Proposal of a new surfactant for CuO/water nanofluids: Optimization of surfactant ratio and ultrasonication time

This study investigates the influence of different CuO mass ratios, Darvan C-N surfactant ratios, and ultrasonication times on the stability of CuO/water nanofluids. Various CuO mass ratios (%1, %2 and %3) and Darvan C-N surfactant ratios (%0.5, %1 and %1.5), which were used for the first time for CuO/water nanofluids, were employed for nanofluid synthesis. Three different ultrasonication times (30, 60 and 90 min) were applied for each mass ratio and surfactant ratio. The sedimentation behavior of 27 different nanofluids was measured at 5-h intervals over a 360-h period. Optimum surfactant ratios and ultrasonication times for 1%, 2% and 3% CuO mass ratios were determined as 1%-30 min, 1%-60 min and 1%-60 min, respectively. Subsequently, thermal conductivity measurements were conducted within the range of 25-60 degrees C for the determined optimal conditions and modeled using artificial neural networks (ANN). Finally, a new thermal conductivity correlation based on mass ratio and temperature was proposed, with an R value of 0.9952 and a deviation from experimental values of 1.56%. The findings provide valuable insights into optimizing the stability and thermal conductivity of CuO/ water nanofluids.