Pool boiling heat transfer of Novec 649 on sandblasted surfaces

Pool boiling represents a potentially efficient mechanism for thermal management of power electronic components. The present study investigates pool boiling heat transfer using Novec 649 on copper substrates with varying surfaces. Sandblasting, which is a relatively simple surface modification technique, has been used to obtain different copper surface roughness levels ranging from 0.1 µm to 9 µm arithmetic mean surface roughness values. The effects of surface modifications and orientation on boiling heat transfer coefficient (HTC), and critical heat flux (CHF), of Novec 649 have been experimentally investigated by performing pool boiling experiments at atmospheric pressure and saturation pool temperature. The experimental results showed that the size and orientation of the boiling surface do not have a significant impact on the CHF, whilst the HTC improves in the nucleate boiling regime with vertical orientation. In addition, for the range of surface roughness investigated improvements of ∼3X and ∼1.5X in HTC and CHF, respectively, were found relative to the original smooth surface.The HTC in the film boiling regime relative to the nucleate boiling regime was also quantified and found to be ∼20X for our geometries.