DCMD and VMD systems and methods for use in desalination applications are provided. The DCMD and VMD systems employ coated porous hydrophobic hollow fiber membranes. The coatings advantageously function to essentially eliminate pore wetting of the membrane, while permitting substantially unimpeded water vapor permeance through the fiber walls. The DCMD and VMD membranes are characterized by larger fiber bore diameters and wall thicknesses. The membranes substantially reduce the loss of brine sensible heat, e.g., heat loss via conductive heat flux through the membrane wall and the vapor space and, in exemplary embodiments, the brine-side heat transfer coefficient is dramatically enhanced by horizontal/vertical cross flow of brine over the outside surface of the coated fibers. Superior water vapor fluxes are achieved with the systems and methods.