CN114504935A - Method and system for dehumidification and atmospheric water extraction with minimal energy consumption - Google Patents

Abstract

Methods, systems, and devices for managing humidity within an HVAC system include a nanostructured desiccant porous material configured to absorb water from an inlet stream at a first air pressure and release water from the material when subjected to a second air pressure, wherein the second air pressure is lower than the first air pressure and is disposed within a specific location so as to allow passage of humid air over the material and to allow adsorption of water onto the material. When coupled with a vacuum pump, water can be collected and released from the materials and systems, regenerating the materials for future use and removing water from the gas stream at much lower cost than existing processes.

Description

Method and system for dehumidification and atmospheric water extraction with minimal energy consumption

Federally sponsored research and development

This disclosure was made with government support under contract DE-AC0576RL01830 awarded by the U.S. department of energy. The government has certain rights in the invention.

Background

Currently, humidity control in building air is primarily passive through condensation on the evaporator coil in the HVAC system. The condensation of water generates a large amount of latent heat, which increases the cooling load of the HVAC system, and therefore, the total energy consumption increases by 30% or more depending on the local environment. Currently, commercially available dehumidifiers are too large and expensive for use in the residential market, and are rarely used in commercial buildings except where humidity management is required. None of these systems provide options for managing CO2 or other gases, such as Volatile Organic Compounds (VOCs), which are becoming increasingly problematic as building envelopes become more compact. The present disclosure provides examples and systems that provide an advancement path that overcomes these problems and provides advantages not found in the prior art.

Additional advantages and novel features of the disclosure will be set forth in the description which follows, and in part will be obvious from the description and the illustrations contained herein. The following description of the present disclosure is, therefore, to be considered as illustrative of the present disclosure and not in any way limiting.

Disclosure of Invention

The following description provides examples of methods, systems, and apparatus for managing humidity within an HVAC system, and in particular in a significantly better and more cost-effective manner than is currently available. In one application, a humidity management system for an HVAC system is described, wherein the system includes a nanostructured desiccant porous material configured to absorb water from an inlet stream at a first air pressure and release water from the material when subjected to a second air pressure, wherein the second air pressure is lower than the first air pressure. Preferably, the nanoporous material is disposed within a structured material such as a desiccant bed, but other configurations including 3D arrangements having configurations in the form of coatings on rods, fins, or other structures are also contemplated in certain applications. Many of these structures may be interconnected or unconnected to other features, such as sealed heat pipes. A vacuum pump is preferably connected to the system and adapted to provide suction to the nanostructured porous material sufficient to reduce the gas pressure and remove water from the nanostructured porous material, thereby regenerating the absorbent material.

In some embodiments, the nanostructured porous material can be MOFs, zeolites, mesoporous silica, covalent organic framework materials; a porous organic polymer; and porous carbon. In one set of embodiments, the material is a MOF, more specifically a MOF 303, MOF 801, or MOF 841, wherein the MOF 303 or MOF 801 exhibits optimal performance in certain circumstances.

In some cases, heat is used to enhance the properties of the material in the device. Heat may be transferred to these materials by operatively connected heat pipes or other means that carry the heated material from the hotter portion of the system to a bed or structure to which the desiccant is attached or attached. In one arrangement, the heat pipe is operatively connected to a set of fins having a desiccant material attached thereto. Then, the water in the air passing over the fins contacts the material and is absorbed. The provision of pairs or groups of desiccant material containing beds or other structures within the air channel path allows contact between the air containing water and the desiccant material as the air is continuously drying as it moves through the structures. This may allow for drying in series and improve efficiency. In addition, if the structures are properly positioned, the channels of these structures can be opened and closed to allow some channels to allow one section to perform a dehumidification operation while a vacuum is applied to another section and water is removed from the system and the absorbent is regenerated.

In use, a method for drying water from ambient air is described. In the method, a flow of aqueous air is passed over a nanostructured porous material configured to absorb water from an inlet flow at a first air pressure and release water from the material when subjected to a second air pressure, wherein the second air pressure is lower than the second air pressure. This collects the water onto the nanostructured porous material and reduces the ambient air pressure to release the water from the nanostructured porous material and regenerate the nanostructured porous material for additional water capture. The reduction of the ambient pressure may be provided by a vacuum pump. The nanostructured porous material may be encapsulated in at least two operatively separated beds, wherein one bed is positioned to capture water from the air stream and the other bed is positioned to release the captured water. If desired, a heat transfer material may be provided in the working fluid connection between the first bed and the second bed such that heat released from one process is transferred to assist the other process. In some cases, the heat transfer material may be contained in a conduit or heat pipe. The result of this arrangement is to allow more cost effective heating and cooling by reducing the energy requirements of the HVAC system.

The purpose of the foregoing summary is to enable the U.S. patent and trademark office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The summary is not intended to limit the disclosure of the application, which is measured by the claims, nor is it intended to limit the scope of the disclosure in any way.

Various advantages and novel features of the disclosure are described herein, and will become more apparent to those skilled in the art from the following detailed description. In the foregoing and following description, by way of illustration of the best mode contemplated for carrying out the present disclosure, applicants have shown and described only the preferred embodiments of the present disclosure. It will be understood that the present disclosure is capable of modification in various respects, all without departing from the present disclosure. Accordingly, the drawings and description of the preferred embodiments set forth below are to be regarded as illustrative in nature, and not as restrictive.

Drawings

Fig. 1 shows a detailed schematic diagram of one example of an embodiment of the invention described in this specification.

Fig. 2 shows a comparison of the amount of power used to regenerate the desiccant bed system of the present application as compared to the load on the HVAC compressor that is removed as a function of the humidity level in the building return air.

FIG. 3 illustrates examples of various exemplary candidate water-absorbing materials based on operating capabilities for various relative humidity (9RH) ranges.

Fig. 4 shows the water uptake performance of three exemplary MOFs (303, 841 and 801) at 25 ℃.

Fig. 5 shows the volumetric energy consumption of an isothermal AWE system for two fan efficiencies.

Fig. 6 shows the bulk water uptake of certain selected nanoporous materials.

FIG. 7 shows the results of the enhanced water absorption capacity by SO3H functionalization in UIO-66.

Fig. 8 shows another embodiment of the invention in which a desiccant is coated on fins made of graphene or other lightweight but thermally conductive supports.

Fig. 9 shows an example of a second illustrative example of the present invention.

Detailed Description

The following description includes one example of the present disclosure. It will be apparent from the description that the present disclosure is not limited to the illustrated embodiments, but the present disclosure also includes various modifications and embodiments made thereto. The description is thus to be regarded as illustrative instead of limiting. While the disclosure is susceptible to various modifications and alternative constructions, it should be understood that there is no intention to limit the disclosure to the specific forms disclosed, but on the contrary, the disclosure is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the disclosure.

In one set of descriptions, a novel desiccant system for managing humidity through a building's HVAC system is described in which a novel nanostructured porous material with ultra-high water capacity is integrated into a desiccant bed and thermally coupled to heat pipes. The building air is then passed over these beds to remove water, however, these advanced absorbents do not utilize heat for desiccant regeneration as in commercial dehumidifiers, but utilize a simple vacuum pump to easily remove the absorbed water at room temperature. Thus, the system eliminates the additional latent heat cooling load from condensation on the HVAC system evaporator coil. The energy savings obtained not only can offset the energy required to operate the vacuum pump, but the equipment footprint and capital cost are half that of today's commercial desiccant dehumidification systems. The system design may also support the inclusion of additional absorbent material in the desiccant bed to allow control of CO₂Content or removal of VOCs from building air.

The operating principle is very simple, warm building air passes over the desiccant bed, which removes moisture. The treated air then passes through an air handler to an evaporator and is cooled as in a standard HVAC system. However, the moisture content of the incoming air has been sufficiently reduced so that its dew point is below the temperature of the evaporator coil, thereby preventing condensation. Once the desiccant reaches its water-absorbing capacity, the building air stream is switched into contact with the second desiccant bed that has completed the regeneration cycle. The use of new ultra high water capacity desiccant materials (MOFs and other desiccants) in our system enables a sufficiently compact unit that can fit within the confines of the standard air handler ducts used in most commercial and residential HVAC facilities. This integrated design eliminates the need for extensive modifications to the building's air handler layout and space for large dedicated dehumidification systems, making it ideal for new installations and retrofit.

Our simpler approach is to use a commercial off-the-shelf (COTS) vacuum pump to provide suction on the desiccant bed during the regeneration cycle of the bed. The temperature of the desiccant beds is controlled by the use of heat pipes to provide thermal coupling between the desiccant beds. This provides a passive but highly efficient heat transfer mechanism to "remove" the heat absorbed by the water vapor generated in the active desiccant bed during dehumidification, using the heat absorbed by the desorption dissipated in the desiccant bed undergoing regeneration. Thus, the desiccant bed regenerates isothermally at the air temperature of the building and does not increase the sensible heat load on the evaporator from the desiccant regeneration. The water vapor discharged by the vacuum pump is only discharged to the environment.

The use of new ultra high water capacity desiccant materials (MOFs and other desiccants) in our system can achieve a sufficiently compact unit that can be installed within the confines of the standard air handler ducts used in most commercial and residential HVAC facilities. This integrated design avoids the need for extensive modifications to the building's air handler layout and space for large dedicated dehumidification systems, making it ideal for new installations and retrofit.

Figures 1-9 illustrate various features and sample embodiments. In one example shown in the drawings, a configuration is shown in which the use of a new ultra high water capacity desiccant material can achieve a sufficiently compact unit that can be installed within the confines of the standard air handler ducts used in most commercial and residential HVAC facilities. This integrated design avoids the need for extensive modifications to the building's air handler layout and space for large dedicated dehumidification systems, making it ideal for new installations and retrofit.

Referring now to the drawings, FIG. 1 shows a schematic diagram of one embodiment of the invention in which a desiccant bed 20 comprising a desired material 22, preferably a metal organic framework material such as MOF, (more preferably MOF 303, MOF 842 or MOF 841, although a variety of other materials may be used depending on the needs and desires of the user) is operatively positioned to allow moist, generally warm air from a source such as warm return air in a conventional HVAC unit to pass over the desiccant bed 20, wherein the material 22 in the desiccant bed absorbs water from the moist air onto the material and passes dry air through the desiccant bed 20. The newly dried air may then be passed for cooling by standard components of a typical HVAC system, which may include an evaporator operatively connected to receive coolant from an expansion valve such that the coolant flows through the evaporator to a compressor that pumps the coolant through a condenser coil cooled by a fan and back to the expansion valve, which controls the passage of the coolant back to the evaporator. The now dried and cooled air can then be delivered to the desired location. The desiccant bed 20 is also operatively connected to a vacuum pump 24, the vacuum pump 24 providing suction to the material 22 in the desiccant bed 20 to remove water from the desiccant bed and discharge the water to another location.

The operating principle is very simple. Warm moist building air passes over a desiccant bed which removes moisture. The now dry air is then passed through an air handler to an evaporator and cooled as in a standard HVAC system. Regeneration of the desiccant occurs as the suction draws moisture from the material of the desiccant bed and discharges it to a separate location. In a continuously operating system, a desiccant tray may be used whereby once the desiccant from a first bed reaches its water absorbing capacity, the building air stream is switched to contact a second desiccant bed which has completed its regeneration cycle, this process may be performed alternately or in series between a plurality of beds, each bed being regenerated by vacuum suction, with the other bed capturing water from a moist, usually warm, source of air.

Various types of materials may be used as the desiccant material 22. Previous research and development efforts for various absorbents for advanced cooling systems have established a unique database of water absorption characteristics for various nanoporous materials, including Metal Organic Framework (MOF) materials, Covalent Organic Framework (COF) materials, Porous Organic Polymers (POPs), zeolites, mesoporous silica, and porous carbon. Our recent work has shown that the excellent thermodynamic properties of certain hydrophilic nanoporous materials with greater water absorption capacity and hydrothermal stability establish adequate and transformative improvements in the size, weight and cost of commercial absorption chillers (mcrail et al, 2014).

In this direction, we have reviewed the data collected on these hydrophilic materials and developed materials that mainly emphasize the absorption kinetics and precisely adjust their water absorption properties. The tunability of the material is advantageous in this application, since the desorption kinetics must be easily achieved under simple vacuum and without heating. Therefore, we have adopted two main approaches for conditioning of desiccant materials: (i) modifying the organic linking chain with hydrophilic/hydrophobic functional groups of appropriate shape/size, and (ii) modifying/adjusting the hydrophilicity of the pre-retained metal cluster-containing nodes with different functional groups. The result is an absorbent material that exhibits mild hydrophobicity at low RH, with a distinct sigmoidal rise in water absorption at RH > 20% V-isotherm).

An example of the isotherm type is expected by utilizing SO at the MOF UIO-66 node₃The ability of H-functionalized pore tuning or pore engineering concepts to tune the absorbent properties, the node shows the water absorption behavior as shown in figure 7. On-node SO₃The concentration of H groups significantly affects their water absorption characteristics. Similarly, terminal functional groups of different Hydrophilicity (HCCO) were used^-、CH3COO^-H2O/OH and PhCOO^-) To modify the clusters resulting in precise control over a range of relative humiditiesThe amount of water absorption within the pores is stepped and this is due to the change in hydrophobic/hydrophilic pore characteristics associated with the difference in pore/cluster/functional shape and size.

While these examples are believed to work for one example, in other arrangements, a material having a V-shaped isotherm shoulder in the range of 20-65% RH and a working capacity of greater than 50 wt% was selected. In particular, two zirconium-based MOFs, MOF-841, MOF-801 and aluminum-based MOF-303, were specifically selected because of their high chemical stability, and their desirable water absorption capacity and renewability as demonstrated by cycling tests to ensure that the absorption characteristics do not deteriorate. Furthermore, we expect commercial synthesis using the atomization-condensation reactor technology of PNNL (moturi, 2016) or other synthesis methods.

The MOF-801 and MOF-303 shown perform best under the current operating conditions. Since the amount of absorbent required is expected to be in the kilogram scale range, we successfully completed the batch synthesis of MOF-801, already prepared/tested on a scale of about 100 grams. To prepare these MOFs, 50mmol each of fumaric acid and ZrOCl2 · 8H2O were dissolved in 500mL screw-cap bottles, dissolved in a mixed solvent of DMF and formic acid (200mL and 70mL), and then heated at 130 ℃ overnight to give a white precipitate, MOF-801. Similarly, the synthesis of MOF-303 was carried out using 43.1mmol of 3, 5-pyrazoledicarboxylic acid monohydrate in deionized water (D) (R)

mL), a base (NaOH or LiOH solution,

mmol). Heating the mixture in a preheating furnace at 120 deg.C

And (3) minutes. After cooling to room temperature, 43.1mmol of AlCl were added with constant vigorous stirring₃·6H₂O was slowly added to the solution. Any precipitate formed in the solution was dissolved under prolonged sonication. Transferring the clear solution toTransferred to an autoclave and heated in a furnace at 100 ℃ for 15-24h to obtain MOF powder. The MOF powder material obtained was activated by solvent and thermal activation before being subjected to water absorption. Powder X-ray diffraction (PXRD) was used to characterize the active materials for crystallinity, thermogravimetric analysis to understand the stability of the material, and N2 absorption isotherms for porosity measurement. Well characterized samples were tested for water absorption measurements at room temperature and then extended to the various temperatures required for this study.

Once characterized, the material was scaled up for mass production by the atomization-condensation reactor technology of PNNL (moturi, 2016). This technique provides a low cost and scalable route to mass production of absorbent materials (e.g., MOFs). While these specific materials are demonstrated in one application, a variety of other materials are also identified for use in such a system. A non-exclusive and non-limiting list includes, but is not limited to, zeolites, such as AlPO₄-34、AlPO₄-LTA、AlPO₄-CHA, 13X, SAPO-34; mesoporous silica such as MCM-41, SBA-15; MOFs including Zr-based and Al-based MOFs, MOFs of the MIL series, Co2Cl2 (BTDD); a covalent organic framework material; a porous organic polymer; porous carbon.

Figure 6 shows the water uptake kinetics of several MOFs. These results show that the flexibility of the design is that the particle size can be reduced from these nominal values to increase the water flux if achieving continuous diffusive transport over these distances proves challenging. In general, our system analysis shows that the water uptake in the absorbent must reach 11 wt% within the target 90s half cycle. There is evidence to be conclusive that this absorption rate as shown in FIG. 6 can be achieved. The absorbent development team will need to select downward desiccants that are capable of achieving this absorption rate through a combination of physical properties including specific surface area, particle size and water diffusion within the crystal.

The system design team ensures that the water vapor delivered to the desiccant surface is sufficient to support the water absorption rate of the desiccant, while minimizing back pressure on the ventilation fan to save energy. Achieving this balance is expected to be the most challenging on the absorption portion of the cycle. Since the vacuum is applied almost uniformly over the desiccant bed during desorption, the water removal rate should be relatively uniform. Since the desorption rate can be well controlled by varying the suction pressure, it should be possible to easily maintain an approximate balance between the water absorption rate in one chamber and the desorption rate in the other chamber by the control system with sufficient sensors to monitor the temperature and discharge RH and feedback.

Conditioning of the desiccant material enables the desired facile removal under specified conditions by (i) modifying the organic connecting chains with hydrophilic/hydrophobic functional groups of appropriate shape/size, and (ii) modifying/adjusting the hydrophilicity of the pre-retained metal cluster-containing nodes with different functional groups. Absorbents exhibiting mild hydrophobicity at low RH>At 20% (V-isotherm), the water uptake increased in a pronounced S-shape. Examples of isotherm types are desired to be engineered through the pores and with the SO₃The ability of H-functionalization to tune the absorber characteristics. (see fig. 7). On-node SO₃Changes in the concentration of H groups significantly affect their water absorption characteristics. Similarly, terminal functional groups of different Hydrophilicity (HCCO) were used^-、CH3COO^-H2O/OH and PhCOO^-) Cluster modification results in a step in water uptake precisely controlled over a range of RH due to changes in hydrophobic/hydrophilic pore characteristics associated with differences in pore/cluster/functional shape and size. Absorbent materials that exhibit promising properties include those with two or three candidates having an optimal V-shaped isotherm shoulder in the range of 20-65% RH and a working capacity of greater than 50 wt%. Preferably, a desiccant material with high chemical stability is used to maintain the long term performance of the system.

Conventional desiccant based dehumidifiers (desiccant wheel, desiccant bed) regenerate the desiccant by heating. This severely limited their application because: 1) desiccant regeneration requires a heat source temperature typically >80 ℃, 2) the heat of absorption released during dehumidification increases the temperature of the desiccant, thereby reducing its dehumidification capacity, and 3) the hot desiccant increases the temperature of the exhaust air, which increases the cooling load on the evaporator and reduces energy savings.

This simpler process allows the desiccant bed to be regenerated using a commercially available (COTS) vacuum pump. The temperature of the desiccant beds may be controlled by using heat pipes to provide thermal coupling between the desiccant beds. This provides a passive but efficient heat transfer mechanism to "remove" the heat absorbed by the water vapor generated in the active desiccant bed during dehumidification, using the heat absorbed by the desorption dissipated in the desiccant bed undergoing regeneration. Thus, the desiccant bed regenerates isothermally at the air temperature of the building and does not increase the sensible heat load on the evaporator from the desiccant regeneration. The water vapour exhausted by the vacuum pump is only exhausted to the environment.

In a preferred embodiment, the desiccant bed is thermally coupled to a "heat pipe". This provides a passive but highly efficient heat transfer mechanism to "remove" the heat absorbed by the water vapor generated in the active desiccant bed by using the heat absorbed by the desorption dissipated in the desiccant bed undergoing regeneration. This Isothermal Water Extraction Cycle (IWEC) allows the drying air stream to cool the condenser unit with minimal temperature change above ambient temperature. A vacuum pump provides suction on the desiccant bed during the regeneration cycle of the desiccant bed and is used to provide moderate compression to sufficiently increase the vapor pressure for condensation to liquid water. This minimizes energy consumption since the compression work is performed only for water vapor. Finally, the condensed water is pumped to atmospheric pressure for discharge into a storage vessel (which consumes a small amount of additional energy).

This innovative AWE system concept eliminates the heat transfer process in conventional temperature swing designs (which generate significant energy losses). Furthermore, the overall energy consumption of the system can be evaluated quite accurately in terms of the power required for: 1) a fan to move air over the desiccant bed and the condenser; 2) a vacuum pump; 3) and a liquid water pump. The air flow rate (CFM) required to introduce sufficient air into the system to produce the desired amount of water is given by the following equation:

wherein M is_wIs that the system is in operation for a time period t_pQuality of water to be produced, p_aIs the air density, m_aIs a mixing ratio (kg-H) determined according to the standard humidity method of humid air₂O/kg-air). Parameter epsilon_RIs the efficiency of the overall system in removing water from the air stream and is a key parameter in linking the absorbent properties to the system performance. In contrast to these other terms, the power required by the water pump is insignificant and will therefore be ignored here. To calculate the power of the vacuum pump, we calculated the compression power required to raise the water vapor pressure from the regenerative desiccant bed to its saturated vapor pressure, assuming that the condenser unit was operated with a change in temperature of 10 ℃ above the ambient air temperature. We assume that the vacuum pump is 80% efficient in the compression work on water vapour. The final assumption is that the suction on the dry bed is sufficient to remove water from the absorbent when operating just at condenser pressure, i.e. the compression ratio is fixed and ≦ 1.2.

For fan power, we used the data provided in Clarke and Ward (2006) to calculate the fan efficiency of a typical ventilation system, as shown in fig. 2. As can be expected, fan efficiency decreases with increasing back pressure. This provides an important constraint on the design of the desiccant bed. Attempts to pass the air stream through a bed of finely packed desiccant particles can result in excessive pressure drop and thus high power consumption. To avoid this, our system design concept passes the air flow through the channels between the fins, similar to the design of a heat sink, and thus can provide minimal back pressure on the fan. For the purposes of the analysis herein, we used two fan efficiency values of 10 and 3CFM/W to complete the energy consumption calculations for our AWE system.

With the simple assumptions outlined above, the energy consumption of our design falls along a single curve determined by the mixing ratio of the ambient air streams. Fan power consumes 80% of the total energy budget. The result provides confidence that our AWE system can achieve the 42W hr/L target if the system design provides a lower back pressure on the fan. An absorber optimized for the conditions of 43 ℃ 60% RH may perform poorly and result in higher power consumption under the more challenging humidity conditions of 27 ℃ 10% RH, and vice versa.

FIG. 8 shows an example of an improved heat pipe heat sink design desiccant bed system formed similar to a heat sink with a set of desiccant coated heat conducting fins made of a very light material (e.g., graphene). As air flows through the channels between the fins, the heat pipes carry heat away from each absorption bed for transfer to another chamber having the same set of beds undergoing regeneration. Heat transfer simulations of this design using the Computational Fluid Dynamics (CFD) code ANSYS-Fluent demonstrated that for the case of 43 ℃, 60% RH (with the lowest air flow rate (1000CFM)), the maximum temperature rise in the absorbent bed was only 5 ℃. This confirms our design premise to be able to thermally couple the absorption-desorption chamber and operate the AWE system substantially isothermally.

This technology is a significant improvement over today's vapor compression cooling systems and provides humidity management with zero energy loss in the conditioned building space. Furthermore, the simple design can be adapted for new HVAC systems and retrofit settings. Based on the expected capacity of advanced desiccants, the size of the dehumidifier system for our 50RT reference case is expected to be only 30ft³The above. This may be as much as 200ft³Compared to a dehumidifier system for a commercial building of the same size air flow (17,000 cfm). Thus, the system contemplated herein may be integrated into standard HVAC air handler units not currently available with dehumidifier systems. Finally, we point out that the desiccant system is suitable for adding other absorbent materials to selectively remove contaminants (e.g., CO)₂Or VOC) which not only saves energy and cost, but also enhances customer appeal.

A second schematic design is shown in fig. 9. In fig. 9, the heat of absorption from the active bed to the regeneration bed is provided by a design utilizing heat pipes. The benefit is a passive heat transfer process that creates isothermal conditions during bed absorption/regeneration. Furthermore, the outer surface of the heat pipe provides a natural support for the desiccant material to be deposited. In addition to the dry bed design, the piping may require diversion of the air flow and vacuum isolation around each bed during regeneration. In the arrangement shown in FIG. 9, it is anticipated that two desiccant sections will be manufactured using cylindrical piping with 1/4 inch diameter heat pipes placed in a cross flow. Each heat pipe will be coated with an absorbent layer around its periphery and have an optimal absorbent layer thickness. The staggered mounting pattern in the flow direction will maximize the exposure of the air stream to the desiccant and promote more turbulence and mixing, resulting in higher heat and mass transfer coefficients. The bed section will be assembled with a vacuum-grade gas flow isolation valve and have autonomous switching control of the air discharge or vacuum pump. The system will be fully instrumented with thermocouples, pressure sensors, Coriolis (Coriolis) flow meters and RH sensors to monitor critical parameters and variables. The water concentration in the ambient air stream will be controlled by a mixing valve that combines the dry air stream with a variable amount of air stream in 100% RH to achieve the specified humidity. Relative humidity sensors (Omega Engineering, inc., model RH-USB) were placed at the inlet and outlet of the desiccant bed to continuously monitor the RH values. This simple test system would enable us to collect all required performance information on the desiccant bed system to evaluate performance and perform thousands of regeneration cycles to look for any degradation in desiccant properties.

While various preferred embodiments of the present disclosure have been shown and described, it is to be clearly understood that this disclosure is not limited thereto but may be embodied in various forms for practice within the scope of the appended claims.

Claims (20)

1. A humidity management system for an HVAC system comprising:

a nanostructured desiccant porous material configured to absorb water from an inlet stream at a first air pressure and release water from the material when subjected to a second air pressure, wherein the second air pressure is lower than the first air pressure.

2. The humidity management system of claim 1, wherein the nanostructured desiccant porous material is disposed within at least one desiccant bed.

3. The humidity management system as claimed in claim 1 or 2, wherein the humidity management system further comprises a vacuum pump adapted to provide a suction to the nanostructured desiccant porous material sufficient to reduce the air pressure and remove water from the nanostructured desiccant porous material.

4. The humidity management system as claimed in any one of claims 1 to 3, wherein the nanostructured desiccant porous material is selected from the group consisting of: MOF, zeolite, mesoporous silica, covalent organic framework materials; a porous organic polymer; and porous carbon.

5. The humidity management system of claim 4, wherein the nanostructured desiccant porous material is a MOF material.

6. The humidity management system of claim 5, wherein the nanostructured desiccant porous material comprises: a MOF selected from the group consisting of MOF 303, MOF 801, or MOF 841.

7. The humidity management system of claim 6, wherein the nanostructured desiccant porous material comprises a MOF 303 or a MOF 801.

8. The humidity management system as claimed in any one of claims 1 to 7, wherein the humidity management system further comprises a heat transfer system for transferring heat to the nanostructured desiccant porous material.

9. The humidity management system as claimed in claim 8, wherein the heat transfer system includes a heat pipe operatively configured to transfer heat to the nanostructured desiccant porous material.

10. The humidity management system as claimed in any one of claims 1 to 9, wherein the nanostructured desiccant porous material is embodied in a coating on a fin.

11. The humidity management system as claimed in any one of claims 1 to 10, wherein the humidity management system further comprises first and second sets of desiccant-containing beds, each of the first and second desiccant-containing beds comprising a nanoporous desiccant material configured to remove water from an air stream passing over the bed.

12. The humidity management system of claim 11, wherein the first desiccant bed and the second desiccant bed comprise the same nanoporous desiccant material.

13. The humidity management system as claimed in any one of claims 1 to 12, wherein the nanostructured desiccant porous material is configured within a three-dimensional shape.

14. The humidity management system of claim 13, wherein said three-dimensional shape is a rod.

15. The humidity management system as claimed in claim 13 or 14, wherein the three-dimensional shape is positioned within an air channel path.

16. A method of removing water from an air stream without additional heating, the method comprising:

passing a flow of air containing water over a nanostructured porous material configured to absorb water from an inlet flow at a first air pressure and release water from the nanostructured porous material when subjected to a second air pressure, wherein the second air pressure is lower than the first air pressure, to collect water onto the nanostructured porous material, and then reducing the ambient air pressure to release water from the nanostructured porous material and regenerate the nanostructured porous material for additional water capture.

17. The method of claim 16, wherein the reduction in ambient pressure is provided by a vacuum.

18. The method of claim 16 or 17, wherein the nanostructured porous material is encapsulated in at least two operatively separated beds, wherein one bed is positioned to capture water from an air stream and the other bed is positioned to release the captured water.

19. The method of claim 18, wherein the at least two operatively separated beds include a first bed and a second bed, the method further comprising providing a heat transfer material in a working fluid connection between the first bed and the second bed such that heat released from one process is transferred to assist another process.

20. The method of claim 19, wherein the heat transfer material is contained within a conduit.

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