Heat transfer characteristic of a closed two-phase
thermosiphon with enhanced boiling surface is studied and
compared with that of a copper mirror surface. Two-phase cooling
improves heat transfer coefficient (HTC) a lot compared to singlephase
liquid cooling. The evaporator surfaces coated with a
pattern of hydrophobic circle spots (non-electroplating, 0.5 2
mm in diameter and 1.5 3 mm in pitch) achieve very high heat
transfer coefficient and lower the incipience temperature
overshoot using water as the working fluid. Sub-atmospheric
boiling on the hydrophobic spot-coated surface shows a much
better heat transfer performance. Tests with heat loads (30 W to
260 W) revealed the optimum thermosiphon performance.
Hydrophobic circle spots coated surface with diameter 1 mm,
pitch 1.5 mm achieves the maximum heat transfer enhancement
with the boiling thermal resistance as low as 0.03 K/W.
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .