EXPERIMENTAL STUDY OF CONTACT ANGLE AND ACTIVE NULEATION SITE DISTRIBUTION ON NANOSTRUCTURE MODIFIED COPPER SURFACE IN POOL BOILING HEAT TRANSFER ENHANCEMENT

A comparison study of heat transfer coefficient (HTC) and critical heat flux (CHF) on nanostructure modified Cu surfaces in terms of nucleation site density and contact angle that significantly influence pool boiling heat transfer of water on copper surfaces has been conducted. The nanostructures on copper surfaces have been created by an electrodeposition technique. It has been found that the nanostructured copper surfaces show an increase in the CHF of up to 142% and an increase in the HTC of 33% over that of a mirror-finished plain copper surface. Calculations for nucleation site density and active nucleation site diameter reveal a direct correlation between these factors and the HTC, as well as the CHF. More interestingly, a contact angle study and active nucleation site calculation on the tested surfaces show that there are strong connections between the contact angle reduction and active nucleation site increase, and CHF enhancement and HTC raise, which confirm the contact angle mechanism of CHF and active nucleation site mechanism of HTC on nanoscale surface structures.