Abstract: An apparatus for removing water vapor from a feed gas is provided that comprises a membrane housing, a membrane that divides a first pressure side and a second pressure side of the membrane housing, a feed gas inlet and outlet on the first pressure side, a sweep gas inlet and outlet on the second pressure side, a sweep gas flow regulator, and a pump. In some embodiments the feed gas can be at ambient pressure and a pressure drop across the membrane can be less than about 1 atm.

Abstract: An apparatus for removing water vapor from a feed gas is provided that comprises a membrane housing, a membrane that divides a first pressure side and a second pressure side of the membrane housing, a feed gas inlet and outlet on the first pressure side, a sweep gas inlet and outlet on the second pressure side, a sweep gas flow regulator, and a pump. In some embodiments the feed gas can be at ambient pressure and a pressure drop across the membrane can be less than about 1 atm. In some embodiments the sweep gas can be a portion of the feed gas exiting the first pressure side. Some embodiments are part of air conditioning, drying, or water recovery systems. Additionally, some embodiments achieve dew points of less than 0° C. and dehumidification efficiencies of 200% to 600%.