Abstract
This study investigates the wetting behavior, condensation dynamics, and
heat transfer performance of stainless steel (SS), graphite composite
(GC), and a modified superhydrophobic graphite composite (SHGC) under
varying relative humidity (RH) conditions. Static and dynamic contact
angle measurements revealed significant differences in wetting behavior,
with SS demonstrating hydrophilic properties ( 6 5 ◦ ± 7 ◦ ), GC
exhibiting hydrophobicity ( 9 7 ◦ ± 2 ◦ ), and SHGC achieving
superhydrophobicity ( > 1 7 0 ◦ ). Condensation experiments
at 100% RH showed that GC and SHGC outperformed SS in both heat flux
densities and heat transfer coefficients (HTCs) at higher RH levels. At
100% RH, GC achieved the highest heat transfer coefficient of 3 0 9 W /
m 2 K ± 2 . 3 % , followed by SHGC 2 4 4 W / m 2 K ± 2 . 9 % , while
SS remained at 1 3 4 W / m 2 K ± 6 . 5 % compared to 60 % and 80 %
RH. Computational fluid dynamics simulations confirmed the experimental
findings, validating laminar flow and demonstrating strong agreement
with measured vapor-side HTCs. The reduced performance of SHGC compared
to GC is attributed to the Wenzel pinning effect and additional thermal
resistances. These findings highlight the need for further optimization
of surface structure and coating uniformity to enhance the condensation
heat transfer performance of SHGC in practical applications.