Thermal-hydraulics performance and stability two-phase flow using Al2O3 nanofluids in an open natural circulation loop

The thermal-hydraulics performance and stability flow using Al2O3 nanofluids in an open natural circulation loop has been investigated. Experiments were conducted with a gradual increase in heating power from 880
up to 1350
. The working fluid used Al2O3 with variations of 0.025
, 0.05
, and 0.1
. The two-phase flow pattern was observed using 1 fps range macro photos. PSD (power spectral density) and DWT (discrete wavelet transform) signal processing were used to analyze the thermal-hydraulics performance and flow stability that occurred during the experiments. The result shows that there are three types of oscillations were found in the observations based on heating power, intermittent oscillation with expulsion-refill-incubation stages, sinusoidal oscillation with expulsion and refill stages, and high subcooling stable flow circulation with only one continuous refill stage. PSD and DWT analysis provided solid agreement between the temperature signal and thermal-hydraulics performance and flow stability.