Abstract: The unsaturated heat and mass transfer characteristics in the porous wick of a CPL evaporator under different geometrical structures and heat flux have been numerically studied based on the field synergy principle.The calculation results indicated that the heat flux and geometrical structures,such as fin width and wick height,exerted great influence on the heat transfer of a CPL evaporator.It demonstrates that the field synergy principle can be applied to optimize the configuration of the evaporator and consequently to enhance the heat transfer in a CPL evaporator.