System and method for efficient air dehumidification and liquid recovery with evaporative cooling
The present invention relates to systems and methods for dehumidifying air by establishing humidity gradients in one or more dehumidification units. Water vapor from relatively humid atmospheric air entering the dehumidification units is extracted by the dehumidification units without substantial condensation into low pressure water vapor vacuum volumes. The water vapor is extracted through water vapor permeable membranes of the dehumidification units into the low pressure water vapor vacuum volumes. The air exiting the dehumidification units is less humid than the air entering the dehumidification units. The low pressure water vapor extracted from the air is compressed to a slightly higher pressure, condensed, and removed from the system at ambient conditions. In addition, each of the dehumidification units may be associated with one or more evaporative cooling units through which the air will be directed, with the evaporative cooling units being upstream and/or downstream of the dehumidification units.
1. A dehumidification system for removing water vapor from an airstream, comprising:
a first and second channel separated by a membrane, wherein the membrane is configured to facilitate removal of water vapor from an airstream flowing through the first channel by facilitating passage of H 2 O from the water vapor to the second channel through permeable volumes of the membrane while substantially blocking all other components of the airstream from passing through the membrane;
a first evaporative cooling unit configured to cool the airstream downstream of the membrane;
a second evaporative cooling unit configured to cool the airstream upstream of the membrane;
a pressure increasing device configured to create a lower partial pressure of water vapor within the second channel than in the first channel, such that the H 2 O moves through the membrane to the second channel, wherein the pressure increasing device is also configured to increase the pressure of water vapor at an outlet of the pressure increasing device to a partial pressure of water vapor in a range suitable for subsequent condensing into liquid water, and
a controller comprising a microprocessor configured to control operations of the dehumidification system.
2. The system of claim 1 , wherein the operations comprise a first evaporative cooling operation provided by the first evaporative cooler, a first dehumidification operation provided by the pressure increasing device, and a second evaporative cooling operation provided by the second evaporative cooler during the operations.
3. The system of claim 2 , wherein the controller is configured to control the operations of the dehumidification system so as to result in psychrometric chart control of the dehumidification system.
4. The system of claim 1 , comprising a condensation device configured to receive water vapor from the pressure increasing device and condense the water vapor into liquid water.
5. The system of claim 4 , comprising a water transport device configured to transport the liquid water from the condensation device.
6. The system of claim 1 , wherein the membrane comprises zeolite.
7. A system, comprising:
a dehumidification unit for removing H 2 O vapor from an airstream, comprising:
an air channel configured to receive an inlet airstream and discharge an outlet airstream; and
an H 2 O permeable material adjacent to the air channel, wherein the H 2 O permeable material is configured to selectively enable H 2 O from H 2 O vapor in the inlet airstream to pass through the H 2 O permeable material to a suction side of the H 2 O permeable material and substantially block other components in the inlet airstream from passing through the H 2 O permeable material to the suction side of the H 2 O permeable material;
an evaporative cooling unit configured to cool the airstream;
a pressure increasing device configured to create a lower partial pressure of H 2 O vapor on the suction side of the H 2 O permeable material than the partial pressure of the H 2 O vapor in the inlet airstream to drive passage of the H 2 O from the H 2 O vapor in the inlet airstream through the H 2 O permeable material, and to increase the pressure at an outlet of the pressure increasing device to a partial pressure of H 2 O vapor suitable for condensing H 2 O vapor into liquid H 2 O; and
a controller comprising a microprocessor configured to control a first operation of the dehumidification unit.
8. The system of claim 7 , comprising a second evaporative cooling unit disposed upstream of the dehumidification unit.
9. The system of claim 7 , wherein the controller is configured to control a second operation of the evaporative cooling unit.
10. The system of claim 7 , comprising a condensation device configured to receive H 2 O vapor from the outlet of the pressure increasing device, and to condense the H 2 O vapor into liquid H 2 O.
11. The system of claim 10 , comprising a liquid pump configured to transport the liquid H 2 O from the condensation device.
12. The system of claim 7 , wherein the H 2 O permeable material comprises an H 2 O permeable membrane.
13. The system of claim 7 , wherein the H 2 O permeable material comprises zeolite.
14. The system of claim 7 , wherein the dehumidification unit is a variable speed dehumidification unit, and the evaporative cooling unit is a variable speed evaporative cooling unit.
15. A method, comprising:
receiving an airstream including H 2 O vapor into an air channel of a dehumidification unit, wherein the airstream has a first partial pressure of H 2 O vapor;
cooling the airstream via an evaporative cooling unit;
suctioning H 2 O into an H 2 O vapor channel of the dehumidification unit through an H 2 O permeable material of the dehumidification unit using a pressure differential across the H 2 O permeable material, wherein the H 2 O permeable material comprises zeolite and the H 2 O vapor channel has a second partial pressure of H 2 O vapor lower than the first partial pressure of H 2 O vapor of the airstream; and
receiving H 2 O vapor from the H 2 O vapor channel into a pressure increasing device and increasing the pressure of the H 2 O vapor from the pressure increasing device to a third partial pressure of H 2 O vapor that is higher than the second partial pressure of H 2 O vapor.
16. The method of claim 15 , comprising cooling the airstream via the evaporative cooling unit before directing the airstream into the dehumidification unit.
17. The method of claim 15 , comprising cooling the airstream via the evaporative cooling unit after receiving the airstream from the dehumidification unit.
18. The method of claim 15 , comprising cooling the airstream via a first evaporative cooling unit before directing the airstream into the dehumidification unit, and cooling the airstream via a second evaporative cooling unit after receiving the airstream from the dehumidification unit.
19. The method of claim 15 , comprising receiving H 2 O vapor from the pressure increasing device into a condensation device and condensing the H 2 O vapor into liquid H 2 O.
20. The method of claim 19 , wherein the airstream has a first partial pressure of H 2 O vapor in a range of approximately 0.2-1.0 psia, the second partial pressure of H 2 O vapor is in a range of approximately 0.1-1.0 psia, and the third partial pressure of H 2 O vapor is in a range of approximately 0.25-1.1 psia.
21. The system of claim 3 , wherein the psychrometric chart control comprises adjusting at least one point on a psychrometric chart.