A three-way heat exchanger for a liquid desiccant air-conditioning system, the three-way heat exchanger comprising a plurality of panel assemblies, each panel assembly comprising: a frame bordering a given space, the frame including a liquid desiccant inlet port , a liquid desiccant outlet port , a heat transfer fluid inlet port , and a heat transfer fluid outlet port ; two plates , each having an outer surface and an inner surface, wherein the plates are joined to opposite sides of the frame to define a heat transfer fluid channel in the given space defined by the inner surfaces of the plates and the frame , wherein the heat transfer fluid inlet port and the heat transfer fluid outlet port are in fluid communication with the heat transfer fluid channel ; and two microporous sheets permitting transfer of water vapor therethrough, each microporous sheet covering the outer surface of a different one of the two plates and defining a liquid desiccant channel between the microporous sheet and the outer surface of the plate , wherein the liquid desiccant inlet port and the liquid desiccant outlet port are in fluid communication with the liquid desiccant channel; wherein the liquid desiccant inlet ports of the frames of the panel assemblies are aligned to form a liquid desiccant inlet manifold, the liquid desiccant outlet ports of the frames of the panel assemblies are aligned to form a liquid desiccant outlet manifold, wherein the heat transfer fluid inlet ports of the frames of the panel assemblies are aligned to form a heat transfer fluid inlet manifold, and the heat transfer fluid outlet ports of the frames of the panel assemblies are aligned to form a heat transfer fluid outlet manifold; and wherein the plurality of panel assemblies have a stacked arrangement such that a microporous sheet on one panel assembly faces a microporous sheet on an adjacent panel assembly and defines an airflow channel therebetween. a frame bordering a given space, the frame including a liquid desiccant inlet port , a liquid desiccant outlet port , a heat transfer fluid inlet port , and a heat transfer fluid outlet port ; two plates , each having an outer surface and an inner surface, wherein the plates are joined to opposite sides of the frame to define a heat transfer fluid channel in the given space defined by the inner surfaces of the plates and the frame , wherein the heat transfer fluid inlet port and the heat transfer fluid outlet port are in fluid communication with the heat transfer fluid channel ; and two microporous sheets permitting transfer of water vapor therethrough, each microporous sheet covering the outer surface of a different one of the two plates and defining a liquid desiccant channel between the microporous sheet and the outer surface of the plate , wherein the liquid desiccant inlet port and the liquid desiccant outlet port are in fluid communication with the liquid desiccant channel; wherein the liquid desiccant inlet ports of the frames of the panel assemblies are aligned to form a liquid desiccant inlet manifold, the liquid desiccant outlet ports of the frames of the panel assemblies are aligned to form a liquid desiccant outlet manifold, wherein the heat transfer fluid inlet ports of the frames of the panel assemblies are aligned to form a heat transfer fluid inlet manifold, and the heat transfer fluid outlet ports of the frames of the panel assemblies are aligned to form a heat transfer fluid outlet manifold; and wherein the plurality of panel assemblies have a stacked arrangement such that a microporous sheet on one panel assembly faces a microporous sheet on an adjacent panel assembly and defines an airflow channel therebetween. <EOS>