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.