Low dewpoint energy-efficient membrane dehumidifier

Abstract

An apparatus for dehumidification comprises a membrane that selectively permeates water vapor; at least a first cold chamber in thermal connection with a refrigeration source; and a vacuum pump configured to generate gas flow through the first membrane and through the first cold chamber, wherein the cold chamber is between the membrane and the vacuum pump.

Description

[0001] Attorney Docket No. tre-oiipct

[0002] LOW DEWPOINT ENERGY-EFFICIENT MEMBRANE DEHUMIDIFIER RELATED APPLICATIONS

[0003] This application claims the benefit of priority to US Provisional Application Nos.

[0004] 63 / 720,011, filed 13 November 2024, and 63 / 746,480, filed 17 January 2025, the entire content of each of which is incorporated herein by reference.

[0005] BACKGROUND

[0006] The discussion of the background state of the art below may reflect hindsight gained from the disclosed invention(s), and these characterizations are not necessarily admitted to be prior art.

[0007] Condensate Dehumidification:

[0008] The majority of dehumidification in buildings today is provided by air conditioners operating by the principle of mechanical vapor compression. As air conditioners cool input air below its dew point, excess moisture in the air condenses, thus simultaneously drying and cooling. This reduces both sensible heat (temperature) and latent heat (humidity) of the air at the same time.

[0009] In a typical comfort application, a desired setpoint may be 72°F (22.2°C) and 50% relative humidity (RH). However, if the input air is relatively humid or warm, then simply cooling to 72°F (22.2°C) will not remove sufficient water to achieve 50% RH. To attain both humidity and temperature comfort setpoints at the same time using mechanical vapor compression, the air conditioner will continue cooling the air, commonly down to a range of 4O-55°F (4.4-12.8°C), and cause further condensation. This can make the air sufficiently dry but colder than desired. This situation is known as overcool-reheat operation and may occur 30-150 days per year, depending on the climate. A simple solution is to use an external heater, such as a gas or electric heater; however, building systems and codes seek to minimize this configuration due to high energy cost. A more common solution is to add a direct expansion (DX) heating coil and use the waste heat of the mechanical vapor compressor to rewarm the air. Yet this addition adds cost to the air conditioner and does not eliminate the energy cost of the initial overcooling step.

[0010] For year-round moist environments such as a basement or commercial kitchen, dehumidifiers are a common solution. The dominant type for comfort applications is condensate dehumidifiers. These are similar to an air conditioner and have a compressor, evaporator, condenser, expansion valve loop with refrigerant; after the air passes the cold coil, it then also passes a hot coil. In essence, a condensate dehumidifier is like an air conditioner operating in a constant state of overcool-reheat. The output air from many humidifiers can be heated well above comfort levels, for example, 95°F (35°C) or more. This can be beneficial because extra heat can reduce buildup of ice on

[0011] i the coils and may help dry out a wet room. However, excess hot air can create additional load on the building air conditioning system and consume even more energy.

[0012] In summary, mechanical vapor compression is a common approach for simultaneous dehumidification and cooling of air. But once air is cooled to the desired temperature, further dehumidification becomes energy-intensive because of the need to overcool and reheat.

[0013] Sorbent Dehumidification

[0014] Condensate dehumidification is not an efficient solution when dry air is needed at dewpoints below about 55°F (12.8°C) and is particularly impractical at dewpoints below about 4O°F (4.4°C) due to the risk of coil freezing. When lower dewpoints are desired for even greater dryness, the dominant technology is a dehumidifier that operates by principles of sorption. These are often solid wheel or liquid systems that adsorb water vapor using desiccants. Commercial vendors include Munters, Drykor, and Niagara Blower. After the desiccants become saturated with water from incoming air, a recharge system, such as a heater, is used to cause the water to be released, where it can be dumped back to external air. US Published App. No. 2007 / 056307 Al describes a solid desiccant wheel. US Pat. No. 4,259,849 describes a liquid desiccant system.

[0015] Desiccants eliminate the need to cool ambient air as a means of removing moisture. Instead, ambient air moves past a surface coated in either liquid or solid desiccant or through the liquid desiccant in bubbles or droplets. An advantage of this approach is that the energy needed to recharge a desiccant is based on the mass of water sorption and not on the volume of ambient air treated. So as air becomes drier and water more sparse, sorbent dehumidifiers become more efficient per water molecule removed than a condensing dehumidifier could be at such a low dewpoint, even despite the exothermic heat release from the sorption and the substantial energy required to recharge the desiccant. In some cases, waste heat is available from an industrial process, heat pumps, or building heating, ventilation, and air-conditioning (HVAC) systems that can be used or heat-exchanged to reduce the load of the recharge cycle. Thus, sorption systems may be preferred, especially for achieving dry dewpoints below 4O°F (4-4°C) or where waste heat is available.

[0016] However, sorbent dehumidifiers face several drawbacks and cost challenges. The recharge system adds complexity, volume, capital, and maintenance not required by a condensing dehumidifier. The sorption is usually exothermic, and the recharge cycle is usually heat-based, which may add to the heat load on the building system. Over time, the desiccant material - typically a salt and, in some cases, a metal-organic framework (MOF) - can degrade or become entrained into the dry air, resulting in dust emission or duct corrosion. In some cases, reducing downstream effects limits the speed at which air can move through the system.

[0017] Membrane Dehumidification:

[0018] Both above methods can involve energy-intensive temperature swings of room air away from the desired setpoint. It would be advantageous to have a third method of dehumidification that is isothermal and would avoid these energy losses.

[0019] The field of the current disclosure is isothermal dehumidification by means of a membrane.

[0020] A major advantage of using a membrane approach is that most input air does not pass through the membrane and thus remains isothermal. Even at 100% relative humidity, water vapor often is less than 2% by mass of room temperature air. For preferred membranes, the atmospheric nitrogen, oxygen, argon, and carbon dioxide, and other non-condensable gases are nearly completely excluded (and any small volume of non-condensable gas that does pass through the membrane is enriched in water vapor). The downstream steps to process the permeate vapor that comes through the membrane (such as chilling or venting described below) can thus be focused on a small fraction of input air, and the bulk of room air is unaffected.

[0021] Thus, membrane dehumidification shares some advantages of the sorbent approach but can be better because it also eliminates the heat generated from exothermic sorption reaction, the heat required for recharge, and the need for potentially corrosive desiccant chemicals.

[0022] At this time, there are few, if any, commercially successful membrane dehumidifiers, likely due to several challenges.

[0023] For a membrane to transport water vapor, the partial pressure of water on the feed (input air) side must be higher than the partial pressure of water on the permeate (dehumidifier) side. In most prior designs, this calls for a vacuum pump to be provided to pull water vapor away from the back of the membrane using mechanical forces. However, the energy required for a large vacuum pump operating at low pressure and high flow would greatly increase the total system energy and might more than offset the gains from operating isothermally. Thus, the large size of the required vacuum pump has been a key challenge for the field. Operating under vacuum also puts substantial force on the membrane and limits practical options to those membrane films with mechanical strength, which poses a further challenge.

[0024] References

[0025] The following papers illustrate the interest and progress in this field:

[0026] • “A review of membrane-based air dehumidification” by Bo Yang, et al., in Indoor and Built Environment 2015, Vol. 24(1) 11-26. • “Humidity’s impact on greenhouse gas emissions from air conditioning” by Jason Woods, et al., in Joule 6, 726-741, April 20, 2022, Elsevier Inc.

[0027] • “Advanced thin zeolite / metal flat sheet membrane for energy efficient air dehumidification and conditioning” by Xing, R., etal., 2013. Chemical Engineering Science, 104(18), pp. 596-609.

[0028] • “Isothermal membrane-based air dehumidification: A comprehensive review” by Ming Qu, Purdue University; Omar Abdelaziz, Oak Ridge National Laboratory; Zhiming Gao, Oak Ridge National Laboratory; Hongxi Yin, Washington University in St. Louis, in Renewable & Sustainable Energy Reviews 82(1-2) (November 2017)

[0029] • “Membrane-based Liquid Desiccant Air Dehumidification: A Comprehensive Review on Materials, Components, Systems and Performances” by Xiaoli Liu, et al., in Renewable and Sustainable Energy Reviews, May 2019, volume 110, pages 444 to 466.

[0030] • “A new approach for drying moist air: The ideal Claridge-Culp-Liu dehumidification process with membrane separation, vacuum compression and sub-atmospheric condensation” by David E. Claridge, et al., in International Journal of Refrigeration 101 (2019) 211-217.

[0031] • “A Performance analysis of the Claridge-Culp-Liu dehumidification process:

[0032] A novel approach for drying moist air based on membrane separation, vacuum compression and sub-atmospheric condensation” by David E.

[0033] Claridge, etal., in International Journal of Refrigeration 122 (2021) 192-200.

[0034] • US Pat. No. 8,641,806 B2 (2014), Claridge, D.E. et al., Systems and Methods for Multistage Air Dehumidification and Cooling.

[0035] • “Membrane Dehumidification: Low Temperature Industrial Processes Workshop,” David Claridge, Proceedings from BU Institute for Global Sustainability, Feb. 3, 2021.

[0036] • “Vapor-selective active membrane energy exchanger for high efficiency outdoor air treatment” by Andrew J. Fix, et al., in Applied Energy 295 (2021) 116950 and follow up paper “Dual-module humidity pump for efficient air dehumidification: Demonstration and performance limitations” by Andrew J. Fix, et al., in Applied Energy, Volume 360, 15 April 2024, 122771.

[0037] • “Studying the performance of a pilot scale vacuum-based membrane dehumidifier” by T.D. Bui, et al., in Applied Energy Volume 351, 1 December 2023, 121907. • “The minimum work requirements for atmospheric water harvesting” by Richard M. Swanson, Heliyon 9 (2023) 017062.

[0038] • “HC-300 Desiccant Dehumidifier” PG0041 product literature by Munters Corporation (June 2019).

[0039] SUMMARY

[0040] Dehumidification apparatus and methods for dehumidification are described herein, where various embodiments of the apparatus and methods may include some or all of the elements, features, and steps described below.

[0041] Described herein is an apparatus for dehumidification, particularly isothermal dehumidification, comprising a membrane that preferentially permeates water vapor, at least a first cold chamber in thermal connection with a refrigeration source, and a vacuum pump, wherein the cold chamber provides gaseous communication between the membrane and the vacuum pump.

[0042] Also described is a membrane stack and frame design (“tile”) for use in a membrane-based dehumidification apparatus comprising a frame structure including a face that includes (a) a recessed volume occupying a majority portion of the face excluding a perimeter area of the face, (b) one or more raised features on the surface of the recessed volume, and (c) an edge inset on the frame face around the perimeter of the recessed cavity; a selectively permeable membrane layer of one or more plies less than 200 microns thick in total; a mesh or support layer in contact with (a) a ply of the membrane layer, (b) the shallow edge inset, and (c) a raised feature in the recessed volume; and an airtight cavity between the membrane layer and the frame that is in gaseous communication with an outlet port.

[0043] The description further describes an arrangement of the tiles (into cassettes and the cassettes into an enclosure) that by orientation greatly raises the water vapor transmission efficiency of a given tile. The disclosure further relates to an apparatus and methods of operation for controlling humidity in a defined space comprising the above apparatus and an assembly of the above tiles.

[0044] Still further described is an apparatus for isothermal dehumidification comprising the cold chamber apparatus and further comprising a tile, wherein the tile is oriented to flow permeate vapor in the opposite direction from the feed air passing over the face of the membrane.

[0045] The disclosed apparatus can overcome the vacuum pump challenge that has confronted the field. For comparison, a membrane dehumidification prototype in T.D. Bui, et al., “Studying the performance of a pilot scale vacuum-based membrane dehumidifier,” Applied Energy, Vol. 351, 121907 (1 December 2023) (hereafter, “Bui), required an 8,300 W, liquid-cooled vacuum pump. At an equivalent water removal rate, we estimate that embodiments of the disclosed apparatus may require only a 300 W vacuum pump, a 96% reduction.

[0046] Although the disclosed apparatus is not restricted to a particular membrane film, we disclose a manufacturable membrane tile assembly with a selectivity above 20,000, which may be compared to 10,000 (A. Fix, et al., “Vapor-selective active membrane energy exchanger for high efficiency outdoor air treatment,” Applied Energy Vol. 295, 116950 (2021) and A. Fix, et al., “Dual-module humidity pump for efficient air dehumidification: Demonstration and performance limitations,” Applied Energy, Vol.

[0047] 360, 122771 (15 April 2024), 2,200 (Bui), or 300 [R. Xing, etal., ].

[0048] In some conditions, a combination of the disclosed apparatus comprising the disclosed tile in the disclosed orientation achieves substantial energy savings over the state of the art. For example, at an input condition of about 75°F and 65.8% relative humidity (RH) [85 grains per pound of dry air (gpp)], the product sheet for a desiccant dehumidifier (HC-300 dehumidifier from Munters Corporation, Amesbury, Massachusetts, USA) reports a moisture removal efficiency (MRE) of 0.78 kg / kWh (1.7 Ib / kWh). In contrast, the disclosed apparatus operates at fairly similar conditions with an MRE of 1.85 kg / kWh. Also, the desiccant dehumidifier exothermically heats output air to about 122°F (5O°C), and cooling energy from the building air conditioning required to return this to comfort levels is not included in the MRE calculation. In contrast, the disclosed apparatus need not heat the output air.

[0049] Relative to other work in the field of membrane dehumidification, the apparatus disclosed herein can also (1) protect the vacuum pump from handling excess condensation and allow for a wide range of commercial off-the-shelf options for further cost reduction or longer operating life; (2) omit the use of a water tower; (3) omit the use of a large novel compressor; and (4) enable the use of a thin and flexible membrane. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic showing apparatus components and general flows.

[0050] FIG. 2 is an isometric view of a prototype of an apparatus for dehumidification at a commercially useful scale.

[0051] FIG. 3 is a side view of the prototype of FIG. 2.

[0052] FIG. 4 is a side view cutaway of the prototype of FIGS. 2 and 3.

[0053] FIG. 5 is a top-down cutaway view of the top box of the prototype, which illustrates the placement of three cassettes.

[0054] FIG. 6 is a view of the top assembly of the prototype, comprising the fan, cassette, and cold chamber.

[0055] FIG. 7 is a cutaway isometric view of the top assembly, which also shows the cassette with membrane assembly and vapor header, and a finned condenser coil type. FIG. 8 is a cutaway side view of the top assembly, illustrating the vapor flow path.

[0056] FIG. 9 illustrates a cylindrical cold chamber.

[0057] FIG. io is a cutaway view of a cylindrical cold chamber comprising a looped condenser coil.

[0058] FIG. 11 illustrates the top assembly of the prototype connected through a manifold to a cold chamber.

[0059] FIG. 12 is a side view of the prototype, illustrating an example of the connection between the vapor headers and a cold chamber

[0060] FIG. 13 illustrates examples of suitable condenser coil geometries, such as looped, finned, and shell and tube.

[0061] FIG. 14 is a schematic diagram illustrating the fluid flows through the refrigeration system and cold chamber

[0062] FIG. 15 is a schematic diagram showing a refrigeration system coupled directly to a cold chamber

[0063] FIG. 16 is a schematic diagram of the refrigeration system and cold chamber, illustrating a cold recovery system with a liquid mechanical-controlled-ventilation (MCV) heat exchanger

[0064] FIG. 17 is a schematic diagram of the refrigeration system and cold chamber, illustrating a cold recovery system with a forced-air evaporative cooling system.

[0065] FIG. 18 is an isometric view of a cassette assembly with vapor headers.

[0066] FIG. 19 is an isometric view of a single tile.

[0067] FIG. 20 is a view of the detail of the tile edge comprising means for vapor to exit. FIG. 21 is an isometric view of a tile showing how it is double-sided.

[0068] FIG. 22 shows a cross-section of the tile with layer stack and channel geometries. FIG. 23 shows an isometric detail of the tile with a layer stack.

[0069] FIG. 24 shows the details of the tile edge and vacuum seal.

[0070] FIG. 25 shows a tile with an external flat outlet port suitable for stacking.

[0071] FIG. 26 shows a tile with an internal flat outlet port suitable for stacking.

[0072] FIG. 27 shows a cross-section schematic for a refrigerated tile.

[0073] FIG. 28 is a plot of moisture vapor transmission rate (MVTR) as a function of manifold (permeate) pressure in a range from 0-60 kPa from Experiment 1.

[0074] FIG. 29 is a plot of moisture vapor transmission rate (MVTR) as a function of manifold (permeate) pressure in a range from 0-10 kPa from Experiment 1.

[0075] FIG. 30 is a plot of moisture vapor transmission rate (MVTR) as a function of the membrane layer count from Experiment 1.

[0076] FIG. 31 is a plot of leak rate as a function of the membrane layer count from Experiment 1. FIG. 32 includes schematic illustrations of permeate flow relative to feed flow, including coflow (left), crossflow (center), and counterflow (right) from Experiment 2.

[0077] FIG. 33 is a plot of moisture vapor transmission rate (MVTR) as a function of the flow mode for the permeate and the feed from Experiment 2.

[0078] FIG. 34 is a plot of permeance across the membrane as a function of the gap between tiles from Experiment 3.

[0079] FIG. 35 includes plots of relative humidity as a function of time for both the feed in (top plot) and the feed out (bottom plot) from Experiment 4.

[0080] FIG. 36 includes plots of temperature as a function of time for the feed in (under 20°C at time o) and the feed out (over 20°C at time o) from Experiment 4.

[0081] FIG. 37 includes plots of power (with peaks from top to bottom: total power, average total power, chill power, vacuum power, and fan power) as a function of time from Experiment 4.

[0082] FIG. 38 includes plots of relative humidity as a function of time for feed in (top) and feed out (bottom) from Experiment 4.

[0083] FIG. 39 includes plots of temperature as a function of time for feed in (below 22°C at time o) and feed out (above 22°C at time o) from Experiment 4.

[0084] FIG. 40 includes plots of power (with peaks from top to bottom: total power, average total power, chill power, vacuum power, and fan power) as a function of time from Experiment 4.

[0085] In the accompanying drawings, like reference characters refer to the same or similar parts throughout the different views; and apostrophes are used to differentiate multiple instances of the same item or different embodiments of items sharing the same reference numeral. The drawings are not necessarily to scale; instead, an emphasis is placed on illustrating particular principles in the exemplifications discussed below. For any drawings that include text (words, reference characters, and / or numbers), alternative versions of the drawings without the text are to be understood as being part of this disclosure; and formal replacement drawings without such text may be substituted therefor.

[0086] DETAILED DESCRIPTION

[0087] The foregoing and other features and advantages of various aspects of the invention(s) will be apparent from the following more particular description of various concepts and specific embodiments within the broader bounds of the invention, as defined by the claims. Various aspects of the subject matter introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the subject matter is not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes. Unless otherwise herein defined, used, or characterized, terms that are used herein (including technical and scientific terms) are to be interpreted as having a meaning that is consistent with their accepted meaning in the context of the relevant art and are not to be interpreted in an idealized or overly formal sense unless expressly so defined herein. For example, if a particular composition is referenced, the composition may be substantially (though not perfectly) pure, as practical and imperfect realities may apply; e.g., the potential presence of at least trace impurities (e.g., at less than 1 or 2%) can be understood as being within the scope of the description. Likewise, if a particular shape is referenced, the shape is intended to include imperfect variations from ideal shapes, e.g., due to manufacturing tolerances. Percentages or concentrations expressed herein can be in terms of weight or volume.

[0088] Although the terms, first, second, third, etc., maybe used herein to describe various elements, these elements are not to be limited by these terms. These terms are simply used to distinguish one element from another. Thus, a first element, discussed below, could be termed a second element without departing from the teachings of the exemplary embodiments.

[0089] Spatially relative terms, such as “above,” “below,” “left,” “right,” “in front,” “behind,” and the like, may be used herein for ease of description to describe the relationship of one element to another element, as illustrated in the figures. It will be understood that the spatially relative terms, as well as the illustrated configurations, are intended to encompass different orientations of the apparatus in use or operation in addition to the orientations described herein and depicted in the figures. For example, if the apparatus in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “above” may encompass both an orientation of above and below. The apparatus may be otherwise oriented e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The term “about” can mean within ±10% of the value recited. In addition, where a range of values is provided, each subrange and each individual value between the upper and lower ends of the range is contemplated and, therefore, disclosed.

[0090] Further still, in this disclosure, when an element is referred to as being “on,” “connected to,” “coupled to,” “in contact with,” etc., another element, it may be directly on, connected to, coupled to, or in contact with the other element or intervening elements may be present unless otherwise specified.

[0091] Some of the terminology used herein is associated with particular embodiments and is not intended to limit more generic exemplifications of the invention. As used herein, singular forms, such as those introduced with the articles, “a” and “an,” are intended to include the plural forms as well, unless the context indicates otherwise. Additionally, the terms “includes,” “including,” “comprises,” and “comprising,” specify the presence of the stated elements or steps but do not preclude the presence or addition of one or more other elements or steps.

[0092] Additionally, the various components identified herein can be provided in an assembled and finished form; or some or all of the components can be packaged together and marketed as a kit with instructions (e.p., in written, video, or audio form) for assembly and / or modification by a customer to produce a finished product.

[0093] A. Overview:

[0094] Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, FIG. 1 is a schematic of the apparatus, while FIGS. 2 through 17 illustrate the dehumidifier apparatus comprising an enclosure 100, a fan 200, a cassette with vapor header 300 and membrane assembly 400, a refrigeration system 500, a cold chamber 600, a drain 700, a vacuum pump 800, and a mechanical support 900, FIG. 18 illustrates one or more cassettes comprising staggered vapor headers 310 and 320, frame components 420, 430, and 440, and an array of tiles 410, and FIGS. 19 through 24 illustrate a tile 410 and various tile details.

[0095] Dehumidification of process air occurs when water is transported across the membrane. Transport occurs when the partial pressure of water on the permeate side is lower than the partial pressure of water on the feed side.

[0096] In the disclosed apparatus, a cold chamber at low temperature reduces the partial pressure of water on the permeate side and drives transport. This reduction in water vapor in the cold chamber relieves the need to rely on mechanical force from a large vacuum pump for transport to occur.

[0097] After reaching the permeate side of the membrane, water vapor flows through the tile outlet port into a header. The water vapor mixes with a quantity of noncondensable gas in the apparatus. Non-condensable gas enters the apparatus through the membrane alongside the water vapor according to selectivity and can also enter through leaks in the apparatus or from air present in the apparatus at startup. When the water vapor reaches the cold chamber, the low temperature causes a portion to condense or deposit. A flow of non-condensable gas and some amount of water vapor exits the cold chamber and moves through the vacuum pump to an exhaust point.

[0098] A notable aspect of the apparatus is that air can be dried as low as a target dewpoint by lowering the temperature of the cold chamber sufficiently.

[0099] To achieve useful results, the apparatus can be designed, assembled, and operated so that the movement of water vapor occurs by viscous flow rather than by diffusion. The water-vapor portion of the combined flow can be the majority e.g., over 90% by molar mass). The membrane can be highly selective and the apparatus adequately free of leaks. The vacuum pump is sized and operated to expel the non-condensable gases that do enter the apparatus above a minimum rate to sustain viscous flow. If the vacuum pump is too small or underpowered, non-condensable gases will accumulate, and water vapor flow will become limited by diffusion through these gases and reduction of heat transfer through an air boundary layer in the heat exchanger / cold chamber.

[0100] The vacuum pump is sized large enough to handle the flow of the apparatus at its lowest specified dewpoint.

[0101] The vacuum pump is also sized and operated to not draw pressure too low. The total vapor pressure at the vacuum pump is somewhat higher than the partial pressure of water in the cold chamber, which in turn is set by the cold chamber temperature. For example, if the cold chamber is at o°C, then the partial pressure of water there will be at or about 611 Pa. As long as there is water in the cold chamber, operating a larger vacuum pump at higher power will not achieve a partial pressure lower than 611 Pa; instead, it will boil water vapor out of the chamber, which is a waste of energy and pump capacity. Even at a vacuum pressure slightly above the partial pressure of water (e.g., 700 Pa), the oversized vacuum pump will draw substantial water vapor out of the cold chamber along with the non-condensable gas, which is again a waste of energy and pump capacity. It is advantageous instead for the vacuum pump to operate at a pressure moderately higher than the cold chamber partial pressure of water (e.g., 800-1,200 Pa) or more provided there is still sufficient pressure to expel non-condensable gases in the given apparatus as described above.

[0102] The apparatus is also sized and operated and the cold chamber designed so that water vapor remains inside the cold chamber long enough for the great majority to condense or deposit before otherwise reaching the vacuum pump.

[0103] B. Schematic of the apparatus:

[0104] In FIG. 1, room air enters an enclosure 100 drawn by the fan 200 and moves past the exterior of vapor headers 300 to flow across the tile assembly 400, whereupon vapor comprising water transports out of the room air and across the membrane into the tiles, and air that exits the enclosure is drier than ambient.

[0105] Transport of water vapor across the membrane is induced by vacuum pressure provided by a cold chamber 600 and a vacuum pump 800 such that the partial pressure of water inside the tile is lower than the partial pressure of water in the input air passing along a length of the tile. In one embodiment, the vapor partial pressure in the permeate is in the range of 0-3,500 Pa. This vacuum region extends from inside the tiles of the membrane assembly 400, through the vapor headers 300, through the cold chamber 600, and to the vacuum pump 800; and the associated piping and connections in between. Therefore, suitable materials and fittings are used in the construction of each of these components and in their assembly and connection. The vapor comprises a mix of water molecules as well as non-condensable molecules, such as nitrogen, oxygen, and carbon dioxide. If the apparatus has leaks, then the vapor will also comprise some portion of room air. These non-water gases add to the workload for the downstream vacuum pump without contributing to dehumidification. Thus, the energy efficiency of the apparatus for each kg of water removed per kWh is greatly affected by the water selectivity of the membranes, the tile assembly, and the air-tightness of the apparatus. In one embodiment, such as described below, the membrane has a selection ratio (ratio of the permeance of water to the permeance of air) of more than 1,000, and the apparatus can maintain a pressure of less than 2,500 Pa with a leak rate of less than 0.04 liter per minute per square meter of membrane surface.

[0106] The permeate vapor flows through the vapor headers 300 into a cold chamber 600 which is cooled by a refrigeration system 500. As explained above, the cold chamber anticipated in this disclosure is sufficiently cold to prevent nearly all water vapor from reaching the vacuum pump.

[0107] The cold chamber is sufficiently cold (with associated low pressure as required by the phase line of water) relative to the apparatus permeate pressure to trap more than 90% of the water vapor, advantageously more than 95% of the water vapor, and ideally over 97.5% of the water vapor.

[0108] The apparatus arrangement and dimensions provide for air flow across substantially all of the faces of the tiles.

[0109] In one embodiment, the components are arranged as shown in FIG. 5 such that the room air flows across the face of the tiles in a direction opposite to that of the water vapor inside the tiles, which flows towards the vapor headers (e.g., counter-flow configuration). The inventors observe this results in higher vapor transport than when arranging the flows in an orthogonal direction and much higher than when arranging the flows in the same direction.

[0110] The area of membrane, the widths of connecting ports and O-rings, the widths of the cassette manifold and its input and exit ports, and the size of the entry ports of the cold chamber advantageously are sized relative to each other so that there are no bottlenecks (e.g., vapor flow conductance losses) upstream of the cold chamber.

[0111] As the temperature in the cold chamber 600 drops, the partial pressure of water behind the membranes in the tile assembly 400 also drops, and water vapor in room air will cross the membrane even in very dry ambient conditions without the need for a large vacuum pump. The cold chamber 600 is maintained sufficiently cold that nearly all water vapor that enters condenses into liquid water or even freezes or deposits into solid ice. The lower the temperature of cold chamber 600, the lower the dehumidification dew point that the apparatus can achieve. The remaining vapor that exits the cold chamber 600 to pass to the vacuum pump 800 is relatively dry and contracted by cold into a relatively small volume. Thus, this disclosure enables smaller, more efficient, less costly, and potentially more reliable vacuum pumps than previously known in the art.

[0112] The apparatus may further comprise other means of capturing water. For example, beetle shells, spider webs, and certain plants are able to collect mist by physical means and their geometries maybe adopted or adapted into this disclosure at any point in the flow of room air or vapor to enhance condensation efficiency.

[0113] C. Enclosure:

[0114] The enclosure 100 is shown in FIGS. 2 through 7, 11, and 12. The enclosure 100 surrounds the fan 200 and also the cassettes, each cassette comprising vapor heads 300 and tile assemblies 400.

[0115] The enclosure 100 is solid enough to guide air and protect the tile assemblies and give structural support to aid assembly but need not be airtight enough for a vacuum. In one embodiment, the enclosure 100 is formed of sheet metal and seated on a wheeled metal frame 900 and secured by screws. Side cavities in the enclosure 100 allow for air input and exit. A bottom cavity allows for vapor heads 300 to connect to a cold chamber 600.

[0116] The enclosure 100 contains membrane surfaces that can be arranged in many ways. In one embodiment, the membrane is provided in tiles 410 are linked into assemblies and further connected by staggered vapor headers 310 and 320 (collectively, a cassette). The dimensions provide for relatively direct flow of air from the fan and uniformly across the membrane surface of the tiles. The enclosure 100 may house tiles in one or more cassettes. In one embodiment, the enclosure 100 contains three cassettes, each having 36 tiles, each having two faces of membrane, for a collective active membrane surface area of 6.1 m2packed into a cubic volume of 0.136 m3 within the enclosure.

[0117] The cavity of the enclosure must be large enough also to contain the fan and may also provide sufficient space for the airflow of the fan to spread out and reach the more distant tile faces directly. The enclosure interior dimension should be relatively snug around the fan and cassettes so as to maximize air flow through rather than around the cassettes. The enclosure may contain permanent or temporary spacers and baffles, for example, to further guide airflow or to minimize movement during shipment.

[0118] The enclosure 100 can provide screw holes or other suitable means of attachment to upstream and / or downstream ducts or other air treatment and air remediation devices, such as filters, heaters, coolers, UV lights, and odor control (not shown) and to suitable means of physical support, stabilization, or suspension. The enclosure 100 can provide a prefilter upstream of the membrane assembly 400. The prefilter filters sufficiently under local conditions to prevent dirt and dust from entering the apparatus and coating the membranes. Prefiltration can also occur in another part of the building system. The enclosure may further provide ports for sensors and cables and connections for cover plates for unused ports or for openings created if cassettes are missing. The enclosure can be at least partially clear and can also comprise lighting.

[0119] Replacement of cassettes with fresh membranes may be useful from time to time to maximize productivity and maintain the apparatus. The enclosure 100 can provide for doors or indicators or other physical grooves and guides to facilitate this step.

[0120] D. Fan:

[0121] In one embodiment, fan 200 is the MSI1769 series motorized impeller (175 mm x 69 mm, 24VDC, 1.8” water / 448 Pa static pressure) from Mechatronics Corporation, Preston, Washington, USA. The feed fan is selected to be low power, with sufficient static pressure to force feed air through the gaps between tiles, and high enough volume at that pressure to achieve the desired velocity and flow volume. A feed fan with an integrated tachometer or pulse sensor for real-time monitoring of fan speed and apparatus operation is also advantageous, along with low noise generation (< 80 dB). As part of a larger product or building system, the flow can be provided by another fan outside the apparatus with sufficient static pressure.

[0122] Any suitable fan can be used. Electronically commutated centrifugal fans are efficient and can be adjusted using electronic speed control to control flow rate. They have high static pressure and can be a backward-inclined type but can alternatively be a forward-curved type. Adjustable-speed mixed flow fans can support moderate static pressures and allow flexible airflow adjustment with electronic speed control and good efficiency. Radial blowers with pulse width modulation (PWM) control can be used at variable flow rates with acceptable power usage. Individual or arrayed variable speed axial fans can be used in configurations with lower static pressures and providing high air flows.

[0123] E. Cold Chamber:

[0124] A detailed view of cold chamber 600 is provided in FIGS. 7 through 13. The cold chamber 600 includes one or more suitable ports to receive the vapor from the cassettes. The cold chamber 600 can be provided directly under the enclosure 1 and within 4 to 10 inches of the exit ports of vapor headers 310 and 320, such that the vapor headers are connected directly to the cold chamber, as in FIGS. 7 and 8. It is also possible to use an intervening pipe, hose, manifold, header, billet, or adapter to connect the vapor headers 310 and 320 from multiple cassettes with the cold chamber 600. In one embodiment, the vapor headers 310 and 320 from each cassette are brought together with a 2-to-i manifold 611 and then connected to the cold chamber 600 through an adapter 6621, as shown in FIGS. 9 and 10. In another embodiment, the vapor headers 310 and 320 from each cassette are brought together with a “Y” shaped 2-to-i manifold 612, which feeds into a 3-to-i manifold 613; this is connected to the cold chamber 600 through an elbow adapter 620, as shown in FIGS. 11 and 12.

[0125] The distance can be minimized between the vapor headers 310 and 320 and the cold chamber 600, and the piping is of sufficiently large diameter and direct path to optimize flow conductance. Short distances may minimize pressure losses between the face of the tile and the pressure created by the low temperatures of the cold chamber 600.

[0126] The cold chamber 6 and any associated piping are insulated and are as short as possible. Minimizing heat loss and flow restrictions will maximize the efficiency of heat transfer from the refrigeration system 500 to the water vapor. Heat losses of the cold chamber, refrigeration system, and associated piping are minimized with insulation elements 660, as described in section J.

[0127] The cold chamber 600 can be formed in any suitable cavity shape, such as a box shape of FIGS. 3 through 8 or a tube shape of FIGS. 9 through 13. The cold chamber 600 has at least one additional port 650 connecting to the vacuum pump 800 and may have further auxiliary ports for attaching sensors; in one embodiment, as shown in FIG.

[0128] 10, at the end of the cold chamber 600 (651), and in another embodiment, as shown in FIG. 12, as a T port on the top of the cold chamber 600 (652).

[0129] The cooling element can be arranged to minimize surface area contact with the walls of the cold chamber so as to reduce thermal conductivity to the exterior.

[0130] The cold chamber can be provided with a sufficient interior cavity volume at the bottom of the chamber that condensed liquid water runs to the bottom of the cold chamber and is no longer in contact with the cooling element, and the surface of the collected liquid at the top of the cavity ideally has minimal surface area exposed to the chamber pressure.

[0131] The drain 700 can be fitted with a reservoir and valves, as shown in FIGS. 14-17, to allow water removal without breaking the vacuum. The apparatus can further comprise a valve for draining collected water. In one embodiment, the drain system has two valves and a connecting pipe. The top valve is opened, and water drains into the pipe or into a suitable cavity by force of gravity or vacuum. The top valve is closed. The bottom valve is opened, and water drains or is pumped from the pipe or cavity into a reservoir. This functions like an air lock to allow water to exit the apparatus with minimal loss of vacuum inside the system. The internal design of the cold chamber can provide for a torturous path of the incoming vapor past a cooling element with many parallel possible channels, such that ice in one region would not block vapor flow. In another embodiment, the cold chamber interior spaces are partially separated by baffles to increase the tortuosity of the vapor path.

[0132] The cold chamber can include fins near the inlet at one or more than one angle, resulting in redirection of water vapor so that it contacts a greater area of the chamber prior to freezing. The cold chamber is designed so that incoming water vapor dwells within the chamber for an adequate amount of time and preferably so that the incoming water vapor molecules have a high likelihood of contacting cold surfaces and depositing water or ice.

[0133] If the cold chamber is operated below freezing and ice forms, the rate of thermal transfer from the metal surfaces to cool the incoming vapor can start to drop as a thickening layer of ice builds up over the metal. Ice is considerably poorer at thermal conductivity than metal. For this reason, it is advantageous for the cold chamber and cooling element to provide sufficient interior surface area such that at capacity, the ice thickness on most surfaces is less than 2mm and advantageously less than imm thick. The cold chamber open interior spaces proximate to the cooling element can be filled with a high surface area porous or permeable heat conductor, such as metal wool or mesh.

[0134] FIG. 13 shows four arrangements of the cooling element 640 suitable for a tubeshaped or box-shaped cold chamber, including a cooling element 641 in the form of a looping coil, a cooling element 642 in the form of a finned tube similar to an electric radiator element, a cooling element 643 in the form of winding tubes that fit within the shell of the cold chamber and including baffle spacers, and a cooling element 644 in the form of a shell-and-tube type cold chamber that comprises two separate internal cavities: an inner system of “tubes” that allow for multiple parallel flows of cooling liquid to pass from one end of the space to the other, and an outer “shell” cavity around the tubes where vapor is collected and brought into contact with the tubes.

[0135] In the single-chamber embodiment illustrated here, the apparatus operates until the cold chamber 600 is sufficiently full of water and / or ice. The vacuum pump 800 and refrigeration system 500 are turned off, and water and melting ice are removed via 700. The apparatus is then restarted.

[0136] The apparatus can have two or more cold chambers to allow for greater capacity and continuity of operation. There may be valves to switch vacuum and water vapor flow or both, such that one chamber is draining or melting out as another chamber is building water or ice. The apparatus can also operate with one chamber that is periodically warmed up to melt out the ice via a drain or water pump separate from the vacuum pump. To hasten melting, the cooling coil may also be repurposed and filled with the same or different liquid at a temperature warmer than freezing; an example is shown in FIGS. 16 and 17. The cold chamber can also contain a heating element, such as an electronic heat source or the hot side of a heat exchange plate.

[0137] In some cases, two or more stages with separate tiles, permeates, and cold chambers are arranged in series and may operate the cold chambers at different temperatures. A “two-stage cooling process” with the second stage at a lower temperature than the first may be provided to achieve ultra-dry air in a more energyefficient manner than just using a single cold chamber. The first stage cold chamber can operate at slightly above o°C, thus condensing the majority of the water vapor to the liquid phase but without paying the energy cost of a phase change to solid. The feed air exiting the first stage enters the second stage, where the second cold chamber then operates below o°C to lower the first stage leaving air dew point from just above o°C to a dew point below o°C for the second stage leaving air. The extracted water vapor in the second stage is converted into a solid phase. The second stage cold chamber temperature can be set as low as needed for the target dewpoint (which can be -5°C in a number of settings or even -3O°C to -7O°C in lithium battery applications). The lower temperatures of the second chamber require greater cooling energy per gram of water collected; however, this is only needed for the incremental amount of water vapor removed after the first stage pass. The method of cooling and any refrigerant materials and size of cooling equipment can be optimized specifically for the temperature swing regime of each different chamber, and the chambers can share a refrigerant source and use separate electronic expansion valves (EEVs) or other expansion device to achieve the desired target temperature. Two or more dehumidification stages can also be included to achieve the temperature range and operating points required.

[0138] In some cases, it may be advantageous to have two cold chambers in gaseous connection in series to reduce the load on the vacuum pump. There may be pressure regulator valves before the first chamber, in between the first and second chamber, and after the second chamber and before the vacuum pump, as needed for efficient operation over a variety of dew points. Operating the final chamber below o°C is advantageous to ensure that the apparatus captures as close to 100% of the humidity as possible, minimizing downstream carry over and wetting potential for the vacuum pump. In another advantageous embodiment, the second-stage cold chamber is directly below the first-stage cold chamber; however, any suitable relative arrangement can be used.

[0139] The dehumidification apparatus elements can be provided and arranged so that a cold chamber is accessible for service. The cold chamber can be made of stainless steel; however, any suitable material, such as metal or plastic, may be used. In another embodiment, the cold chamber, cooling element, baffles, or metal wool can be treated or coated to promote dropwise condensation and to promote drainage without water adhering to the various surfaces. For example, a hydrophobic chemical coating or polymer, such as polytetrafluoroethylene (TEFLON fluoropolymer), may be used to promote drainage.

[0140] The cold chamber can include or be connected to a liquid water or solid ice collection reservoir. A reservoir entrance can be located below the cold chamber, and gravity causes condensed water to flow into the reservoir. The reservoir can be shaped suitably (for example, flask-like) to distance the condensed water from the permeate vapor flowing through the cold chamber and to minimize the exposed surface area of the condensed water. The apparatus can comprise any combination of a drain, drain pump, or container that is removable by the user.

[0141] In some embodiments, cold water or ice removed from the apparatus is then used for further purposes. Without limiting the generality of the uses of ice and water, the inventors envision it being used to cool the condenser side of the refrigeration system 500 and improve the coefficient of performance (COP) of the apparatus; two possible examples of this are illustrated in FIGS. 16 and 17. The removed ice / water can also be used for future humidification if the ambient conditions become too dry. The removed ice / water can also be used as a source of water for evaporative cooling. The ice / water can be used to pre-chill the water vapor before it reaches the cold chamber. The ice / water can provide cooling for the vacuum pump. The ice / water can cool a neighboring desiccant system. The ice / water can be used to supply a chilled beam cooling system. The ice / water can be used with a heat exchanger to improve the energy efficiency of other building systems. The ice / water can be used directly for building system components, such as cooling towers, boilers, or sprinklers. The ice / water can provide solid ice that is moved elsewhere for cooling or air conditioning. The ice / water can be treated for potable drinking water.

[0142] The cold chamber can be arranged such that solid ice is removed directly without melting out into liquid. As is known in the art of ice making, solid ice can form on a dangling or protruding element over an air gap. Once ice has formed, the element is heated. After a small amount of ice touching the element melts, the ice block then falls.

[0143] The cold chamber 6 can be arranged with suitable means of physical support rather than hanging freely from the enclosure 100, as shown in FIG. 6.

[0144] The apparatus can include any suitable logical and / or physical means of assessing the fullness of the cold chamber. For example, the apparatus can include a scale or stress sensor, temperature measurement, or other electronic method for detecting ice or water as the apparatus fills. Also, the apparatus can compute water collection by measuring the incoming and outgoing moisture levels as air enters and leaves the enclosure.

[0145] Various cold chamber sizes can be employed as appropriate. A larger chamber can be emptied less frequently but may add expense and weight and may be subject to higher thermal loss and thus be more expensive to cool. Nevertheless, the cold chamber is designed to provide sufficient surface area and dwell time for incoming water vapor to reach a cold surface and condense or deposit before exiting the chamber. Baffles and other means of creating a tortuous path for the vapor can help improve dwell time and direct the vapor to the full surface area available. The sizing of the surface area is adequate to prevent thick accumulations of ice, which has a lower heat transfer rate of ice than metal. The ratio of the surface area of the membrane to that of the cold chamber is at least 4 square meters of membrane per 1 square meter of cold chamber surface area.

[0146] F. Refrigeration System

[0147] The refrigeration system 500 can operate by any suitable means to chill the cooling element of the cold chamber 600. The refrigeration system 500 or cold chamber 600 can include a thermoelectric cooling element, vapor-compression directly or via a secondary heat transfer fluid (for example, propylene glycol) loop, cooling tower, absorption chiller, or other suitable source of cooling.

[0148] The refrigeration system 500 can work by conventional vapor-compression that cools a circulating glycol loop as shown in FIG. 14. The refrigeration loop has (a) a compressor to pressurize the refrigerant, (b) a mechanically compressed vapor (MCV) condenser to cool the pressurized liquid / gas into a liquid, (c) an expansion valve to allow control of the flow of refrigerant and regulate the pressure between the condenser and evaporator, and (d) an evaporator where the liquid evaporates and absorbs heat. The evaporator resides in a tank where it is immersed in glycol chiller fluid that is subsequently cooled. A pump (shown as an immersion pump but could be outside the tank) circulates the cooled glycol liquid into the cold chamber 600, where vapor enters and is condensed / frozen, as described in Section F. The refrigeration system can include components to improve efficiency, such as electronic expansion valves, variable speed compressors, variable speed condenser fans, and a large area / oversized condenser, as well as components to improve durability and reliability, such as an accumulator and filter dryer.

[0149] Glycol chillers are commercially available units with low cost and high reliability. In one embodiment, the system is a V2 HP glycol chiller (from Penguin Chillers, Knoxville, Tennessee, USA) producing 2500 BTU / hr of cooling at 28°F (-2.2°C).

[0150] The superiority of this disclosure’s energy efficiency is due to the membrane, which filters out most non-condensable gases; and thus the volume and mass of air to be cooled by the refrigeration system 500 is just the water vapor. This is a potentially large energy savings because the composition of most room air is less than 4% water vapor, and can be less than 0.25% water vapor. For dry room applications, the fraction is even less.

[0151] The cold chamber can be chilled cost-effectively, simply, and reliably using an off-the-shelf mechanical vapor compression system of low global warming potential (GWP) and a liquid coolant that remains liquid down to -ioo°F (-73.3°C) comprising a non-toxic mixture of propylene glycol, glycerol, ethanol, additives, and water. The coolant can circulate through a cooling element (for example, a coil, radiator, or other suitable geometry provided inside the cold chamber); the cold chamber may be submerged entirely or in part or otherwise surrounded by the coolant; or a combination thereof can be practiced.

[0152] In one embodiment, the refrigerant used in the chiller has a low global warming potential (GWP) that reduces the environmental impact of the vapor-compression system, such as hydrofluoroolefins or natural refrigerants, such as ammonia, propane, butane, or carbon dioxide.

[0153] In the current embodiment, the circulating liquid coolant meets several criteria: (1) being non-toxic; (2) being non-corrosive; (3) having a freezing point well below the customer’s target dew point, such as below -5°C or even below -2O°C or less; and (4) maintaining a low viscosity even when cold so as to limit the workload required from the circulation pump. In our experiments, we used mixtures of water, propylene glycol, and, in some cases, ethanol.

[0154] In other embodiments, the circulation loop can be a closed system with a suitable, low-viscosity synthetic heat-transfer fluid for the temperature range required. The circulating liquid can further comprise surfactants, thinners, thickeners, getters, inhibitors, or other corrosion and clog prevention additives.

[0155] The pump pressure, flow rate of the coolant, the surface area and diameter of pipes, and the size and type of fittings can be traded off, as is known in the art of glycol refrigeration. In combination, they should provide sufficient cooling to chill the water vapor coming in as required for the function of a cold chamber to achieve the desired apparatus performance across its operating range.

[0156] The refrigeration system can be incorporated inside the dehumidifier apparatus or provided in a separate apparatus connected by any means of heat transfer or piping. The refrigeration system may exhaust all, partially, or not at all into the output air. The refrigeration system can be located indoors or outdoors, while exhausting all or partially to the outdoors.

[0157] In another embodiment, the source of cooling provided by the evaporating refrigerant is incorporated into the cold chamber 6, as shown in FIG. 15. The refrigeration system may further comprise a compressor, condenser, and thermal expansion or thermostatic expansion valve. Rather than having the MCV evaporator immersed in a heat transfer liquid to cool a secondary loop as described above, evaporation can take place directly inside the cooling element of the cold chamber. The circulating refrigerant may convert from liquid to gas phase inside the cooling element of the cold chamber, causing the element to absorb heat from the water vapor in the cold chamber so that it will condense or freeze. The circulating refrigerant may comprise any suitable refrigerant or refrigerant blend commonly used for air conditioning or refrigeration, such as R410A, R134A, R32, R454B, Ri234yf, R513A, R514A, R600, R290, or R466A or their components or other refrigerant types, such as ammonia and carbon dioxide. The refrigerant can further comprise oils, surfactants, thinners, thickeners, getters, inhibitors, or other corrosion and clog prevention additives.

[0158] If the system is operated below o°C, the flow of refrigerant can be reversed (as in a heat pump) such that the heat from the compressor is absorbed by the ice, causing it to melt so it can be drained.

[0159] The system can include means of cold recovery from the chilled water being drained from the cold chamber, as in FIGS. 16 and 17. The system includes a glycol chiller loop, as in the embodiment shown in FIG. 16. If the cold chamber is operating below freezing and is full, the valves on the ends of the cold chamber change to a second, closed glycol loop using the same fluid as the chiller. This second loop runs through a heat exchanger immersed in a cold recovery water bath, which does not require glycol as the liquid water is above o°C. As the second pump circulates glycol in the frozen cold chamber that has been warmed by the cold recovery to be >o°C, so the water inside the cold chamber melts. Melted water can be drained directly into the water bath, which will keep the cold recovery bath cool but above o°C.

[0160] If the cold chamber is operating above o°C, the cold, condensed water drains directly into the cold recovery bath. If the bath is kept at a small volume relative to the condensed / melted water rate, this cold water can keep the temperature of the bath relatively low. An overflow valve is incorporated to drain some water from the cold recovery bath to keep it from overflowing. The cold recovery bath has an immersion pump that moves the cold water to the MCV condenser, where it passes through a heat exchanger with the hot, mixed-phase refrigerant. The heat exchanger is a commercial, water-cooled refrigerant condenser, such as a tube-in-tube heat exchanger or similar. An air-cooled MCV condenser can only achieve a temperature at or slightly above the ambient temperature, which sets the efficiency (COP) of the refrigeration system for a given temperature in the cold chamber. The circulation of cold water cools the high-pressure mixed-phase refrigerant into liquid at a lower temperature (and higher COP) than could be achieved with air cooling alone. This increases the efficiency of the apparatus and recovers energy expended by making ice or chilled water.

[0161] The circulating water absorbs heat in the MCV condenser and is returned to the cold recovery bath, where it warms the bath and increases the melt-out speed for an ice-filled cold chamber if operating <o°C. The heat load of the MCV condenser and the heat capacity of the chilled water must be monitored to keep in balance. It may be desirable to include an air circulation fan that impinges on the water-cooled heat exchanger should the heat capacity of the cold recovery bath be insufficient to maintain a temperature below ambient (for example, in a very dry environment where only a small water volume is captured).

[0162] In another embodiment, the water from the cold chamber supplies an evaporative cooler that blows the cooled air across a conventional air-cooled MCV condenser, as shown in FIG. 17.

[0163] The refrigeration system can also have one or more evaporators connected to a single refrigeration circuit. In this design, a single compressor and condenser are used to circulate refrigerant through multiple evaporators with independent expansion valves and control. One evaporator can be directly integrated into the cold chamber or operate within the chiller to achieve the water capture described above. A second evaporator can be located in line with the feed flow, before or after the tile cassette described below, and used to sensibly cool the air entering the target space. Placing the second evaporative before the tile cassette lowers the feed air temperature, lowering its dewpoint (increasing its relative humidity), reducing its moisture-holding capacity, and increasing the water removal efficiency of the dehumidification apparatus. When sensible cooling is not needed, or precooling is not beneficial, a valve in the refrigeration circuit may be used to bypass or turn off the second evaporator. The evaporators may be configured in sequential or parallel configurations. In a sequential configuration, the refrigerant passes through the first evaporator in the cold chamber, which can achieve the coldest desired temperature for water capture while a portion of the refrigerant is partially evaporated. The refrigerant then passes through the second evaporator in the feed flow, where the refrigerant is fully evaporated, absorbing the maximum possible heat while cooling at a warmer temperature than the first evaporator, a temperature that is still suitable for comfort cooling. In a parallel configuration, the refrigerant flows from the compressor to both evaporators. The temperature at each evaporator is controlled through a combination of sensing, refrigerant flows, compressor operation, and fan speeds. In both configurations, the refrigerant returns to the compressor, repeating the process. Multiple evaporators can improve the MCV system’s performance via supercooling or subcooling of the refrigerant, improved heat extraction, improved compressor workload (full evaporation), and reduced refrigerant flow.

[0164] In another embodiment, the refrigerant used is a low-GWP hydrocarbon refrigerant with fire risk, such as R6ooa or R290 refrigerant. A further embodiment features a modular design, allowing its maximum water capture capacity to be tailored to the maximum allowable refrigerant charge in compliance with international safety standards, the specific application type, and the installation location. In this design, one or more modules are installed to achieve a target water capture capacity. In another instance, the dehumidification apparatus can also be a larger, stand-alone design that achieves a target water capture capacity by using one or more MVC systems with refrigeration circuits sized according to the maximum allowable refrigerant charge, in line with international safety standards, application type, and installation location.

[0165] An additional option for the disclosed system is to incorporate a method of refrigeration that operates by the principle of waste heat. For example, adsorption refrigeration systems utilize a thermally driven cycle to provide cooling by leveraging the physical adsorption of a refrigerant, typically water, onto a solid adsorbent material, such as silica gel or zeolite. The system operates in alternating adsorption and desorption phases, where low-grade heat e.g., hot water at 4O-5O°C) is used to regenerate the adsorbent by desorbing the refrigerant, which then condenses and releases heat to a cooling water loop. The evaporated refrigerant subsequently absorbs heat from a chilled water loop, providing cooling at temperatures typically in the range of io-i5°C. These systems are highly suitable for waste heat recovery applications due to their ability to operate at low driving temperatures and their minimal electrical energy requirements, limited to circulation pumps and control systems. With a coefficient of performance (COP) typically between 0.3 and 0.6, adsorption chillers may offer an efficient solution for utilizing waste heat to generate cooling.

[0166] G. Vacuum Pump:

[0167] Any suitable type of vacuum pump or means of generating vacuum pressure below 3,200 Pascals can be employed in the disclosed apparatus.

[0168] The cold chamber temperature is made cold enough that the permeate side of the membranes experiences a partial pressure of water below the feed side of the membranes, thus causing transport of water vapor across the membrane. During operation, the partial pressure of water inside the cold chamber will change according to the temperature.

[0169] The vacuum pump is set to maintain a total vapor pressure at the exit of the cold chamber that is moderately greater than the partial pressure of water inside the cold chamber, typically by a margin of about 200-600 Pa, as this difference sufficiently allows most water to condense or deposit in the cold chamber while only a small amount of water vapor will enter the vacuum pump along with the non-condensable gas. Operating at a smaller margin (stronger vacuum) will draw more water vapor into the vacuum pump and requires a higher volumetric capacity pump, but this does not add to total water removal. Operating at a greater margin (higher pressure) will reduce the volume requirement on the pump. This might save 30% of the pump energy, depending on the pump type and characteristics. It may allow the use of a smaller, lower-power pump, where the energy savings could be even more substantial.

[0170] The vacuum pump can be a dry scroll pump; however, the apparatus may function with any means of providing sufficient vacuum, for example, a dry screw pump, a dry claw pump, a dry roots (lobe) pump, a dry piston pump, or a single- or multi-stage diaphragm pump. An oil-free or “dry” vacuum pump is advantageous to minimize the risk of contamination of lubrication oil with carryover water vapor that might lead to increased service requirements or corrosion within the oil-lubricated vacuum pump. In some embodiments, the dry vacuum pump is outfitted with a controllable gas ballast. The gas ballast reduces the ability for water vapor to condense and accumulate within the internal cavity of the vacuum pump. The ability to close the gas ballast is beneficial in validating apparatus performance (for example, checking non-condensable or non-condensed vapor permeance, absolute base pressure, etc.). It is expected that the vacuum pump will operate with the gas ballast open during normal operation.

[0171] Further, the vacuum pump can operate with a variable frequency drive or other means of controlling the volumetric flow rate and / or total vapor pressure operating setpoint of the vacuum pump. In one embodiment, the vacuum pump body can be externally cooled by liquid (for example, cooling water flow through an external jacket integrated into or affixed to the body of the pump wherein the cold liquid may be available from the refrigeration system 5, from condensed water generated by the cold chamber 600, or in some settings from internal building or industrial systems) or by forced convection of cool air across the pump body to minimize heat losses and improve operating efficiency.

[0172] In one embodiment, the vacuum pump was an IDP-3 dry scroll pump (125W, 3 m3 / hr) from Agilent Technologies, Inc., Santa, Clara, California, USA, and, in another, an MDi Vario multistage diaphragm pump (60W, 1 m3 / hr) from VACUUBRAND GMBH + CO KG, Wertheim, Germany, or an XDS series dry scroll pump models 6i-2oi (300W, 6-20 m3 / hr) from Edwards Vacuum, Haverhill, Massachusetts, USA.

[0173] The apparatus can use multiple vacuum pumps in parallel to cover a range of pumping speed / capacity and pressures in an efficient manner and to allow redundancy and service. Dry air requires a low temperature / pressure in the cold chamber, and the vacuum is operated at low pressure and high pumping speed. In one embodiment, a multistage vacuum pump can be used for very low dew points or to reduce the compression ratio of each stage for energy efficiency. In a method of use for such a configuration, when operating at higher pressures / lower flows, only one would be used; and, as required for lower pressures or efficiency, the second pump can be activated in series with the first.

[0174] H. Cassette:

[0175] A detailed view of a cassette is shown in FIG. 18, and the tile is shown in FIG. 19. In this exemplification, each cassette holds 18 tiles 410 arrayed vertically, though in another embodiment the tiles 410 can be arrayed horizontal to reduce plastic fatigue and sag over time in use In one embodiment, each tile 410 has a central framework 411 with tab-holes 412. Plastic scaffolds 430 align the exteriors of the tab-holes of each tile 410 and reinforce the determined spacing between tiles 410. A metal rod 440 is then pushed through the tab-holes to provide vertical alignment and rigidity. The rear plastic scaffolds are screwed into the vapor headers 310 and 320; and, in combination with the metal rods, this ensures that the tiles 410 stay adequately connected to the vapor headers 310 and 320 to hold the vacuum without leaks.

[0176] Each tile 410 includes an exit port 413 with a circular groove. A nitrile rubber O-ring is placed into the groove to facilitate an air-tight connection.

[0177] The tiles are then pushed into vapor headers 310 and 320, each made of metal or plastic. To allow tighter tile packing, the odd tiles are connected into 310 and the even into 320. An alternating staggering may be achieved with a single tile frame design by placing the exit port 413 off-center and then flipping every other tile in the array. Vapor headers 310 and 320 should be sized appropriately and optimized for the targeted vapor flow conductance while minimizing obstruction of inter-tile gaps and incoming feed air flow. Vapor headers 310 and 320 may feature integrated O-rings or gaskets to add an additional sealing interface with the face of the exit port 413 of each tile 410.

[0178] O-rings 419 are provided at the exit of each vapor header 310 and 320 for airtightness. The O-rings 419 can be made from nitrile rubber, silicone rubber, ethylene propylene diene monomer (EPDM) rubber, or any other suitable elastomer.

[0179] Alternatively, the tile 410 can be welded to the vapor header using hot plate welding, ultrasonic welding, or any other suitable air-tight joining technique.

[0180] Once assembled, all of the tiles of the cassette can be qualified in one step by pumping the cassette in dry air down under vacuum and recording the steady state pressure. If the pressure is not below a threshold of 1,000 Pa or preferably 600 Pa with a leak rate of 0.2 standard cubic feet per hour (atmospheric pressure) or, advantageously, 0.04 standard cubic feet per hour (atmospheric pressure), the cassette may contain leaks and should be disqualified. A similar method can be used to assess individual tiles, as described in Section I.

[0181] In one embodiment, the cassettes are 340mm tall and hold 36 double-sided tiles, each tile with a channel depth of 2.5mm, an overall thickness of 7.5mm, and a core thickness of 2mm. The air gap between opposing faces of two adjoining tiles is 2mm.

[0182] The specific cassette and tile dimensions can be readily changed. A dense tile packing into a given enclosure is preferred because it allows the costs and size of the rest of the apparatus to be amortized over a greater surface area of membrane and thus over a greater quantity of water removed. The air gap should be wide enough for adequate airflow at the intended fan speeds and humidity levels to deliver adequate moisture flow across the tile face, with an air gap of i-iomm preferred.

[0183] Alternatively, cold water or refrigerant tubes are provided to cool vapor headers 310 and 320 or adjacent piping. This helps pre-cool the vapor before it reaches the cold chamber and improves the coefficient of performance (COP) of the refrigeration system 500. Cold liquid may be available from the refrigeration system 500, from condensed water generated by the cold chamber 600, or in some settings from internal building or industrial systems.

[0184] The apparatus can further provide means of directing room air flow through the cassette and over the membrane. In one embodiment, the cassette is open for air to flow straight from fan to exhaust, while orthogonal flow (in the direction of a neighboring cassette) is blocked or baffled. Suitable means include closing the cassette side gaps by covering the gaps with tape or a sticker or by providing solid plates along the cassette side, where the plates can be part of the cassette and / or part of enclosure 100. The means of blocking sideways airflow may or may not be part of a cassette article of sale or manufacture.

[0185] The cassette can be an article of manufacture and / or an article of sale.

[0186] A cassette or article comprising a cassette may be provided with protective foam, cushioning, a removable insert inside the cassette, an air-sealed bag or container, a box, label, instructions, desiccant, sensors, trackers, a radiofrequency identification (RFID) tag, a hologram, or other means of authentication, a package suitable for return shipping a used cassette without breakage of a structural element. The cassette or article may be treated with irradiation, biocide, or other means of sterilization. The cassette or article may be inspected by a method that comprises any combination of: measuring pressure under vacuum, imaging by visible light, imaging by X-ray or other penetrating spectra, weighing, vibrating, or measuring dimensions. The cassette or article may be recycled by a method that comprises any combination of: removing tiles, sanitation, disinfection, replacing tiles, or repackaging. I. Tile:

[0187] FIGS. 19 through 24 refer to a tile 410 and its detailed features and components. In one embodiment, the tile comprises a frame 411 with tab-holes 412 at one or more corners and an exit port 413. The frame surrounds a rectangular inset cavity filled with raised channel walls 414.

[0188] The frame 411 can be injection molded, compression molded, thermoformed, 3D printed, laminated roll-to-roll from multiple layers, or produced by any suitable means. A low-cost method is particularly advantageous given that many tiles are required for higher machine capacity. The materials and manufacturing process should be selected to maintain a flatness across the tile that is suitable to ensure effective heat sealing and adequate air gaps between faces when assembled in the cassette. A potato chip or taco shape for a nominally flat part is a common defect. In one embodiment, the variation of height across frame 411 when laid flat on a table is no more than 5%.

[0189] Referring to FIG. 20, the channel walls 414 stop short of the edge to provide a continuous gutter-like cavity 415, along which vapor from each channel can collect and pass through a slot 416 and then out through the exit port 413. The external perimeter of the exit port has a groove for holding an O-ring 419 to promote an airtight seal into the vapor header 310 or 320.

[0190] The channel walls 414 can be positioned in the tile cavity in many forms and geometries, such as parallel lines, diverging lines, narrowing or thickening lines, or vein-like patterns, to optimize water vapor transport from the underside of the membrane to the tile exit port.

[0191] Referring to FIG. 21, in one embodiment, the tile 410 is double-sided with two active faces sharing one exit port (not visible). The frame’s support ribs are primarily covered by an underlying mesh layer 420, which is a permeable support, and then an overlying layer 421 that is a water-selective membrane.

[0192] The selective membrane 421 can be an unlaminated stack of two identical thermoplastic elastomer film plies composed of a polyether-polyamide block copolymer, each measuring 15 micrometers in thickness, and the underlying support mesh 420 is a woven monofilament mesh made from polyamide fibers with an open area of over 40%.

[0193] Referring to FIGS. 23 and 24, to assemble a tile face, the support mesh 420 is first cut from a roll of material by any suitable means, such as a laser cutter, and then placed on the frame 411 and positioned within a shallow inset that overlies the tops of the support ribs. Thus, the mesh 420 lies flush across the tops of the ribs and further extends outside the region covered by ribs while lying within the shallow inset. Next, a planarizing adhesive material 422 is provided along the perimeter edges of the shallow inset and imbued into the mesh 420 at its edge. An adhesive material 423 is applied along the sealing surface of the tile 410, and the membrane 421 is placed over this adhesive. The edge is then taped over by a non-permeable metal foil 424, which is heat-sealed along its outermost few millimeters, fusing the membrane layers and adhering and sealing the membrane to the tile. The heat seal maybe a curable resin. The process is repeated on the other face. The resulting double-sided tile can withstand vacuum pressures across both faces without damaging the fragile selective film 421 and without leaking at the edges.

[0194] The selective membrane layer 421 comprises one or more layers of film. One embodiment has two layers to reduce the probability of a tile leak. The double layer is more robust because a pinhole, crack, or tear in one layer is protected by the other layer. Even if the film has some defects, the odds of two defects aligning proximately are low. Adding a third or fourth layer could reduce the odds of a leak further— however, only by a small likelihood. Three or more layers, while feasible, are a less favored embodiment because the handling of films could be more difficult if the layers are thinner, and alternatively increasing a greater total thickness of the membrane 421 could cause a reduction in vapor transmission efficiency. Therefore, if the film has relatively few defects, a double layer is advantageous.

[0195] The heat seal edges of the membrane can be further reinforced with tape or film 424 or left as is. The welding process can be heat, radio frequency, ultrasonic, or any other suitable plastic welding method. If an adhesive 422 / 423 is used, a hot melt or a dispensed single- or multiple-component adhesive can be used.

[0196] The tiles, vapor headers, and membrane can be made from polyamide-based materials, which create a monomaterial cassette that can be more easily recycled.

[0197] The relative ratio between polyether and polyamide blocks in the copolymer formulation can be varied to tune desired material properties, for example, water permeability, flexural modulus, or hardness. When selective membrane layer 421 comprises one or more layers of film, the individual films may be composed of differing chemistries to improve overall dehumidification efficiency, permeability, robustness, strength, or other properties. In one embodiment, the outer layer (air feed contact) is composed of a block copolymer or blend with higher polyether concentration to enhance the water absorption characteristics, whereas the inner layer (support contact) is composed of a block copolymer or blend with higher polyamide concentration to enhance rigidity and resistance to mechanical deformation or damage.

[0198] The selective membrane film layer of the disclosed tile can comprise any suitable material known to the field of membrane dehumidification, for example, any combination of (1) a polymer such as ethyl cellulose, cellulose acetate, poly( ethylene oxide) poly(butylene terephthalate) block copolymers, polyether-polyurethane block copolymers, polyacrylonitrile, polyamide 6, polycarbonate, polydimethylsiloxane, polyethersulfone, polyimide, poly(phenyleneoxide), polysulfone, polyvinylalcohol, polyvinylchloride, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated polyimide, sulfonated polytetrafluoroethylene (Nation); (2) a zeolite; (3) a mixed membrane, such as a nanofilter, organic-inorganic nanocomposite, or nanoparticle dispersed in film; or (4) a supported liquid membrane. These materials in any combination may be mixed with the copolymer formulation described above, substituted for the copolymer formulation provided above, or added to the membrane film layer stack as an additional ply. The resulting membrane film stack should offer selectivity above about 2000:1 (air) and permeance and mechanical properties similar or better than the thermoplastic elastomer film disclosed above.

[0199] Sealing the membrane to the tile is critical for making a vacuum-proof tile and must be done with care. If heat sealing, the temperature should be sufficient to bond the membrane to the tile or tile adhesive, but not so hot as to cause over melting or tears. A flat heat-sealing bar with a non-stick layer, such as polytetrafluoroethylene (PTFE)-coated fiberglass, is useful to avoid displacing the membrane in the heat-sealing zone and also preventing the heated membrane from sticking to the bar. A heat seal width of 4mm is advantageous, but heat seal widths from 2mm to 10mm are suitable depending on tile size, tile geometry, and available heat-sealing areas.

[0200] Polyether block amide film is highly selective for water, passing up to 200,000 times as much water as air under optimal conditions. If the cold chamber is effective in capturing water, there should be very little air for the vacuum pump to work on. In practice, the tiles and the apparatus can have leaks where air bypasses the membrane and must be pumped out, and this amount of air can be tox the amount of air passing through the membrane. In our demonstration apparatus, we have measured a leak rate of 1.2 x io-3 liters per minute per tile, averaged over the 108 tiles and apparatus (15X selection air). Any decrease in this leak rate reduces the pump energy required to operate the apparatus.

[0201] The prevalence of leaks arising from the seals between the membranes 421 and the tile frame 411 can be reduced by increasing the ratio of membrane area to total edge length. In our demonstration apparatus, one side of a single tile consists of an exposed membrane area of 0.0344 square meters with a corresponding edge length of 0.75 meters.

[0202] It is possible for the frame 411 to comprise a check valve with a specific cracking pressure in communication with the channel between orifice ports 413 and 416, such that a leak in the tile will cause the valve to close automatically and seal the tile from the rest of the vapor head.

[0203] Alternatively, the heat seal is eliminated or augmented by pressing one or more of the overlying films into a groove (not shown) with a suitable spline. In additional embodiments, additional features are provided on or in the topmost membrane layer, such as textures, dimples, open gaps in the top ply, adhered particles, or other suitable means, so as to induce greater turbulence as air flows over the surface.

[0204] The relative proportions of the tile greatly affect its performance. The tile can be arranged so that the permeate flow runs opposite to the flow of air over the surface. The tile can be longer in that flow / counter-flow direction, thus maximizing the time for air contact with the membrane. The average depth of the cavity between the membrane and the tile base surface can be shallow and not more than 3mm, and advantageously less than 2mm, thus ensuring a higher velocity of permeate flow. The outlet port or ports of the tile are sufficiently wide to avoid constriction of the flow, and the outlet port can have an interior cross-sectional area of at least 18 mm2for a surface area of 0.0696 m2of membrane.

[0205] Care is taken to ensure that the tile construction is free of leaks. The tile is inspected to ensure the leak rate while under tooPa vacuum permeate pressure is advantageously less than 0.01 standard cubic feet per hour (0.00028 std. m3 / hr) at atmospheric pressure and ideally below 0.001 standard cubic feet per hour (0.000028 std. m3 / hr) at atmospheric pressure.

[0206] In an alternate embodiment, the membrane is provided in a canister. The canister contains a wound spiral film that is a composite of a membrane layer of at least one ply plus an air-permeable spacer layer of about 3mm height. The spacer layer creates a cavity that is in gaseous communication with an outlet port. The canister can withstand vacuum pressures below 3,200Pa.

[0207] In another embodiment, the tiles are stacked. Referring to FIGS. 25 and 26, in one embodiment, the cassette may comprise a series of stacked-gasketed tiles with integrated manifolds, as shown in FIGS. 25 and 26. The tile can comprise an exit port opening 413 in the upper vapor header 310 on the short side of the frame 411 of the stacked gasket cassette with edge port 401 or in the exit port 413 of the frame 411 inside the corner of the frame 411. Vapor in the channels passes through one or more slots 416 and then go out through the exit port 413. The external perimeter of the top and bottom of the exit port has a groove for holding an O-ring or gasket 419 to promote an airtight seal. The stacking of an array of tiles creates a header conduit for permeate gas that is in gaseous communication with the cold chamber or other manifolds.

[0208] The exit port opening 413, external perimeter, groove, and O-ring or gasket are sized appropriately and optimized for the targeted vapor flow conductance while minimizing obstruction of inter-tile gaps and incoming feed airflow so as to optimize feed airflow. The promotion of an airtight seal at the exit port is facilitated by one or more guide holes 417 that accept tightening bolts to compress the stack of tiles using plates, washers, and tightening nuts. Tile alignment and spacing are further promoted by tab-holes 412 or self-registering spacer-pins 418 at one or more corners. Particularly for the frame 411 of the stacked-gasket cassette with a corner port 402, the channel walls 414 can wrap around the internal geometry of the tile, such as to increase productive use of the tile frame area and effectively guide collected water vapor to the exit port.

[0209] In another embodiment, a pre-refrigerant of any suitable cooling composition runs through the cassette, the tiles, and / or the vapor headers; or runs close to heat-conductive fins or other elements that extend to the cassette, vapor headers, or tiles. This can cause pre-cooling of water vapor and may increase the capacity of the apparatus. In some variations, the pre-refrigerant comes from the refrigeration system of the apparatus. In some variations, the pre-refrigerant is a different material but is chilled at least in part by a shared element of the refrigeration system of the apparatus. In some variations, the pre-refrigerant causes condensation of the water vapor at least in part before the water vapor exits the headers. In some variations, the tile is oriented so that condensed moisture exits the outlet port through gravity. In some variations, the headers serve as cold chambers for the purposes of this disclosure. In some variations, a majority of water vapor condenses in the various headers at temperatures above freezing, while the remaining water vapor enters a subsequent cold chamber operating at a temperature below freezing.

[0210] Referring to the embodiment in FIG. 27, a tile in vertical orientation has a lefthand membrane 415 and a mesh layer 414 adjacent a channel support 414 and is constructed in a manner similar to the top faces from FIGS. 19 through 24. The mesh may be constructed of any suitable material, such as polymer or metal. Permeate vapor flows down toward an outlet port along with condensation. Behind the face is a channel through which refrigerant flows, in this case, in a loop orthogonal to both the flow of input air and the flow of permeate (which are counter to each other). The refrigerant loop behind the frame adjacent to the membrane is not shown and can be provided in any suitable shape, such as an S-curve, manifold, or contiguous area behind the frame. On the right-hand side of FIG. 27, advantageously, a second membrane face shares the same refrigerant loop and completes a double-sided tile.

[0211] J. Other Apparatus and Building System Components:

[0212] Insulation can be applied to prevent heat loss from and between the refrigeration system 500, the cold chamber 600, and any piping or tubing between them. Providing sufficient insulation around these elements ensures the cold chamber stays sufficiently cold to condense water vapor, reduces energy loss in the energy transfer from the refrigeration system to the cold chamber, and allows the refrigeration system to be run at more optimal efficiency. The insulation can be at least1 / 2-inch thick and advantageously 3 inches or more thick, and should have a sufficiently low thermal conductivity to provide necessary insulation in the applied thickness. The insulation is advantageously vapor-tight to increase insulating effects and reduce insulation degradation. The apparatus may comprise insulation in the forms of rigid board, foam sheets, spray foam, tape, tape wrap, open-cell foam, closed-cell foam, aerogel board or powder, fiberglass composites, rockwool, or other suitable insulation materials, or an evacuated jacket around the chamber inner walls.

[0213] The apparatus design advantageously minimizes the distance of flow between the tile and the cold chamber, e.g., to 5 meters or less. The pressure, parameters, and scale of the apparatus provide that the permeate vapor moves to the cold chamber in a state of viscous and not diffusive flow.

[0214] The apparatus can include an expansion valve, Swagelok fitting, Danfoss fitting, O-ring, gasket, gate, inline valve, angle valve, ball, butterfly, conductance controllers, diaphragm, gas control or leak valve, relief valve, straight through valves, or other valves and fittings suitable for vacuum.

[0215] The apparatus can also include grease, tape, caulk, solder, pipe dope, or other edge sealants and crack fillers suitable for preserving the vacuum.

[0216] For sealants, the apparatus can include O-rings and gaskets made of nitrile rubber, silicone rubber, ethylene propylene diene monomer (EPDM) rubber, or any suitable elastomer.

[0217] For fluid flow, the apparatus can include pipes known to be impermeable under vacuum, such as copper pipes, aluminum pipes, stainless steel pipes, or plastic pipes.

[0218] The apparatus can also include a connector that allows the vacuum pump or cold chamber to be removed and attached easily for service.

[0219] The apparatus can further include a connector that allows the vapor headers and tile cassettes to be removed and attached easily for service or replacement.

[0220] For maintaining reduced pressure, the apparatus can include more than one vacuum pump and a manifold by which one, some, or all of the vacuum pumps can jointly pull from the one or more cold chambers.

[0221] For sensing operating conditions, the apparatus can include a temperature, pressure, speed, fluid level, and / or moisture sensor (i) of the ambient air, (ii) within a tile, (iii) between a tile and at least one cold chamber, (iv) within at least one cold chamber, (v) between at least one cold chamber and at least one vacuum pump, (vii) within at least one vacuum pump, or (viii) between at least one vacuum pump and at least one dry air exit point.

[0222] For controlling operation of the apparatus in carrying out a dehumidification process, the apparatus can include an instrument panel; wireless or wired data transmission equipment; and a computer-readable medium non-transitorily storing firmware, software, algorithms, artificial evidence (Al), internal and external sensors, algorithms, service call logic, predictive maintenance logic, logs, service call logic, predictive maintenance logic, etc., wherein the computer-readable medium is in communication with a processor connected with various system components for communication and / or control. The apparatus can collect, transmit, and analyze performance data. The apparatus may employ fuzzy logic control algorithms. The apparatus may receive over-the-air or manual updates. The apparatus may provide physical or virtual instructions for installation, commissioning, operation, service, and decommissioning. The apparatus maybe programmed to operate differently at different times of day, days of the week, or calendar dates. The apparatus may be programmed to change feed fan speed / flow, cold chamber temperature, vacuum pump speed / pressure, and other settings in response to weather conditions, weather forecast, utility cost, or other factors. The apparatus may notify the user of error / fault conditions or maintenance interval service requirements.

[0223] The apparatus can include an interface for receiving control instructions, issuing control instructions, and communicating sensor data or other information with other elements of a building HVAC system. The apparatus may be compatible with BACnet, LonTalk, Modbus, DALI, M-Bus, KNX, OPC UA, EnOcean, W3C, Zigbee, Clipsal C-Bus, and / or HD-PLC systems.

[0224] Means of quality testing the apparatus for vacuum readiness may include smoke tests, audible tests, camera inspection at visible and non-visible wavelengths, ultrasound, nitrogen and helium leak detection, testing pressure drop of each component under vacuum, and / or other means known in the field of vacuum leak detection. The apparatus can include putty, tapes, oils, and / or other materials useful to prevent or repair vacuum leaks. The apparatus may provide active or passive means of detecting and deactivating one or more tiles or cassettes that are leaking. The apparatus may provide control logic that is responsive to leak rates. The apparatus may provide for shutdown or service call indication in the case of insufficient vacuum or responsive to the presence of leaks.

[0225] The apparatus can include a sensor, logic, timer, or counter for knowing when to replace the cassettes and which cassette to replace.

[0226] The apparatus can further include means of air filtration, disinfection, sanitation, remediation, cooling, heating, re-humidification, odor treatment, and / or deionization.

[0227] The apparatus can further include a solar panel, generator, battery or other means of providing electricity to the apparatus.

[0228] The cold chamber or drainage system can include a moisture sensor or water level sensor. The apparatus can further include a static or removable vessel for accumulating ice or water from the cold chamber. The vessel can include a valve or connector that can be operated by hand.

[0229] The apparatus can include quality of life or safety features, such as fuses, grounds, button covers, lighting, warning alarms, emergency stop and power shutoffs, power interlock on outer panel, e-stop, safety instrumented system (SIS), and / or rubberized surfaces.

[0230] The apparatus can further include a damping mechanism, such as a cover, mat, spring, or insulation for vibration damping or noise control from the apparatus.

[0231] The apparatus can include additional techniques of sonication, microwave, desiccation, or photonic dehumidification to augment or replace the moisture removal effect of the cold chamber.

[0232] The apparatus or a method of delivering and installing the apparatus can further include one or more housings, pallets, means of leveling, and means of attachment for lifting, crane, hoist, forklift, or aerial suspension.

[0233] The apparatus can further include security means for preventing unauthorized physical or logical access, for locking out during maintenance, for physically securing the apparatus against theft or movement, or for monitoring room air for dangerous substances.

[0234] The apparatus described above can be sold standalone or bundled physically or provided as a component or subsystem of a more complicated building system. It may be used for the application purposes described above or for other purposes. It maybe used as a component of a dedicated outdoor air system (DOAS) or energy recovery ventilator. It may be used in combination with a desiccant wheel or liquid desiccant system.

[0235] A building system can operate the dehumidification apparatus described above in combination with other building systems. For example, a building system can improve efficiency by operating the dehumidification apparatus described above to remove latent heat prior to or in combination with air conditioning. This can improve air conditioner efficiency, reduce the tons of air conditioning required by the building, and eliminate the need for a reheat operation.

[0236] The apparatus can further include a fresh air intake with a motorized damper to control fresh air mixing with the conditioned interior return air.

[0237] K. Operation:

[0238] The apparatus is provided with a control system, including, e.g., as a control panel, a user interface, a processor, and a computer-readable medium non-transitorily storing software and in communication with the process. The control system is in communication with at least one electronic component of the apparatus. A method for operating the apparatus can include a start-up routine that includes diagnostics and which starts various components at different times and power levels prior to routine operating mode, possibly using timers or sensors to adjust. In one embodiment, the apparatus begins by first operating the cold chamber cooling until a certain temperature is achieved, for example, -io°C. Second, the vacuum pump is activated until a certain pressure is achieved, and there is minimal water vapor coming from the cold chamber (indicating it is dry). Third, the input fan is activated to increase the rate at which water vapor enters the cold chamber. Activation of the vacuum pump prior to the fan also causes the membrane of each tile to be drawn down onto the mesh firmly, minimizing potentially unwanted motion of the membranes in response to the fan. However, the method is not limited by this example procedure; and the components maybe controlled in any suitable order, frequency, or level; and the controller may or may not refer to any suitable sensor.

[0239] During operation, the controls can adjust the setpoint temperature of the cold source for the cold chamber and regulate the vacuum pressure as feed side conditions change (for example, 1.2 kPa regulator and 2°C cryo for 24°C / 6o% RH and 0.8 kPa and -5°C for 35% RH).

[0240] During operation, the control system can react responsively to sensors. For example, the apparatus can suspend operation if: room air falls below a dew point threshold; the cold chamber is too warm; sufficient liquid moisture is detected in the cold chamber or vacuum pump; a cold chamber is full; or the drain reservoir is full.

[0241] The control processes can also include a method of de-icing the one or more cold chambers from time to time during operation or during a shutdown stage. This method can include running a warming fluid through the cold chamber instead of a cooling fluid.

[0242] Changing the phase of incoming water vapor to liquid requires a substantial energy workload to cover the latent heat of condensation. Further, changing the phase from liquid to solid requires relatively less work and results in extremely dry air.

[0243] However, in one embodiment, when the control system senses the ambient air is much wetter than desired and enters the apparatus at a dewpoint well above the target, the control system can set the cold chamber to run slightly above freezing so that only condensation and no deposition or freezing occurs in the cold chamber. This is moderately more energy efficient, and the chamber can therefore be drained quite quickly once it reaches capacity. As the ambient air becomes drier, the control system only then lowers the cold chamber to below freezing, thus continuing to dry the room air all the way down to a target.

[0244] The control system can monitor pressure drop at various points of the vapor flow to detect a leak. The control system can monitor the pressure before and after the cold chamber to ensure correct operation and to detect a blockage of flow, for example, coming from ice blocking the channels.

[0245] The control logic can receive input from onboard and external sensors, wired or wirelessly or by manual input; measuring air or materials using, for example, hygrometers, aluminum oxide sensors, salt equilibrium sensors, electrolytic hygrometers, coulombic titration devices, infrared absorption sensors, equilibrium change detectors, resistance moisture sensors, microwave absorption sensors, RF capacitance sensors, wet and dry bulb thermometers, psychrometers, electronic capacitance and / or resistance sensors; and associated recorders, controllers, loggers, and / or databases.

[0246] The control logic can provide a way to anticipate future moisture loads (perhaps by user input, sensor analysis, or machine learning based on past demands) and to operate the apparatus in advance to help achieve a future setpoint goal. For example, control logic can anticipate a weather report or loading door opening period and may cause the apparatus to dehumidify air below a setpoint ahead of time so that the air arrives at a setpoint later. The control logic can account for goals such as staying with application humidity tolerance, minimizing energy use, minimizing cost of energy from the grid, staying within the capacity of the apparatus, accounting for capacity and timing of water collection from cold chambers.

[0247] The apparatus can further comprise a moisture detector for detecting moisture exiting the vacuum pump. The presence of moisture in the exhaust can indicate that there is a leak in the upstream vacuum portions of the apparatus or that the pump pressure is too low relative to the temperature / pressure of the cold chamber.

[0248] The apparatus can include equipment to measure the operation and lifetime of parts requiring maintenance, for example, the fan, compressor, and / or vacuum pump, and to notify a party of a status, upcoming maintenance, and / or overdue maintenance need.

[0249] The apparatus can make adjustments to trade off water capture capacity (kg / hr) and efficiency (kg / kWh) by adjusting the feed flow, cold chamber temperature, and / or vacuum pump speed / pressure. The apparatus can also take into account dehumidification load conditions and energy cost as input to optimize dehumidification and operating cycles, such as melt out.

[0250] The apparatus can also close off a portion of the cassettes under high humidity conditions if the amount of water vapor in the apparatus exceeds the capacity of the refrigeration system, to reduce feed side flow, or for another optimization. L. Exemplary Applications:

[0251] The apparatus and systems disclosed herein can be used in the following exemplary applications:

[0252] (1) Reduction in Refrigerants: While mechanical vapor can be efficient, today’s systems often rely on refrigerants that have a high greenhouse warming potential (GWP), such as hydrofluorocarbons (RFCs) with GWP thousands of times more powerful than carbon dioxide; chlorofluorocarbons (HCFCs), which are a potent greenhouse gas and contributes to ozone depletion; and trifluoromethane (HFC-23 or R-23) with a GWP at 14,800. Therefore, there is a perceived need for an alternate means of dehumidification that can reduce reliance on high GWP refrigerants.

[0253] Improved dehumidification can, in turn, expand the applicability of non-refrigerant air conditioning methods, such as direct and indirect evaporative cooling, and to further reduce the need for high-GWP refrigerants.

[0254] This disclosure provides a method of dehumidification using similar or less energy than condensate dehumidification, yet eliminating or reducing the volume of high-GWP refrigerant required. Refrigerant use can be further reduced by treating the dry air from the apparatus with an evaporative cooler.

[0255] (2) Comfort: As buildings become better insulated and as public health standards call for more fresh air, such as 30% fresh air in the building, there is a growing demand for dedicated outdoor air systems (DOAS) that can handle a wide range of outdoor air temperatures and humidities to precondition air before it enters the building. More generally, a building system that provides an intermittent dehumidification capability can reduce the load on its primary air conditioners on peak days, thus still ensuring comfort on peak days while reducing the required maximum capacity of its air conditioning equipment and thus saving money, space, and energy.

[0256] A dehumidification system that is separate from building air conditioners also allows independent control of temperature and humidity. The availability of dry air may encourage occupants to use less air conditioning.

[0257] Current building system designs may specify substantial air conditioning capacity to cover the combined latent and sensible heat load on the most extreme days of the year. Alternatively, the building owner can purchase a reduced air conditioning capacity sufficient to cover only the sensible heat load on the most extreme days of the year and use the presently disclosed system to cover the remaining latent heat load. The combined system can first dehumidify the air, and then the air conditioner can run at the target space temperature [e.g., 7O°F (21.1°C)], at a higher coefficient of performance (COP)as it cools drier air rather than 4O-55°F (4.4-12.8°C) required to achieve the same dew point. This combination of smaller systems may be less expensive to own and operate than one large air conditioning system.

[0258] When sensible cooling needs are low but the moisture load is high, an air conditioning system may not be able to achieve comfortable humidity without also overcooling the air below a comfortable temperature. For example, the air conditioning in a movie theater may be able to offset the humidity of an audience to attain dry air; however, the audience members may need to wear a sweater. Some building systems experience reheat, meaning they must run both air conditioning and heating at the same time to achieve the desired comfort conditions, even though this is energy-intensive. Reheat can be prevalent in humid conditions, or when there is a high internal moisture load, or when humidity must be closely controlled, such as in a hospital. In these situations, an isothermal dehumidification apparatus may be an energy-efficient solution over a reheat.

[0259] (3) Very Dry and Ultra-Dry Air: Some applications benefit from providing a source of dry air at a dew point below 4O°F (4.4°C). Examples include common humid places such as auditoriums, classrooms, gyms, produce aisles, submarines, and pools; preservation needs of museums, archives, metal products, and equipment; data centers; production and processing of food, plastics, and pharmaceuticals; preventing ice buildup in rinks and freezer aisles; and manufacturing of lithium batteries. The desired dewpoints can be 45°F (7.2°C), 2O°F (-6.7°C), 15°F (-9-4oC), 5°F (-15°C), -5°F (-2.6°C), and even from -3O°F (-34.4°C) to -8o°F (-62.2°C).

[0260] Because the water in the air is sparse in these drier conditions, a compressed vapor dehumidifier would need to run colder than in comfort applications and process more air than in comfort applications to remove each liter of water, and this is inefficient. Instead, the dominant industrial technology for dry and ultra-dry air relies on sorption.

[0261] This disclosure provides a method of dehumidification that uses less energy than sorption dehumidification, even for very dry and ultra-dry air.

[0262] (4) Wet or Sweating Ducts and Sanitation: A common issue for existing dehumidifiers is that they may accumulate standing water and promote bacteria and mold growth. Room air passes over these biological contaminants, which can lead to odors and infection passing back into the room air, and this is a particular concern in medical settings. In some buildings, moisture that accumulates in ducts can lead to biological growth and pose a health hazard or odor problem. Famously, Legionnaire’s disease was first identified after 182 attendees of an American Legion convention all fell ill; the bacterium was found breeding in the cooling tower of the hotel's air conditioning system, which spread through the building. Wet ducts can also lead to weakening of beams and deterioration of insulation and drywall. Duct condensation also reduces the efficiency of classic HVAC heating and cooling.

[0263] Wet ducts may occur whenever a building system routes cool air below the ambient dewpoint through ducts, leading to condensation.

[0264] In some settings, the introduction of a standard condensing dehumidifier to dry the ducts is impractical. For example, in indoor farming, the downside of mildew is so financially costly that the owner would like to maintain lower dewpoints in the ducts than a condenser-type dehumidifier can handle, and the sensible cooling system does not have excess cooling capacity to offset a highly exothermic desiccant dehumidifier. An isothermal dehumidifier is an advantageous solution. In another setting, a tall multi-floor building provides cooling by piping chilled water up to a loop that circles each floor. However, cold condensation forms on the exterior of the chilled water lines inside the walls of the building that would be energy-intensive for a condensing-type dehumidifier to eliminate. A dehumidifier that can gracefully handle lower dewpoints is advantageous.

[0265] This disclosure provides an efficient means of dehumidification at dewpoints below 4O°F (4.4°C) to reduce the risk of odor and infection entering the room air or to eliminate leaks from wet ducts.

[0266] (5) Broader Use of Evaporative Cooling: Evaporative cooling is widely adopted in arid, Arizona-like climates, such as Koppen climate classification "B," in place of mechanical vapor compression due to lower ownership cost and elimination of refrigerants. Adding a membrane dehumidifier alongside can be beneficial by allowing the building’s existing system to continue to cool effectively during humid days.

[0267] Evaporative cooler manufacturers can then sell their efficient cooling solution across a wider set of climates and geographies.

[0268] The systems and methods described herein enable more energy-efficient cooling in residential, commercial, and industrial settings by combining a membrane-based dehumidification system with an evaporative cooling system.

[0269] (6) Atmospheric Water Extraction (AWE): In settings where piped water is expensive or unavailable, it may be advantageous to extract water from the atmosphere. Rural villages, remote industrial operations, and military units may lack access to running water or a nearby water source. It is advantageous that a method of condensing water from the air be energy efficient per liter, even when the air is dry. Although sorbents can be used relatively efficiently for dry air, to extract water for drinking would require further adding a condensation step to the recharge cycle. Additionally, sorbent systems are relatively complex and bulky and hard to service remotely.

[0270] R. Swanson, proposed that membranes were a feasible path toward economic AWE while noting that the engineering design of the apparatus and the materials selected were major determinants of efficiency and would ultimately determine commercial viability.

[0271] This disclosure provides means for atmospheric water extraction in arid climates that is energy-efficient and practical.

[0272] (7) Independent Temperature and Moisture Control: Isothermal dehumidification allows for reduction of latent heat without affecting sensible heat. This can be useful to improve the overall function of integrated building systems.

[0273] In a museum, cleanroom, laboratory, food factory, or other environment where both temperature and humidity must be precisely controlled, this disclosure provides an efficient means for reducing humidity without affecting temperature.

[0274] (8) Energy savings: Although condensate dehumidifiers cool room air to cause condensation, the required workload creates significant heat. Nearly all residential dehumidifiers and many commercial and industrial dehumidifiers release heat back into the room and leave the room air warmer than it was at the start. If the room is already at a comfort temperature, the added heat creates a cooling load that can be significant. Sorption dehumidifiers create substantial heat loads because the sorption is an exothermic process. In contrast, an isothermal dehumidifier, as disclosed herein, can create less heat by comparison because only the water vapor is cooled, not the entire mass of the room air. Furthermore, the disclosed system can operate with a refrigeration system venting that vents outdoors or may even be split out and located outdoors. The present invention can accordingly offer substantial energy savings.

[0275] (9) Water recovery: Numerous industrial processes rely on water that must be replaced due to evaporative losses. In arid regions, this water usage may create tension with local stakeholders and increase operational costs. Current solutions fail to address both water scarcity and the rising demand for sustainable operations effectively. Our proposed technology enables efficient water recovery using membrane dehumidification, offering high-purity water while reducing overall costs and environmental impact. Significant loss of water is caused by evaporative cooling towers. Examples of evaporative cooling tower applications include (1) HVAC cooling for commercial and institutional buildings, such as office complexes, hospitals, and universities; (2) process cooling at industrial facilities, such as chemical plants, refineries, and food processing operations; (3) handling waste heat from turbines and generators from both conventional and nuclear power generation; (4) reduction of heat generated by the high density of servers and networking equipment at data centers; (5) cooling equipment, quenching heated materials, or regulating temperature in heated production methods, as may be found in factories for steel, aluminum, paper, plastics, or textiles; and (6) maintaining precise temperatures for refrigerated processing and cold storage for breweries, dairies, meat processing plants and other food and beverage facilities to keep products fresh, extend shelflife, and comply with food safety standards.

[0276] Further industrial processes that are sensitive to evaporate loss of water in a concentrated location include (i) enclosed washing systems used in food processing, electronics manufacturing, or other industries where hot water and steam are used to clean or rinse products; (2) boilers and steam systems; (3) controlled environment chambers in research laboratories, indoor farms, and greenhouses; (4) high-pressure process lines that lose water at connection points or hatches; (5) chemical scrubbers that lose water to evaporation; and (6) steam escape from sterilizers or autoclaves in medical settings.

[0277] The water lost in the processes and settings described above is frequently more valuable than simple tap water. Cooling towers and industrial processes often require water that has been specially purified to prevent corrosion, scaling, or biofouling and to assure minimal suspended solids and proper pH balance; and purification may reduce the required frequency of periodic cleaning, such as blowdown to remove contaminants.

[0278] It is possible to provide membrane dehumidification using the principles described herein to recover industrial process water in any suitable configuration. In some configurations, the membrane tiles are provided near the point of water evaporation. In a cooling tower, membrane tiles may be provided at the top of the tower to process water vapor that is exiting the tower. The membrane tiles may, for example, be arranged to form an angled side wall, a hemispheric dome, or a cylinder over the top of the tower.

[0279] Experimental Results:

[0280] Experiment 1: Two-Ply Membrane (FIGS. 28-31):

[0281] One layer of polyether block amide (PEBA) film has pinholes that allow water transport when the permeate is above the partial pressure of water in the feed. This transport would lead to unacceptable leak rates when many tiles are used in the apparatus. Two layers of PEBA film have pinholes in different locations that do not align, and are, therefore, blocked. The two-layer samples show a transport threshold onset exactly at the partial pressure of water in the feed and linear in partial pressure below the threshold. Plotted in FIGS. 28 and 29 are moisture vapor transmission rate (MVTR) vs. manifold (permeate) pressure. New MVTR = 2 layers, and old MVTR = 1 layer.

[0282] We also measured MVTR for 1-4 layers (in FIG. 30) and also the leak rate (in FIG. 31, standard cubic feet per hour) by checking the exhaust flow rate from the pump. Error bars indicate roughly the precision in the MVTR measurement. The MVTR drops slightly with two layers but is not ¥2 the value for one layer, likely due to surface polarization. The leak rate for configurations featuring more than one layer was below our detection threshold of 0.01 standard cubic feet per hour.

[0283] Experiment 2: Counter- Flow Orientation (FIGS.32 and 33):

[0284] We compared the MVTR effects in three orientations of permeate flow relative to feed flow:

[0285] • Co-flow: feed and permeate flow parallel in the same direction

[0286] • Crossflow: feed and permeate in perpendicular flow

[0287] • Counterflow: feed and permeate flow in parallel and in opposite directions The results show a significant increase in MVTR with counterflow due to the flow maintaining a high vapor pressure difference across the membrane for entering and leaving feed flow. Coflow minimizes the vapor pressure difference, and crossflow is in between.

[0288] Experiment 3: Close Tile Packing with Narrow Gap (FIG.34):

[0289] Permeance is MVTR divided by the difference in partial pressure of water between the feed side and permeate side of the membrane and has units kmol / kPa-m2-s. Permeance is used to normalize the membrane flow for pressure differences in different conditions.

[0290] The average permanence for the counterflow experiments in Experiment 2 is 2.77 x io6kmol / kPa-m2-s. In order to establish that the apparatus operates over a range of gap sizes (gap is the feed air space between the tiles), we did an experiment with four tiles spaced with a 2 mm gap and again a 10 mm gap under 28°C / 85% RH conditions.

[0291] For the 10 mm gap, the velocity in the slot was >3 m / s, and the measured permeance was 2.24 x 10-6 kmol / kPa-m2-s. For the 2 mm gap, the velocity was ~2.5 m / s with a corresponding permeance of 2.43 x 10-6 kmol / kPa-m2-s. The results are shown in FIG. 34 with the error bars indicating a typical range of values for the same experiments. These results show that narrowing the slot width from 10mm to 2mm for higher packing density does not prohibitively reduce the flow of moisture across the membrane at these similar feed conditions.

[0292] Experiment 4: Isothermal Dehumidification with cold chamber below o°C (FIGS.

[0293] 35-37) and above o°C (FIGS. 38-40):

[0294] We set up a scaled-up prototype of our disclosure with the following characteristics (cold chamber below o°C, FIGS.35-37): • 108 tiles with two layers of polyether block amide film on each surface. The total surface area of the membrane was ~6.i m2.

[0295] • Tiles were arranged with a 2-mm gap and with a feed velocity of ~3 m / s through the gap.

[0296] • Feed conditions were targeting 24°C / 43%RH or an equivalent partial pressure of water on the feed side of 1.26 kPa.

[0297] • The cold chamber was operated below freezing at a temperature of approximately -1.7°C as measured at the interior coils of the condenser. The graphs of FIGS. 35 and 36 show the feed conditions during the experiment. The average input was 2i.o°C / 53.8% RH (1.34 kPa), and the average output was 21.2°C / 44.8%RH (1.12 kPa). The graph shows a steady, isothermal removal of moisture from the feed stream, even as there are small variations in the feed conditions. During this experiment, 0.708 kg of water was collected in the cold chamber.

[0298] As shown in FIG. 37, the power required to collect and freeze the water in the permeate comes from four sources: the chiller providing coolant, the circulation pump, the vacuum pump, and the feed fan.

[0299] • The chiller cycled on and off as needed, as shown in the graph below. The average power during the experiment was 266 Watts.

[0300] • The circulation pump for the coolant was operated at 25 Watts.

[0301] • The vacuum pump was operated at 116 Watts.

[0302] • The feed fan was operated at 15 Watts.

[0303] The total average power was 421 Watts, and over the 122-minute experiment, 0.855 kWh of power was used.

[0304] The Moisture Removal Efficiency (MRE) was calculated as 0.708 kg / 0.855 kWh = 0.828 kg / kWh.

[0305] We set up a scaled-up prototype of our disclosure with the following characteristics (cold chamber above o°C, FIGS. 38-40):

[0306] • 108 tiles with two layers of polyether block amide film on each surface. The total surface area of the membrane was ~6.i m2.

[0307] • Tiles were arranged with a 2-mm gap with a feed velocity of about 2.6 m / s through the gap

[0308] • Feed conditions were targeting 24°C / 66%RH or an equivalent partial pressure of water on the feed side of 1.94 kPa.

[0309] • The cold chamber was operated above freezing at a temperature of approximately +4.8°C as measured at the interior coils of the condenser. The graphs of FIGS. 35, 36, 38, and 39 show the feed conditions during the experiment. The average input was 21.9^ / 76.7% RH (2.02 kPa), and the average output was 22.3°C / 63.2%RH (1.70 kPa). The graph shows a steady, isothermal removal of moisture from the feed stream, even as there are small variations in the feed conditions. During this experiment, water was removed at intervals of 10-30 minutes, and a total of 2.013 kg of water was collected from the cold chamber in 180 minutes.

[0310] The power required to collect and condense the water in the permeate comes from four sources: the chiller providing coolant, the circulation pump, the vacuum pump, and the feed fan.

[0311] • The chiller cycled on and off as needed, as shown in the graph below. The average power during the experiment was 214 Watts.

[0312] • The circulation pump for the coolant was operated at 25 Watts.

[0313] • The vacuum pump was operated at 111 Watts.

[0314] • The feed fan was operated at 13 Watts.

[0315] The total average power was 363 Watts, and over the 180-minute experiment, 1.088 kWh of power was used.

[0316] The moisture removal efficiency (MRE) was calculated as 2.013 kg / 1.088 kWh = 1.850 kg / kWh.

[0317] Parts List / Hierarchy:

[0318] 100 - enclosure

[0319] 200 - fan

[0320] 300 - vapor header

[0321] 310 - upper vapor header

[0322] 320 - lower vapor header

[0323] 400 - cassette array of tiles

[0324] 401 - stacked-gasket cassette with edge port

[0325] 402 - stacked-gasket cassette with corner port

[0326] 410 - a tile

[0327] 411 - polymer frame

[0328] 412 - the alignment loops

[0329] 413- exit port

[0330] 414 - channel walls

[0331] 415 - gutter

[0332] 416 - slot

[0333] 417 - guide holes

[0334] 418- alignment pins

[0335] 419 - o-ring

[0336] 420 - mesh

[0337] 421 - membrane 422 - planarizing adhesive

[0338] 423 - sealing adhesive

[0339] 424 - edge tape

[0340] 425 - heat seal

[0341] 426 - mesh encapsulation

[0342] 430 - plastic rails

[0343] 440 - metal rods

[0344] 500 - refrigeration system

[0345] 501 - condenser

[0346] 502 - fan

[0347] 503 - compressor

[0348] 504 - expansion valve

[0349] 505 - chiller tank

[0350] 506 - immersion pump

[0351] 507 - liquid heat exchanger

[0352] 508 - melt-out cycle with second glycol pump 509 - bath with water pump for cold recovery 510 - evaporative cooling with forced air system 600 - cold chamber

[0353] 610 - manifold

[0354] 611 - 2-1 block manifold

[0355] 612 - 2-1 Y manifold

[0356] 613 - 3-1 T manifold

[0357] 620 - connector to cold chamber

[0358] 621 - custom adapter for 611 block manifold 622 - elbow adapter

[0359] 630 - cold chamber shell

[0360] 640 - the cooling element (any type)

[0361] 641 - spiral type

[0362] 642 - fin type

[0363] 643 - tube & baffle type

[0364] 644 - shell & tube type

[0365] 650 - ports to the cold chamber shell

[0366] 651 - end cap type

[0367] 652 - T type

[0368] 660 - insulation

[0369] 700 - drain

[0370] 800 - vacuum pump 900 - supportive frame

[0371] In describing embodiments herein, specific terminology is used for the sake of clarity. For the purpose of description, specific terms are intended to at least include technical and functional equivalents that operate in a similar manner to accomplish a similar result. Additionally, in some instances where a particular embodiment includes a plurality of system elements or method steps, those elements or steps may be replaced with a single element or step. Likewise, a single element or step may be replaced with a plurality of elements or steps that serve the same purpose. Further, where parameters for various properties or other values are specified herein for embodiments, those parameters or values can be adjusted up or down by i / iooth, i / 50th, i / 20th, i / ioth, 1 / 5*, i / 3rd, 1 / 2, 2 / 3rd, 3 / 4th, 475th, 9 / ioth, 19 / 20*, 49 / 50*, 99 / 100*, etc. (or up by a factor of 1, 2, 3, 4, 5, 6, 8, 10, 20, 50, 100, etc.), or by rounded-off approximations thereof or within a range of the specified parameter up to or down to any of the variations specified above (e.g., for a specified parameter of 100 and a variation of 1 / 100*, the value of the parameter may be in a range from 0.99 to 1.01), unless otherwise specified. Further still, where methods are recited and where steps / stages are recited in a particular order— with or without sequenced prefacing characters added for ease of reference— the steps / stages are not to be interpreted as being temporally limited to the order in which they are recited unless otherwise specified or implied by the terms and phrasing.

[0372] Additional examples consistent with the present teachings are set out in the following numbered clauses:

[0373] Apparatus with membrane, cold chamber, and vacuum pump:

[0374] 1. An apparatus for dehumidification, comprising:

[0375] a first membrane that selectively permeates water vapor;

[0376] at least a first cold chamber in thermal connection with a refrigeration source; and

[0377] a vacuum pump configured to generate gas flow through the first membrane and through the first cold chamber before reaching the vacuum pump.

[0378] 2. The apparatus of clause 1, wherein the cold chamber is positioned relative to the first membrane such that the linear distance permeate vapor travels from a nearest surface of the first membrane to an entrance of the cold chamber is less than about 5 meters.

[0379] 3. The apparatus of clause 1 or 2, further comprising any combination of: a fan configured to direct gas across the first membrane, an enclosure guiding airflow over the first membrane, a heat source configured to heat the first cold chamber, or drain for the first cold chamber. 4- The apparatus of any of clauses 1-3, wherein the first membrane, the first cold chamber, and the vacuum pump are configured such that the average moisture removal efficiency when the input air is at 21°C and 54%RH is greater than 1 kg of water per kWh of energy.

[0380] 5. The apparatus of any of clauses 1-4, further comprising at least a second cold chamber in parallel gaseous communication with the first membrane and vacuum pump, wherein the apparatus is configured to pass permeate only to a subset of the cold chambers.

[0381] 6. The apparatus of any of clauses 1-4, further comprising at least a second membrane in gaseous communication with a second cold chamber, wherein the second cold chamber is configured for input air to pass adjacent the first membrane and then adjacent the second membrane.

[0382] 6.1 The apparatus of clause 6, wherein the first and second cold chambers are each in gaseous communication with a shared vacuum pump.

[0383] 6.2. A method of operating the apparatus of clause 6, wherein the internal environment of the second cold chamber is at the same or lower average temperature than the internal environment of the first cold chamber.

[0384] 7. The apparatus of any of clauses 1-6.2, further comprising a heat exchanger positioned between the first membrane and the first cold chamber in terms of gaseous flow, wherein the heat exchanger is configured to pre-cool permeate vapor between the first membrane and the first cold chamber.

[0385] 8. The apparatus of clause 7, further comprising a compressor, wherein the heat exchanger is configured to cool the compressor.

[0386] 9. The apparatus of any of clauses 1-8, where the vacuum pump is a dry scroll pump, dry screw pump, dry claw pump, dry roots (lobe) pump, dry piston pump, or single or multi-stage diaphragm pump.

[0387] 10. The apparatus of any of clauses 1-9, where the first cold chamber comprises inlet fins at two or more different angles.

[0388] 11. The apparatus of any of clauses 1-10, where the first cold chamber comprises baffles configured to increase tortuosity of the vapor path.

[0389] 12. The apparatus of any of clauses 1-11, wherein the first cold chamber includes a reservoir cavity or a drain, and wherein the cold chamber is oriented relative to gravity to cause condensed water in the cold chamber to flow into the reservoir cavity or drain.

[0390] 13. The apparatus of any of clauses 1-12, where the first cold chamber comprises a reservoir cavity with a depth greater than its aperture width. 14- The apparatus of any of clauses 1-13, further comprising a drain with two valves, configured such that cold water or ice collected in the first cold chamber can be removed while the first cold chamber remains under vacuum pressure.

[0391] 15. The apparatus of clause 14, further comprising a drain pump configured to draw water or ice from the first cold chamber through the drain.

[0392] 16. The apparatus of any of clauses 1-15, further comprising a heat source configured to heat the first cold chamber.

[0393] 17. The apparatus of clause 16, wherein the heat source comprises a reverse valve and warm refrigerant from the refrigeration source.

[0394] 18. The apparatus of any of clauses 1-17, further comprising a second cold chamber, wherein the first cold chamber is configured to operate with an internal environment at a temperature just above freezing and the second cold chamber is configured to operate with an internal environment below freezing.

[0395] 19. The apparatus of any of clauses 1-18, wherein the first cold chamber is attached to the rest of the apparatus via connectors that are configured to be removed by hand.

[0396] 20. The apparatus of any of clauses 1-19, further comprising a subassembly designed for mistake-proof assembly or field installation of the apparatus via means of asymmetry, physical guides, tabs, slots, visual guides, or fiducials.

[0397] 21. The apparatus of any of clauses 1-20, where the refrigeration source is configured to cool via mechanical vapor compression.

[0398] 21.1. The apparatus of any of clauses 1-21, further comprising a tile that includes the first membrane, wherein the first membrane is a selectively permeable membrane layer that comprises one or more plies less than 200 microns thick in total, the tile further comprising:

[0399] a frame structure including a face that includes (a) a recessed cavity occupying a majority portion of the face, excluding a perimeter area of the face; (b) one or more raised features on a surface of the recessed cavity; and (c) an edge inset on the frame face around the perimeter of the recessed cavity;

[0400] a mesh or permeable support layer in contact with (a) a ply of the one or more plies of the selectively permeable membrane layer, (b) the edge inset, and (c) a raised feature in the recessed cavity; and

[0401] an airtight cavity between the selectively permeable membrane layer and the frame that is in gaseous communication with an outlet port of the dehumidification apparatus.

[0402] 22. A method for dehumidification using the apparatus of any of clauses 1-21,

[0403] comprising: operating the fan to cause input air to pass adjacent the membrane faster than 0.5 meters per second; and

[0404] operating the refrigeration source to cause an internal environment defined in the cold chamber to drop below 15°C.

[0405] 23. A method for dehumidification, comprising:

[0406] flowing input air that includes water vapor adjacent a membrane that preferentially permeates water vapor over other gases to deliver a permeate vapor to a cold chamber;

[0407] operating a refrigeration source to cool the permeate vapor in an environment below 15°C in the cold chamber and to condense or deposit water from the permeate vapor in the cold chamber; and

[0408] operating a vacuum pump to draw gas from and to reduce pressure in the cold chamber, to remove noncondensable gas, and to enhance flow of the permeate vapor through the membrane into the cold chamber before reaching the vacuum pump.

[0409] 23.1. The method of clause 23, further comprising operating a fan to flow the input air adjacent the membrane faster than 0.5 meters per second,

[0410] 24. The method of clause 23 or 23.1, wherein condensation or deposition of the water from the permeate vapor via the cooling in the cold chamber results in less than 20% of the water that enter the cold chamber in the permeate vapor entering the vacuum pump.

[0411] 25. The method of any of clauses 23-24, wherein the water vapor that travels from the membrane to the cold chamber is in a state of viscous flow.

[0412] 26. The method of any of clauses 23-25, where the total vapor pressure in the vacuum pump is between tooPa and 8ooPa greater than the partial pressure of water in the cold chamber.

[0413] Operation and Control:

[0414] 27. The apparatus of any of clauses 1-21, further comprising at least one sensor selected from a temperature, pressure, speed, or moisture sensor, wherein the at least one sensor is configured to sense (i) the ambient air; (ii) the permeate vapor flowing from the membrane; (iii) the vapor between the membrane and the cold chamber; (iv) within the cold chamber; (v) the vapor between the cold chamber and the vacuum pump; (vii) within the vacuum pump; or (viii) between the vacuum pump and a dry air exit point from the apparatus.

[0415] 28. The apparatus of any of clauses 1-21 or 27, further comprising a controller programmed and configured to change any combination of (a) cold chamber temperature; (b) feed air fan speed; (c) vacuum pump average power; (d) refrigeration source average power; (e) a motor, valve, or other powered component; responsive to conditions, set points, or control logic.

[0416] 29. The apparatus of any of clauses 1-21, 27, or 28, further comprising any combination of a solar panel, generator, or battery configured to provide electricity to the apparatus.

[0417] 30. The apparatus of any of clauses 1-21 or 27-29, further comprising a vessel positioned and configured to accumulate ice or water from the cold chamber. 31. The apparatus of any of clauses 1-21 or 27-30, further comprising a damping mechanism configured to dampen vibration or control noise from the apparatus.

[0418] 32. The apparatus of any of clauses 1-21 or 27-31, further comprising any combination of housings, pallets, fuse boxes, means of leveling, means of attachment for lifting, crane, hoist, forklift, or aerial suspension.

[0419] 33. The apparatus of any of clauses 1-21 or 27-32, further comprising any combination of the following safety features configured to interrupt or limit power delivery to or within the apparatus: (i) a fuse box, (ii) button covers, (iii) rubberized surfaces, (iv) a power interlock on an outer panel, (v) an emergency stop mechanism, or (vi) a safety instrumented system (SIS).

[0420] 34. The apparatus of any of clauses 1-21 or 27-33, wherein the membrane is oriented such that the direction of air flow across a feed side of the membrane is opposite to the direction of permeate vapor flow from a permeate side of the membrane.

[0421] 35. The apparatus of any of clauses 1-21 or 27-34, wherein the vacuum pump is attached to the first cold chamber via a connector configured to be removed by hand.

[0422] 36. The apparatus of any of clauses 1-21 or 27-35, further comprising at least one additional vacuum pump and a manifold by which some or all of the vacuum pumps can pull from the first cold chamber in parallel.

[0423] 37. A method of controlling the apparatus of any of clauses 1-21 or 27-36, the method comprising the following steps in staggered or serial order upon startup of the apparatus: (a) cooling the cold chamber; and (b) operating the vacuum pump.

[0424] 38. The method of clause 37, wherein the apparatus further comprises a fan that directs air across the membrane, the method further comprising (c) powering the fan in staggered or serial order with steps (a) and (b).

[0425] 39. A method of controlling the apparatus of any of clauses 1-21 or 27-38, the method further comprising changing the temperature of the first cold chamber responsive to a change in a target dewpoint of output air.

[0426] 40. A method of controlling the apparatus of clause 18, the method comprising: while input air is above a threshold dewpoint, operating at least one cold chamber above o°C; and

[0427] while input air is below a threshold dewpoint, operating at least one cold chamber above o°C and at least one cold chamber below o°C.

[0428] 41. A method of controlling the apparatus of any of clauses 1-21 or 27-38, wherein the apparatus further comprises a fan configured to direct air across the membrane, while input air remains below a threshold dewpoint, further comprising reducing fan speed or reducing vacuum pump power or both while continuing to power the refrigeration source.

[0429] 42. A method of controlling the apparatus of clause 5, comprising (1) drawing a vacuum through a first cold chamber and not a second cold chamber until a first cold chamber is at capacity; then (2) drawing a vacuum through the second cold chamber.

[0430] 43. A method of operating a building system comprising

[0431] sensing input air for an air conditioning system;

[0432] determining a gap between target and actual sensible heat; determining a gap between target and actual latent heat; determining the sensible heat ratio of the air conditioning system; calculating whether excess latent heat will remain after the air conditioning system operates is sufficient to eliminate the gap between the target and actual sensible heat; and

[0433] operating the apparatus of any of clauses 1-21 or 27-38 to remove the excess latent heat.

[0434] 44. An integrated apparatus comprising the dehumidification apparatus described in any of clauses 1-21 or 27-38 in gaseous communication with an air conditioner operating by principle of mechanical vapor compression.

[0435] 45. An integrated apparatus comprising the dehumidification apparatus described in any of clauses 1-21 or 27-38 in gaseous communication with an air conditioner operating by principle of evaporative cooling.

[0436] 46. An integrated apparatus of clause 44 or 45, further comprising an air heater in gaseous communication with the apparatus or an air conditioner.

[0437] Membranes and tiles:

[0438] 47. A tile for use in a membrane-based dehumidification apparatus comprising:

[0439] a frame structure including a face that includes (a) a recessed cavity occupying a majority portion of the face, excluding a perimeter area of the face; (b) one or more raised features on a surface of the recessed cavity; and (c) an edge inset on the frame face around the perimeter of the recessed cavity; a selectively permeable membrane layer of one or more plies less than 200 microns thick in total;

[0440] a mesh or permeable support layer in contact with (a) a ply of the selectively permeable membrane layer, (b) the edge inset, and (c) a raised feature in the recessed cavity; and

[0441] an airtight cavity between the selectively permeable membrane layer and the frame that is in gaseous communication with an outlet port of the dehumidification apparatus.

[0442] 48. The tile of clause 47, wherein the leak rate of the tile under 1,000 Pa is less than 1.2 x 10’3 liters per minute per tile.

[0443] 49. The tile of clause 47 or 48, wherein the selectively permeable membrane layer comprises a hydrophilic thermoplastic elastomer layer comprising both polyether and polyamide, wherein the selectivity of the selectively permeable membrane layer for water vapor relative to air vapor is greater thani,ooo.

[0444] 50. The tile of any of clauses 47-49, wherein the selectively permeable membrane layer is an article of manufacture that exhibits any combination of the following mechanical properties: i) a Shore D hardness measured after 15 seconds below 50; ii) a tensile modulus below too MPa; iii) a stress at 50% strain of no more than 14 MPa; iv) a strain at break not exceeding 55%; v) a Charpy impact strength, at +23°C or at -3O°C, demonstrating an observable break; or vi) a Charpy notched impact strength, at +23°C, demonstrating an observable break.

[0445] 51. The tile of any of clauses 47-50, where the recessed cavity is less than 3mm average height orthogonal to the membrane layer.

[0446] 52. The tile of any of clauses 47-51, where a portion of the selectively permeable membrane layer adjacent to the recessed cavity that is occluded by mesh or raised features touching the selectively permeable membrane layer is less than 35% of the surface area of the selectively permeable membrane layer during operation.

[0447] 53. The tile of any of clauses 47-52, further comprising any combination of the following features: i) a layer of two or more plies of the selectively permeable membrane layer; ii) the outlet port comprising an O-ring; iii) the frame structure comprising a polymer; iv) the mesh or permeable support layer comprising a polymer or a metal; v) the tile being double-sided, with a selectively permeable membrane layer and a cavity on each side, wherein the cavities share a common outlet port; vi) a planarizing material in contact with the mesh or permeable support layer and the edge inset; vii) a heat-seal or curable resin adhering the selectively permeable membrane layer and the frame; viii) notches, tabs, holes, grooves, connectors, slots, guides, fiducials; ix) the edge inset having a depth approximately equal to the height of the mesh or permeable support layer; x) the raised feature being a rib or island; or xi) the outlet port being provided off- center.

[0448] 54. The tile of any of clauses 47-53, wherein the membrane layer is configured to drape over the mesh or permeable support layer at pressures less than 3,200 Pa such that the raised surface feature simultaneously contacts the selectively permeable membrane layer and the mesh or permeable support layer.

[0449] 55. The tile of any of clauses 47-54, wherein the selectively permeable membrane layer is configured to drape over the mesh or permeable support layer at pressures less than 3,200 Pa, and wherein an exterior ply of the membrane layer has a surface area at pressures less than 3,200 Pa that is at least 3% higher than its surface area at ambient pressure.

[0450] 56. The tile of any of clauses 47-55, wherein the minimum interior cross-section area of the outlet port is at least 18 square millimeters in area.

[0451] 57. The tile of any of clauses 47-56, wherein the frame structure is formed of a polymer that can be injection molded.

[0452] 58. The tile of any of clauses 47-57, wherein at least 60% of the mass of the tile is recycled or recyclable polymers.

[0453] 59. A method of manufacturing the tile of any of clauses 47-58, the method further comprising spot heating the selectively permeable membrane layer or a subassembly comprising the selectively permeable membrane layer to adhere to the frame structure.

[0454] 60. A method of manufacturing the tile of any of clauses 47-58, the method further comprising preventing the selectively permeable membrane layer from bulging out when moist that is any combination of one or more of the following: (i) spot heating, laminating, bonding, or gluing the selectively permeable membrane layer to the mesh layer at one or more locations other than the edges; (ii) tensioning the selectively permeable membrane layer; or (iii) providing a mesh or other open physical constraint over the selectively permeable membrane layer that limits bulging while occluding less than 20% of active surface of the selectively permeable membrane layer.

[0455] 61. The method of clause 60, wherein the physical constraint includes overlaying tape, a second mesh, or an air-permeable porous spacer compressed between the selectively permeable membrane layers of stacked or adjacent tiles.

[0456] 62. An apparatus for membrane dehumidification comprising the tile of any of clauses 47-58, wherein the tile is oriented so the direction of gas flow across a feed side of the membrane layer is opposite to a direction of permeate vapor flow from a permeate side of the membrane layer toward the outlet port. Cassette:

[0457] 63. A cassette, comprising at least two of the tiles of any of clauses 47-58.

[0458] 64. The cassette of clause 63, wherein the cassette further comprises a header that connects at least two tile outlet ports.

[0459] 65. The cassette of clause 63 or 64, wherein the cassette comprises two headers and an array of the tiles with asymmetric outlet port locations.

[0460] 66. The cassette of any of clauses 63-65, wherein the distance separating the faces of two adjacent tiles is between about 1 and 10mm.

[0461] 67. An article of sale, comprising the cassette of any of clauses 63-66 and at least one element selected from: protective cushioning between the cassette and a box; a removable insert inside the cassette, an air-sealed bag containing the cassette, desiccant, sensors, trackers, RFID tag, hologram or other means of authentication, a package suitable for return shipping a used cassette without breakage of a structural element.

[0462] 68. The article of clause 67, wherein at least one selected element has been sterilized.

[0463] 69. A method of inspecting a tile or cassette of any of the preceding clauses, wherein the method comprises any combination of: measuring pressure under vacuum, imaging by visible light, imaging by X-ray or other penetrating spectra; weighing, vibrating, measuring dimension.

[0464] 70. A method of recycling a cassette of any of the preceding clauses that comprises any combination of: removing tiles, sanitizing tiles, disinfecting tiles, replacing tiles, or repackaging tiles.

[0465] Alternate cassette forms:

[0466] 71. A canister for use in a membrane dehumidification apparatus comprising:

[0467] a film comprising (i) a membrane layer of at least one ply and (ii) an air- permeable spacer layer of about 3 mm in height, wherein the film is wound in a spiral;

[0468] a cavity in gaseous communication with at least one open space in the air- permeable spacer layer; and

[0469] an outlet port in gaseous communication with the cavity,

[0470] wherein the air-permeable spacer layer provides sufficient mechanical strength that a vacuum pressure below 3200 Pa can be drawn on the outlet port without collapsing a majority of the cavity.

[0471] 72. The tile of any of clauses 47-58, wherein the outlet port defines an opening inside the frame structure and a gasket or O-ring such that stacking an array of the tiles creates a header conduit for permeate gas passing through the selectively permeable membrane layer. 73- The tile of any of clauses 47-58, further comprising or adjacent to a heat sink, thermal conductor, or channel for refrigerant.

[0472] Combined apparatus, tile, and orientation:

[0473] 74. The apparatus of any of clauses 1-21 or 27-38, further comprising the tile of any of clauses 47-58, wherein the tile is oriented and the apparatus is configured so the direction of gas flow across a feed side of the membrane layer is opposite to a direction of permeate vapor flow from a permeate side of the membrane layer toward the outlet port.

[0474] 75. The apparatus of clause 74, further comprising any combination of a sensor, a logic processor, timer, counter, or control software configured to determine and indicate when to replace a cassette of clause 63.

[0475] 76. The apparatus of any of clauses 1-21 or 27-38, further comprising a device to detect and deactivate the tile of clause 60 or a cassette of clause 77 that is leaking above a threshold value, the device comprising any combination of sensor, actuator, solenoid, or check valve.

[0476] While this invention has been shown and described with references to particular embodiments thereof, those skilled in the art will understand that various substitutions and alterations in form and details may be made therein without departing from the scope of the invention. Further still, other aspects, functions, and advantages are also within the scope of the invention; and all embodiments of the invention need not necessarily achieve all of the advantages or possess all of the characteristics described above. Additionally, steps, elements, and features discussed herein in connection with one embodiment can likewise be used in conjunction with other embodiments. The contents of references, including reference texts, journal articles, patents, patent applications, etc., cited throughout the text are hereby incorporated by reference in their entirety for all purposes; and all appropriate combinations of embodiments, features, characterizations, and methods from these references and the present disclosure may be included in embodiments of this invention. Still further, the components and steps identified in the Background section are integral to this disclosure and can be used in conjunction with or substituted for components and steps described elsewhere in the disclosure within the scope of the invention.

Claims

CLAIMSWhat is claimed is:

1. An apparatus for dehumidification, comprising:a first membrane that selectively permeates water vapor;at least a first cold chamber in thermal connection with a refrigeration source; anda vacuum pump configured to generate gas flow through the first membrane and through the first cold chamber before reaching the vacuum pump.

2. The apparatus of claim 1, where the cold chamber is positioned relative to the first membrane such that the linear distance permeate vapor travels from a nearest surface of the first membrane to an entrance of the cold chamber is less than about 5 meters.

3. The apparatus of claim 1, wherein the first membrane, the first cold chamber, and the vacuum pump are configured such that the average moisture removal efficiency when input air is at 21°C and 54%RH is greater than 1 kg of water per kWh of energy.

4. The apparatus of claim 1, further comprising at least a second cold chamber in parallel gaseous communication with the first membrane and vacuum pump, wherein the apparatus is configured to pass permeate only to a subset of the cold chambers.

5. The apparatus of claim 1, further comprising at least a second membrane in gaseous communication with a second cold chamber, wherein the second cold chamber is configured for input air to pass adjacent the first membrane and then adjacent the second membrane.

6. The apparatus of claim 1, further comprising a heat exchanger positioned between the first membrane and the first cold chamber in terms of gaseous flow, wherein the heat exchanger is configured to pre-cool permeate vapor between the first membrane and the first cold chamber.

7. The apparatus of claim 6, further comprising a compressor, wherein the heat exchanger is configured to cool the compressor.

8. The apparatus of claim 1, where the first cold chamber comprises inlet fins at two or more different angles.

9. The apparatus of claim 1, where the first cold chamber comprises baffles configured to increase vapor-path tortuosity.

10. The apparatus of claim 1, further comprising a heat source configured to heat the first cold chamber, wherein the heat source comprises a reverse valve and warm refrigerant from the refrigeration source.

11. The apparatus of claim 1, further comprising a second cold chamber, wherein the first cold chamber is configured to operate with an internal environment at a temperature from about o°C to 15°C, and wherein the second cold chamber is configured to operate with an internal environment from about -2O°C to o°C.

12. The apparatus of claim 1, wherein the first cold chamber is attached to the rest of the apparatus via connectors that are configured to be removed by hand.

13. The apparatus of claim 1, further comprising a subassembly designed for mistake-proof assembly or field installation of the apparatus via means of asymmetry, physical guides, tabs, slots, visual guides, or fiducials.

14. The apparatus of claim 1, where the refrigeration source is configured to cool via mechanical vapor compression.

15. The apparatus of claim 1, further comprising a tile that includes the first membrane, wherein the first membrane is a selectively permeable membrane layer that comprises one or more plies less than 200 microns thick in total, the tile further comprising:a frame structure including a face that includes (a) a recessed cavity occupying a majority portion of the face, excluding a perimeter area of the face; (b) one or more raised features on a surface of the recessed cavity; and (c) an edge inset on the frame face around the perimeter of the recessed cavity;a mesh or permeable support layer in contact with (a) a ply of the one or more plies of the selectively permeable membrane layer, (b) the edge inset, and (c) a raised feature in the recessed cavity; andan airtight cavity between the selectively permeable membrane layer and the frame that is in gaseous communication with an outlet port of the dehumidification apparatus.

16. A method for dehumidification, comprising:flowing input air that includes water vapor adjacent to a membrane that preferentially permeates water vapor over other gases to deliver a permeate vapor to a cold chamber;operating a refrigeration source to cool the permeate vapor in an environment below 15°C in the cold chamber and to condense or deposit water from the permeate vapor in the cold chamber; andoperating a vacuum pump to draw gas from and to reduce pressure in the cold chamber, to remove noncondensable gas, and to enhance flow of the permeate vapor through the membrane into the cold chamber before reaching the vacuum pump.

17. The method of claim 16, further comprising operating a fan to flow the input air adjacent the membrane faster than 0.5 meters per second.

18. The method of claim 16, wherein condensation or deposition of the water from the permeate vapor via cooling in the cold chamber results in less than 20% of the water that enters the cold chamber in the permeate vapor entering the vacuum pump.

19. The method of claim 16, wherein the water vapor that travels from the membrane to the cold chamber is in a state of viscous flow.

20. The method of claim 16, where the total vapor pressure in the vacuum pump is between tooPa and 8ooPa greater than the partial pressure of water in the cold chamber.

21. The method of claim 16, wherein the membrane is oriented such that the direction of air flow across a feed side of the membrane is opposite to the direction of permeate vapor flow from a permeate side of the membrane.

22. The method of claim 16, further comprising changing the temperature of the cold chamber responsive to a change in a target dewpoint of output air.

23. The method of claim 16, further comprising operating a fan to direct air across the membrane, while input air remains below a threshold dewpoint, further comprising reducing fan speed or reducing vacuum pump power or both while continuing to power the refrigeration source.

24. A tile for use in a membrane-based dehumidification apparatus comprising: a frame structure including a face that includes (a) a recessed cavity occupying a majority portion of the face, excluding a perimeter area of the face; (b) one or more raised features on a surface of the recessed cavity; and (c) an edge inset on the frame face around the perimeter of the recessed cavity;a selectively permeable membrane layer of one or more plies less than 200 microns thick in total;a mesh or permeable support layer in contact with (a) a ply of the selectively permeable membrane layer, (b) the edge inset, and (c) a raised feature in the recessed cavity; andan airtight cavity between the selectively permeable membrane layer and the frame that is in gaseous communication with an outlet port of the dehumidification apparatus.

25. The tile of claim 24, wherein the leak rate of the tile under 1,000 Pa is less than 1.2 x 10-3 liters per minute per tile.

26. The tile of claim 24, wherein the selectively permeable membrane layer comprises a hydrophilic thermoplastic elastomer layer comprising both polyether and polyamide, wherein the selectivity of the selectively permeable membrane layer for water vapor relative to air vapor is greater than 1,000.

27. The tile of claim 24, where the recessed cavity is less than 3mm average height orthogonal to the membrane layer.

28. The tile of claim 24, where a portion of the selectively permeable membrane layer adjacent to the recessed cavity that is occluded by mesh or raised features touching the selectively permeable membrane layer is less than 35% of the surface area of the selectively permeable membrane layer during operation.

29. The tile of claim 24, further comprising any combination of the following features: i) a layer of two or more plies of the selectively permeable membrane layer; ii) the outlet port comprising an O-ring; iii) the frame structure comprising a polymer; iv) the mesh or permeable support layer comprising a polymer or a metal; v) the tile being double-sided, with a selectively permeable membrane layer and a cavity on each side, wherein the cavities share a common outlet port; vi) a planarizing material in contact with the mesh or permeable support layer and the edge inset; vii) a heat-seal or curable resin adhering the selectively permeable membrane layer and the frame; viii) notches, tabs, holes, grooves,connectors, slots, guides, fiducials; ix) the edge inset having a depth approximately equal to the height of the mesh or permeable support layer; x) the raised feature being a rib or island; or xi) the outlet port being provided off- center.

30. The tile of claim 24, wherein the membrane layer is configured to drape over the mesh or permeable support layer at pressures less than 3,200 Pa such that the raised surface feature simultaneously contacts the selectively permeable membrane layer and the mesh or permeable support layer.

31. The tile of claim 24, wherein the selectively permeable membrane layer is configured to drape over the mesh or permeable support layer at pressures less than 3,200 Pa, and wherein an exterior ply of the membrane layer has a surface area at pressures less than 3,200 Pa that is at least 3% greater than its surface area at ambient pressure.

32. The tile of claim 24, wherein the frame structure is formed of a polymer that can be injection molded.

33. A cassette, comprising at least two of the tiles of claim 24.

34. The cassette of claim 33, wherein the distance separating faces of two adjacent tiles is between about 1 and 10mm.6o

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