Experimental study on boiling heat transfer of γ-Fe${}_2$O${}_3$ nanofluids on a downward heated surface

This investigation reports on the experimental outcomes of the pool boiling heat transfer characteristics, specifically on the downward heated surface, concerning reverse osmosis water and γ-Fe${}_2$O${}_3$ nanofluids. To conduct the pool boiling experiments, γ-Fe${}_2$O${}_3$ nanofluids were prepared with variable concentrations ranging from 2 mg/L to 10 mg/L. Analysis of the experimental data revealed that a concentration of 5 mg/L yielded the greatest enhancement effect on critical heat flux (CHF), with an increase of 13.5 %. However, the results also indicated that excessively high concentrations of nanofluid had a negative impact on CHF enhancement. The impact of nanofluids on heat transfer performance was investigated by analyzing the observed bubble behavior during the boiling process, measuring the drop angle and surface roughness post-experiment, and characterizing the heated surface morphology via scanning electron microscopy (SEM). Through these methods, the underlying mechanism behind the impact of nanofluids on heat transfer performance was identified and analyzed.