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This study investigates the effect of water flowrate on the copper alloy corrosion by using a hydrodynamic corrosion test in operating conditions of water flow rate range between 0.05 and 3.5 m/s, the temperature range between 20 and 45 °C. Dissolved oxygen concentration was in the range between 6.1 and 9.2 mg/l. The effects of water properties density, viscosity, and the tube geometric dimensions also considered. Corrosion rate determined by the weight loss calculation method and the tested samples microstructures characterized using FESEM. The results showed that the copper surface layer more affected by water flow at the beginning of turbulent flow condition, while at fully developed turbulent flow condition the surface covered with a fixed oxide layer. Therefore, corrosion found to be at higher rates during the initial stage of the turbulent flow condition, but it reduced at fully developed turbulent flow conditions at higher water velocity. These results indicate that the overall flow rate conditions, which include physical properties of the fluid, hydrodynamic parameters, and the geometric tube dimensions, have the dominant influence on corrosion rate.

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The high gas-sensing performance of semiconductors is mainly due to the high surface-to-volume ratio because it permits a large exposed surface area for gas detection. This paper presents an evaluation study for the effects of nano-CuO coating parameters on the CO gas-sensing performance. The effects on gas-sensing performance and heat transfer efficiency of CuO coating were evaluated by investigating the effects of coating parameters (concentration, temperature, and solution speed) on thickness, grain size, and porosity. The CuO nanoparticle coatings were synthesized using the oxidation method at various operating conditions. Coating characteristics were investigated using X-ray diffraction, energy dispersive X-ray Spectroscopy, field emission scanning electron microscopy, and electrical resistivity meter. The average coating thickness, grain size, and porosity were around 13 μm, 48 nm, and 30%, respectively. The thermal transfer and gas-sensing properties of CuO coating were evaluated according to the total surface area of the coating formed at various operating conditions. The gas-sensing and thermal transfer performance were obtained from the optimization of coating parameters based on the coating morphology to achieve the highest contact surface area. The coating’s surface area was increased by 350 times, which improved the heat transfer efficiency of 96.5%. The result shows that the coating thickness increased with the increase in solution concentration and decrease the temperature. The results also show that the sensitivity of the coating for CO gas was increased by 50% due to the reduction of coatings grain size.