Experimental study of CuO/Water nanofluid pool boiling on the copper flat surface and measurement of the critical heat flux

Boiling heat transfer is one of the most applicable heat transfer processes in the industry. In recent years, many studies have been investigated in nanofluid pool boiling field and reported some contradictory results. This research is a qualitative and quantitative investigation to understand the behavior of nanofluid during pool boiling heat transfer. For this purpose, a low concentration (up to 1000mg/l) of CuO-water nanofluid and a copper plate surface heater with a diameter of 10 mm and surface roughness of 7.5 nm were used. CuO-water nanofluids have been created by 40nm nanoparticles and 1 to 1000 mg/l of concentrations are used in this research. The measurement of critical heat flux at different concentrations of nanofluid showed that critical heat flux has improved 92% in optimized concentration of 100 mg/l compared to distilled water. Atomic force microscopy, scanning electron microscopy and contact angle measurements have been done for analyzing properties of surface and nanocoated which are formed after nanofluid boiling. Results demonstrate that there is a positive effect in increasing roughness and a negative impact of thickness enhancement on critical heat flux.