Direct exchange (DX) water evaporators with internal capillary structure have been developed and tested. The performances of three evaporators, two with internal open grooves (IOG) and one with a layer of sintered metal powder, are presented for various air velocities and temperatures. The internally powder coated (IPC) evaporator was found to offer the best performance, and achieved an average evaporation capacity of 700 W. The two IOG evaporators achieved average evaporation capacities of 500 and 300 W, for evaporators having deep and shallow grooves (SG), respectively. The IPC evaporator also had higher boiling and overall heat transfer coefficients compared with the two IOG evaporators.