Indirect evaporative cooler using membrane-contained, liquid desiccant for dehumidification

A mass and heat transfer assembly for use in an evaporative cooler, comprising:

• a first stack comprising an upper membrane, a lower membrane, and a separation wall between the upper and lower membranes, the upper and lower membranes being permeable to water in vapor form and the separation wall being substantially impermeable to liquid and vapor;
• a second stack comprising an upper membrane, a lower membrane, and a separation wall between the upper and lower membranes, the upper and lower membranes being permeable to water in vapor form and the separation wall being substantially impermeable to liquid and vapor;
• and
• a third stack comprising an upper membrane, a lower membrane, and a separation wall between the upper and lower membranes, the upper and lower membranes being permeable to water in vapor form and the separation wall being substantially impermeable to liquid and vapor;
• wherein the first stack and second stack are spaced apart to define a flow channel for receiving a first stream of air and wherein the second and third stack are spaced apart to define a flow channel for a second stream of air.

A method of conditioning a process air, comprising:

• first directing the process air through a first flow channel;
• second directing a stream of a liquid desiccant adjacent a wall of the first flow channel, the liquid desiccant being separated from the process air in the first flow channel by a membrane that contains the liquid desiccant and allows water vapor from the process air to flow into the liquid desiccant, whereby the process air is dehumidified;
• concurrently with the first and second directing, third directing a stream of purge air through a second flow channel proximate to the first flow channel, the purge air being at a temperature lower than at least a portion of the process air;
• and
• concurrently with the first, second, and third directing, fourth directing a stream of liquid coolant adjacent a wall of the second flow channel, the liquid coolant being separated from the purge air in the second flow channel by a membrane that contains the liquid coolant and allows vapor from the liquid coolant to flow into the purge air, whereby heat is released from the liquid coolant and the process air is cooled concurrent with the dehumidification.

An indirect evaporative cooler for cooling a stream of inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air, comprising:

• a first flow channel for receiving the stream of inlet supply air;
• and
• a second flow channel adjacent to the first flow channel and for receiving the stream of exhaust air at a temperature lower than the first temperature;
• wherein the second flow channel is defined in part by a sheet of a membrane at least partially permeable to water vapor,
• wherein the stream of liquid coolant flows on a side of the membrane opposite the second flow channel, and
• wherein the exhaust air comprises a portion of the stream of inlet supply air entering the second flow channel at about the second, lower temperature.

An indirect evaporative cooler for cooling a stream of inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air, comprising:

• a first flow channel for receiving the stream of inlet supply air;
• and
• a second flow channel adjacent to the first flow channel and for receiving the stream of exhaust air at a temperature lower than the first temperature;
• wherein the second flow channel is defined in part by a sheet of a membrane at least partially permeable to water vapor,
• wherein the stream of liquid coolant flows on a side of the membrane opposite the second flow channel, and
• wherein the stream of inlet supply air flows in a first direction in the first flow channel and the stream of exhaust air flows in a second direction in the second flow channel, the second direction being in at least one of cross or counter to the second direction.