High efficiency solar thermal desiccant systems and methods

Abstract

A water generation system includes a housing having a surface to collect solar radiation; a sorption layer comprising a hygroscopic material to capture water vapor from a process gas during a sorption mode and release water vapor to a regeneration fluid during a desorption mode; and a thermally insulative transparent layer disposed above or upstream of the hygroscopic material to allow solar radiation to pass therethrough to the hygroscopic material and reduce thermal conductance from the hygroscopic material to the external environment. Generating water includes allowing solar radiation to pass through a thermally insulative transparent layer to a hygroscopic material; directing a regeneration fluid in a regeneration flow path to collect heat from the thermally insulative transparent layer and transfer collected heat to the hygroscopic material to release water vapor to the regeneration fluid; and condensing, via a heat exchange assembly, water vapor from the regeneration fluid.

Description

[0001] HIGH EFFICIENCY SOLAR THERMAL DESICCANT SYSTEMS AND METHODS

[0002] This application claims the benefit of U.S. Patent Application No. 63 / 673,583 filed on July 19, 2024, which is incorporated herein by reference in its entirety.

[0003] TECHNICAL FIELD

[0004] [1] This disclosure is related to systems and related methods for efficient conversion of solar radiation to thermal energy to heat a hygroscopic material or absorber. Systems described herein provide high thermal insulation in combination with high transmission of solar radiation via thermally insulative and transparent element(s) or layer(s) in combination with hygroscopic material(s) or absorber(s).

[0005] BACKGROUND

[0006] [2] Solar thermal units are widely used for converting sunlight into thermal energy for applications such as water heating, space heating, and power generation. These units typically comprise a collector that absorbs solar radiation and transfers the heat to a working fluid. To enhance efficiency and minimize heat loss, vacuum-insulated layers are often employed in the design of solar thermal units. The vacuum insulation significantly reduces thermal conductivity and convection, thereby maintaining higher operating temperatures and improving overall system performance.

[0007] [3] Vacuum insulated layers, panels or units provide thermal insulation by creating a vacuum space between two layers of material, typically glass. The vacuum reduces heat transfer by conduction and convection. Common materials used in vacuum insulated glass (VIG) include low-emissivity coatings on the glass to reduce radiative heat transfer and spacers made from materials such as ceramics or stainless steel to maintain the vacuum gap and structural integrity. Vacuum insulated glass is commonly used in commercial and residential windows where high thermal insulation is required, as well as in refrigeration and consumer appliances to provide superior energy efficiency compared to traditional insulating glass units.

[0008] [4] There exists a need for improved systems and related methods for efficient conversion of solar radiation to thermal energy to heat hygroscopic materials that can be employed in both established and entirely new applications needing highly effective insulation, mechanical strength and / or other properties based on the particular application.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS

[0010] [5] The following drawings illustrate by way of example and not limitation. For the sake of brevity and clarity, every feature of a given structure is not always labeled in every figure in which that structure appears. Identical reference numbers do not necessarily indicate an identical structure. Rather, the same reference number may be used to indicate a similar feature or a feature with similar functionality, as may non-identical reference numbers. Views in the figures are drawn to scale (unless otherwise noted), meaning the sizes of the depicted elements are accurate relative to each other for at least the embodiment in the view.

[0011] [6] FIG. 1 A depicts a side view of a system including a hygroscopic absorber and a top vacuum insulated glass layer;

[0012] [7] FIG. IB depicts a side view of a system including a hygroscopic absorber and a top layer including vacuum insulated glass and a photovoltaic panel;

[0013] [8] FIG. 1C depicts a side view of a system including a hygroscopic absorber, a top vacuum insulated glass layer and an interstitial vacuum insulated glass layer; [9] FIG. 2A depicts a side view of a system including a hygroscopic absorber and a top thermally insulative transparent layer;

[0014]

[0010] FIG. 2B depicts a side view of a system including a photovoltaic panel, a hygroscopic absorber and a top thermally insulative transparent layer;

[0015]

[0011] FIG. 2C depicts a side view of a system including a hygroscopic absorber, a top thermally insulative transparent layer and an interstitial thermally insulative transparent layer;

[0016]

[0012] FIG. 2D depicts a side view of a system including a hygroscopic absorber and a top thermally insulative transparent layer comprising a patterned material;

[0017]

[0013] FIG. 3A depicts a front perspective view a water generation system installed on a mounting surface;

[0018]

[0014] FIG. 3B depicts a rear perspective view a water generation system installed on a mounting surface;

[0019]

[0015] FIG. 3C depicts a side view of a water generation system installed on a mounting surface;

[0020]

[0016] FIG. 4A depicts a series process flow path in a water generation system comprising a thermally insulative transparent front surface during a sorption cycle;

[0021]

[0017] FIG. 4B depicts a parallel process flow path in a water generation system comprising a thermally insulative transparent front surface during a sorption cycle;

[0022]

[0018] FIG. 5A depicts a series regeneration flow path in a water generation system comprising a thermally insulative transparent front surface during a desorption cycle;

[0023]

[0019] FIG. 5B depicts a parallel regeneration flow path in a water generation system comprising a thermally insulative transparent front surface during a desorption cycle;

[0020] FIG. 6A depicts an axial view of an annular system including a vacuum insulated solar collector;

[0024]

[0021] FIG. 6B depicts a side cross sectional view of an annular system including a vacuum insulated solar collector;

[0025]

[0022] FIG. 7 depicts a method of operating a system of the present technology.

[0026]

[0023] For simplicity and clarity of illustration, the drawing figures show the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.

[0027] DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0028]

[0024] The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the disclosure.

[0029]

[0025] Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and / or any other possible attachment option. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

[0030]

[0026] This disclosure includes embodiments of systems and methods, such as, for example, for water treatment and storage. The term “coupled” is defined as connected, although not necessarily directly, and not necessarily mechanically. The terms “a” and “an” are defined as one or more unless this disclosure explicitly requires otherwise. The term “substantially” is defined as largely but not necessarily wholly what is specified (and includes what is specified; e.g., substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by a person of ordinary skill in the art. In any disclosed embodiment, the terms “substantially,” “approximately,” “partially” and “about” may be substituted with “within [a percentage] of’ what is specified, where the percentage includes 0.1, 1, 5, 10 and 20%. Further, a device or system that is configured in a certain way is configured in at least that way, but it can also be configured in other ways than those specifically described.

[0031]

[0027] The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”), and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, an apparatus that “comprises,” “has,” “includes,” or “contains” one or more elements possesses those one or more elements, but is not limited to possessing only those elements Likewise, a method that “comprises,” “has,” “includes,” or “contains” one or more operations or steps possesses those one or more operations or steps, but is not limited to possessing only those one or more operations or steps.

[0032]

[0028] Any embodiment of any of the apparatuses, systems, and methods can consist of or consist essentially of — rather than comprise / include / contain / have — any of the described steps, elements, and / or features. Thus, in any of the claims, the term “consisting of’ or “consisting essentially of’ can be substituted for any of the open-ended linking verbs recited above, in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb. The feature or features of one embodiment may be applied to other embodiments or implementations, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of the embodiments.

[0033]

[0029] This disclosure is directed to solar thermal systems or thermal desiccant systems, which may also be referred to as solar thermal desiccant systems, comprising a thermally insulative transparent unit, component or layer in combination with a hygroscopic material (e.g., hygroscopic absorber). Systems of the present technology are configured to provide high thermal insulation in combination with high transmission of solar radiation to provide a high degree of solar thermal collection efficiency. In particular, systems of the present technology facilitate efficient water vapor sorption / desorption cycling of desiccants via highly efficient thermal insulation. Stated differently, systems of the present technology are configured to maximize photons input to or collected by the system while minimizing phonons output or lost from the system, wherein photons are the primary carriers of solar radiation energy and phonons are the primary carriers of heat (e.g., in materials where the thermal conductance or conductivity is largely determined by how phonons propagate and scatter within it).

[0030] Systems of the present technology are configured to convert solar energy or insolation to thermal energy that can be utilized in heating a desiccant or hygroscopic material (e.g., hygroscopic absorber of the system). In various implementations, systems of the present technology can transfer energy from sunlight to a heat absorbing fluid, regeneration fluid or “working” fluid (e g., air) that flows through the system. The heat absorbing fluid can accumulate heat from the thermally insulative transparent layer (e.g., upon flow across one or more surfaces of the thermally insulative transparent layer) and can heat the hygroscopic material (e.g., upon flow across and / or through the hygroscopic material).

[0034]

[0031] In at least some examples, systems of the present technology may be configured such that the temperature gradient increases in the direction (e.g., downward from upper layers to lower layers of the system) that the heat absorbing fluid flows along a flow path from layer(s) of the system facing the sun toward a hygroscopic material or absorber (e.g., disposed below the upper layer(s) facing the sun). Solar thermal energy or heat can be substantially extracted or directed away from the upper layer(s) and / or upstream portions of the system, with minimal conductive and / or convective loss to the external environment while still maintaining high radiative transmission of solar energy toward the hygroscopic material or absorber.

[0035]

[0032] Thermally insulative transparent units, components or layers of the present technology can provide high thermal insulation in combination with high transmission of solar radiation or solar collection efficiency for heating a hygroscopic material or absorber. As an illustrative example, the thermally insulative transparent layer can have a thermal “R-value” greater than 3 and an optical transmittance greater than 80% (e.g., for wavelengths between 300 and 2000 nm).

[0033] Systems of the present technology comprise a thermally insulative transparent layer having a high resistance to heat flow, or “R-value” which is reported herein in units of ft2°F- h / BTU normalized to 1 inch thickness. Thermally insulative transparent layers of the present technology can exhibit R-values greater than R-3, greater than R-5, greater than R-8, greater than R-10, greater than R-12, greater than R-14 and / or greater than R-16. In one example, the thermally insulative transparent layer comprises a vacuum layer between two glass panes to effectively reduce or eliminate conductive heat transfer. Such vacuum insulated glass (VIG) layers can exhibit R-values greater than R-14 and / or greater than R-16. For comparison, conventional double glazing including a gas-filled space (e.g., two glass panes separated by an air or inert gas, like argon, filled space) can reduce heat transfer, but the overall thermal resistance is in the range of R-3 to R-4 which is significantly lower relative to vacuum insulation within the transparent layer. As another comparison, triple glazing with an additional pane and gas-filled space, can further reduce heat transfer and improve insulation compared to double glazing, but still only reaching R-values in the range of R-5 to R-7.

[0036]

[0034] Systems of the present technology comprise thermally insulative transparent component(s), unit(s) or layer(s) that provide distinctive thermal insulation properties to maximize input of solar radiation with minimal heat loss to the external environment. These are highly versatile in their applications. For example, they can be deployed in building structures, thermal management systems, water-from-air harvesting or generation systems, dehumidifiers and / or the like. The present technology can be deployed in both established and entirely new applications that may benefit from effective thermal insulation and efficient water vapor sorption and desorption cycling. An exemplary application for generating water from air is described herein as an exemplary application of the present technology using thermally insulative transparent layers in combination with highly efficient water sorption / de sorption cycling performance of a hygroscopic material across a range of ambient conditions.

[0037]

[0035] In an illustrative application, a system comprising a thermally insulative transparent layer combined with a hygroscopic material is used to produce liquid water by extracting water vapor from ambient air. Certain challenges in generating water from ambient humidity can be associated with maximizing a water production rate and / or efficiency at a low cost and high reliability. There exists a need for improved systems and methods for producing liquid water from atmospheric air and in some cases, by compact or modular devices that are configured for high efficiency, reliability for extended field lifetime, simple manufacture and low cost. As a nonlimiting illustrative application, this disclosure describes various systems and methods for efficient solar dehumidification and / or water production from a process gas like ambient air.

[0038]

[0036] FIG. 1A-C depicts system 100, which can be operated as a system for generating water from ambient humidity, comprising housing 110 having a front surface 112 to face the sun and a rear surface 113 opposite the front surface. System 100 further comprises a plurality of sidewalls 111 extending downward from the periphery of the front surface 112 to the rear surface 113 to form a unitary structure having a substantially planar form in a space-efficient assembly that minimizes structural complexity while maintaining high water production rates.

[0039]

[0037] In an embodiment, system 100 can be provided as a system for generating liquid water from a process gas such as ambient air containing water vapor. System 100 comprises a hygroscopic material that can be present in one or more sorption bodies or layers 1 18 to capture water vapor from the process gas during a water uptake, loading or sorption operational mode of the system (e.g., during nighttime, periods of high ambient relative humidity and / or periods of low ambient temperature). During a regeneration, release or desorption operational mode, solar radiation impinging upon the front surface of the system can be converted into both solar thermal energy (e.g., directly and / or indirectly heat the hygroscopic material) and in some implementations, solar electric energy (e.g., via photovoltaic conversion).

[0040]

[0038] A thermally insulative transparent layer 120 can allow solar radiation to enter housing 110. The front surface 112, which can also be referred to as a top layer or cover layer of the housing, can be exposed to the ambient environment to collect solar radiation. An outer surface of the thermally insulative transparent layer 120 can be provided as a front surface 112 of the housing exposed to the ambient environment as depicted in FIG. 1A-C, FIG. 4A-B and FIG. 5A- B.

[0041]

[0039] System 100 can comprise one or more interstitial layers (e.g., 116) between a top cover layer (e.g., 120) and the hygroscopic material (e.g., 118). During operation, a working fluid can flow along the one or more interstitial layers and then through the hygroscopic material such that the working fluid collects heat from an inner surface of thermally insulative transparent layer 120 (e g., inner surface of glass layer 124), collects heat from the one or more interstitial layers and collects water vapor from the hygroscopic material (e.g., 118) during a desorption cycle.

[0042]

[0040] The thermally insulative transparent layer (e.g., 120, 220) can be provided as a front surface of the housing such that its outer surface is front surface 112 (and / or portions of front surface 112a, 112b). Furthermore, the thermally insulative transparent layer can be provided as a as an interstitial layer and in some implementations, both atop cover layer and an interstitial layer of the system can comprise thermally insulative transparent layers of the types described herein. In various embodiments, the one or more interstitial layers (e.g., 116, 216) can be identical or similar to thermally insulative transparent layer (e.g., 120, 220) at a front surface of the system.

[0041] Various system configurations where the thermally insulative transparent layer 120 is provided as a vacuum insulated transparent layer (e.g., a vacuum insulated glass (VIG) layer) are illustrated in FIG. 1A-C. The thermally insulative transparent layer 120 includes rigid transparent panel 122 (e.g., glass) and rigid transparent panel 124 (e.g., glass) with a sealed gap 126 (e.g., vacuum sealed gap) at a pressure less than atmospheric pressure (e.g., a vacuum pressure less than or equal to 0. 1 Pascal) therebetween. Spacers 128 can be located within sealed gap 126 and a hermetic seal or frame surrounding the first and second rigid transparent panels can provide structural support and sealing of the gap.

[0043]

[0042] The thermally insulative transparent layer 120 (e.g., vacuum insulated glass) can be provided as the front surface of the housing such as shown in FIG. 1A and FIG. 1C. Furthermore, the thermally insulative transparent layer 120 (e.g., vacuum insulated glass) can be provided at least partially the front surface 112a such as depicted in FIG. IB. Additionally, thermally insulative transparent layer 120 (e.g., vacuum insulated glass) can be provided as an interstitial layer 116C within the housing as depicted in FIG. 1C.

[0044]

[0043] Spacers (e.g., 128) within the gap (e.g., 126) can be provided to maintain a consistent distance between the panes (e.g., 122 and 124), ensure structural stability of the layer and / or maintain a vacuum. Spacers can be made from materials with low thermal conductivity to minimize heat transfer and prevent compromising the insulation performance of the layer. For example, spacers can comprise a ceramic material, a metal, a metal alloy, a polymer or a combination thereof. Spacers can include nickel-based “superalloys” such as Inconel, Hastelloy, Monel and / or the like. Furthermore, a distance between adjacent spacers can be greater or equal to 4 cm, greater than 5 cm, greater than 6 cm. Furthermore, a height of the spacer, and a such the sealed gap, can be between 0.1 to 0.5 mm.

[0044] Gaps at low or reduced pressures (e.g., below atmospheric pressure) can comprise getter material(s) and / or passivation layer(s) to enhance the performance and longevity of vacuum insulated units. Getter materials can be provided to absorb and trap residual gases within the vacuum gap or space, thereby maintaining a high vacuum level essential for maximum thermal insulation. Getters can comprise non-evaporable alloys such as zirconium, vanadium, and iron, or evaporable substances like barium, or other materials to actively react with gases such as oxygen, hydrogen, water vapor, and carbon dioxide to ensure the vacuum remains intact over extended periods. Passivation layers can be provided as thin films or coatings applied to the surfaces of rigid panels to protect them from environmental factors like corrosion, oxidation, or chemical reactions. Passivation layers can comprise oxides such as silicon dioxide, nitrides like silicon nitride, or various organic compounds, or other materials to act as barriers, preventing surface degradation and enhancing chemical and thermal stability. Any desired type or combination of getter materials to maintain low pressure by gas absorption and / or passivation layers can be employed to safeguard surfaces from reactive elements can be used.

[0045]

[0045] System 100 comprises a hygroscopic material 118 (e.g., hygroscopic absorber) located within the housing and capable of absorbing thermal energy (e.g., via solar radiation and / or via convective flow of a working fluid) as well as absorb and desorb water vapor. A heat absorbing fluid or “working fluid” can accumulate heat upon flowing along at least one surface of thermally insulative transparent layer(s) within the system, as well as accumulate water vapor upon flow across or through the hygroscopic material 118 (e.g., in a closed loop to recycle heat and humidity within the system).

[0046]

[0046] The thermally insulative transparent layer 120 can be positioned so as to allow solar radiation to impinge upon the hygroscopic material 118 upon transmission therethrough (e g., be disposed above the hygroscopic material in the installed state) and / or upstream of the hygroscopic material (i.e., in relation to a heat absorbing fluid flowing through the system depicted in dashed lines of FIG. 1A-C). As such, the thermally insulative transparent layer can maximize solar radiation on the hygroscopic material (e.g., photons) and reduce thermal conductance or conductivity (e.g., phonons) from the hygroscopic material to the external environment.

[0047]

[0047] In some implementations, a photovoltaic layer or panel 114 can be provided adjacent to the thermally insulative transparent layer 120 such that both are positioned at a front surface of the housing to collect solar radiation such as depicted in FIG. IB. In other implementations, a photovoltaic layer or panel 114 can be provided at an interstitial layer or below the thermally insulative transparent layer such as depicted in FIG. 1 A and FIG. 1C.

[0048]

[0048] System 100 can be configured such that a front surface comprises a solar thermal portion (e.g., 112a) including the thermally insulative transparent layer allows solar radiation to impinge upon the hygroscopic material 118 and, a solar electric portion (e.g., 112b) including a photovoltaic panel positioned above a heat exchange assembly (e.g., 130).

[0049]

[0049] As shown in FIG. IB, the system can comprise a solar thermal layer or portion 112a adjacent to a solar electric portion or layer 112b at the upper portion of the system and exposed to collect solar radiation for conversion to both heat and electricity. The solar electric unit or portion can comprise a PV panel (e.g., 114) comprising a plurality of photovoltaic cells, which can in some cases be encapsulated between a top transparent layer (e.g., glass) and / or a backsheet material that can reflect solar radiation back towards PV cells. The system can further comprise a sorption unit or layer (e.g., hygroscopic material or absorber 118) below the solar thermal portion (e.g., to allow solar radiation to impinge upon sorption layer 118) and adj acent to a heat exchange assembly (e.g., 130) provided below the solar electric portion.

[0050] As another illustrative example, FIG. 2A-C depict systems comprising thermally insulative transparent layers including a “static” material layer configured to minimize convective heat transfer or convective currents of a heat absorbing fluid flowing in an adjacent layer.

[0050]

[0051] FIG. 2A-D depict various configurations of system 200 comprising a thermally insulative transparent layer 220 and FIG. 1A-C depict various configurations of system 100 comprising a thermally insulative transparent layer 120. Unless otherwise specified, the numerical indicators used to refer to components in system 100 are similar to those used to refer to components or features of system 200, except that the index has been incremented by 100.

[0051]

[0052] Thermally insulative transparent layer 220 can comprise “static” layer 228, wherein static can refer to a layer that does not have working fluid flowing therein. The static layer can also refer to a layer comprising a transparent matrix material (e.g., aerogel) comprising a solid framework (e.g., silica) that constitutes a small fraction of its volume, while the majority is filled with air, thereby providing a low density and thermal conductivity. The static layer can comprise an extensive network of air gaps or spaces within its matrix to minimize heat transfer therethrough. As such, the static layer 228 can provide thermal insulation by reducing heat losses via convection in an adjacent layer having working fluid flow. In various implementations, static layer 228 comprises a composite matrix material having high thermal insulation (minimal / low convective heat transfer) as well as optical clarity.

[0052]

[0053] In some implementations, the thermally insulative transparent layer 220 can comprise a heterogenous or matrix-like layer, such as static layer 228, having features to break up convection heat losses while maintaining optical clarity. Various non-limiting examples will be described such as a static layer (e.g., 228) having an aerogel filled space (e.g., an aerogel material between support layers such as rigid glass panes) and a patterned transparent polymer layer (e.g., 229), however other types, materials and configurations can be employed to minimize convective heat losses while maintaining optical clarity. Accordingly, the material composition and configurations described herein can be modified such that additional embodiments may be realized with operational, logical, chemical, compositional, structural and / or mechanical changes without departing from the spirit and scope of the disclosure.

[0053]

[0054] As illustrative examples, a static layer (e.g., 228) can comprise a silica aerogel, a transparent silicone material, polydimethylsiloxane (PDMS), polycarbonate, poly(methyl methacrylate)(PMMA), polyethylene terephthalate (PET), polyurea polyethylene terephthalate (PET), polyurea, polyvinyl butyral (PVB), or a combination thereof. Furthermore, the thermally insulative transparent layer 220 and / or the static layer 228 or 229 can be provided with a thickness between 2 mm to 20 mm. Furthermore, the static layer can comprise an aerogel material, a transparent patterned polymer material, porous matrix material, a composite polymer structure, a molded polymer structure, derivative, or combinations thereof.

[0054]

[0055] Various system configurations with the thermally insulative transparent layer 220 provided as a static transparent layer (e.g., aerogel, patterned polymer) are illustrated in FIG. 2A- D. One or more rigid transparent panels can provide structural support to the material of the static layer. For example, the thermally insulative transparent layer 220 can include rigid transparent panel 222 (e.g., glass) and rigid transparent panel 224 (e.g., glass) with gap or space therebetween comprising a static material layer 228.

[0055]

[0056] As another illustrative example, the thermally insulative transparent layer (e.g., 229) can be patterned, for example in honeycomb or hexagonal patterns, triangular patterns, square patterns, circular patterns, and / or the line. The thermally insulative transparent layer can comprise transparent materials having low conductance formed or molded into non uniform patterns like weaves, tendrils, and / or the like. Various materials and forms can be employed to provide a structure or pattern having more air volume than polymer or filler volume, for example the thermally insulative transparent layer (e.g., 229) can comprise 75% or more air by volume, thereby leveraging a lower thermal conductivity of the air. The form or pattern of the thermally insulative transparent layer (e.g., 229) can be configured to prevent convection cells, and depending on the flow characteristic of the system a spacing between polymer or filler walls or cells (with air spaces or gaps in between) can be less than or equal to 5 mm, less than or equal to 10 mm, less than or equal to 20 mm, and / or less than or equal to 30 mm.

[0056]

[0057] The thermally insulative transparent layer can be provided with various configurations and types of materials that alone or in combination (e.g., as a matrix, composite or other heterogeneous material layer) are both transparent and exhibit low thermal conductivity. Suitable components of the thermally insulative transparent layer include, but are not limited to, a porous matrix, such as a silica aerogel or clear pellets of suitable materials, providing superior thermal insulation while maintaining optical clarity. Additionally, a composite polymer structure, which may comprise a macro pattern of a molded polymer, can be utilized to achieve a balance between transparency and thermal performance. In some implementations, an aerogel material, such as a silica aerogel can be used, for example positioned adjacent to one or more support layers to enhance structural integrity and thermal insulation properties. Additionally, a transparent patterned polymer material or layer designed to optimize light transmission while minimizing heat transfer can be used. Various polymer materials can be used such as polydimethylsiloxane (PDMS), polycarbonate, poly(methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polyurea, polyvinyl butyral (PVB), transparent silicone material, or a combination thereof. Suitable materials can be selected for their ability to maintain high transparency while offering a high degree of thermal insulation, making them ideal for a wide range of applications.

[0057]

[0058] The thermally insulative transparent layer 220 can be provided as at least a portion of the front surface of the housing such as shown in FIG. 1 A-D. Furthermore, thermally insulative transparent layer 220 can be provided as an interstitial layer 216C within the housing as depicted in FIG. 2C.

[0058]

[0059] Systems of the present technology can be operated as water generation systems that can convert solar insolation to thermal energy by transferring energy from sunlight to a regeneration fluid or gas, a heat absorbing fluid or gas, or a “working” fluid or gas that flows through the system, for example in a regeneration flow path (e.g., depicted in dashed lines of FIG. 1A-C and FIG. 2A-D). Systems of the present technology can be provided as a solar thermal collector to convert radiant solar energy into thermal energy, and in turn, heat the hygroscopic material and / or regeneration fluid. Furthermore, systems of the present technology can be provided as a hybrid solar collector, or photovoltaic thermal solar collector that converts solar radiation into both thermal and electrical energy such that the generated heat is transferred to the hygroscopic material and / or regeneration fluid and the generated electricity powers the components of the water generations system (e.g., fan(s), compressors), controller(s) and / or the like). Systems of the present technology can comprise side-by-side or adjacent front surface portions provided for solar thermal performance (e.g., 112a) and solar electric performance (e.g., 112b).

[0059]

[0060] Additional examples of water generation systems comprising thermally insulative transparent layer(s) of the present technology are depicted in FIG. 3A-C, FIG. 4A-B and FIG. 5A- B. System 100 comprises a sorption unit or layer 118 (that in some cases can be provided as a plurality of sorption bodies 118a and 118b) located within the housing 110 and below first side 1 112a comprising a transparent cover layer (e.g., glass). Sorption layer 118 comprises a hygroscopic material to capture water vapor from a process gas during a sorption mode, and release water vapor to a regeneration fluid during a desorption mode.

[0060]

[0061] Water generation systems 100 can comprise a hygroscopic material included in a sorption unit, body or layer 118. The sorption unit, layer or body 118 can comprise a light absorbing material to absorb solar radiation, for example during daytime hours. In an embodiment, the sorption layer 118 comprises or is formed of a hygroscopic material to capture (e.g., adsorb, absorb) water vapor from a process gas (e.g., ambient air at atmospheric temperature and pressure) upon flow across and / or therethrough, for example during a sorption operational cycle (e.g., nighttime hours). Furthermore, the sorption layer 118 can transfer water vapor heat and / or heat to a regeneration or working gas during a desorption operational cycle.

[0061]

[0062] The sorption unit(s) or layer(s) (e.g., 118) can have various compositions and structures. In an example, the sorption layer can be provided as one or more porous hygroscopic bodies or layers. The ‘porous’ or ‘porosity’ term used herein can describe a flow-through implementation, as opposed to flow-over or flat plate implementation of the sorption layer. While flow-over or flat plate implementations could be employed without departing from the scope of this invention, it can be preferable to keep the boundary layers small with a high degree of percolation for example as can be provided in porous flow-through bodies, units or layers. A porous sorption unit or layer comprising hygroscopic material(s), can absorb thermal energy (e.g., radiative solar thermal energy) and release captured water vapor to a working or regeneration fluid, for example during a desorption / release operational mode or cycle. In one example, a hygroscopic material and / or hygroscopic composite can be arranged within a flow distributor, such as but not limited to a lattice structure, top and bottom rigid porous plates, inter-corrugated fluidic channels, interdigitated fluidic channels, and / or woven and fiber meshes to sustain back pressure and distribute the flow. A hygroscopic composite can be provided as a composite assembly such that its structure provides the system with structural properties, pressure drop, flow paths, and / or thermal properties.

[0062]

[0063] System 100 further comprises heat exchange assembly 130 below a second side 112b. In such an implementation, a PV panel or layer of second side 112b can collect solar radiation to convert it to electrical energy. As such, solar radiation is converted to solar electric energy at second side 112b of system 100, whereas solar radiation directly heats sorption layer (e.g., 118a-b) via a transparent cover layer of first side 112a. In some implementations, it can be preferable to include one or more insulation layer(s) between heat exchange assembly 130 and PV layer (e.g., 114).

[0063]

[0064] A unit, sorption body or layer can receive heat from at least one thermal source, for example a regeneration gas, solar radiation, a photovoltaic cell, a heater, a heat exchanger and / or the like. A regeneration fluid or gas can accumulate heat and water vapor upon flowing across or through the sorption layer 118 and then be cooled upon flowing through the heat exchange assembly 130 to condense water therefrom before returning to sorption layer to accumulate more heat and water vapor (i.e., in a closed loop flow path within system 100).

[0064]

[0065] Water generation systems of the present technology can be characterized by an efficient combination of 1) solar thermal generation and 2) solar electric generation in a compact configuration (e.g., offset, side-by-side), which can be particularly advantageous to maximize the water production efficiency, water production amount and / or water production rate of the system (e.g., via the ratio or relative areas for solar thermal collection and solar electric collection and / or the relative surface areas for water sorption and heat exchange to drive water condensation upon desorption).

[0065]

[0066] A compact, lightweight and / or slim water generation panel of the present technology can include a sorption unit or layer comprising hygroscopic material(s) disposed beneath a solar thermal unit or portion and a heat exchange assembly disposed beneath a solar electric unit or portion. In the field of water harvesting from ambient humidity, there exists a need to balance thermal energy considerations and power needs for both efficient and compact systems with maximized water production (e.g., amount of water produced over a diurnal cycle), particularly in the autonomous or self-powered (e.g., off-grid) application.

[0066]

[0067] The system configurations and related operational methods of the present technology have been found to harness solar irradiance effectively for water generation. The solar thermal and solar electric collectors, in combination with hygroscopic materials and heat exchange assembly, exhibit unique characteristics and efficiencies in response to wide ranging environmental conditions on earth. In addition to efficiently generating and distributing thermal and electric energy to hygroscopic material and heat exchange subsystems, the disclosed systems facilitate deployment with no or minimal maintenance. The present technology presents an advancement in utilization of collected solar energy, aligning with the necessity to balance thermal energy and electrical power requirements. The disclosed systems and methods maximize thermal efficiency while concurrently meeting the power demands via an interplay between the solar thermal and solar electric collectors in coordination with the sorption and heat exchange units.

[0067]

[0068] Achieving a delicate equilibrium between the thermal and electric power generation functions is imperative for sustained and efficient operation of autonomous and deployable water generation systems. An inherent challenge lies in the dynamic nature of solar irradiance, ambient humidity and ambient temperature and a need to adaptively modulate the system’s response to fluctuations in environmental conditions. The disclosed systems and methods represent a significant advancement in addressing the balance between thermal and electrical energy needs for water generation systems comprising hygroscopic materials.

[0068]

[0069] FIG. 3 A-C depict water generation system 100 installed on a mounting surface, that can be accomplished for example by one or two people. FIG. 3 A depicts a front perspective view, FIG. 5B depicts a rear perspective view and FIG. 5C depicts a side view of water generation system 100 installed on a horizontal mounting surface (e.g., flat roof, ground). Water generation system 100 can comprise a mounting assembly 104 that can be oriented and installed on a surface to receive incoming solar radiation, for example in a fixed tilt configuration. While FIG. 3 A-C depict water generation system 100 installed on a substantially horizontal mounting surface, water generation system 100 can alternatively be mounted on an inclined surface (e.g., sloped roof of a structure) with or without the use of an adjustable mounting assembly. System 100 can be installed or mounted above a ground surface or rooftop via adjustable mounting assembly 104 which extends from the system housing to position the system in a fixed tilt configuration at an angle relative to a substantially horizontal ground surface or flat rooftop. System 100 can be oriented toward the southern sky for an installation in the Northern Hemisphere, or toward the northern sky for an installation in the Southern Hemisphere. The descriptive terms used herein such as front, rear, above, below, top, bottom, over, under, etc. are used to aid understanding of the invention are not used in a limiting sense. Furthermore, the directions north, south, east and west may be used herein assuming the installation site is in the Northern Hemisphere, however opposite directions can be used for installations in the Southern Hemisphere without departing from the spirit and scope of the present disclosure.

[0070] The exposed solar collection area, or geometric area, at the front surface of the water generation system can be apportioned for solar thermal energy and solar electric power generation such that an autonomous, self-powered and compact water generation system is possible. A water generation panel having a compact and slim geometry while maintaining a high or maximized water production capability (e.g., greater than 4 liters per day, greater than 6 liters per day, greater than 8 liters per day, greater than 10 liters per day and / or greater than 15 liters per day) can be desirable and as such, its front surface area facing the sun can be considered as a constraint or boundary condition (i.e., in combination with water production requirements). For example, within the confines of the water generation system geometry, the front surface area (e.g., 1-3.5 m2, 0.5-4 m2, less than 4 m2, less than 3.5 m2, equal to or less than 3 m2) of the water generation system can be apportioned or split between a solar thermal generation area (e.g., indicated by 112a) and solar electric generation area (e.g., indicated by 112b). The ratio of the solar thermal to solar electric collection area, or the percentage of the front surface area for solar thermal conversion vs the percentage of the front surface area for solar electric conversion, is constructed such that a water production efficiency or water production amount or rate is maximized (e.g., amount of daily water production is greater than 4 liters per day, greater than 6 liters per day, greater than 8 liters per day, greater than 10 liters per day and / or greater than 15 liters per day) in a compact and / or slim panel geometry.

[0069]

[0071] Water generation systems the present technology can include 10-90%, 20-80% or 40-60% of the front surface area for solar thermal generation with 10-90%, 20-80%, or 40-60% of the front surface area for solar electric generation. As an illustrative example, in installation regions having lower average ambient temperatures, it may be preferable to deploy a water generation system having a greater area for solar thermal generation (e.g., 112a) than the area for solar electric generation (e.g., 112b) so as to increase heating of the sorption layer.

[0070]

[0072] As depicted in FIG. 3 A-C, support assembly 104 comprises a plurality of adjustable or collapsible mounting arms that can support the water generation system at fixed angle above the mounting surface (e.g., ground surface or rooftop). The mounting arms can retract or fold into housing 111, for example during transport or storage. The mounting arms of support assembly 104 can extend from the housing 111 and engage or interlock into a fixed position to securely orient the front surface of system (e.g., front surface 112) at fixed tilt angle to face a southern direction, for example when installed on a flat or horizontal mounting surface. When in an installed state, the system 100 can be supported at an angle relative to the mounting surface and also allow for ambient air intake and / or exhaust from a rear panel of the housing 111 (e g., via loading inlet 106 for inputting process gas and loading outlet 108 for exhausting process gas). In other embodiments, a support assembly may not be present, or may not be employed during installation, for example when mounting the system on a sloped roof. The embodiments depicted in FIG. 3B and FIG. 4A- B depict loading inlet 106 and loading outlet 108 disposed at the rear side of panel. However in other embodiments, the inlet(s) and / or outlet(s) can be disposed at one or more sides of the panel.

[0071]

[0073] In various embodiments, one or more fdters can be provided to filter process gas (e g., remove contaminants like dust and the like from ambient air) in advance of input to the water generation system. For example, a replaceable or serviceable filter tray (e.g., indicated at 106) can mate (e.g., slide) into a housing receptacle to cover process or ambient air inlet 106. In various embodiments, one or more replaceable air filters can be provided as part of a housing assembly, a system fan assembly and / or a valve assembly, to filter ambient air in advance of ingress into system 100 during a sorption cycle. As another example, a replaceable or serviceable filter tray (e.g., indicated at 152) can mate (e.g., slide) into a housing receptacle to cover cooling flow or ambient cooling air inlet during a desorption cycle.

[0072]

[0074] Heat exchange assembly 130 comprises a condenser 150 to condense water from the regeneration fluid via heat transfer from the regeneration fluid to ambient environment and / or a cooling fluid (e.g., ambient air flow through condenser). Heat exchange assembly 130 further comprises recuperator 140 to transfer heat from a first hot-side regeneration fluid flow output from the sorption layer 130 to a second cold-side regeneration fluid flow output from the condenser 150. The term recuperator or recuperative heat exchanger refers to a type of heat exchange unit that has separate flow paths for each fluid throughout its passages and heat is transferred through separating walls.

[0073]

[0075] In various implementations, assembly 130 can be referred to as an enthalpy exchange or transfer assembly, heat exchange or transfer assembly and / or energy exchange or transfer assembly. As such, an exchange or transfer assembly (e.g., 130) can comprise one or more of: 1) passive sensible heat transfer units or subassemblies (e.g. a heat exchanger), 2) passive latent energy transfer units or subassemblies (e.g. vapor transfer membrane, vapor permeable membrane), 3) passive total heat transfer (i.e. sensible and latent energy) transfer units or assemblies (e.g. rotary desiccant wheel), and / or 4) active heat transfer units or subassemblies (e.g., refrigeration unit, vapor compression cycling unit and / or the like). In some implementations, both heat (i.e. sensible) energy and moisture (i.e. latent) energy are transferred or exchanged by the assembly 130. In other implementations, only sensible heat is exchanged, for example with a conventional heat exchanger. Sensible heat can be transferred in the form of a temperature difference between flow segments. Latent heat can be transferred in the form of a moisture difference (e g., concentration gradient, water vapor partial pressure gradient) between different fluid flow segments. In some implementations, assembly 130 can comprise a plurality of sub-units or sub-assemblies, for example a heat exchange sub-unit and a moisture exchange sub-unit, and / or multiple heat and / or moisture exchange sub-units. In one example, exchange surfaces, elements or plates (e.g., 131) of the recuperator and / or condenser can facilitate transport of water vapor across adjacent flow layers via vapor permeable air barriers or membranes (e.g., expanded polytetrafluoroethylene (PTFE)).

[0074]

[0076] In various embodiments, heat exchange assembly is provided as a unitary device with distinct sections optimized for recuperative heat transfer and water condensation encapsulated in a slim and low-profile structure. The heat exchange assembly can comprise thin heat exchange plates for flowing regeneration fluid flow in recuperative heat exchange portion (e.g., 140) and condensation portion (e.g., 150) set in a geometry to enhance heat transfer from hot-side regeneration fluid to cold-side regeneration fluid (i.e., in recuperative section) and the ambient environment (i.e., in condenser section) for efficient water production.

[0075]

[0077] The heat exchange assembly layers, which can also be referred to as a “ministack”, are defined and organized to minimize spatial requirements within the larger system structure, thereby driving water production performance and spatial efficiency. Furthermore, “ministack” heat exchange assemblies disclosed herein can have the advantage of simplifying manufacturing enabling scale and reducing overall system costs. In one example, a slim or low profile water generation system can be realized at least in part due to thin heat transfer plates, for example below 2 mm, below 1 mm and / or in the range of 0.2 to 1 mm, 0.4 mm to 0.8 mm, 0.5 to 0.8 mm in thickness, with flow channels or layers having spacing less than 12 mm, less than 10 mm, between 4 mm to 12 mm, and / or between 6 mm to 10 mm. Furthermore, the number of flow channels or layers can vary between 4 to 8 layers. As such, the overall thickness of the heat exchange assembly can range between 8 cm to 18 cm, and in turn the overall thickness of the water generation system can range between 10 cm to 25 cm.

[0076]

[0078] Various features can be provided to enhance condensation efficiency in the heat exchange assembly. For example, condenser surface treatments can be provided to increase hydrophobicity and facilitate dropwise condensation. The application of hydrophobic coatings (e.g., fluorinated coatings, epoxy coatings selected for safety in contact with drinking water that may be under NSF / ANSI Standard 61 or other regional regulation) on condenser surfaces can promote droplet formation and facilitate the shedding of condensed water, thereby minimizing the occurrence of filmwise condensation. Additionally, macrogeometric features such as microfms and / or enhanced surface roughness can increase the available surface area for condensation. Features configured for turbulent flow, such as flow diverters within the condenser unit, can be included to increase heat transfer rates by preventing laminar boundary layers and / or contribute to “effective” condenser area by redirecting the flow of the condensing vapor and enhancing contact with the heat exchange surfaces.

[0077]

[0079] In various implementations, a recuperator and / or the condenser can comprise a plurality of longitudinally extending heat exchange plates defining alternating flow layers. For example, recuperator 140 comprises a plurality of longitudinally extending heat exchange plates defining alternating flow layers of a first hot-side regeneration fluid flow output from the sorption layer 118 and a second cold-side regeneration fluid flow output from the condenser 150.

[0078]

[0080] As depicted, condenser 150 comprises a plurality of longitudinally extending heat exchange plates defining alternating flow layers of regeneration fluid output from the recuperator 140 to ambient air-cooling flow. As such, the condenser 150 exchanges heat between the regeneration fluid and ambient air and the recuperator 140 exchanges heat between the ‘hot-side’ regeneration fluid in advance of the condenser and the ‘cold-side’ regeneration fluid output from the condenser so as to pre-cool the regeneration fluid before it enters the condenser and to pre-heat the regen air before it returns to sorption layer 118 (after water has extracted from the regeneration fluid in the condenser).

[0079]

[0081] System 100 can comprise a controller to increase the relative humidity in the regeneration fluid output from the sorption bodies 118a and 118b to drive condensation of water vapor in the condenser, thereby producing liquid water during the desorption mode.

[0080]

[0082] FIG. 4A and FIG. 4B illustrate water generation system 100 having a low profde or compact panel configuration during a sorption, uptake or loading operational mode or cycle. FIG. 4A depicts a series process flow path (indicated by dashed arrows) wherein the process gas flows through sorption bodies 118a and 118b sequentially or ‘in series.’ Separator 119 positioned between sorption bodies 118a and 118b can direct flow in a series configuration. FIG. 3B depicts a parallel process flow path (indicated by dashed arrows) wherein the process gas flows through sorption bodies 118a and 118b concurrently or ‘in parallel.’ While two sorption bodies 118a and 118b without any separator or divider are depicted, a single unitary sorption unit, body or layer can also be employed.

[0081]

[0083] A process gas such as ambient air can be directed into water generation system along a process or loading flow path in the housing (such as indicated by dashed arrows of FIG. 4A or FIG. 4B) via a fan assembly, a valve assembly and / or the like. System 100 uptakes water vapor from the process gas upon flow through hygroscopic material bodies 118a and 1 18b) during a sorption or loading operational mode before being exhausted to the ambient environment. In various embodiments, a fan and / or valve assembly can adjust the flow rate of the process gas by a controller. 1

[0084] FIG. 5 A and FIG. 5B illustrate water generation system 100 having a low profile or compact panel configuration during a desorption, release or unloading operational mode or cycle. FIG. 5A depicts a series regeneration flow path (indicated by dashed arrows) in the housing wherein the regeneration gas flows through sorption bodies 118a and 118b sequentially or ‘in series.’ FIG. 5B depicts a parallel regeneration flow path (indicated by dashed arrows) wherein the regeneration gas flows through sorption bodies 118a and 118b concurrently or ‘in parallel.’

[0082]

[0085] As depicted in FIG. 5A and FIG. 5B, a regeneration flow path (indicated by dashed arrows) can be entirely, or at least partially, closed-loop and can include multiple flow segments through system 100 including: 1) a regeneration flow path segment along upper layer 112 (e.g., to collect heat from top cover layer glazing and / or PV panel(s)); 2) a regeneration flow path segment within sorption layer 118 (e.g., during which the regeneration fluid uptakes heat and water vapor upon flow through hygroscopic material bodies 118a and 118b); 3) a hot-side regeneration fluid flow segment exiting sorption layer 118 and through recuperator 140 (e.g., being cooled so as to condense water vapor from the regeneration fluid); 4) a regeneration flow segment through condenser 150 (e.g., condensation of water vapor via ambient air cooling); and, 5) a cold-side regeneration fluid flow segment through recuperator 140 before returning to a upper layer 112 (e g., for reheating before flowing again through sorption layer 118).

[0083]

[0086] Water generation system 100 comprises an offset panel configuration including sorption bodies offset, or side-by-side, in relation to a heat exchange assembly (in addition to offset or side-by-side solar thermal and solar electric upper or top layers), however other system configurations are possible.

[0084]

[0087] Disclosed heat exchange assemblies can improve a system’s overall efficiency by cooling a high temperature incoming fluid or air stream to a temperature closer to a desired temperature via the transfer of thermal energy from a low temperature fluid or air stream. Disclosed heat exchange assemblies allow for efficient transfer of heat from a hot-side flow to a cold-side flow while maintaining isolation of the two flows or streams from each other. Disclosed compact configurations of sorption units and heat exchange assemblies can be desirable, especially for field deployable water generation systems, in order to reduce size and material costs of the system, all while providing high heat exchange effectiveness to maximize heat recuperation and water production.

[0085]

[0088] For maximum heat exchange effectiveness and water production for a compact water generation system, it can be preferable to maximize the area of the heat exchange surfaces in order to maximize the heat transfer capability. In the same compact water generation system, it is desirable to minimize system volume to facilitate deployment. As such, the configurations and approaches disclosed herein can achieve high water production performance in a compact form factor with maximum heat transfer and water capture areas while minimizing backpressure (which in turn drive power demand for fluid flow). Furthermore, the relative orientation of fluid flow in adjacent layers through the heat exchange assembly 130 is presented here for special relevance in water generation technology.

[0086]

[0089] Condenser sections or portions of heat exchange assembly (e.g., condenser 150) of the present technology can include alternating flow layers of regeneration fluid and ambient air- cooling flow such that heat is exchanged between the regeneration fluid and an ambient air flow. In preferred implementations, the regeneration fluid flows in a direction at least partially counter to the direction of ambient airflow (i.e., counter-flow) to drive effectiveness of water vapor condensation form the regeneration fluid as it cools. In some preferred implementations, the condenser exchanges heat from the regeneration fluid to the ambient environment (e.g., ambient air-cooling flow) in a counter-flow arrangement. Furthermore, some implementations can include serpentine, sinuous or otherwise curved flow paths to increase the velocity of the cooling fluid and / or regeneration fluid flowing through the condenser.

[0087]

[0090] The recuperative heat exchange portions or sections (e.g., recuperator 140) of the present technology can be provided in various orientations to transfer heat from hot-side regeneration fluid flow output from the sorption layer and cold-side regeneration fluid flow output from the condenser. Furthermore, heat exchange assembly can be provided as a single or multiple pass system and furthermore, comprise counter-flow, partially counter flow, parallel flow sections and any combination thereof.

[0088]

[0091] As another example, the water generation system can maximize water production by directing the regeneration fluid to first flow along surface(s) of the PV layer (e.g., bottom and top surfaces of PV layer 114) after exiting the heat exchange assembly 130 such that the PV layer stays cooler, thus operates at high PV efficiency, and then allow the heated regeneration fluid to absorb more of the infrared (IR) backscatter heat from the sorption layer(s) (e.g., 118), top cover 112a (e.g., thermally insulative transparent layer 120 provided as a front surface of the housing exposed to the ambient environment) and / or interstitial layer (e.g., 116 which can also be provided as a thermally insulative transparent layer such as 120, 220), such as depicted in FIG. 4A.

[0089]

[0092] The heat exchange assemblies (e.g., 130) of the present technology can increase the relative humidity and / or the partial pressure of water vapor in the regeneration fluid to drive condensation of water vapor from the regeneration gas during the release or desorption operational mode or cycle. The heat exchange assembly 130 can reduce the temperature of at least a portion of the regeneration fluid by rejecting heat to ambient environment (e.g., in the condenser portion 150), another cooler portion of the regeneration fluid (e.g., in the recuperative portion 140) and / or another heat absorbing fluid, e g., a refrigerant if a vapor compression cycling (VCC) unit is included. The recuperative heat exchange assembly 130 can be provided as a single unit provided as an assembly of components or be a component of a heat transfer cycle or system.

[0090]

[0093] The heat exchange assembly can provide a high surface area for heat transfer to drive condensation of water vapor from the regeneration fluid, for example with minimal pressure drop upon flow across or therethrough. In one example, heat exchange assembly 130 can comprise a heat sink and / or heat transfer surfaces (e.g., heat dissipating surfaces, fins, ridges, ribs, protrusions, clamshell, passive heat sink and / or the like) to reject heat from the regeneration fluid to the ambient environment or other fluid at a lower temperature. In some embodiments, heat exchange assembly 130 can form an outer portion of the system housing so as to reject heat to the ambient environment. In other embodiments, the heat exchange assembly 130 can be located entirely within the system housing.

[0091]

[0094] In addition to heat dissipating features, heat exhaust approaches and / or active or passive flow directing elements, additional components can be included to improve water production efficiency, for example, to improve the efficiency of liquid water condensation for the production of water from the regeneration flow path(s). This can be advantageous, for example when the system is in a high system water content state such that the hygroscopic materials of the system and / or the regeneration fluid are water rich (e.g., high absolute humidity, high equilibrated humidity or equilibrated water content of hygroscopic materials) to balance the efficiency of water release relative to water uptake or loading cycles. In some operational conditions or system states, water condensation can limit water production rather than water uptake or other system functions being limiting. In such states, it may be preferable to boost or improve the systems water condensation efficiency, for example by providing additional power to heat exchange assembly

[0092] 130 (e.g., increase power to fan(s) for ambient air cooling).

[0093]

[0095] The heat exchange assembly 130 can be provided as an air-cooled component (e.g., formed from polymeric, plastic and / or metallic materials) that can condense water from the regeneration fluid of the regeneration flow path(s). The system can power blower(s) or fan(s) to flow ambient air over and / or through the heat exchange assembly 130, thereby improving heat transfer, water condensation efficiency and therefore water production. In such implementations, ambient air cools (via heat transfer across and / or through surfaces of the heat exchange assembly 130) the hot-side regeneration fluid flow through heat exchange assembly 130 in order to extract water and excess heat is exhausted to the outside environment.

[0094]

[0096] Water generation systems and their component heat exchange assemblies of the present disclosure can be simple in design and easy to manufacture. In some implementations, water generation systems can operate in a hybrid or dynamic manner wherein an operational setpoint is adjusted (e.g., power distribution to fan(s) for flowing process air, fan(s) for ambient air cooling and / or regeneration fan(s) via a controller) based on a system operational state (e.g., system power state, system water content) and / or an environmental condition (e.g., ambient relative humidity, ambient temperature) to improve water production performance. In particular, water generation systems of the present technology can increase the relative humidity (% RH) in at least a segment of the regeneration flow path to drive condensation of water vapor therefrom. Furthermore, the heat exchange assembly can increase the relative humidity in at least one segment of the regeneration flow path to drive condensation of water vapor therefrom, thereby improving liquid water production during a release operational mode or cycle.

[0097] While the embodiments described above comprise substantially planar form factors, alternative form factors can be employed. For example, an annular or tube-like configuration can be employed wherein an outer evacuated tube conductively moves heat from within the tube to a header or other surface, thereby removing heat via convection or other methods for example towards a hygroscopic material. In another implementation, a hygroscopic material can be coated or embedded within an inner portion of an evacuated solar collector tube.

[0095]

[0098] In addition to substantially planar system configurations depicted in FIG. 1 A-C and FIG. 2A-D, various other configurations can be employed to maximize solar radiation into the system (e.g., photons to directly heat the hygroscopic material) and reduce heat loss from the system to the external environment. As another illustrative example, FIG. 6A-B depict a non- planar system configuration such as annular-type evacuated tube solar collection system 300 that can maximize the surface area exposed to sunlight, for example by capturing solar radiation from different angles throughout the day, thereby increasing the overall efficiency of the collector. Unless otherwise specified, the numerical indicators used to refer to components in system 100 and system 200 are similar to those used to refer to components or features of system 300, except that the index has been incremented by 100. System 300 comprises a double-wall glass tube-type thermally insulative transparent layer 320 having an evacuated space or gap 326 between an outer glass layer 322 and an inner glass layer 324 such that the vacuum gap 326 serves as a thermal insulator, significantly reducing heat loss through conduction and convection, thereby reducing heat loss in an adjacent layer having working fluid flow circulating through the tubes, absorbing thermal energy (e.g., working fluid flow depicted in dashed lines of FIG. 6B). Sunlight passing through the outer glass tube 322 can be absorbed by the selectively coated inner tube 324 to heat the working fluid flowing through the tube. The working fluid can flow through the tube and transfer the absorbed heat to a hygroscopic material.

[0096]

[0099] In one implementation, an inner surface of the inner glass tube e.g., 324 can be coated with a selectively absorbing material and / or a hygroscopic material. Alternatively, or in combination, an inner element can comprise a hygroscopic material (e.g., 318). In yet other embodiments, the hygroscopic material can be provided as a porous absorber, layer or bed configured to allow fluid flow therethrough. The flexibility in hygroscopic material location allows for customization to meet a particular application and / or desired performance criteria. In various embodiments, the heat of water vapor adsorption in the hygroscopic material and / or water vapor condensation from the working fluid can be recycled to heat and release vapor from moistureladen hygroscopic material(s).

[0097]

[0100] In some implementations, the evacuated tube solar collector system may include a heat pipe design, where an inner tube houses a heat pipe containing a working fluid such that the heat pipe’s working fluid accumulates water vapor from the hygroscopic material upon absorbing solar energy, with the water vapor rising to a condenser at the top of the tube, transferring heat to the circulating fluid via a heat exchanger.

[0098]

[0101] FIG. 7 illustrates method 1000 of operating a water generation system. At operation 1002, a process gas (e.g., ambient air) flows through a hygroscopic material or sorption layer during a sorption or loading operational mode or cycle (e.g., nighttime). At operation 1002 hygroscopic material can capture water vapor from the process gas. In some embodiments, the process gas or ambient air is provided as the cooling fluid and flows through a cooling fluid path of the recuperative heat exchange assembly.

[0102] At operation 1002, a system controller can determine the flow rate of process gas through the water generation system, for example based on or in response to a change or threshold ambient temperature or humidity, time of day, amount of water produced, a solar insolation or irradiance, a power availability and / or the like). In one example, the controller can set or reduce the process gas flow rate or power input level (e.g., to a fan assembly) to reduce or minimize power consumption such that the length of loading mode or cycle is extended without increasing an onboard battery capacity (e.g., of onboard battery) and / or other power source requirement of the system which can result in a greater amount of water capture and generation for a given loading mode or cycle. In one example, the flow rate of process gas or regeneration gas through the water generation system can be between 10-250 cubic feet per minute (CFM), between 20-100 CFM, between 30-70 CFM, less than 200 CFM, and / or less than 100 CFM. Furthermore, the system components (e.g., flow through absorber, heat exchange assembly) can be designed for minimal pressure drop, for example a pressure drop through the heat exchange assembly can be between 0.05-1 inches of water (in H2O), between 0.15-0.7 inches of water (in H2O), less than 1 inches of water (in H2O) and / or less than 0.8 inches of water (in H2O).

[0099]

[0103] At operation 1004, the method includes transitioning from the sorption or load mode to a desorption, release or regeneration mode (e g., daytime or morning). In one example, the method comprises monitoring ambient conditions (e.g. solar irradiance, relative humidity, temperature), system power availability, and / or actual or estimated amount of water produced or in a water generation system (e.g. loading equivalent relative humidity of the hygroscopic material) and, based on the monitored or estimated data, transitioning from a loading or sorption mode to a release or desorption mode.

[0104] Various methods comprise flowing regeneration fluid or gas along in a regeneration flow path (e.g., via actuating one or more fans) that can include the hygroscopic material at operation 1006. At operation 1006, the regeneration fluid can accumulate both heat and water vapor released from the hygroscopic material.

[0100]

[0105] At operation 1006, a system controller can determine the flow rate of regeneration fluid through the water generation system, for example based on or in response to a change or threshold temperature or humidity of the regeneration fluid, time of day, amount of water produced, a solar insolation or irradiance, a power availability and / or the like). A system controller can determine if a solar insolation, system water content (e.g., absolute humidity of regeneration fluid, equilibrated water of hygroscopic materials or the like) or temperature of the regeneration fluid flowing in the regeneration flow path is above a predetermined threshold (e.g., via a sensor, via calculation or estimation based on amount of captured or produced water and / or the like), a power availability (e.g., battery SOC, PV power). In one example, system controller can reduce the flow rate of the regeneration fluid if a constant solar thermal input is received by the solar thermal unit. Reducing the regeneration fluid flow rate can increase the moisture received from the hygroscopic material resulting in greater water production.

[0101]

[0106] At operation 1008, the method includes condensing water vapor from the regeneration gas in the regeneration flow path of the condenser to produce liquid water during the desorption cycle.

[0102]

[0107] At operation 1010, the method further comprises transitioning from the desorption or regeneration operational mode to the sorption or load mode. At operation 1010, the process can be repeated or cycled. Transitioning between the desorption mode and sorption mode can be varied based on: a user selection, data received from one or more sensors (e g. data relating to one or more ambient conditions, data relating to water content, etc.), power availability, forecast conditions, programmatic control, an algorithm, combinations thereof or by any other desirable bases. In one example, the method comprises continuous monitoring of ambient conditions (e.g., solar irradiance, relative humidity, temperature) and / or actual or estimated amount of water in the sorption layer and, based on the monitored or estimated data. In various implementations, the method can include determining if a water mass uptake by the sorption layer is greater than a predetermined mass associated with a nighttime relative humidity (e.g., average relative humidity at the panel) during a during nighttime or sorption time.

[0103]

[0108] The controller can adjust or determine one or more system operational ranges and / or setpoints based on an environmental condition (e.g., solar irradiance, ambient temperature) and / or a system state (e.g., amount of onboard power available, a temperature of regeneration fluid flow), so as to efficiently condense water from the regeneration fluid. For example, a controller can adjust the flow rate of the regeneration fluid in the regeneration fluid pathway, adjust the flow rate of the cooling fluid, or a combination thereof. In an embodiment, the controller can operate the system between a plurality of operational modes including: a loading mode wherein the hygroscopic material captures water vapor from a process gas (e.g., ambient air) upon flow in a process flow path; a release mode wherein the regeneration fluid accumulates heat and water vapor upon flow in the regeneration flow path, and, wherein a relative humidity in the regeneration fluid increases upon flow through the recuperative heat exchange assembly; and, a hibernation or power save mode wherein electrical power is not being consumed by the system (e.g., if available power is below a predetermined threshold, if the ambient environment is at a freezing condition).

[0104]

[0109] The above specification and examples provide a complete description of the structure and use of illustrative embodiments. Although certain embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the various illustrative embodiments of the methods and systems are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than the one shown may include some or all of the features of the depicted embodiment. For example, elements may be omitted or combined as a unitary structure, and / or connections may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and / or functions and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.

[0105] [HO] Furthermore, the materials selection and controls approach can be employed for any material systems used in water generators that having a lower and / or upper operational bound or limit relating to a weeping potential, swelling potential, low vapor pressure condition, swelling, a pressure drop on water uptake, mechanical instability, chemical instability, cycling stability, or combinations thereof. Accordingly, the material design and control approaches described herein can be modified such that additional embodiments may be realized with operational, logical, chemical, and / or mechanical changes without departing from the spirit and scope of the disclosure. The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) "means for" or "step for," respectively. The term “about” or “substantially,” as used herein, is intended to encompass minor deviations rather define an exact value.

Claims

CLAIMS1. A system comprising: a housing; a hygroscopic material located within the housing, the hygroscopic material being configured to absorb water vapor and thermal energy; and, a thermally insulative transparent layer disposed above or upstream of the hygroscopic material to allow solar radiation to pass therethrough to the hygroscopic material and reduce thermal conductance from the hygroscopic material to the external environment.

2. The system of claim 1, wherein the thermally insulative transparent layer has a thermal R value greater than 3 and an optical transmittance greater than 80%.

3. The system of claim 1, wherein the housing includes a working fluid inlet and a working fluid outlet, such that a working fluid accumulates heat and water vapor upon flowing from the working fluid inlet, along a surface of the thermally insulative transparent layer, across or through the hygroscopic material, and to the working fluid outlet.

4. The system of claim 1, further comprising a photovoltaic layer adjacent to the thermally insulative transparent layer at a front surface of the housing to collect solar radiation, wherein the housing further comprises a plurality of sidewalls extending downward from a periphery of the front surface to a rear surface.

5. The system of claim 1, wherein the housing comprises a front surface to collect solar radiation, the front surface comprising: a solar thermal portion including the thermally insulative transparent layer to allow solar radiation to impinge upon the hygroscopic material; and, a solar electric portion including a photovoltaic panel positioned above a heat exchange assembly.

6. The system of claim 1, wherein the thermally insulative transparent layer comprises a vacuum insulated layer including a sealed gap at a pressure less than atmospheric pressure.

7. The system of claim 6, wherein the vacuum insulated transparent layer comprises a first glass panel and a second glass panel separated by the sealed gap at a vacuum pressure less than or equal to 0.1 Pascal.

8. The system of claim 6, further comprising one or more spacers within the sealed gap.

9. The system of claim 7, wherein the one or more spacers comprise a ceramic material, a metal, a metal alloy, a polymer or a combination thereof.

10. The system of claim 7, wherein the one or more spacers comprise a nickel superalloy.

11. The system of claim 7, wherein spacing between adjacent spacers is greater or equal to 4 cm.

12. The system of claim 6, wherein a height of the sealed gap is between 0.1 to 0.5 mm.

13. The system of claim 6, further comprising a getter material within the sealed gap to adsorb residual gases.

14. The system of claim 6, further comprising a passivation layer applied to provide a barrier against gas diffusion.

15. The system of claim 14, wherein the passivation layer comprises a silicon oxide, a silicon nitride, or a combination thereof.

16. The system of claim 6, further comprising a hermetic seal or frame surrounding the first and second rigid transparent panels to provide structural support and seal the vacuum- sealed gap.

17. The system of claim 6, wherein a surface of the vacuum insulated layer is a top surface of the housing.

18. The system of claim 6, further comprising one or more interstitial layers between a top cover layer and the hygroscopic material, wherein the heat absorbing fluid flows along the one or more interstitial layers and then through the hygroscopic material such that the heat absorbing fluid collects heat from the one or more interstitial layers below the transparent cover layer and collects water vapor from the hygroscopic material.

19. The system of claim 18, wherein the interstitial layer comprises the vacuum insulated layer.

20. The system of claim 1, wherein the thermally insulative transparent layer comprises a static layer comprising a matrix material including a network of air gaps or spaces within its matrix to reduce heat transfer through the thermally insulative transparent layer.

21. The system of claim 20, wherein the static layer comprises a matrix material having 75% or more air by volume and an optical transmittance greater than 80%.

22. The system of claim 20, wherein static layer comprises an aerogel material, a transparent patterned polymer material, a porous matrix material, a composite polymer structure, a molded polymer structure, or a combination thereof.

23. The system of claim 21, wherein the static layer comprises a matric material including a silica aerogel, a transparent silicone, polydimethylsiloxane (PDMS), polycarbonate, poly(methyl methacrylate)(PMMA), polyethylene terephthalate (PET), polyurea, polyvinyl butyral (PVB), or a combination thereof.

24. The system of claim 21, wherein the static layer is positioned at a front surface of the housing.

25. The system of claim 21, wherein the static layer is positioned in an interstitial layer above or upstream of the hygroscopic material.

26. The system of claim 21, wherein the static layer comprises a thickness between 2 mm to 20 mm.

27. A water generation system comprising: a housing having a front surface to collect solar radiation; a sorption layer comprising a hygroscopic material to capture water vapor from a process gas during a sorption mode, and release water vapor to a regeneration fluid upon heating during a desorption mode; a thermally insulative transparent layer disposed above or upstream of the hygroscopic material to allow solar radiation to pass therethrough to the hygroscopic material and reduce thermal conductance from the hygroscopic material to the external environment.

28. The system of claim 27, wherein the front surface comprises: a solar thermal portion a thermally insulative transparent layer having a first area to convert solar radiation collected thereon to heat, the solar thermal portion comprising the thermally insulative transparent layer; and a solar electric portion having a second area to convert solar radiation collected thereon to electrical energy; wherein the first area of the solar thermal portion for solar thermal generation and the second area of the solar electric portion for solar electric generation are configured to maximize a water production rate.

29. A method for generating water comprising: allowing solar radiation to pass through a thermally insulative transparent layer to a hygroscopic material; directing a regeneration fluid in a regeneration flow path to collect heat from the thermally insulative transparent layer and transfer collected heat to the hygroscopic materialto release water vapor to the regeneration fluid, thereby reducing thermal conductance from the hygroscopic material to the external environment; condensing, via a heat exchange assembly, water vapor from the regeneration fluid.

30. The method of claim 29, further comprising: flowing ambient air in a process flow path; transitioning between a sorption mode and a desorption mode; generating electrical energy via a PV panel to power one or more fans to flow the regeneration fluid in the regeneration fluid path; or, a combination thereof.

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