Liquid dessicant dehumidification and absorption chilling using mechanical vapor recompression

Abstract

The present disclosure includes methods and systems of liquid desiccant absorption chilling and / or dehumidification. Specifically, the systems and methods disclosed herein utilize mechanical vapor recompression to avoid harmful refrigerants and increase liquid desiccant cooling and dehumidification efficiencies.

Description

LIQUID DESSICANT DEHUMIDIFICATION AND ABSORPTION CHILLING USING MECHANICAL VAPOR RECOMPRESSIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and benefit of U.S. Provisional Application Serial No. 63 / 555,870, filed February 20, 2024, which is incorporated by reference in its entirety.FIELD

[0002] The present disclosure relates generally to methods and systems of liquid desiccant dehumidification and absorption chilling, and more specifically to methods and systems of liquid desiccant dehumidification and absorption chilling using mechanical vapor recompression.BACKGROUND

[0003] Vapor-compression (“VC”) technology has dominated refrigeration, air conditioning, and heat pumping for the past century by using hydrofluorocarbons (“HFC”). It is predicted that by 2050, HFC emissions will account for up to 20% of equivalent global CO2 emissions due to rapid growing demand for refrigeration and electrification of heating in the world. Other alternatives to HFC are being implemented, but these low Global Warming Potential (“GWP”) refrigerants are still slightly flammable, have smaller power densities and efficiencies compared to HFC, and pose other environmental concerns.

[0004] Legislation has been signed into law to curb HFC use and transition the world to a next generation refrigerant. That next generation refrigerant is uncertain and appears to be a choice between hydrofluor-olefins (“HFO”), which acidify our water (irreparably), or natural refrigerants such as propane, which are explosive. The heating and cooling industries are trying to wean off HFC, but they do not have an acceptable alternative that has low-GWP, zerotoxicity, and zero-flammability.

[0005] In addition to using harmful refrigerants, vapor-compression utilizes a very energy intensive process for dehumidification. To remove water vapor from air, vapor-compression relies on dew-point dehumidification in which the water vapor from air is condensed onto a cold surface created by a vapor-compression driven heat pump. Historically, the dew-point dehumidification approach has dominated air conditioning for more than 100 years. However, converting water vapor to a liquid through condensation on a cold plate can require more thanten times the theoretical minimum amount of energy to remove the water vapor from the air stream.

[0006] Typical dew point settings can be about ~7-9 degrees Celsius (corresponding to 40- 50% relative humidity at 20°C intake air). As such, typical evaporator coils can be at temperatures of around 5°C to provide a sufficient driving force to reach dehumidification targets. However, for occupant comfort, the supply air comes into a room around 15-20°C (depending on outdoor temperature). Thus, the air gets cooled to around 5°C for dehumidification, and then must get reheated to about 15-20°C before it enters the room that is being conditioned. In essence, the evaporator coils overcool the air to meet dehumidification targets, and then are reheated to meet temperature comfort settings, which is an inefficient process.BRIEF SUMMARY

[0007] Provided herein are methods and systems for increasing cooling efficiency and / or dehumidification efficiency without using harmful refrigerants. The methods and systems disclosed herein can replace harmful refrigerants or thermal regeneration of liquid desiccants using mechanical vapor recompression, thereby increasing cooling and / or dehumidification efficiency.

[0008] In some embodiments, a dehumidification system includes a dehumidifier comprising a liquid desiccant, wherein the liquid desiccant comprises salt and water, and the liquid desiccant absorbs water vapor from a humid air stream received by the dehumidifier, thereby decreasing a concentration of the salt in the liquid desiccant to form a diluted liquid desiccant; a chamber configured to receive the diluted liquid desiccant and to evaporate a portion of the water from the diluted liquid desiccant to form water vapor and increase the concentration of the salt in the liquid desiccant; a compressor configured to receive the water vapor from the chamber and increase a pressure of the water vapor, wherein the chamber is configured to receive the compressed water vapor and condense the compressed water vapor to form a liquid water; and a humidifier configured to receive the liquid water and an air stream and evaporate the liquid water such that a concentration of the water vapor in the air stream increases. In some embodiments, the system includes a heat exchanger configured to transfer heat from the concentrated liquid desiccant and the liquid water from the chamber to the diluted liquid desiccant from the dehumidifier. In some embodiments, the dehumidifier is configured toreceive the concentrated liquid desiccant from the chamber to be used as the liquid desiccant in the absorber.

[0009] In some embodiments, a dehumidification method includes removing water vapor from a humid air stream with a liquid desiccant, wherein the liquid desiccant comprises salt and water, thereby decreasing a concentration of the salt in the liquid desiccant to form a diluted liquid desiccant; evaporating a portion of the water from the diluted liquid desiccant to form a second water vapor and increase the concentration of the salt in the liquid desiccant; compressing the second water vapor to increase a pressure of the second water vapor; condensing the compressed second water vapor to form liquid water; and increasing a concentration of water vapor in an air stream by evaporating the liquid water in the presence of the air stream. In some embodiments, the method includes transferring heat from the concentrated liquid desiccant and the liquid water to the diluted liquid desiccant. In some embodiments, the method includes using the concentrated liquid desiccant as the liquid desiccant diluted by the removal of water vapor from the humid air stream.

[0010] In some embodiments, an absorption chilling system includes an absorber comprising a liquid desiccant, wherein the liquid desiccant comprises salt and water, wherein the absorber is configured to condense a first water vapor, thereby decreasing a concentration of the salt in the liquid desiccant to form a diluted liquid desiccant; a chamber configured to receive the diluted liquid desiccant and to evaporate a portion of the water from the diluted liquid desiccant to form a second water vapor and increase the concentration of the salt in the liquid desiccant; a compressor configured to receive the second water vapor and increase a pressure of the second water vapor, wherein the chamber receives the compressed second water vapor and condenses the compressed second water vapor to form a liquid water; and an evaporator configured to receive the liquid water and evaporate the liquid water to form the first water vapor received by the absorber. In some embodiments, the system includes a heat exchanger configured to transfer heat from the concentrated liquid desiccant and the liquid water from the chamber to the diluted liquid desiccant from the absorber. In some embodiments, the evaporator comprises a second heat exchanger comprising a heat transfer fluid, wherein the heat transfer fluid provides heat to the liquid water for evaporation, thereby cooling the heat transfer fluid. In some embodiments, the cooled heat transfer fluid is used to absorb heat from a building. In some embodiments, the absorber is configured to receive the concentrated liquid desiccant from the chamber to be used as the liquid desiccant in the absorber. In someembodiments, the absorber comprises a third heat exchanger comprising a second heat transfer fluid, wherein the second heat transfer fluid receives heat from the first water vapor during condensation of the first water vapor. In some embodiments, the heated second heat transfer fluid is sent to a cooling tower.

[0011] In some embodiments, an absorption chilling method includes condensing a first water vapor, thereby decreasing a concentration of salt in a liquid desiccant to form a diluted liquid desiccant; evaporating a portion of water from the diluted liquid desiccant to form a second water vapor and increase the concentration of the salt in the liquid desiccant; compressing the second water vapor to increase a pressure of the second water vapor; condensing the compressed second water vapor to form a liquid water; and evaporating the liquid water to form the first water vapor. In some embodiments, the method includes transferring heat from the concentrated liquid desiccant and the liquid water to the diluted liquid desiccant. In some embodiments, the method includes heating the liquid water with a heat transfer fluid for evaporation, thereby cooling the heat transfer fluid. In some embodiments, the method includes using the cooled heat transfer fluid to cool a building. In some embodiments, the method includes using the concentrated liquid desiccant as the liquid desiccant diluted by the condensed first water vapor. In some embodiments, the method includes transferring heat from the first water vapor to a second heat transfer fluid during condensation of the first water vapor.

[0012] In some embodiments, an absorption chilling an dehumidification system includes a liquid desiccant reservoir comprising a liquid desiccant, wherein the liquid desiccant comprises salt and water; a water reservoir comprising water; a dehumidifier configured to receive liquid desiccant from the liquid desiccant reservoir and a humid air stream comprising water vapor, wherein the liquid desiccant absorbs water vapor from the humid air stream, thereby decreasing a concentration of the salt in the liquid desiccant to form a first diluted liquid desiccant; an absorber configured to receive liquid desiccant from the liquid desiccant reservoir and to condense a first water vapor stream, thereby decreasing a concentration of the salt in the liquid desiccant to form a second diluted liquid desiccant; a chamber configured to receive the first and / or second diluted liquid desiccant from the absorber and / or dehumidifier and to evaporate a portion of the water from the first and / or second diluted liquid desiccant to form a second water vapor stream and increase the concentration of the salt in the first and / or second liquid desiccant; a compressor configured to receive the second water vapor stream and increase a pressure of the second water vapor stream, wherein the chamber receives the compressedsecond water vapor stream and condenses the compressed second water vapor stream to form a liquid water that is sent to the water reservoir; a humidifier configured to receive an air stream and liquid water from the water reservoir and evaporate the liquid water such that a concentration of the water vapor in the air stream increases; and an evaporator configured to receive liquid water from the water reservoir and evaporate the liquid water to form the first water vapor stream received by the absorber. In some embodiments, the system includes a heat exchanger configured to transfer heat from the concentrated liquid desiccant and the liquid water from the chamber to the diluted liquid desiccant from the dehumidifier and / or absorber. In some embodiments, the evaporator comprises a second heat exchanger comprising a heat transfer fluid, wherein the heat transfer fluid provides heat to the liquid water for evaporation, thereby cooling the heat transfer fluid. In some embodiments, the cooled heat transfer fluid is used to absorb heat from a building. In some embodiments, the absorber comprises a third heat exchanger comprising a second heat transfer fluid, wherein the second heat transfer fluid receives heat from the first water vapor stream during condensation of the first water vapor stream. In some embodiments, the heated second heat transfer fluid is sent to a cooling tower.

[0013] In some embodiments, an absorption chilling and dehumidification method includes removing water vapor from a humid air stream with liquid desiccant, thereby decreasing a concentration of a salt in the liquid desiccant to form a first diluted liquid desiccant; condensing a first water vapor stream using the liquid desiccant, thereby decreasing a concentration of the salt in the liquid desiccant to form a second diluted liquid desiccant; evaporating a portion of the water from the first and / or second diluted liquid desiccant to form a second water vapor stream and increase a concentration of the salt in the first and / or second liquid desiccant; compressing the second water vapor stream to increase a pressure of the second water vapor stream; condensing the compressed second water vapor stream to form liquid water; evaporating the liquid water to form the first water vapor; and increasing a concentration of water vapor in an air stream by evaporating the liquid water in the presence of the air stream. In some embodiments, the method includes transferring heat from the concentrated liquid desiccant and the liquid water to the diluted liquid desiccant. In some embodiments, the method includes heating the liquid water with a heat transfer fluid for evaporation, thereby cooling the heat transfer fluid. In some embodiments, the method includes using the cooled heat transfer fluid to cool a building. In some embodiments, the method includes transferring heat from the first water vapor stream to a second heat transfer fluid during condensation of the first water vapor stream.

[0014] The embodiments disclosed above are only examples, and the scope of this disclosure is not limited to them. Particular embodiments may include all, some, or none of the components, elements, features, functions, operations, or steps of the embodiments disclosed above. Embodiments according to the disclosure herein are in particular disclosed in the attached claims directed to methods and systems, wherein any feature mentioned in one claim category, e.g., method, can be claimed in another claim category, e.g., system, as well. The dependencies or references back in the attached claims are chosen for formal reasons only. However, any subject matter resulting from a deliberate reference back to any previous claims (in particular multiple dependencies) can be claimed as well, so that any combination of claims and the features thereof are disclosed and can be claimed regardless of the dependencies chosen in the attached claims. The subject-matter which can be claimed comprises not only the combinations of features as set out in the attached claims but also any other combination of features in the claims, wherein each feature mentioned in the claims can be combined with any other feature or combination of other features in the claims. Furthermore, any of the embodiments and features described or depicted herein can be claimed in a separate claim and / or in any combination with any embodiment or feature described or depicted herein or with any of the features of the attached claims.

[0015] Additional advantages will be readily apparent to those skilled in the art from the following detailed description. The examples and descriptions herein are to be regarded as illustrative in nature and not restrictive.

[0016] All publications, including patent documents, scientific articles and databases, referred to in this application are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication were individually incorporated by reference. If a definition set forth herein is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications and other publications that are herein incorporated by reference, the definition set forth herein prevails over the definition that is incorporated herein by reference.BRIEF DESCRIPTION OF THE FIGURES

[0017] The present application can be understood by reference to the following description taken in conjunction with the accompanying figures.

[0018] FIG. 1 illustrates an exemplary system for a standard absorption chiller process.

[0019] FIG 2 illustrates an exemplary system for a mechanical vapor recompression process in accordance with some embodiments disclosed herein.

[0020] FIG. 3 illustrates an exemplary system for an absorption chiller process that utilizes mechanical vapor recompression in accordance with some embodiments disclosed herein.

[0021] FIG. 4 illustrates an exemplary system for a liquid desiccant dehumidifier process that utilizes mechanical vapor recompression in accordance with some embodiments disclosed herein.

[0022] FIG. 5 illustrates an exemplary system for a combined absorption chiller and liquid desiccant dehumidifier process that utilizes mechanical vapor recompression in accordance with some embodiments disclosed herein.

[0023] In the Figures, like reference numerals refer to like components unless otherwise stated herein.DETAILED DESCRIPTION

[0024] Applicant has discovered an approach to increasing cooling efficiency and / or dehumidification efficiency, without using harmful refrigerants, involving the mechanical regeneration of liquid desiccants used to drive an absorption-based cooling cycle and / or a liquid desiccant dehumidification cycle. An absorption chiller can create cold by evaporating water at low temperature (absorbing energy) and condensing that water into a highly concentrated salt solution (releasing energy). FIG. 1 illustrates a standard or typical absorption cooling or chiller system. In some embodiments, a typical absorption chiller system can include an evaporator 7, such as a falling film over horizontal tubes or flooded evaporator, and an absorber 1 (e.g., an absorber heat and mass exchanger). In some embodiments, the evaporator can be configured to receive liquid water 17 and evaporate the liquid water to form water vapor (i.e., gaseous water) 8. In some embodiments, the pressure in the evaporator can be very low (e.g. 1-2000 Pa). In this lower pressure environment, the boiling point of the liquid water can decrease. As the liquid water evaporates, it can cool itself down. In some embodiments, the evaporator can include a heat exchanger 24. In some embodiments, the heat exchanger in the evaporator can be a coil-based heat exchanger carrying a heat transfer fluid. In some embodiments, the heat exchanger in the evaporator can be plate and frame, shell and tube, concentric tubes, or a combination thereof. In some embodiments, the heat transfer fluid entering 18 the evaporator can provide the heat for the liquid water to evaporate. In otherwords, heat can be transferred from the inlet heat transfer fluid 18 to the liquid water (i.e., absorbed by the liquid water), thereby evaporating the liquid water and cooling the heat transfer fluid such that the outlet heat transfer fluid 19 is at a lower temperature (e.g., about 2-10°C) than the inlet heat transfer fluid (e.g., about 12-15°C). In some embodiments, the heat transfer fluid can include water (water mixture with glycol for example) or air. For example, in a chiller, water can be the heat transfer fluid and air can be the heat transfer fluid for an air conditioner. In some embodiments, the evaporator temperature can be about 5-6°C. In some embodiments, the inlet heat transfer fluid can be the return from an inside of a home or building and the outlet heat transfer fluid can be the outlet to the building in order to cool the building. In some embodiments, the outlet heat transfer fluid can be chilled and can be pumped through the home or building to absorb heat, and then returned to the inlet of the device to transfer the absorbed heat from the building to the evaporating water.

[0025] In some embodiments, the absorber 1 can be configured to receive the gaseous water 8 from the evaporator 7. In some embodiments, the absorber can include a concentrated liquid desiccant solution 14. In some embodiments, a liquid desiccant can be an aqueous solution that has very low water vapor pressure (e.g., about 0.2 kPa to 5 kPa). In some embodiments, liquid desiccants can be one or more salts in a solvent. In some embodiments, any suitable salts may be used provided the salt(s) is provided at a high enough concentration in water to pull additional water in. In some embodiments, the salts may include calcium chloride (CaCh), magnesium chloride (MgCh), lithium chloride (LiCl), lithium bromide (LiBr), or any combinations thereof. In some embodiments, the solvent comprises or is water, acetone, ethanol, ionic liquids, ammonia, or combinations thereof. In some embodiments, the absorber can be configured to receive a concentrated liquid desiccant 14. In some embodiments, the concentration of salt in the concentrated liquid desiccant can be about 5-65 wt.%. At these high concentrations of salt, the vapor pressure of the solvent (e.g., water) can be lowered significantly.

[0026] In some embodiments, there is a strong chemical potential that can generate a pressure difference between the gaseous water 8 entering the absorber and the concentrated liquid desiccant 14 that can drive the gaseous water towards the concentrated liquid desiccant. Once in contact with the concentrated liquid desiccant, the gaseous water can chemically absorb into the liquid desiccant solution, where it can condense, thereby releasing heat. In other words, the absorber can be configured to condense the gaseous water such that it further dilutes theconcentrated liquid desiccant. In some embodiments, the concentration of salt in the diluted liquid desiccant 9 is less than the concentration of salt in the concentrated liquid desiccant 14. In some embodiments, the concentration of salt in the diluted liquid desiccant can be about 0- 60 wt.% or about 1-60 wt.%.

[0027] In some embodiments, the absorber can include a heat exchanger 28. In some embodiments, the heat exchanger in the absorber can be a coil-based heat exchanger carrying a heat transfer fluid, a plate and frame heat exchanger, a shell and tube heat exchanger, a spiral plate heat exchanger, a concentric tube heat exchanger, or combinations thereof. In some embodiments, the heat transfer fluid entering 20 the absorber can provide cooling for the water vapor to condense. In other words, heat can be transferred from the inlet water vapor 8 to the inlet heat transfer fluid 20, thereby condensing the gaseous water and heating the heat transfer fluid such that the outlet heat transfer fluid 21 is at a higher temperature than the inlet heat transfer fluid (e.g., water, water with other components such as glycol, or air). In some embodiments, the absorber temperature can range from slightly above ambient to about 20°C above ambient (e.g., about 20-55°C). In some embodiments, the heat can be rejected to ambient or to a cooling tower. In some embodiments, fluid 20 can be heat transfer fluid that has been cooled (e.g., from a cooling tower), it can then absorb energy from the absorber, and the heat transfer fluid 21 can leave to go back where it came from (e.g., the cooling tower). In some embodiments, fluid 20 can be air from outside that is at ambient temperature, the air can absorb energy from the absorber, and then the hot air can be rejected to ambient.

[0028] In some embodiments, the diluted liquid desiccant can be “regenerated” or reconcentrated to form the concentrated liquid desiccant to redo this process. As such, in some embodiments, the diluted liquid desiccant 9 from the absorber can be sent (via pump 2) to a thermal generator 4 as shown in FIG. 1. In some embodiments, the thermal generator can be a natural gas fired / powered boiler, a concentrated solar collector (that can boil water in tubes that run at the focal point), and / or a condensing steam boiler. In some embodiments, the thermal generator can heat the diluted liquid desiccant such that excess water is boiled off to form gaseous water stream 15. In some embodiments, the thermal generator can include a heat exchanger 22 to heat the diluted liquid desiccant such that excess water is boiled off the diluted liquid desiccant. The remaining liquid desiccant solution 12 is now more concentrated since water was removed from the diluted liquid desiccant. This can allow for the remaining liquiddesiccant 12 to be reused as the concentrated liquid desiccant in the absorber (as it can once again be good at lowering the vapor pressure of water in the absorber).

[0029] The water vapor stream 15 can then be sent to a condenser 5 to condense the water vapor back into liquid water 16 by rejecting the heat of condensation 23 to air or a cooling tower. In some embodiments, the condenser can be any heat exchanger such as those disclosed herein. In some embodiments, the condenser can be a heat exchanger coil with a fan that blows ambient air over the outside of the coil while the water vapor condenses on the inside of the coil, transferring its heat to the air. The resulting liquid water from the condenser can then be sent back to the evaporator 7 to repeat the process. In some embodiments, an expansion valve can be used to reduce the pressure of the liquid water stream 16 before entering the evaporator 7. In some embodiments, the pressure on the low pressure side of the expansion valve can be about 0.1 kPa to 1.5 kPa and the pressure on the high pressure side of the expansion valve can be about 50-100 kPa.

[0030] In some embodiments, the liquid desiccant 12 after the thermal generator can be sent back to the absorber to restart the cooling cycle. In some embodiments, the absorption chilling system can include a solution heat exchanger 3. In some embodiments, the heat exchanger can be a plate and frame heat exchanger, a plate heat exchanger (e.g., brazed plate), a shell and tube heat exchanger, others, or combinations thereof. In some embodiments, the liquid desiccant 12 from the thermal generator can heat the diluted desiccant solution 10 from pump 2 and the absorber 1. By transferring heat from the liquid desiccant 12 to the diluted liquid desiccant 10, the heating requirements of the thermal generator 4 can be reduced. In some embodiments, expansion valve 25 can reduce the pressure of the liquid desiccant 13 leaving heat exchanger 3 before it enters the absorber. In some embodiments, liquid desiccant 13 can be at a high pressure and liquid desiccant 14 can be at a low pressure. Thus, the expansion valve can act to maintain that pressure difference. In some embodiments, expansion valve can maintain the pressure in the absorber and separate out the high pressure part of the system from the low pressure part of the system. Thus, concentrated liquid desiccant 13 leaving heat exchanger 3 is at a lower temperature than when it entered and diluted liquid desiccant 11 is at a higher temperature than when it entered heat exchanger 3.

[0031] Thermal regeneration of the liquid desiccant is very inefficient. There can be a significant thermodynamic penalty incurred using heat to drive the work of separation between the water and the liquid desiccant. If regeneration is instead done mechanically or electrically,there may be no or a smaller thermodynamic penalty, and the process can approach the thermodynamic minimum amount of energy required for separation of water from the liquid desiccant.

[0032] Applicant discovered that the thermal generator 4 and condenser 5 architecture shown in FIG. 1 can be replaced with a mechanical vapor recompression architecture. Specifically, Applicant’s approach to increasing cooling efficiency and dehumidification efficiency without using harmful refrigerants involves the mechanical regeneration of a liquid desiccant solution that can be used to drive an absorption-based cooling cycle and / or a liquid desiccant dehumidification cycle.

[0033] FIG. 2 illustrates a mechanical vapor recompression scheme to generate water by concentrating an initially dilute solution. As shown in FIG. 1, the thermal generator 4 can boil water off from the diluted liquid desiccant, thereby re-concentrating the liquid desiccant for reuse in the absorber 1. The boiled water can then be condensed in the condenser for re-use in the evaporator 7 again. By using mechanical vapor recompression, the same streams can be obtained without using thermal energy as an input. Mechanical vapor recompression can take a dilute input stream 33 (e.g., diluted liquid desiccant), performs a mechanically driven chemical separation, and results in a concentrated solution stream 35 (e.g., concentrated liquid desiccant) and a liquid water stream 34 (e.g., pure liquid water).

[0034] To drive the chemical separation, a superheated water vapor 46 above a concentrated liquid desiccant 45, which is at low pressure (salt in the solution lowers the pressure of the water vapor at a given temperature), can be compressed using a compressor 32 to increase the saturation temperature of the vapor 47 so that it can then condense at a temperature higher than the solution temperature. In some embodiments, the compressor can be a screw compressor, a roots blower, a turbo compressor, a centrifugal compressor, or combinations thereof. The compressor can increase the pressure of the water vapor stream 46 such that water vapor stream 47 exiting the compressor has a higher pressure than inlet water vapor stream 46. In some embodiments, the water vapor stream entering the compressor can have a pressure of about 2- 100 kPa and the water vapor stream leaving the compressor can have a pressure of about 10- 300 kPa. The pressurized vapor stream exiting the compressor can then re-enter the MVR chamber 31. The MVR chamber 31 can include a heat exchanger 44 (such as metal heat exchanger coils, falling film in a vertical tube, falling film on a horizontal tube, forced circulation evaporators, rising film evaporators, flash evaporation, calandria evaporators, orcombinations thereof). In the MVR chamber, the pressurized vapor stream 47 can condense to form water stream 40 when it contacts the heat exchanger 44 (e.g., inside the coils of the metal heat exchanger). The heat of condensation 43 of the pressurized vapor stream can be transferred to the diluted liquid desiccant 42 that entered the MVR chamber. This heat can be used to boil more water vapor 46 off the diluted liquid desiccant 42 to form a concentrated liquid desiccant 45. As such, the heat required to evaporate excess water from the incoming diluted liquid desiccant can be provided by the heat rejected from the condensation of the compressed water vapor. In some embodiments, few energy inputs can be required. In some embodiments, the only energy input can be the electrical input to drive the compressor 32.

[0035] Because the vapor density of water can be very low near room temperature, and the compression ratios required to regenerate a concentrated liquid desiccant are high, practical application of mechanical vapor recompression to liquid desiccant regeneration can be done at high temperature. At high temperatures, the vapor density of water can significant increase (e.g., about 100 times), and the pressure ratios required can go down due to decreased activity coefficients of the salt in the water. The combination of the two can permit use of modem compressor technology. To operate MVR at a high temperature, the diluted desiccant solution 33 can be heated. In some embodiments, the MVR system can include a heat exchanger 30. In some embodiments, the heat exchanger can be a counterflow heat exchanger. In some embodiments, the heat exchanger of the MVR system can recuperate heat from the high temperatures of the concentrated liquid desiccant 45 and the liquid water 40 from the MVR chamber. Through this heat exchanger, the diluted liquid desiccant 33 can enter the MVR chamber as stream 41 at a higher temperature than when it entered the heat exchanger 30. In contrast, the inlet concentrated liquid desiccant stream 45 and inlet liquid water stream 40 of the heat exchanger can leave the heat exchanger as lower temperature streams 35 and 34, respectively. In other words, heat from the liquid water and concentrated liquid desiccant from the MVR chamber can be transferred to the diluted liquid desiccant before it enters the MVR chamber.

[0036] Using mechanical vapor recompression separation, the thermal generator 4 and condenser 5 of the standard absorption chilling system of FIG. 1 can be replaced to create an all mechanically absorption chilling system as shown in FIG. 3. As shown in FIG. 3, in some embodiments, absorption chiller system can include an evaporator 7 and an absorber 1 (e.g., an absorber heat and mass exchanger). In some embodiments, the evaporate can be an adiabaticevaporator, a two phase evaporator, a flooded evaporator, a falling film evaporator, or combinations thereof. In some embodiments, the evaporator can be configured to receive liquid water 17 and evaporate the liquid water to form water vapor (i.e., gaseous water) 8. In some embodiments, the pressure in the evaporator can be very low (e.g., about 0.1 kPa to 2 kPa). In this lower pressure environment, the boiling point of the liquid water can decrease. As the liquid water evaporates, it can cool itself down. In some embodiments, the evaporator can include a heat exchanger 24. In some embodiments, the heat exchanger in the evaporator can be a coil-based heat exchanger (e.g., plate and frame, brazed plate, concentric tube, shell and tube, falling film, or combinations thereof) carrying a heat transfer fluid. In some embodiments, the heat transfer fluid entering 18 the evaporator can provide the heat for the liquid water to evaporate. In other words, heat can be transferred from the inlet heat transfer fluid 18 to the liquid water (i.e., absorbed by the liquid water), thereby evaporating the liquid water and cooling the heat transfer fluid such that the outlet heat transfer fluid 19 is at a lower temperature (e.g., about 2-10°C) than the inlet heat transfer fluid (e.g., water, air, water with other component such as glycol) (e.g., about 12-15°C). In some embodiments, the evaporator temperature can be about 5-6°C. In some embodiments, the inlet heat transfer fluid can be the return from an inside of a home or building and the outlet heat transfer fluid can be the outlet to the building in order to cool the building. In some embodiments, the outlet heat transfer fluid can be chilled and can be pumped through the home or building to absorb heat, and then returned to the inlet of the device to transfer the absorbed heat from the building to the evaporating water.

[0037] In some embodiments, the absorber 1 can be configured to receive the gaseous water 8 from the evaporator 7. In some embodiments, the absorber can include a concentrated liquid desiccant solution 14. As stated above, a liquid desiccant can be an aqueous solution that has very low water vapor pressure(e.g., about 0.2 kPa to 5 kPa). In some embodiments, liquid desiccants can be one or more salts in a solvent. In some embodiments, the salts can be calcium chloride (CaCh), magnesium chloride (MgCh), lithium chloride (LiCl), lithium bromide (LiBr), or combinations thereof. In some embodiments, the solvent can be water. In some embodiments, the absorber can be configured to receive a concentrated liquid desiccant 14. In some embodiments, the concentration of salt in the concentrated liquid desiccant can be X-X. At these high concentrations of salt, the vapor pressure of the solvent (e.g., water) can be lowered significantly.

[0038] In some embodiments, there is a strong chemical potential that can generate a pressure difference between the gaseous water 8 entering the absorber and the concentrated liquid desiccant 14 that can drive the gaseous water towards the concentrated liquid desiccant. Once in contact with the concentrated liquid desiccant, the gaseous water can chemically absorb into the liquid desiccant solution, where it can condense, thereby releasing heat. In other words, the absorber can be configured to condense the gaseous water such that it further dilutes the concentrated liquid desiccant. In some embodiments, the concentration of salt in the diluted liquid desiccant 9 is less than the concentration of salt in the concentrated liquid desiccant 14. In some embodiments, the concentration of salt in the diluted liquid desiccant can be about 5- 65 wt.%.

[0039] In some embodiments, the absorber can include a heat exchanger 28. In some embodiments, the heat exchanger in the absorber can be a coil-based heat exchanger carrying a heat transfer fluid, a plate and frame heat exchanger, a shell and tube heat exchanger, a spiral plate heat exchanger, a concentric tube heat exchanger, or combinations thereof. In some embodiments, the heat transfer fluid entering 20 the absorber can provide cooling for the water vapor to condense. In other words, heat can be transferred from the inlet water vapor 8 to the inlet heat transfer fluid 20, thereby condensing the gaseous water and heating the heat transfer fluid such that the outlet heat transfer fluid 21 is at a higher temperature than the inlet heat transfer fluid (e.g., water, water with other components such as glycol, or air). In some embodiments, the absorber temperature can range from slightly above ambient to about 20°C above ambient (e.g., about 20-55°C). In some embodiments, the heat can be rejected to ambient or to a cooling tower. In some embodiments, fluid 20 can be heat transfer fluid that has been cooled (e.g., from a cooling tower), it can then absorb energy from the absorber, and the heat transfer fluid 21 can leave to go back where it came from (e.g., the cooling tower). In some embodiments, fluid 20 can be air from outside that is at ambient temperature, the air can absorb energy from the absorber, and then the hot air can be rejected to ambient.

[0040] In some embodiments, the diluted liquid desiccant can be “regenerated” or reconcentrated to form the concentrated liquid desiccant to redo this process. As such, in some embodiments, the diluted liquid desiccant 9 from the absorber can be sent (via pump 2) to MVR system such as that of FIG. 2 (also shown in the top of FIG. 3). In some embodiments, a diluted liquid desiccant from the absorber can be sent to a MVR system. In some embodiments, water from a diluted liquid desiccant 42 can be boiled to form water vapor 46 in an MVR chamber31. In some embodiments, the water vapor 46 can be compressed via compressor 32 to form a compressed water vapor stream 47 with pressure greater than the inlet water vapor stream 46. The compressed water vapor stream can then reenter the MVR chamber where it can be condensed to form a liquid water stream 40. In some embodiments, the heat of condensation of the compressed vapor stream can be transferred to the diluted liquid desiccant 42 that entered the MVR chamber. This heat can be used to boil more water vapor 46 off the diluted liquid desiccant 42 to form a concentrated liquid desiccant 45. As such, the heat required to evaporate excess water from the incoming diluted liquid desiccant can be provided by the heat rejected from the condensation of the compressed water vapor. In some embodiments, few energy inputs can be required. In some embodiments, the only energy input can be the electrical input to drive the compressor 32.

[0041] Because the vapor density of water can be very low near room temperature, and the compression ratios required to regenerate a concentrated liquid desiccant can be high, practical application of mechanical vapor recompression to liquid desiccant regeneration can be done at high temperature. At high temperatures, the vapor density of water can significantly increase and the pressure ratios required can go down due to decreased activity coefficients of the salt in the water. The combination of the two can permit use of modern compressor technology. To operate MVR at a high temperature, the diluted desiccant solution 33 from the absorber can be heated before entering the MVR chamber. In some embodiments, the MVR system can include a heat exchanger 30. In some embodiments, the heat exchanger can be a counterflow heat exchanger. In some embodiments, the heat exchanger of the MVR system can recuperate heat from the high temperatures of the concentrated liquid desiccant 45 and the liquid water 40 from the MVR chamber. Through this heat exchanger, the diluted liquid desiccant 33 can enter the MVR chamber as stream 41 at a higher temperature than when it entered the heat exchanger 30. In contrast, the inlet concentrated liquid desiccant stream 45 and inlet liquid water stream 40 of the heat exchanger can leave the heat exchanger as lower temperature streams 35 and 34, respectively. In other words, heat from the liquid water and concentrated liquid desiccant from the MVR chamber can be transferred to the diluted liquid desiccant before it enters the MVR chamber.

[0042] The resulting liquid water 34 from the MVR system can then be sent back to the evaporator 7 to repeat the process. In some embodiments, an expansion valve can be used to reduce the pressure of the liquid water stream 34 before entering the evaporator 7. In someembodiments, the pressure on the low pressure side of the expansion valve can be about 0.1 kPa to 1.5 kPa and the pressure on the high pressure side of the expansion valve can be about 50-100 kPa. In some embodiments, the concentrated liquid desiccant 35 after the MVR system can be sent back to the absorber to restart the cooling cycle.

[0043] With respect to dehumidification, another way of dehumidifying the air besides dew point dehumidification is through liquid desiccant dehumidification. Liquid desiccant dehumidification can approach the theoretical minimum energy of dehumidification. In some embodiments, liquid desiccant dehumidification works by interfacing the liquid desiccant solution with humid air, and the moisture in the air is drawn to the liquid desiccant solution (due to a vapor pressure difference driven by a chemical potential between the air stream and the desiccant) and is absorbed into the solution and condensed, resulting in a less humid air stream and more dilute liquid desiccant solution. As water is absorbed into the liquid desiccant solution, it can become so dilute that the vapor pressure difference between it and the water vapor in the air stream becomes so small that absorption can no longer occur. The liquid desiccant solution then can be “regenerated” or re-concentrated by removing the water that it just absorbed. In some embodiments, traditional regeneration is done thermally.

[0044] Similar to the absorption chilling system, Applicant discovered that the thermal generator can be replaced with a mechanical vapor recompression architecture. FIG. 4 illustrates an exemplary system for a liquid desiccant dehumidifier process that utilizes mechanical vapor recompression. As shown in FIG. 4, concentrated liquid desiccant 61 from desiccant reservoir 50 can be inserted (e.g., via spraying) into a dehumidifier 55 that receives a humid air stream 64. In some embodiments, the dehumidifier can be a chamber where liquid desiccant and an air stream interact. In some embodiments, the concentrated liquid desiccant can be sprayed into an incoming humid air stream. In some embodiments, the water vapor in the air stream can be absorbed by the concentrated liquid desiccant to form a diluted liquid desiccant 68 in the dehumidifier. In some embodiments, the water in the humid air stream can condense, diluting the concentrated liquid desiccant and heating it up (due to heat of mixing and condensation). The resulting outlet air stream(s) 66 from the dehumidifier has less water content. In other words, the humidity of the air stream is lowered by the dehumidifier.

[0045] In some embodiments, liquid water 59 from a liquid water reservoir 49 can be inserted (e.g., via spraying) into a humidifier 54 that receives an air stream 63. In some embodiments, the liquid water can be sprayed into an incoming air stream. In some embodiments, the watercan evaporate in the humidifier and is transferred into the air stream raising the humidity of the air and leaving as humid air 65. This evaporation can cool the water that enters the humidifier.

[0046] In some embodiments, the cooled water 67 and the diluted liquid desiccant 68 can be sent to a heat exchanger 56. In some embodiments, the heat exchanger can be a plate heat exchanger, brazed plate heat exchanger, shell and tube heat exchanger, spiral plate heat exchanger, double pipe heat exchanger, or combinations thereof. In the heat exchanger, heat from the diluted liquid desiccant 68 can be transferred to the cooled liquid water 67. In some embodiments, the outlet liquid water from the heat exchanger 56 can be sent back to water reservoir 49.

[0047] In some embodiments, the outlet diluted liquid desiccant 57 from the heat exchanger 56 can be sent back to the desiccant reservoir 50. In some embodiments, diluted liquid desiccant 33 from the desiccant reservoir and / or from the heat exchanger 56 (or dehumidifier 55) can be sent to a mechanical vapor recompression similar to that shown in FIGS. 2-3. For example, through heat exchanger 30, the diluted liquid desiccant 33 can enter the MVR chamber as stream 41 at a higher temperature than when it entered the heat exchanger 30. In contrast, the inlet concentrated liquid desiccant stream 45 and inlet liquid water stream 40 of the heat exchanger can leave the heat exchanger as lower temperature streams 35 and 34, respectively. In other words, heat from the liquid water and concentrated liquid desiccant from the MVR chamber can be transferred to the diluted liquid desiccant before it enters the MVR chamber. In some embodiments, the MVR chamber can reconcentrate the diluted liquid desiccant as water is separated from the diluted liquid desiccant as previously explained. The concentrated (and post heat exchanger 30) liquid desiccant 35 can be sent back to the desiccant reservoir 50. Similarly, the resulting liquid water 34 from the MVR system can then be sent back to the water reservoir 409 to repeat the process.

[0048] The combined systems of FIGS. 3 (absorption chilling) and 4 (desiccant dehumidification) is shown in FIG. 5. As shown in FIG. 5, water 17 from the water reservoir 49 can be used in the evaporator 7 of the absorption chilling process shown and described in FIG. 3. In addition, concentrated liquid desiccant 14 can be used in the absorber 1 of the absorption chilling process shown and described in FIG. 3. As such, the concentrated liquid desiccant and water streams can be simultaneously used to provide cooling through the evaporation / absorption process shown in FIG. 3 and described in the corresponding FIG. 3description, as well as dehumidification through the humidification / dehumidification process shown in FIG. 4 and described in the corresponding FIG. 4 description.

[0049] In some embodiments, dehumidification can efficiently remove water from the incoming humid air stream, which can reduce the sensible requirements from the chiller because the temperature may no longer need to be lowered to a given dew point. In some embodiments, the chiller can operate at a higher cold side temperature, which can allow it to operate with much higher efficiency. This can result in the same (20°C) air with about 45% relative humidity, but the theoretical efficiency of the two-step process can be almost twice as high as the single cooling / dehumidification processes that are used today.ADDITIONAL DEFINITIONS

[0050] Unless defined otherwise, all terms of art, notations and other technical and scientific terms or terminology used herein are intended to have the same meaning as is commonly understood by one of ordinary skill in the art to which the claimed subject matter pertains. In some cases, terms with commonly understood meanings are defined herein for clarity and / or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art.

[0051] Reference to “about” a value or parameter herein includes (and describes) variations that are directed to that value or parameter per se. For example, description referring to “about X” includes description of “X”. In addition, reference to phrases “less than”, “greater than”, “at most”, “at least”, “less than or equal to”, “greater than or equal to”, or other similar phrases followed by a string of values or parameters is meant to apply the phrase to each value or parameter in the string of values or parameters.

[0052] This application discloses several numerical ranges in the text and figures. The numerical ranges disclosed inherently support any range or value within the disclosed numerical ranges, including the endpoints, even though a precise range limitation is not stated verbatim in the specification because this disclosure can be practiced throughout the disclosed numerical ranges.

[0053] As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is also to be understood that the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It is further to be understood that the terms“includes, “including,” “comprises,” and / or “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, components, and / or units but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0054] The scope of this disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments described or illustrated herein that a person having ordinary skill in the art would comprehend. The scope of this disclosure is not limited to the example embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates respective embodiments herein as including particular components, elements, feature, functions, operations, or steps, any of these embodiments may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated anywhere herein that a person having ordinary skill in the art would comprehend. Furthermore, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Additionally, although this disclosure describes or illustrates particular embodiments as providing particular advantages, particular embodiments may provide none, some, or all of these advantages.

Claims

CLAIMS1. A dehumidification system, comprising: a dehumidifier comprising a liquid desiccant, wherein the liquid desiccant comprises salt and water, and the liquid desiccant absorbs water vapor from a humid air stream received by the dehumidifier, thereby decreasing a concentration of the salt in the liquid desiccant to form a diluted liquid desiccant; a chamber configured to receive the diluted liquid desiccant and to evaporate a portion of the water from the diluted liquid desiccant to form water vapor and increase the concentration of the salt in the liquid desiccant; a compressor configured to receive the water vapor from the chamber and increase a pressure of the water vapor, wherein the chamber is configured to receive the compressed water vapor and condense the compressed water vapor to form a liquid water; and a humidifier configured to receive the liquid water and an air stream and evaporate the liquid water such that a concentration of the water vapor in the air stream increases.

2. The system of claim 1, further comprising a heat exchanger configured to transfer heat from the concentrated liquid desiccant and the liquid water from the chamber to the diluted liquid desiccant from the dehumidifier.

3. The system of claim 1 or 2, wherein the dehumidifier is configured to receive the concentrated liquid desiccant from the chamber to be used as the liquid desiccant in the absorber.

4. A dehumidification method, comprising: removing water vapor from a humid air stream with a liquid desiccant, wherein the liquid desiccant comprises salt and water, thereby decreasing a concentration of the salt in the liquid desiccant to form a diluted liquid desiccant; evaporating a portion of the water from the diluted liquid desiccant to form a second water vapor and increase the concentration of the salt in the liquid desiccant; compressing the second water vapor to increase a pressure of the second water vapor; condensing the compressed second water vapor to form liquid water; andincreasing a concentration of water vapor in an air stream by evaporating the liquid water in the presence of the air stream.

5. The method of claim 4, further comprising transferring heat from the concentrated liquid desiccant and the liquid water to the diluted liquid desiccant.

6. The method of any one of claims 4-5, using the concentrated liquid desiccant as the liquid desiccant diluted by the removal of water vapor from the humid air stream.

7. An absorption chilling system, comprising: an absorber comprising a liquid desiccant, wherein the liquid desiccant comprises salt and water, wherein the absorber is configured to condense a first water vapor, thereby decreasing a concentration of the salt in the liquid desiccant to form a diluted liquid desiccant; a chamber configured to receive the diluted liquid desiccant and to evaporate a portion of the water from the diluted liquid desiccant to form a second water vapor and increase the concentration of the salt in the liquid desiccant; a compressor configured to receive the second water vapor and increase a pressure of the second water vapor, wherein the chamber receives the compressed second water vapor and condenses the compressed second water vapor to form a liquid water; and an evaporator configured to receive the liquid water and evaporate the liquid water to form the first water vapor received by the absorber.

8. The system of claim 7, further comprising a heat exchanger configured to transfer heat from the concentrated liquid desiccant and the liquid water from the chamber to the diluted liquid desiccant from the absorber.

9. The system of any one of claims 7-8, wherein the evaporator comprises a second heat exchanger comprising a heat transfer fluid, wherein the heat transfer fluid provides heat to the liquid water for evaporation, thereby cooling the heat transfer fluid.

10. The system of claim 9, wherein the cooled heat transfer fluid is used to absorb heat from a building.

11. The system of any one of claims 7-10, wherein the absorber is configured to receive the concentrated liquid desiccant from the chamber to be used as the liquid desiccant in the absorber.

12. The system of any one of claims 7-11, wherein the absorber comprises a third heat exchanger comprising a second heat transfer fluid, wherein the second heat transfer fluid receives heat from the first water vapor during condensation of the first water vapor.

13. The system of claim 12, wherein the heated second heat transfer fluid is sent to a cooling tower.

14. An absorption chilling method, comprising: condensing a first water vapor, thereby decreasing a concentration of salt in a liquid desiccant to form a diluted liquid desiccant; evaporating a portion of water from the diluted liquid desiccant to form a second water vapor and increase the concentration of the salt in the liquid desiccant; compressing the second water vapor to increase a pressure of the second water vapor; condensing the compressed second water vapor to form a liquid water; and evaporating the liquid water to form the first water vapor.

15. The method of claim 14, further comprising transferring heat from the concentrated liquid desiccant and the liquid water to the diluted liquid desiccant.

16. The method of any one of claims 14-15, further comprising heating the liquid water with a heat transfer fluid for evaporation, thereby cooling the heat transfer fluid.

17. The method of claim 16, using the cooled heat transfer fluid to cool a building.

18. The method of any one of claims 14-17, using the concentrated liquid desiccant as the liquid desiccant diluted by the condensed first water vapor.

19. The method of any one of claims 14-18, transferring heat from the first water vapor to a second heat transfer fluid during condensation of the first water vapor.

20. A absorption chilling and dehumidification system comprising:a liquid desiccant reservoir comprising a liquid desiccant, wherein the liquid desiccant comprises salt and water; a water reservoir comprising water; a dehumidifier configured to receive liquid desiccant from the liquid desiccant reservoir and a humid air stream comprising water vapor, wherein the liquid desiccant absorbs water vapor from the humid air stream, thereby decreasing a concentration of the salt in the liquid desiccant to form a first diluted liquid desiccant; an absorber configured to receive liquid desiccant from the liquid desiccant reservoir and to condense a first water vapor stream, thereby decreasing a concentration of the salt in the liquid desiccant to form a second diluted liquid desiccant; a chamber configured to receive the first and / or second diluted liquid desiccant from the absorber and / or dehumidifier and to evaporate a portion of the water from the first and / or second diluted liquid desiccant to form a second water vapor stream and increase the concentration of the salt in the first and / or second liquid desiccant; a compressor configured to receive the second water vapor stream and increase a pressure of the second water vapor stream, wherein the chamber receives the compressed second water vapor stream and condenses the compressed second water vapor stream to form a liquid water that is sent to the water reservoir; a humidifier configured to receive an air stream and liquid water from the water reservoir and evaporate the liquid water such that a concentration of the water vapor in the air stream increases; and an evaporator configured to receive liquid water from the water reservoir and evaporate the liquid water to form the first water vapor stream received by the absorber.

21. The system of claim 20, further comprising a heat exchanger configured to transfer heat from the concentrated liquid desiccant and the liquid water from the chamber to the diluted liquid desiccant from the dehumidifier and / or absorber.

22. The system of any one of claims 20-21, wherein the evaporator comprises a second heat exchanger comprising a heat transfer fluid, wherein the heat transfer fluidprovides heat to the liquid water for evaporation, thereby cooling the heat transfer fluid.

23. The system of claim 22, wherein the cooled heat transfer fluid is used to absorb heat from a building..

24. The system of any one of claims 20-23, wherein the absorber comprises a third heat exchanger comprising a second heat transfer fluid, wherein the second heat transfer fluid receives heat from the first water vapor stream during condensation of the first water vapor stream.

25. The system of claim 24, wherein the heated second heat transfer fluid is sent to a cooling tower.

26. An absorption chilling and dehumidification method comprising: removing water vapor from a humid air stream with liquid desiccant, thereby decreasing a concentration of a salt in the liquid desiccant to form a first diluted liquid desiccant; condensing a first water vapor stream using the liquid desiccant, thereby decreasing a concentration of the salt in the liquid desiccant to form a second diluted liquid desiccant; evaporating a portion of the water from the first and / or second diluted liquid desiccant to form a second water vapor stream and increase a concentration of the salt in the first and / or second liquid desiccant; compressing the second water vapor stream to increase a pressure of the second water vapor stream; condensing the compressed second water vapor stream to form liquid water; evaporating the liquid water to form the first water vapor; and increasing a concentration of water vapor in an air stream by evaporating the liquid water in the presence of the air stream.

27. The method of claim 26, further comprising transferring heat from the concentrated liquid desiccant and the liquid water to the diluted liquid desiccant.

28. The method of any one of claims 26-27, further comprising heating the liquid water with a heat transfer fluid for evaporation, thereby cooling the heat transfer fluid.

29. The method of claim 28, using the cooled heat transfer fluid to cool a building.

30. The method of any one of claims 26-29, transferring heat from the first water vapor stream to a second heat transfer fluid during condensation of the first water vapor stream.

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