Experimental study of pool boiling on hydrophilic and hydrophobic thin films deposited on copper surfaces using atmospheric cold plasma

Abstract

Critical heat flux (CHF) is considered a safety constraint in various types of thermal systems. Enhancement of CHF threshold brings about noticeable improvements in safety measures and overall economic structures. In this study, SiO2-like hydrophilic and polymer-like SiOxCyHz hydrophobic thin films are deposited on copper surfaces using atmospheric pressure plasma enhanced chemical vapor deposition of Ar/HMDSO in the presence/non-presence of O2. Pool boiling experiments are performed on prepared surfaces under atmospheric saturation conditions. The aim is to investigate the effect of surface modifications on CHF and such other key parameters as the onset of nucleate boiling (ONB) as well as heat transfer coefficient (HTC). Scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDX), and contact angle measurement are employed to determine the morphology and composition of the thin films. Experimental results demonstrate that the hydrophilic films deposited on surfaces give rise to significant increases in CHF and HTC compared to bare surfaces. Also observed was a reduction of up to 53% in the ONB of the hydrophobic films deposited on copper surfaces.