  We demonstrate that smooth and flat surfaces combining hydrophilic and
hydrophobic patterns improve pool boiling performance. Compared to a
hydrophilic surface with 7 degree wetting angle, the measured critical heat
flux and heat transfer coefficients of the enhanced surfaces are up to
respectively 65 and 100% higher. Different networks combining hydrophilic and
hydrophobic regions are characterized. While all tested networks enhance the
heat transfer coefficient, large enhancements of critical heat flux are
typically found for hydrophilic networks featuring hydrophobic islands.
Hydrophilic networks indeed are shown to prevent the formation of an insulating
vapor layer.
