Characterization of evaporator and condenser thermal resistances of a screen mesh wicked heat pipe

The heat transfer mechanisms in the condenser and evaporator sections of a copper-water wicked heat pipe with 3 layers of screen mesh were investigated experimentally. The individual condenser and evaporator thermal resistances were measured using thermocouples on the outer wall and within the core of the heat pipe. The heat transfer in the condenser section was found to be only by conduction. In the evaporator, however, either conduction or boiling heat transfer can occur. The transition between the two modes was found to be dependent on the vapor pressure and heat flux, and was reasonably well predicted by the bubble nucleation criterion outlined by Van Stralen and Cole [S. Van Stralen, R. Cole, Boiling Phenomena, vol. 1, McGraw-Hill Inc., 1979]. The experimental data for the boiling heat transfer in the evaporator was well correlated by [St][Pr]0.6[Np]0.2=0.13[Re]−1.43. A composite heat transfer model for the heat pipe is proposed that considers both conduction and boiling heat transfer in the evaporator.