuXO doped nanoparticles were first fabricated by the sol-gel auto-combustion method using glycine as fuel with different molar ratios of glycine/metal ions. Different values of X = 0.02, 0.03, 0.04, 0.06, 0.07, and 0.08 were used to fabricate the Zn1-XCuXO doped nanoparticles. The X-ray diffraction patterns showed that the substitution of Zn atoms with Cu atoms was completed for X = 0.02 and 0.03, so X = 0.03 was obtained as the solubility limit for fabricating Zn1-XCuXO doped nanoparticles. The Zno, CuO, and Zn0.97Cu0.03O doped nanoparticles were then used as an additive to prepare ethylene glycol-based nanofluids with different nanoparticle concentrations. The results showed the highest observed thermal conductivity enhancement was 12.5 % and related to the nanofluid containing Zn0.97Cu0.03O doped nanoparticles at a concentration of 0.5 wt%. Moreover, adding Cu to the ZnO structure increased the thermal conductivity of the ethylene glycol-based nanofluid containing Zn0.97Cu0.03O doped nanoparticles due to its high thermal conductivity.