High Pressure Pool Boiling on a Hydrophobic Surface

The purpose of this research is to investigate heat transfer enhancement on a Teflon© coated hydrophobic surface compared to a plain copper surface at increased pressures with deionized water. Previous research has shown that hydrophobic surfaces promote bubble nucleation and increase heat transfer coefficient. However, heat transfer enhancement on hydrophobic surfaces at high pressures is not widely studied. To carry out the experiments, we designed and fabricated a special experimental facility that will withstand the high pressures (up to 20 bar/ 290 psi) and high temperatures (270 °C /518 °F). A copper surface is coated with Telfon© AF solution using dip coating. Boiling tests are done on a plain copper surface and the Teflon© coated hydrophobic surface at elevated pressures. Test results show that both high pressure and hydrophobic coating will enhance the boiling performance. Bubble nucleation on the hydrophobic surface starts at lower heat fluxes. The effect of pressure on the Teflon© coated surface is smaller compared to the plain copper surface. Approximately 40% of increase of heat transfer coefficient is observed for the Teflon© coated copper surface at 15 psig.