METHODS AND SYSTEMS FOR DIRECT-CONTACT EVAPORATION AND CONDENSATION, AND DESALINATION METHODS AND SYSTEMS EMPLOYING THE SAME

1 . A water desalination system, comprising:

a direct-contact humidifier, configured to receive a first stream of a carrier gas and a first stream of a brine and place the first stream of the carrier gas and the first stream of the brine in direct contact to cause transfer of heat and water from the first stream of the brine to the first stream of the carrier gas to form a second stream of the carrier gas and a second stream of the brine, wherein the first stream of the brine has a brine set point temperature;

a direct-contact condenser, configured to receive the second stream of the carrier gas and a first stream of a condensate and place the second stream of the carrier gas and the first stream of the condensate in direct contact to cause transfer of heat and water from the second stream of the carrier gas to the first stream of the condensate to form a third stream of the carrier gas and a second stream of the condensate, wherein the first stream of the condensate has a condensate set point temperature;

a blowdown conduit, configured to discharge a portion of the second stream of the brine from the water desalination system to form a third stream of the brine;

a makeup brine conduit, configured to combine the third stream of the brine with a stream of makeup brine to form a fourth stream of the brine;

a gas discharge conduit, configured to discharge a portion of the second stream of the carrier gas to form a third stream of the carrier gas;

a makeup carrier gas conduit, configured to combine the third stream of the carrier gas with a makeup carrier gas stream to form the first stream of the carrier gas for recycle to the direct-contact humidifier;

a product water conduit, configured to discharge a portion of the second stream of the condensate from the water desalination system as a product water stream and thereby form a third stream of the condensate;

a recuperator, configured to receive the fourth stream of the brine and the third stream of the condensate and exchange heat from the third stream of the condensate to the fourth stream of the brine to form a fifth stream of the brine and a fourth stream of the condensate;

a heat source, configured to heat the fifth stream of the brine to the brine set point temperature and thereby form the first stream of the brine for recycle to the direct-contact humidifier; and

a heat sink, configured to cool the fourth stream of the condensate to the condensate set point temperature and thereby form the first stream of the condensate for recycle to the direct-contact condenser.

2 . The water desalination system of claim 1 , wherein the heat source is a heat engine comprising:

an evaporator, configured to receive heat from a thermal source and supply at least a portion of the received heat to a working fluid of the heat engine;

an expander and an electric generator, collectively configured to extract mechanical work from the working fluid to produce electricity; and

a condenser, configured to receive the working fluid and the fifth stream of the brine and exchange heat from the working fluid to the fifth stream of the brine.

3 . The water desalination system of claim 1 -or wherein the heat sink comprises an organic Rankine cycle-integrated dry air cooler.

4 . The water desalination system of claim 1 , wherein the heat source and the heat sink are collectively configured as a heat pump comprising:

a first heat exchanger, configured to receive the fourth stream of the condensate and a first stream of a refrigerant and exchange heat from the fourth stream of the condensate to the first stream of the refrigerant to form a second stream of the refrigerant;

a compressor, configured to compress the second stream of the refrigerant to form a third stream of the refrigerant; and

a second heat exchanger, configured to receive the fifth stream of the brine and the third stream of the refrigerant and exchange heat from the third stream of the refrigerant to the fifth stream of the brine to form the first stream of the refrigerant for recycle to the first heat exchanger.

5 . The water desalination system of claim 1 , wherein at least one of the direct-contact humidifier and the direct-contact condenser comprises a stacked cassette tower.

6 . The water desalination system of claim 1 , wherein a total dissolved solids content of the product water stream is no more than about 20 ppm.

7 . The water desalination system of claim 1 , wherein the carrier gas comprises air.

8 . The water desalination system of claim 1 , further comprising a blower configured to induce a pressure gradient of the carrier gas in the direct-contact humidifier.

9 . The water desalination system of claim 1 , wherein the portion of the second stream of the carrier gas discharged by the gas discharge conduit is about 5.0% to about 15.0%, by mass or volume, of the second stream of the carrier gas.

10 - 25 . (canceled)

26 . A method for producing fresh water, comprising:

(a) contacting a first stream of a carrier gas and a first stream of a brine to cause transfer of heat and water from the first stream of the brine to the first stream of the carrier gas to form a second stream of the carrier gas and a second stream of the brine, wherein the first stream of the brine has a brine set point temperature;

(b) contacting the second stream of the carrier gas and a first stream of a condensate to cause transfer of heat and water from the second stream of the carrier gas to the first stream of the condensate to form a third stream of the carrier gas and a second stream of the condensate, wherein the first stream of the condensate has a condensate set point temperature;

(c) discharging a portion of the second stream of the brine to form a third stream of the brine;

(d) combining the third stream of the brine with a stream of makeup brine to form a fourth stream of the brine;

(e) discharging a portion of the second stream of the carrier gas to form a third stream of the carrier gas;

(f) combining the third stream of the carrier gas with a makeup carrier gas stream to form the first stream of the carrier gas for recycle to step (a);

(g) discharging a portion of the second stream of the condensate as a product water stream to thereby form a third stream of the condensate;

(h) exchanging heat from the third stream of the condensate to the fourth stream of the brine to form a fifth stream of the brine and a fourth stream of the condensate;

(i) heating the fifth stream of the brine to the brine set point temperature to thereby form the first stream of the brine for recycle to step (a); and

(j) cooling the fourth stream of the condensate to the condensate set point temperature to thereby form the first stream of the condensate for recycle to step (b).

27 . The method of claim 26 , wherein step (i) comprises:

receiving heat from a thermal source and supplying at least a portion of the received heat to a working fluid of a heat engine;

extracting mechanical work from the working fluid to produce electricity; and

exchanging heat from the working fluid to the fifth stream of the brine.

28 . The method of claim 26 , wherein:

step (j) comprises exchanging heat from the fourth stream of the condensate to a first stream of a refrigerant to form a second stream of the refrigerant;

the method further comprises compressing the second stream of the refrigerant to form a third stream of the refrigerant; and

step (i) comprises exchanging heat from the third stream of the refrigerant to the fifth stream of the brine to form the first stream of the refrigerant for recycle to step (j).

29 . The method of claim 26 , wherein a total dissolved solids content of the product water stream is no more than about ppm.

30 . The method of claim 26 , wherein the carrier gas comprises air.

31 . The method of claim 26 , wherein the portion of the second stream of the carrier gas discharged in step (e) is about 5.0% to about 15.0%, by mass or volume, of the second stream of the carrier gas.

32 - 44 . (canceled)

45 . A stacked cassette tower (SCT) useful as a direct-contact condenser and/or a direct-contact evaporator, comprising:

N interconnected cassettes arranged in a vertical stack, where Nis an integer greater than or equal to two, each cassette having a circular or nearly circular cross-section and comprising:

a lower chamber, comprising a substantially fluid-impermeable floor;

an upper chamber;

a vertical wall, disposed about a circumference of the cassette and defining an outermost extent of the cassette, comprising a plurality of orifices in a portion of the vertical wall associated with the upper chamber;

a barrier layer, lying between the lower chamber and the upper chamber and comprising a perforation array, the perforation array comprising a plurality of perforations extending through an entirety of a thickness of the barrier layer and permitting flow of a carrier gas from the lower chamber into the upper chamber; and

a downpipe, in fluid communication with the upper chamber and extending downwardly from the upper chamber through an entirety of a height of the lower chamber;

an outer cylinder, having a circular or nearly circular cross-section and comprising:

a base;

at least one carrier gas inlet, in fluid communication with both a source of the carrier gas and the lower chamber of at least one cassette and configured to convey the carrier gas from the source of the carrier gas into the lower chamber of the at least one cassette; and

at least one liquid inlet, in fluid communication with both a source of a liquid and the upper chamber of at least one cassette and configured to convey the liquid from the source of the liquid into the upper chamber of the at least one cassette; and

a lid, comprising a carrier gas outlet,

wherein an outer diameter of each of the cassettes is less than an inner diameter of the outer cylinder such that an annular space exists within the outer cylinder between the stack of cassettes and the outer cylinder,

wherein the plurality of orifices in the vertical wall of each cassette is in fluid communication with the annular space and permits flow of the carrier gas from the upper chamber of each cassette into the annular space,

wherein a lower end of the downpipe of each cassette other than the bottom-most cassette in the stack penetrates through the floor of the lower chamber and thereafter terminates in, and is in fluid communication with, an upper end of the downpipe of the immediately below cassette, and

wherein a lower end of the downpipe of the bottom-most cassette in the stack is in fluid communication with, and configured to dispense a stream of the liquid into, a reservoir contained within the base of the outer cylinder.

46 . The SCT of claim 45 , wherein the SCT comprises from two to ten cassettes.

47 - 49 . (canceled)

50 . The SCT of claim 45 , wherein the perforation array of at least one cassette comprises about 2,000 to about 200,000 perforations.

51 . (canceled)

52 . The SCT of claim 45 , wherein at least one of the following is true:

(i) the at least one carrier gas inlet comprises N carrier gas inlets, wherein each of the N carrier gas inlets is in fluid communication with the dry chamber of a separate cassette; and

(ii) the at least one liquid inlet comprises N liquid inlets, wherein each of the N liquid inlets is in fluid communication with the wet chamber of a separate cassette.

53 - 56 . (canceled)

57 . The SCT of claim 45 , wherein at least one cassette is mechanically interlocked and/or interconnected to the lid.

58 . (canceled)