High-efficiency atmospheric water harvesting device and method of using the same

Abstract

Provided herein are water harvesting systems for capturing water from ambient air and methods for using such systems. The systems and methods use a water-capturing material to adsorb water from the air. For example, the water-capturing material may be a metal-organic framework. The systems and methods desorb this water in the form of water vapor, which is condensed into liquid water and collected. The liquid water is suitable for use as drinking water.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims priority to U.S. Provisional Patent Application No. 62 / 976,824, filed on February 14, 2020, and U.S. Provisional Patent Application No. 63 / 053,428, filed on July 17, 2020, and U.S. Provisional Patent Application No. 62 / 976,824 and U.S. Provisional Patent Application No. 63 / 053,428 are hereby incorporated by reference in their entirety.

[0002] (Field) The present disclosure generally relates to water harvesting, and more specifically, to systems and methods for collecting water from ambient air using metal - organic frameworks and / or other water - capturing materials.

Background Art

[0003] (Background) A large portion of the world's population is experiencing water shortages. Water in the form of water vapor and water droplets in the atmosphere is a natural resource that can be used to address global water problems. The capture of dew and fog from humid air is an example of an attempt to capture water from air, but such processes require either 100% relative humidity or the frequent presence of large amounts of energy. Thus, such processes are not commercially viable solutions for capturing water from air. See generally Kim et al., Science 356, 430 - 434 (2017).

[0004] What is desired in the art are commercially viable systems and methods that can collect water from ambient air with minimal energy requirements and can be powered by low - grade energy sources (e.g., sunlight).

Summary of the Invention

Means for Solving the Problems

[0005] (Brief Summary) In some scenarios, a water harvesting system for capturing water from ambient air is provided, and the water harvesting system comprises an adsorption / desorption unit, at least one condensation device, and at least one air circulation unit. In some embodiments, the adsorption unit comprises a plurality of modules and a mode switching structure.

[0006] In some embodiments, the plurality of modules are configured such that at least one module operates in an adsorption mode and, in parallel, at least one of the remaining modules operates in a desorption mode, each module comprises at least one structural element, at least a part of each structural element supports at least one water capture material, and at least one water capture material adsorbs water from ambient air when the module is in the adsorption mode and desorbs water in the form of water vapor when the module is in the desorption mode.

[0007] In some embodiments, the mode switching structure is configured to perform in parallel switching at least one module from an adsorption mode to a desorption mode and switching at least one module from a desorption mode to an adsorption mode. In some embodiments, the mode switching structure comprises a rotating mechanism, and the plurality of modules are connected to the rotating mechanism and arranged in a rotary configuration.

[0008] In some embodiments, at least one condensation device is positioned proximal to at least one module in the desorption mode and is configured to condense water vapor into liquid water.

[0009] In some embodiments, at least one air circulation unit is configured to draw ambient air into each module in the adsorption mode, thereby assisting in the adsorption of water from ambient air by at least one water capture material.

[0010] In some aspects, a water harvesting system for capturing water from ambient air is provided, the water harvesting system comprising an adsorption / desorption unit, at least one condenser, and at least one air circulation unit.

[0011] In some variations, the adsorption / desorption unit comprises at least one structural element, at least a portion of each structural element supporting at least one water capture material, the at least one water capture material adsorbing water from ambient air when in the adsorption mode and desorbing water in the form of water vapor when in the desorption mode. In some embodiments, the at least one structural element is a conductor element, the conductor element being resistively heated by passing electricity therethrough to facilitate desorption of water from the water capture material coated thereon.

[0012] In some embodiments, the at least one condenser is positioned proximal to at least one structural element and is configured to condense water vapor into liquid water.

[0013] In some embodiments, the at least one air circulation unit is configured to simultaneously (i) draw ambient air into at least one module operating in the adsorption mode, thereby assisting in the adsorption of water from ambient air by at least one water capture material within the module, and (ii) circulate air to cool at least one condenser.

[0014] In some aspects, a water harvesting system for capturing water from ambient air is provided, the water harvesting comprising an adsorption / desorption unit, at least one condenser, and at least one air circulation unit. In some embodiments, the adsorption / desorption unit comprises a plurality of modules arranged in a rotary configuration and a rotation mechanism.

[0015] In some embodiments, each module comprises at least one conductor element, at least a portion of each conductor element is coated with at least one water capture material, and the at least one water capture material adsorbs water from the ambient air when the module is in the adsorption mode and desorbs water in the form of water vapor when the module is in the desorption mode.

[0016] In some embodiments, a plurality of modules are mounted on a rotation mechanism, and the rotation mechanism is configured to concurrently switch at least one module from the adsorption mode to the desorption mode and switch at least one module from the desorption mode to the adsorption mode.

[0017] In some embodiments, at least one condenser is positioned proximal to at least one module in the desorption mode and is configured to condense water vapor into liquid water.

[0018] In some embodiments, at least one air circulation unit draws ambient air into each module in the adsorption mode and circulates the air within the adsorption / desorption unit, thereby assisting the adsorption of water from the ambient air by the at least one water capture material. The present invention provides, for example, the following items. (Item 1) A water harvesting system for capturing water from ambient air, An adsorption / desorption unit, A plurality of modules configured such that at least one module operates in an adsorption mode and, in parallel, at least one of the remaining modules operates in a desorption mode, Each module includes at least one structural element, At least a part of each structural element supports at least one water capture material, The at least one water capture material adsorbs water from ambient air when the module is in the adsorption mode and desorbs water in the form of water vapor when the module is in the desorption mode, A plurality of modules, A mode switching structure configured to concurrently switch at least one module from the adsorption mode to the desorption mode and switch at least one module from the desorption mode to the adsorption mode An adsorption / desorption unit including, At least one condensation device positioned proximal to the at least one module in the desorption mode and configured to condense water vapor into liquid water, At least one air circulation unit configured to draw ambient air into each module in the adsorption mode, thereby assisting the adsorption of water from the ambient air by the at least one water capture material A water harvesting system including. (Item 2) The system according to Item 1, wherein the mode switching structure includes a rotating mechanism, and the plurality of modules are connected to the rotating mechanism and arranged in a rotary configuration. (Item 3) The system according to Item 1 or Item 2, further comprising at least one vapor redirection unit configured to redirect the water vapor desorbed from the at least one module in the desorption mode to the at least one condensation device. (Item 4) The system according to any one of Items 1 to 3, wherein each module further includes a frame for holding the structural elements together. (Item 5) A water harvesting system for capturing water from ambient air, An adsorption / desorption unit including at least one structural element, At least a part of each structural element supports at least one water capture material, When in the adsorption mode, the at least one water capture material adsorbs water from the ambient air, and when in the desorption mode, desorbs water in the form of water vapor. An adsorption / desorption unit, At least one condensation device positioned proximal to the at least one structural element and configured to condense water vapor into liquid water, At least one air circulation unit configured to simultaneously (i) draw ambient air into the at least one module operating in the adsorption mode, thereby assisting the adsorption of water from the ambient air by the at least one water capture material within the module, and (ii) circulate air to cool the at least one condensation device A water harvesting system comprising. (Item 6) The system according to any one of Items 1 to 5, wherein the at least one structural element is a conductor element. (Item 7) The system according to any one of Items 1 to 6, wherein the adsorption / desorption unit is configured to directly heat the at least one structural element and minimize waste heat. (Item 8) The system according to any one of Items 1 to 6, further comprising at least one heat exchange manifold connected to or positioned around the at least one structural element. (Item 9) The system according to any one of Items 1 to 8, wherein the at least one structural element is at least one plate. (Item 10) The system according to Item 9, wherein the at least one plate is arranged radially within the module or arranged parallel to each other. (Item 11) A water harvesting system for capturing water from ambient air, An adsorption / desorption unit, A plurality of modules arranged in a rotary configuration, Each module comprises at least one conductor element, At least a portion of each conductor element is coated with at least one water capture material, When the module is in the adsorption mode, the at least one water capture material adsorbs water from the ambient air, and when the module is in the desorption mode, desorbs water in the form of water vapor. A plurality of modules, A rotating mechanism, wherein the plurality of modules are mounted on the rotating mechanism and are configured to perform in parallel switching at least one module from an adsorption mode to a desorption mode and switching at least one module from the desorption mode to the adsorption mode, the rotating mechanism An adsorption / desorption unit comprising At least one condensation device positioned proximal to the at least one module in the desorption mode and configured to condense water vapor into liquid water At least one air circulation unit configured to draw ambient air into each module in the adsorption mode, circulate the air within the adsorption / desorption unit, thereby assisting in the adsorption of water from the ambient air by the at least one water capture material A water harvesting system comprising (Item 12) The system according to item 11, further comprising at least one vapor redirection unit configured to redirect water vapor desorbed from the at least one module in the desorption mode to the at least one condensation device (Item 13) The system according to item 11 or item 12, wherein the at least one condensation device is positioned inside the plurality of modules arranged in a rotary configuration (Item 14) The system according to any one of items 1 to 13, wherein the at least one conductor element is at least one metal plate (Item 15) The system according to item 14, wherein the at least one metal plate is arranged radially within the module or arranged parallel to each other (Item 16) The system according to any one of items 1 to 15, wherein the at least one water capture material comprises a metal organic framework (Item 17) The system according to any one of items 1 to 15, wherein the at least one water capture material includes a desiccant material (Item 18) The system according to any one of the above items, further comprising a sealing structure configured to seal one or more modules in the desorption mode (Item 19) The system according to any one of the above items, further comprising at least one collection unit configured to receive the liquid water from the at least one condensation device (Item 20) The system according to any one of the preceding items, further comprising a control system configured to monitor and control adsorption, desorption, and condensation, the control system comprising at least one sensor and at least one processor unit. (Item 21) The system according to any one of the preceding items, wherein the airflow exits the at least one condenser, and the system further comprises at least one recirculation unit configured to reuse the airflow exiting the at least one condenser in at least one module in desorption mode. (Item 22) The system according to any one of the preceding items, further comprising at least one float valve configured to collect the liquid water by gravity without any substantial air loss. (Item 23) The system according to item 22, further comprising at least one collection unit configured to receive the liquid water exiting the at least one condenser through the at least one float valve. (Item 24) The system according to any one of the preceding items, further comprising at least one storage unit for holding the adsorption / desorption unit, at least one condenser, and at least one air circulation unit. (Item 25) A method of collecting water from ambient air using the water harvesting system according to any one of items 1 to 3 and 17 to 24, comprising: a) adsorbing water from ambient air in at least one module in adsorption mode; b) desorbing at least a portion of the water in at least one of the remaining modules in desorption mode; c) using the at least one condenser to condense at least a portion of the water vapor released from the at least one module in desorption mode to produce liquid water, steps (a) to (c) occurring simultaneously; and d) switching at least one module in adsorption mode to desorption mode and switching at least one of the remaining modules in desorption mode to adsorption mode. A method as described above. (Item 26) A method of collecting water from ambient air using the water harvesting system according to any one of items 4 to 9 and 17 to 24, comprising: a) Drawing in ambient air into at least one module in adsorption mode to assist in the adsorption of water by the at least one water capture material and to assist in the cooling of the at least one condenser, wherein the air is recycled or reused to assist in adsorption and cooling; b) Heating at least one of the remaining modules in desorption mode to assist in the desorption of at least a portion of the water from the at least one water capture material; c) Using the at least one condenser to condense at least a portion of the water vapor released from the at least one module in desorption mode to produce liquid water. A method comprising the above. (Item 27) A method for collecting water from ambient air using the water harvesting system according to any one of Items 10 to 24, comprising: a) Adsorbing water from ambient air in at least one module in adsorption mode; b) Desorbing at least a portion of the water in at least one of the remaining modules in desorption mode; c) Using the at least one condenser to condense at least a portion of the water vapor released from the at least one module in desorption mode to produce liquid water, wherein steps (a) to (c) occur simultaneously; d) Rotating at least one module in adsorption mode to desorption mode and rotating at least one of the remaining modules in desorption mode to adsorption mode. A method comprising the above. (Item 28) The method according to any one of Items 25 to 27, wherein an air flow exits from the at least one condenser, and the method further comprises recycling the air flow exiting from the at least one condenser to at least one module in desorption mode.

Brief Description of the Drawings

[0019] (Brief Description of the Drawings) This application can be best understood by reference to the following description, which is to be read in conjunction with the accompanying drawings included herein. The drawings in this specification are not drawn to scale.

[0020]

Figure 1

[0021]

Figure 2A

Figure 2B

[0022]

Figure 3A

Figure 3B

Figure 3C

[0023]

Figure 4A

Figure 4B

[0024]

Figure 5A

Figure 5B

Figure 5C

Figure 5D

[0025]

Figure 6

[0026]

Figure 7

[0027] Figures 8A, 8B, and 8C depict graphs showing the change in weight of modules in an exemplary water harvesting system.

Figure 8A

Figure 8B

Figure 8C

[0028]

Figure 9

[0029]

Figure 10

DETAILED DESCRIPTION

[0030] (Detailed Description) The following description relates to exemplary methods, parameters, etc. However, it should be recognized that such description is not intended as a limitation of the scope of the present disclosure, but rather is provided as an explanation of exemplary embodiments.

[0031] In some aspects, a water harvesting system for capturing water from ambient air is provided herein. In some embodiments, the system includes at least one adsorption / desorption unit, at least one condensation device, and at least one air circulation unit. The adsorption / desorption unit has a plurality of modules that include a water capture material. When the system is operating in a steady state, at least one of the modules is in an adsorption mode, and simultaneously, at least one of the remaining modules is in a desorption mode. In the adsorption mode, the water capture material within a given module adsorbs water from the ambient air. The air circulation unit draws ambient air into each module in the adsorption mode, thereby assisting the adsorption of water from the ambient air by the water capture material. Then, when a module is switched to the desorption mode, the module desorbs water in the form of water vapor or steam.

[0032] In one aspect, the system provided herein further includes a switching structure that switches at least one module from the adsorption mode to the desorption mode and switches at least one of the remaining modules from the desorption mode to the adsorption mode. In some variations, the mode switching structure is a rotary structure on which a plurality of modules are mounted. The rotary structure rotates to shift at least one module from the adsorption mode to the desorption mode and to shift at least one of the remaining modules from the desorption mode to the adsorption mode.

[0033] When water desorbs from a given module in the desorption mode, the water vapor is condensed into liquid water via at least one condensation device positioned proximal to at least one of the modules in the desorption mode. The liquid water can then be collected by a storage tank. In some variations, the system described herein further includes at least one vapor redirection unit that redirects the water vapor desorbed from a given module in the desorption mode to the condensation device.

[0034] In other aspects, a water harvesting system for capturing water from ambient air is also provided herein, which includes an adsorption / desorption unit, at least one condenser, and at least one air circulation unit. The at least one air circulation unit simultaneously (i) draws ambient air into at least one module operating in an adsorption mode, thereby assisting in the adsorption of water from the ambient air by at least one water capture material within the module, and (ii) circulates air to cool at least one condenser. In effect, the ambient air drawn in by the air circulation unit can be recycled or reused to achieve at least two different purposes, namely, adsorbing water and cooling the condenser.

[0035] The water harvesting system described herein increases the efficiency and ease of water collection. In some aspects, the time for each adsorption / desorption cycle can be shortened. In some embodiments, a compressor is not required, which results in less operating noise and lower costs. In other aspects, simultaneous adsorption / desorption enables a more efficient design of the water harvesting system. In some variations, the systems described herein do not require a compressor or a separate cooling mechanism, a shut-off valve, a chamber, or a vacuum pump.

[0036] In other aspects, a method for capturing water from ambient air using the systems provided herein is also provided herein. In some embodiments, the method includes adsorbing water from ambient air in at least one module in an adsorption mode, desorbing at least a portion of the water in at least one of the remaining modules in a desorption mode, using at least one condenser to condense at least a portion of the water vapor released from at least one module in a desorption mode to produce liquid water, wherein adsorption, desorption, and condensation occur in parallel, and switching at least one module in the adsorption mode to the desorption mode and switching at least one of the remaining modules in the desorption mode to the adsorption mode.

[0037] In some embodiments, the method comprises drawing ambient air into at least one module in adsorption mode to assist in the adsorption of water by at least one water capture material and to assist in the cooling of at least one condenser, the air being recycled or reused to assist in both adsorption and cooling, heating at least one of the remaining modules in desorption mode to assist in the desorption of at least a portion of the water from at least one water capture material, and condensing at least a portion of the water vapor released from at least one module in desorption mode using at least one condenser to produce liquid water.

[0038] In some embodiments, the method comprises adsorbing water from ambient air in at least one module in adsorption mode, desorbing at least a portion of the water in at least one of the remaining modules in desorption mode, and condensing at least a portion of the water vapor released from at least one module in desorption mode using at least one condenser to produce liquid water, wherein adsorption, desorption, and condensation occur in parallel, and rotating at least one module in adsorption mode to desorption mode and rotating at least one of the remaining modules in desorption mode to adsorption mode.

[0039] The system, and a method of using such a system for water harvesting, are described in further detail below.

[0040] Adsorption / Desorption Unit In some embodiments, a water harvesting system for capturing water from ambient air comprises an adsorption / desorption unit. In some embodiments, the adsorption / desorption unit comprises a plurality of modules and a mode switching structure.

[0041] a) Modules In some embodiments, the plurality of modules are configured such that at least one module operates in an adsorption mode and, in parallel, at least one of the remaining modules operates in a desorption mode. In some embodiments, the plurality of modules are arranged in a rotary configuration. In some embodiments, the plurality of modules are connected to or mounted on a rotating base.

[0042] In some embodiments, each module comprises at least one structural element. Referring to FIG. 1, an exemplary plate-like structural element 1020 is coated by adsorption layers 1022 and 1024. The structural element 1020 supports a water capture material coated on both sides of the structural element, and the structural element is a heating substrate that can be heated, for example, by passing an electric current. It should be understood that in some variations, each adsorption layer may have the same or different water capture materials. In other variations, each adsorption layer may have the same or different thicknesses. In yet other variations, only one side of the structural element is coated by an adsorption layer.

[0043] In some embodiments, the adsorption / desorption unit is configured to directly heat at least one structural element and can minimize waste heat. In some embodiments, at least one structural element is a conductor element. In some embodiments, the conductor element is resistively heated by passing an electric current through the conductor element. In some embodiments, the conductor element is a metal or a metal plate.

[0044] Referring to FIG. 6, the structural element 1020 is a conductor element (or a resistive substrate). During desorption, the structural element 1020 is resistively heated by passing an electric current 6000 through it, thereby assisting in the desorption of water in the form of vapor 6100 from the adsorption layers 1022 and 1024 made of the water capture material coated on the conductor element 1020.

[0045] Referring to FIGS. 2A and 2B, an air flow flowing into the adsorption / desorption unit through the gaps between adjacent structural elements is depicted. During adsorption, ambient air flows through the gaps between adjacent structural elements, enabling the adsorption layer to adsorb water from the ambient air. FIG. 2A depicts a plurality of exemplary plate-like structural elements 1020, 1030, and 1040 arranged in parallel, along with the gaps (1025 and 1035) between adjacent structural elements (1020 and 1030, and 1030 and 1040 respectively), and the air flowing between those gaps (represented by a set of arrows 1045). FIG. 2B depicts a plurality of exemplary plate-like structural elements (2000) arranged radially, along with the gaps between adjacent structural elements and the air flowing between those gaps (represented by a set of arrows 1045). As depicted in this figure, each structural element is a heating substrate coated on both sides with an adsorption layer. For example, structural element 1020 is coated on both sides with adsorption layers 1022 and 1024. It should be understood that in some variations, each adsorption layer may have the same or different water capture materials. In other variations, each adsorption layer may have the same or different thicknesses. In yet other variations, only one side of the structural element is coated with an adsorption layer.

[0046] In some embodiments, the power applied to the conductor element is E ads Since the desorption rate dm / dt of water as the heat of adsorption of water into the water capture material or MOF layer is related to the power W by the following equation, the desorption time can be adjusted to optimize it.

Equation

[0047] Therefore, the electrical resistance of the substrate R and the current I flowing through it can be adjusted for an optimal desorption rate since the power W is related to R and I through the following equation.

Equation

[0048] In some embodiments, the structural elements are designed and arranged to allow for the diffusion of water from the ambient air to the water capture material during the adsorption stage. Referring to FIG. 10, layers 7022 and 7024 of the water capture material are coated on adjacent structural elements, and exemplary air molecules 7020 are shown as dots passing through the gaps between those structural elements. In some embodiments, again referring to FIG. 10, the structural elements are designed and arranged such that d / v > c×(w / 2) 2 / D, where (i) d is the depth of travel by air (excluding water vapor) through the gap between the structural elements during the adsorption stage, (ii) v is the average velocity of air (carrying water vapor) through the structural elements during the adsorption stage, (iii) c is a constant, (iv) w is the average spacing between the water capture material layers 7022 and 7024 on adjacent structural elements, and (v) D is the diffusion constant or diffusion rate of water vapor.

[0049] d / v > c×(w / 2) 2 / D, in the left side of the inequality notation, i.e., d / v, is referred to as the "travel time" and can be denoted as t Trans . The right side of the inequality notation without the constant c, i.e., (w / 2) 2 / D, is referred to as the "diffusion time" and can be denoted as t Diff . The condition d / v > c×(w / 2) 2 / D is equivalently expressed as t Trans > c×t Diff or described as the travel time of the air molecules being greater than a certain percentage of the diffusion time of the water vapor. For example, when c is 30%, the structural elements are arranged such that the travel time is greater than 30% of the diffusion time.

[0050] In some variations, the constant c is at least about 5%, at least about 10%, at least about 30%, at least about 50%, or at least about 75%, or about 1% - about 5%, about 5% - 50%, about 10% - about 50%, about 30% - about 75%, or about 50% - 150%.

[0051] In some embodiments, the structural elements are arranged radially, continuously, or in parallel to form modules. In some embodiments, the structural elements are either welded together, soldered together, held in a compressed state, or electrically connected by any other means. Referring to FIG. 3A, exemplary module 3010 includes a plurality of plate-like structural elements 2000, which are coated with a water capture material and radially arranged and held together by frame 3012.

[0052] In some embodiments, the structural elements are flexible. In some embodiments, the structural elements are held under tension to maintain even spacing and prevent each element from contacting one another. In some embodiments, the tension mechanism is a whiffle tree or a whipple tree. In some embodiments, the whipple tree is formed by one or more flexible members.

[0053] In some embodiments, a plurality of modules are configured to form a cylinder. Referring to FIGS. 3B and 3C, exemplary adsorption / desorption unit 3000 includes six modules (3010, 3020, 3030, 3040, 3050, and 3060), which are arranged in a rotary configuration and mounted on mode switching structure 3002 (FIG. 3B). The mode switching structure depicted herein is a rotary carousel. As depicted in the exploded view of FIG. 3C, mode switching structure 3002 includes a rotating base 3004. Although six modules are depicted within the exemplary adsorption / desorption unit of FIGS. 3B and 3C, it should be understood that in other variations, the adsorption / desorption unit may include any number of modules within the plurality of modules.

[0054] In some embodiments, the module is rotated such that one or more of the modules are moved into the desorption area and one or more of the modules are moved into the adsorption area. In some embodiments, the rotation of the module is performed by a rotating plate driven by a motor through a belt. In some embodiments, the rotation of the module is performed by a rotating plate driven by a motor through a system of one or more gears.

[0055] In some embodiments, at least one structural element is at least one plate. In some embodiments, at least one plate is arranged radially within the module or arranged parallel to each other. In some embodiments, at least one plate is independently coated on one or both sides of the water capture material.

[0056] In some variations, the plates are arranged radially or parallel to each other, and there is a gap between adjacent plates. The plate can be made of any suitable material including any suitable metal. For example, in some variations, the plate includes aluminum. In some variations, the plate includes solid metal. In one variation, the plate is in the shape of a blade.

[0057] In one variation, the plate has a flat surface. In other variations, each plate has a breathable design, and its surface intersects with small channels in a lattice pattern to form a water capture material area (e.g., square) that allows for a thermal expansion mismatch between the plate and the water capture material. In other variations, each plate has a rough surface with topographical features that can enhance the water adsorption / desorption performance and / or reliability. In one variation, the topographical features are holes, bumps, ridges, or grooves, or any combination thereof. In another variation, the plate includes a mesh. For example, in one variation, the plate includes an aluminum mesh.

[0058] In some embodiments, the relative spacing of the gaps between adjacent plates with respect to the length of each plate achieves an optimal air flow and maximizes water adsorption. In some variations, the gap between adjacent plates is from about 1% to about 5% of the length of the plate.

[0059] In some embodiments, the plates are coated with a layer of water capture material having a thickness of from about 10 microns to about 500 microns, or from about 50 microns to 500 microns, or from about 10 microns to about 50 microns, respectively. The thickness of the layer can allow for faster adsorption and desorption (e.g., as compared to a thicker layer). In other embodiments, the plates are coated with a layer of water capture material having a thickness of from about 0.1 to about 1 cm, respectively. Such a thickness of the layer can allow for the production of a greater amount of water (e.g., as compared to a thinner layer).

[0060] In one embodiment, each layer of water capture material on the plate is porous. In some variations, the porosity is at least about 40%, at least about 50%, at least about 60%, at least about 70%, or at least about 80%, or from about 40% to about 90%, from about 50% to 90%, from about 40% to about 80%, from about 50% to about 80%, or from about 60% to 80%. In other embodiments, the layer of water capture material is non-porous.

[0061] In some embodiments, the ratio of the thickness of the layer of water capture material is greater than the thickness of the plate. In one embodiment where both sides of the plate are coated with water capture material, the ratio of the thickness of the first (e.g., upper) layer of water capture material to the thickness of the plate to the thickness of the second (e.g., bottom) layer of water capture material optimizes water desorption and the energy used to heat the plate within the chamber. In some variations where the layer is non-porous, the thickness of each layer of water capture material can be greater than at least half the thickness of the plate.

[0062] In some of the foregoing variations, the layer of water capture material can be mixed with one or more additional components. In some variations, a binder can be mixed into the layer. In one variation, an organic binder can be used. In one variation, a silicon binder can be used. In one variation, a silicone resin binder can be used. In some variations, the layer can further include one or more materials that aid in thermal conductivity to accelerate transfer. In one variation, the layer further includes graphite.

[0063] In some variations, the water capture material is uniformly dispersed on the plate. Any suitable technique known in the art can be employed to coat the layer of water capture material onto the plate. For example, in one variation, the layer of water capture material is deposited onto the plate.

[0064] b) Water capture material In some embodiments, at least a portion of each structural element supports at least one water capture material. In some embodiments, at least a portion of each structural element is coated with at least one water capture material. In some embodiments, at least one water capture material adsorbs water from the ambient air when the module is in the adsorption mode and desorbs water in the form of water vapor when the module is in the desorption mode.

[0065] In some variations, the water capture material comprises a metal organic framework (MOF). A MOF is a porous material having repeating secondary structure units (SBUs) connected to organic ligands. In some variations, an SBU may include one or more metals or metal-containing complexes. In other variations, the organic ligand has acid and / or amine functional group(s). In one variation, the organic ligand has a carboxylic acid group.

[0066] In the systems provided herein, any suitable MOF that can adsorb and desorb water may be employed. In one variation, MOF-303 having the structure of Al(OH)(HPDC) may be used, where HPDC represents 1H-pyrazole-3,5-dicarboxylate (which may also be referred to as 3,5-PyzDC). Other suitable MOFs may include, for example, CAU-10, MIL-53, MOF-801, MOF-841, and MIL-160. See, for example, Kalmutzki et al., Adv. Mat., 30(37), 1704304 (2018); Furukawa et al., J. Am. Chem. Soc. 2014, 136, 4369-4381. Combinations of MOFs may also be used.

[0067] In some variations, the MOF has a pore size of about 0.5 nm to about 1 nm, or about 0.7 nm to about 0.9 nm. In one variation, the MOF has a hydrophilic pore structure. In one variation, the MOF has a hydrophilic pore structure containing acid and / or amine functional groups. In one variation, the MOF has 1D channels that enable reversible water adsorption.

[0068] In some variations, the water capture material is microporous aluminum phosphate (AlPO4-LTA). See, for example, Y. Tu et al, Joule, Vol 2, Issue 8(15), 1452-1475 (2018).

[0069] In other variations, the water capture material is a desiccant material. Any suitable desiccant material may be used.

[0070] Any combination of the water capture materials described herein may also be used.

[0071] In some embodiments, the water capture material is mixed with a binder to improve its properties with respect to adhesion to a substrate.

[0072] c) Mode switching structure In some embodiments, the mode switching structure is configured to switch at least one module from the adsorption mode to the desorption mode and to switch at least one module from the desorption mode to the adsorption mode. In some embodiments, the mode switching structure comprises a rotation mechanism, and the plurality of modules are connected to the rotation mechanism and arranged in a rotary configuration.

[0073] In some variations, the system includes an adsorption / desorption unit having a plurality of modules including at least one water capture material arranged in a rotary configuration, a rotation mechanism on which the plurality of modules are mounted and which is configured to switch at least one module from the adsorption mode to the desorption mode and to switch at least one module from the desorption mode to the adsorption mode, at least one condensation device positioned proximal to at least one module in the desorption mode and configured to condense water vapor into liquid water, and at least one air circulation unit configured to draw ambient air into each module in the adsorption mode and to circulate the air within the adsorption / desorption unit, thereby assisting in the adsorption of water from the ambient air by at least one water capture material. In one of the aforementioned variations, at least one condensation device is positioned inside a plurality of modules arranged in a rotary configuration. In one of the aforementioned variations, the air drawn in from the ambient air is recycled or reused to achieve more than one purpose, such as adsorbing water and cooling the condensation device.

[0074] Referring to FIGS. 5A and 5B, two views of an exemplary water harvesting system 5000 with a rotary mode switching structure or carousel and a storage unit 5010 are depicted. An air circulation device 5004 (the fan depicted in FIG. 5A) draws ambient air 5102 from the side of the carousel, passes it through a module 3010 in adsorption mode, and through a condensation device 5008 (the condensation coil of FIG. 5B) wound around a vapor redirection device 5006 (a condensation fan in this embodiment), and blows air 5100 out at the top of the carousel. The cross-sectional view in FIG. 5B depicts a carousel 3002 including a carousel motor 5002.

[0075] Sealing structure In some embodiments, the water harvesting system further includes a sealing structure configured to seal one or more modules in a desorption mode. In some embodiments, the sealing structure completely or partially isolates one or more modules in a desorption mode from one or more modules in an adsorption mode. In some embodiments, the sealing structure is within each module. In some embodiments, the sealing structure is external to each module. In some embodiments, the sealing structure is partially within each module and partially external to each module.

[0076] In some embodiments, a structural element coated with a water capture material is placed within a frame to form a module. In some embodiments, the frame or enclosure is partially or completely sealed during desorption and opened during adsorption.

[0077] Condensation device In some embodiments, the water harvesting system further includes at least one condensation device. In some embodiments, the condensation device is positioned proximal to at least one module in a desorption mode and is configured to condense water vapor into liquid water.

[0078] In some embodiments, at least one condenser is positioned inside a plurality of modules arranged in a rotary configuration.

[0079] In one embodiment, a water harvesting system includes one or more condensers. The condenser is positioned proximal to one or more of the modules. In some variations, multiple condensers are used. In one variation where multiple condensers are used, the condensers are arranged in series or in parallel.

[0080] In some embodiments, the condenser is a tube. In some embodiments, water vapor is condensed inside the tube. In some embodiments, the tube has a coil structure or is a coil of the tube. In some embodiments, the tube is cooled by circulating air or blowing air outside the condenser. In some embodiments, the air that is circulated or blown outside the condenser is the air used for adsorption. In some embodiments, the air that is circulated or blown outside the condenser is the air cooled by cryogenic storage. In some embodiments, the condenser is cooled on the low temperature side of a refrigeration cycle. In some embodiments, the condenser is an active chiller based on, for example, a refrigeration cycle or cryogenic storage.

[0081] Referring to FIG. 5C, an exemplary condenser 5008 is a condenser coil and is wound around a vapor re - directing device 5006 (a condenser fan in this example). The vapor re - directing device 5006 re - directs or sucks the water vapor or vapor 5202 generated in the module in the desorption mode into the condenser 5008 (the condenser coil in this example) and condenses the water vapor into liquid water.

[0082] Referring to FIG. 5D, after condensation, the water 5200 is directed (e.g., by gravity) into a float valve 5012 that enables its collection. The condensed air stream 5104 is then recirculated into the module 3060 in desorption mode to minimize moisture and energy loss to the surrounding air.

[0083] Air circulation unit In some embodiments, the water harvesting system comprises at least one air circulation unit. In some embodiments, the air circulation unit is configured to draw ambient air into each module in adsorption mode, thereby assisting in the adsorption of water by at least one water capture material from the ambient air.

[0084] In some embodiments, at least one air circulation unit is configured to simultaneously (i) draw ambient air into at least one module operating in adsorption mode, thereby assisting in the adsorption of water from the ambient air by at least one water capture material within the module, and (ii) circulate air to cool at least one condenser.

[0085] Vapor redirection unit In some embodiments, the water harvesting system comprises at least one vapor redirection unit. In some embodiments, the vapor redirection unit is configured to redirect water vapor desorbed from at least one module in desorption mode to at least one condenser. In one variation, the vapor redirection unit is a fan or a positive displacement pump.

[0086] Condenser recirculation air stream In some embodiments, the water harvesting system comprises at least one recirculation unit. In some embodiments, the recirculation unit is configured to reuse the air stream exiting the condenser coil in at least one desorption module.

[0087] Water collection unit In some embodiments, the water harvesting system comprises at least one float valve and is configured to collect condensed liquid water by gravity without any air loss or any substantial air loss.

[0088] In some embodiments, the water harvesting system comprises at least one collection unit configured to receive liquid water. In some embodiments, the water harvesting system comprises at least one collection unit configured to receive liquid water exiting from at least one condensation device through at least one float valve. In some variations, the water collection unit is a storage tank.

[0089] Control system In some embodiments, the water harvesting system includes a control system configured to monitor and control adsorption, desorption, and condensation. In some embodiments, the control system includes one or more sensors and one or more processor units.

[0090] In some embodiments, the control system is used to increase or decrease the amount of electrical power delivered to a module to accelerate or decelerate the desorption rate. In some embodiments, the control system is used to increase or decrease the rate at which water vapor is removed from a module in a desorption area or in desorption mode and / or the rate at which air is pushed into a module in a desorption area or in desorption mode. In some embodiments, the control system is used to increase or decrease the time a module spends in desorption mode. In some embodiments, the control system is used to increase or decrease the amount of time a module spends in adsorption mode. In some embodiments, the control system is used to increase or decrease the rate at which air is moved across a module during adsorption.

[0091] In some embodiments, the control system monitors and controls the water harvesting system based on environmental conditions such as temperature and humidity. In some embodiments, temperature or humidity sensors are installed inside or in the vicinity of the adsorption module (module in adsorption mode) and the desorption module (module in desorption mode).

[0092] In some embodiments, the control system monitors and controls the water harvesting system to maximize the total amount of water captured over a plurality of adsorption and desorption cycles, rather than optimizing the adsorption or desorption amount individually.

[0093] In some embodiments, the control system is designed such that the time steps for rotation of the module or adsorption / desorption unit can be adjusted so that (i) the time spent in the adsorption mode (total adsorption time) before each module switches to the desorption mode is just sufficient to soak most of the water into the water capture material within that module, and (ii) the time spent in the desorption mode (total desorption time) before each module switches to the adsorption mode is just sufficient to desorb most of the water captured by the water capture material in that module.

[0094] In some embodiments, the control system controls the speed of the vapor redirection unit and the amount of electric power provided to heat the structural elements to accelerate or decelerate desorption to match the adsorption rate. Similarly, the speed of the air circulation unit can be increased or decreased to accelerate or decelerate the adsorption rate to match the desorption rate. This control can be important because different temperature and humidity levels affect the time required for adsorption and desorption.

[0095] Power source In some variations, the systems provided herein further include one or more solar power sources. In one variation, the system further includes a photovoltaic (PV) cell or a passive solar capturer, or a combination thereof.

Example

[0096] (Example) The following examples are merely illustrative and are not meant to limit any aspect of the present disclosure in any way.

[0097] (Example 1) A water harvesting system for generating drinking water Water harvesting system An MOF layer paste composed of MOF powder (MOF-303 in this example) mixed with 5 - 15% organic binder was deposited as a thin film on a conductive substrate (conductor element). After curing, the MOF layer was tightly bonded to the substrate using excellent mechanical and thermal properties. A series of these substrates coated with the MOF layer were electrically connected and assembled into a module. The small gaps between the substrates allowed air to flow.

[0098] The modules were assembled within a rotary structure called a carousel (Figs. 3A and 3B). The carousel was constructed such that while one or more modules were in the adsorption mode, other modules were in the desorption mode. In this example, the carousel consisted of a total of six modules with five modules in the adsorption mode and one module in the desorption mode (Fig. 4A). When the carousel was rotated, the modules moved from position N to position N + 1, initiated the adsorption mode, and finally entered the desorption mode (Fig. 4B).

[0099] In the module in the adsorption mode, air is drawn through the center of the structure using the central fan and pushed between the MOF layer substrates that enable moisture to be captured by the MOF layer (Figs. 5A and 5B). When the module enters the desorption mode, current passes through the substrates and heats them (Fig. 6).

[0100] The vapor that exited the desorption MOF layer was moved from the desorption area to the condensation area. In this example, the vapor was drawn from the module into the desorption area by a small fan and sent to a spiral tube type condenser installed inside the carousel (Figs. 5A, 5B, and 5C). The vapor was cooled to room temperature by the air flowing around the coil, and the coil condensed the water and drained it downward to be collected inside the collection tank. Referring to Fig. 7, the ambient air 5102 was circulated to the module(s) 3010 in the adsorption mode, and the module(s) 3010 cooled the condenser 5008, sent out the air 5100, desorbed water as vapor 6100 from the module(s) 3060 in the desorption mode, condensed the vapor 6100 to water using the condenser 5008, and collected the water using the water tank 5204, and recycled or reused the air 5102 for these purposes.

[0101] Results Figs. 8A, 8B, and 8C show examples of the system's performance. The modules illustrated in Figs. 2A and 2B were installed on a precision scale. During adsorption (Fig. 8A), the weight of the module increased rapidly until about 3 grams of water was adsorbed. The exponential fit yielded a time constant of 52 seconds. During desorption (Fig. 8B), the weight of the module decreased even more rapidly, and about 3 grams of water was desorbed. The exponential fit yielded a time constant of 40 seconds. Fig. 8C shows multiple adsorption / desorption cycles and demonstrates the ability of this system to collect water extremely efficiently. Fig. 9 shows the reliability of the system. After more than 1,000 adsorption / desorption cycles, there was no change in water uptake, which demonstrates the excellent robustness of the system.

Claims

1. A water harvesting system for capturing water from ambient air, an adsorption / desorption unit, a plurality of modules configured such that at least one module operates in an adsorption mode and, in parallel, at least one of the remaining modules operates in a desorption mode, each module comprising at least one structural element, at least a portion of each structural element supporting at least one water capture material, the at least one water capture material adsorbing water from ambient air when the module is in the adsorption mode and desorbing water in the form of water vapor when the module is in the desorption mode, a plurality of modules, and a mode switching structure configured to concurrently switch at least one module from the adsorption mode to the desorption mode and at least one module from the desorption mode to the adsorption mode and an adsorption / desorption unit comprising; at least one condensation device positioned proximal to the at least one module in the desorption mode and configured to condense water vapor into liquid water, at least one air circulation unit configured to draw ambient air into each module in the adsorption mode, thereby assisting the adsorption of water from the ambient air by the at least one water capture material A water harvesting system comprising.

2. The system of claim 1, wherein the mode switching structure comprises a rotating mechanism, and the plurality of modules are connected to the rotating mechanism and arranged in a rotary configuration.

3. The system according to claim 1 or claim 2, further comprising at least one vapor redirection unit configured to redirect water vapor detached from the at least one module in the detachment mode to the at least one condensation device.

4. The system according to any one of claims 1 to 3, wherein each module further comprises a frame for holding the structural elements together.

5. A water harvesting system for capturing water from ambient air, An adsorption / desorption unit comprising a plurality of modules, Each of the plurality of modules comprises at least one structural element, At least a part of each structural element supports at least one water capture material, The at least one water capture material adsorbs water from ambient air when in the adsorption mode and desorbs water in the form of water vapor when in the desorption mode, An adsorption / desorption unit, At least one condensation device positioned proximal to the at least one structural element and configured to condense water vapor into liquid water, At least one air circulation unit configured to simultaneously (i) draw ambient air into at least one of the plurality of modules operating in the adsorption mode, thereby assisting the adsorption of water from the ambient air by the at least one water capture material in the at least one module, and (ii) circulate air to cool the at least one condensation device A water harvesting system comprising.

6. The system according to any one of claims 1 to 5, wherein the at least one structural element is at least one conductor element.

7. The adsorption / desorption unit directly heats the at least one structural element and is configured to minimize waste heat, the system according to any one of claims 1 to 6.

8. The at least one structural element is at least one plate, the system according to any one of claims 1 to 7.

9. The at least one plate is arranged radially within the module or arranged parallel to each other, the system according to claim 8.

10. A water harvesting system for capturing water from ambient air, An adsorption / desorption unit, A plurality of modules arranged in a rotary configuration, Each module comprises at least one conductor element, At least a part of each conductor element is coated with at least one water capture material, The at least one water capture material adsorbs water from ambient air when the module is in the adsorption mode and desorbs water in the form of water vapor when the module is in the desorption mode, A plurality of modules, A rotation mechanism, wherein the plurality of modules are mounted on the rotation mechanism and are configured to switch at least one module from the adsorption mode to the desorption mode and to switch at least one module from the desorption mode to the adsorption mode in parallel, a rotation mechanism An adsorption / desorption unit comprising, At least one condensation device positioned proximal to the at least one module in the desorption mode and configured to condense water vapor into liquid water, At least one air circulation unit configured to draw ambient air into each module in the suction mode and circulate the air within the adsorption / desorption unit, thereby assisting the adsorption of water from the ambient air by the at least one water capture material A water harvesting system comprising. **Claim 11** The system according to claim 10, further comprising at least one vapor redirection unit configured to redirect the water vapor desorbed from the at least one module in the desorption mode to the at least one condenser. **Claim 12** The system according to claim 10 or 11, wherein the at least one condenser is positioned inside the plurality of modules arranged in a rotary configuration. **Claim 13** The system according to any one of claims 6 or 10, wherein the at least one conductor element is at least one metal plate. **Claim 14** The system according to claim 13, wherein the at least one metal plate is arranged radially within the module or arranged parallel to each other. **Claim 15** The system according to any one of claims 1 to 14, wherein the at least one water capture material comprises a metal organic framework. **Claim 16** The system according to any one of claims 1 to 14, wherein the at least one water capture material comprises a desiccant material. **Claim 17** The system according to any one of claims 1 to 16, further comprising a sealing structure configured to seal one or more modules in the desorption mode. **Claim 18** The system according to any one of claims 1 to 17, further comprising at least one collection unit configured to receive the liquid water from the at least one condenser.

19. Further comprising a control system configured to monitor and control adsorption, desorption, and condensation, said control system comprising at least one sensor and at least one processor unit, the system according to any one of claims 1 to 18.

20. An airflow exits the at least one condensation device, the system further comprising at least one recirculation unit, said at least one recirculation unit being configured to reuse the airflow exiting the at least one condensation device in at least one module in desorption mode, the system according to any one of claims 1 to 19.

21. Further comprising at least one float valve configured to collect the liquid water by gravity without any substantial air loss, the system according to any one of claims 1 to 20.

22. Further comprising at least one collection unit configured to receive the liquid water exiting the at least one condensation device through the at least one float valve, the system according to claim 21.

23. Further comprising at least one storage unit for holding the adsorption / desorption unit, at least one condensation device, and at least one air circulation unit, the system according to any one of claims 1 to 22.

24. A method of collecting water from ambient air using the water harvesting system according to any one of claims 1 to 3 and 16 to 23, comprising: a) adsorbing water from ambient air in at least one module in adsorption mode; b) desorbing at least a portion of the water in at least one of the remaining modules in desorption mode; (c) using the at least one condenser to condense at least a portion of the water vapor released from the at least one module in the desorption mode to produce liquid water, wherein steps (a) to (c) occur simultaneously; (d) switching at least one module in the adsorption mode to the desorption mode and switching at least one of the remaining modules in the desorption mode to the adsorption mode; A method comprising.

25. A method for collecting water from ambient air using the water harvesting system according to any one of claims 4 to 8 and 16 to 23, comprising: (a) drawing ambient air into at least one module in the adsorption mode to assist in the adsorption of water by the at least one water capture material and to assist in the cooling of the at least one condenser, wherein the air is recycled or reused to assist in adsorption and cooling; (b) heating at least one of the remaining modules in the desorption mode to assist in the desorption of at least a portion of the water from the at least one water capture material; (c) using the at least one condenser to condense at least a portion of the water vapor released from the at least one module in the desorption mode to produce liquid water; A method comprising.

26. A method for collecting water from ambient air using the water harvesting system according to any one of claims 9 to 23, comprising: (a) adsorbing water from ambient air in at least one module in the adsorption mode; (b) desorbing at least a portion of the water in at least one of the remaining modules in the desorption mode; c) using the at least one condenser to condense at least a portion of the water vapor released from the at least one module in desorption mode to produce liquid water, wherein steps (a) to (c) occur simultaneously; and d) rotating at least one module in adsorption mode to desorption mode and rotating at least one of the remaining modules in desorption mode to adsorption mode; A method comprising: **Claim 27** The method according to any one of claims 24 to 26, wherein an air flow exits from the at least one condenser, and the method further comprises reusing the air flow exiting from the at least one condenser in at least one module in desorption mode.

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