Abstract:
Systems and methods are disclosed for water collection from atmospheric moisture in large quantities in uncontrolled outdoor environments where the temperature may be cold and humidity levels low. To extract water from air when the dew point is low, a heat exchanger cools to a point where water vapor is deposited on its surface as ice. The heat exchanger then cycles through a heating phase to melt the ice and generate liquid water. The accumulation of frost is advantageous. Frost accumulation enables water collection when the dew point is low. Disclosed variations enhance efficiency and environmental tolerance.

Description:
FIELD OF ART 
     The disclosed device relates to water production and purification, and more particularly to the generation of potable water from atmospheric humidity. 
     BACKGROUND 
     The need for water is universal. In many places, reliable sources of clean water are insufficient to meet human needs. The lack of clean water may be due to infrastructure damage, such as the damage to water supply systems caused by an earthquake or flood. The lack of clean water may also be due to migration, such as population displacements into refugee camps during a war. 
     It is difficult to provide clean water quickly and efficiently. Water is heavy. It can be expensive to transport water to the areas that need it. Digging wells and building water treatment facilities requires time, energy and equipment. 
     The prior art discloses methods and systems for water collection from atmospheric moisture in small quantities in controlled indoor environments where the temperature is warm and humidity levels are moderate or high. 
     There is a need for a system that can reliably and quickly provide clean water. The present systems and methods enable the extraction of liquid water from humidity when the dew point is low. 
     SUMMARY 
     The present application discloses systems and methods for water collection from atmospheric moisture in large quantities in uncontrolled outdoor environments where the temperature may be cold and humidity levels may be low. 
     Technical Problem 
     There are several challenges related to the production and purification of potable water from atmospheric moisture or surface water sources. It is difficult to provide a system that is mobile, easy to set up, modular, capable of functioning without infrastructure-provided water or power, sanitary, designed for multicultural use in its control interface, maintainable with minimal technical skills needed for routine maintenance, rugged enough for use outside when temperatures fluctuate, and capable of producing water from humidity when the dew point is low. 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools, and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
     Technical Solution 
     Several technical solutions are disclosed to address the challenges relating to environmental tolerance, energy efficiency, ease of operation, transport considerations, and operation at low temperature and humidity levels. 
     The production of potable water for humans and livestock is often needed in outdoor areas. Environmental tolerance is important because the system may be installed outdoors or in facilities without environmental controls. Embodiments of the system are designed to withstand freezing temperatures and function in near-freezing cold. One the technical solutions includes the use of metal filter housings that resist cracking under the pressure exerted by water expansion when the water freezes or heats up. 
     Embodiments of the system can function outdoors where temperature fluctuations are common. To extract water from air when the dew point is low, the evaporator cools to a point where water vapor is deposited on its surface as ice. The evaporator then cycles through a heating phase to melt the ice and generate liquid water. The accumulation of frost is good. Frost accumulation enables water collection when the dew point is low. The dew point is often low when relative humidity levels are low. Relative humidity is the actual amount of humidity relative to the maximum amount of humidity possible at that same temperature and pressure. The dew point is also often low when air temperatures are low because cooler air does not hold as much moisture. Cycling through frosting and melting allows the system to collect water from ambient air with relative efficiency in conditions that would otherwise be adverse to water production through dehumidification. 
     Surface water may be contaminated with microbes, heavy metals, chemical byproducts of agriculture, and other contaminants. Through filtration and irradiation these contaminants may be neutralized or removed. Some disclosed embodiments use reverse osmosis, carbon filters, zeolite filters, ozone, and ultraviolet light to produce potable water for consumption. 
     Embodiments of the system are designed to be resistant to pest animals and insects. Screens cover air vents. Conduit and panels cover wires. Interior spaces are accessible to human inspection. 
     Energy efficiency is important because the system requires power to function. Power supplies may be limited. In one embodiment, a diesel generator is included. In another embodiment, solar panels are included. In another embodiment, the system uses a wind turbine for energy. In another embodiment power is provided by conventional electrical utility infrastructure. To conserve energy, a variable compressor is used. To further enhance efficiency, the fans are configured to optimize the air flow through the system. Sanitization may be accomplished with ozone, ultraviolet light, chemical addition, heat, microfiltration or combinations thereof. Gravity may assist the flow of liquid water through the filters. Pump activation can be controlled by the programmable logic controller (PLC). The PLC can regulate processes that require power. The PLC may be programmed to optimize energy consumption or to shift energy use from times of the day associated with peak energy consumption to off-peak times. Power optimizing or production optimizing settings may be preprogrammed. 
     The system may incorporate many features to facilitate use. The human-machine interface may offer multiple languages, allowing a user to select a language, it may also incorporate pictographic icons and touch-screen control. The PLC is designed for multiple inputs and outputs. The PLC is tolerant of extended temperature ranges, immune to electrical noise, and resistant to vibration and impact. Parts of the system requiring periodic replacement or manual adjustment are positioned accessibly. 
     To facilitate transport, embodiments of the water system are configured to fit into a standard shipping container or onto a standard truck bed. In one embodiment an integrated bottling system is disclosed to facilitate distribution of the water produced. 
     Advantageous Effects 
     The combination of features disclosed has an advantageous effect of providing a potable water generating system that can be transported, set up, and used with relative ease and with minimal infrastructure in a broad range of environments. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a simplified air flow and water path through the system. 
         FIG. 2  shows a simplified refrigerant flow path in a frosting configuration. 
         FIG. 3  shows a simplified refrigerant flow path in a defrosting configuration. 
         FIG. 4  shows an alternate simplified refrigerant flow path in a system where the functionality of the condenser and evaporator may be reversed. 
         FIG. 5  shows an alternate simplified refrigerant flow path in a system where the functionality of the condenser and evaporator may be reversed. 
         FIG. 6  shows the simplified system with additional sensors and control modules. 
         FIG. 7  shows an embodiment of the system with power generation, filtration, water storage, and bottling features incorporated. 
         FIG. 8  is a flow chart showing a prior art method. 
         FIG. 9  is a flow chart showing one of the disclosed methods. 
         FIG. 10  is a flow chart showing an alternate embodiment of the disclosed methods. 
         FIG. 11  depicts a standard graph of the grains of water vapor per cubic foot held by air when saturated at several temperatures. 
         FIG. 12  is a prior art chart showing the relationship between dew point, temperature and relative humidity. 
     
    
    
     Before explaining the disclosed embodiments of the disclosed device in detail, it is to be understood that the device is not limited in its application to the details of the particular arrangements shown, since the device is capable of other embodiments. It is to be understood that the embodiments and figures disclosed herein are intended to be illustrative rather than limiting. Also, the terminology used herein is for the purpose of description and not of limitation. 
     DETAILED DESCRIPTION 
     The following description is provided to enable any person skilled in the art to make and use the disclosed apparatus. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present apparatus have been defined herein specifically to provide for a system and method for the generation of potable water from atmospheric humidity. 
       FIG. 1  presents a simplified version of an embodiment showing air and water flow paths. Inflow air  101  enters through a particulate filter  102 . It then passes by a condenser  103 . The condenser  103  is hotter than the inflow air  101  and the air provides a cooling function on working fluid contained in the condenser  103 . The air then passes the evaporator  104  which is cold. Condensate or frost forms on the evaporator  104 . The fan unit  105  then blows the dehumidified air  107  out the air exit  106 . 
     Unprocessed water  108  is collected in the water collector  109  and directed to the collection vessel  110 . The collected water pump  111  pushes water through a first filter  112  and a second filter  113 . Additional filters may be used to achieve the desired result. Many types of filters provide beneficial effect. For example: reverse osmosis filers, activated carbon filters, resin filters, ion exchange filters, adsorption filters, ultrafiltration membrane filters, microporous ceramic filters, zeolite filters, diatomaceous earth filters, and particulate filters. 
     After filtration, water enters the holding vessel  114 . In the holding vessel  114 , water safety may be facilitated by a sanitizing ultra violet (uv) device  115 , an ozone device  117 , or by the addition of chemicals such as chlorine compounds. Water may be drawn from the holding vessel  114  through a purified water outlet valve  116 . If it is desired to use the system for filtration of available liquid water, the liquid water may be added to the system through an optional grey-water inlet  118 . 
       FIGS. 2 and 3  show one embodiment in two configurations.  FIG. 2  shows a simplified refrigerant flow path in a frosting configuration, while  FIG. 3  shows a defrosting configuration. Working fluid, or refrigerant, is shown traveling in a loop. Thick lines with arrows show the flow path. 
     In  FIG. 2 , refrigerant flows through the evaporator  104 , through the compressor  201 , through the condenser  103 , through an expansion device  202 , and back through the evaporator  104 . Fluid passing through the expansion device  202  expands as pressure is reduced. This expansion is generally accompanied by a phase change; the refrigerant goes from a liquid to a gas and it absorbs heat, cooling the exterior of the evaporator  104 . In  FIG. 2  the bypass valve  203  is closed and there is no flow through the bypass shunt  204 . 
     In  FIG. 3 , the bypass valve  203  is open and refrigerant from the compressor  201  flows through the bypass shunt  204 . Fluid exits the compressor  201  at a high temperature. The hot fluid passes through the bypass valve  203  and bypass shunt  204  relatively unchanged in pressure and temperature. Thus, it is hot when it enters the evaporator  104  and it melts ice that may have formed on the evaporator  104 . 
       FIGS. 4 and 5  show an alternate simplified refrigerant flow path in a system where the functionality of the condenser and evaporator may be reversed. In this embodiment there is a flow-directing valve  401  shown here as a four-way valve. The expansion device  202  may incorporate one or more capillaries  402 . The flow can be reversed so that the evaporator  104  and condenser  103  can switch function. The flow-directing valve  401  changes the flow path to do this. The flow-directing valve  401 , shown here as a four-way valve, connects the compressor flow circuit  403  to the heat exchangers selectively determining the path of the working fluid. 
       FIG. 6  shows the simplified system of  FIG. 1  with additional sensors and control modules. These include: a frost sensor  601 , an intake humidity sensor  602 , an intake temperature sensor  603 , a collection vessel level sensor  604 , a holding vessel level sensor  605 , and a regulator or controller  606 . Various controllers and/or regulators may take input from the optional sensors. The various controllers and regulators can control aspects of the system such as the evaporator temperature, the valves, the expansion device, the compressor speed, the fans  105 , the collected water pump  111 , and other aspects of the system as discussed hereinafter. 
       FIG. 7  shows an embodiment of the system with power generation, filtration, water storage, and bottling features incorporated within the bounds of a standard 20-foot freight container. The integrated system includes at least one atmospheric water unit  701 , diesel generator  702 , shipping container boundary wall  703  with apertures for air flow  711 , and at least one door  707 . The integrated unit may also comprise a water bottling, filling, and capping unit  704  having an input conveyor  705  and a bottle output conveyor  706 . The fuel storage  708  is segregated from the airflow intake areas by one or more boundary walls  703  to avoid contamination by fumes. There is also an electrical control  709  and a maintenance passage  710 . 
       FIG. 8  shows a prior art method for operating prior art atmospheric water generators. Analogous systems are known in the art of similar systems in the field of refrigeration and air conditioning. In these prior art systems, frost on the evaporator is not desired because frost may obstruct air flow. The prior art method shown in  FIG. 8  begins with the prior art initiation step  801 , a first input step is in the form of a frost sensor signal  802 , a decision point of frost detection  803  follows. If frost is not detected the refrigeration continues or repeats. If frost is detected, the defrost cycle  804  is initiated. 
       FIG. 9  shows one of the disclosed methods where frost is desired. It starts with a frost cycle initiation step  901 , a first input step is in the form of a frost sensor signal  802 , a decision point of frost detection  803  follows. If frost is not detected the cooling cycle continues or repeats. If frost is detected, the frost accumulation timer  902  starts, followed by the melt cycle  903 . Melted frost is collected as water. The method steps may be repeated as many times as needed to collect the desired quantity of water. 
     It is contemplated that frost cycle initiation step  901  comprises starting of compressor  201  and allowing frost to form on evaporator  104 . Melt cycle  903  comprises stopping of compressor  201  after frost has accumulated for a predetermined amount of time, allowing a predetermined amount of time to pass is allowed to pass, activating bypass valve  203  thereby switching condenser  103  and evaporator  104 , restarting compressor  201  and allowing defrosting to occur. Melt cycle  903  further comprises stopping compressor  201 , allowing a predetermined amount of time to pass and deactivating bypass valve  203  so the system may repeat the process, namely commencing step  901 . 
       FIG. 10  depicts an alternate method of extracting liquid water from humidity by means of frosting. It is contemplated that melt cycle  903   b  comprises the operation of the system without the stopping and/or restarting of compressor  201 . Similar to the process shown in  FIG. 9 , frost cycle initiation step  901  comprises starting of compressor  201  and allowing frost to form on evaporator  104 . In this example bypass valve  203   b  is a one-way valve which can be automatically activated after frost has accumulated for a predetermined amount of time. Here, switching of condenser  103  and evaporator  104  occurs without having to turn the compressor on or off. Switching of condenser  103  and evaporator  104  occurs by activating and deactivating bypass valve  203   b . In melt cycle  903   b  defrosting is allowed to occur. Deactivating bypass valve  203   b  causes the valve to close, thereby switching condenser  103  and evaporator  104  to allow frosting to occur. This embodiment saves time and the enables the system to increase water output. 
     It is contemplated that bypass valve  203 ,  203   b  serves to balance the refrigerant pressure as quickly as possible during the refrigerant exchange from condenser  103  and evaporator  104 . Bypass valve  203   b  helps to prevent potential damage to compressor  103  which in some embodiments must undergo a starting process, a stopping process and a restarting process. 
     Generally referring to  FIGS. 1-10 : Air flows into the system. It is dehumidified and then exits the system. In many embodiments, the air flows through a particulate filter, then past a condenser, then past an evaporator, then through the fan area, and finally exiting the system. 
     A compressor circulates refrigerant or working fluid through a condenser, through an expansion device such as an expansion valve or an adjustable capillary valve, and then through an evaporator, often configured as a finned evaporator coil. Expansion of the working fluid as it passes through the expansion valve into the evaporator results in a state change of the working fluid from a liquid to a gas and the working fluid absorbs heat, cooling the evaporator. 
     Air passing by the evaporator is cooled. This lowers the air temperature to or below its dew point, causing water to condense. If the evaporator temperature is sufficiently low, the air drops to or below the frost point, causing deposition of frost on the exterior surface of the evaporator. A fan pushes filtered air over the evaporator. Water is collected from the condensate that drips off of the evaporator or by melting the frost on the evaporator and collecting the melt-water. The resulting water is then passed into a holding tank and is further purified, filtered, and treated to produce potable water. 
     In many embodiments, the air flows first past the condenser coils and then past the evaporator coils. The condenser is hot. The air flow helps to cool the working fluid inside the condenser. Condenser fins also help dissipate heat. The air flowing past the evaporator is cooled. Evaporator fins provide a large surface area for condensation and frost deposition. In one embodiment, there are several capillary tubes directing refrigerant to multiple evaporator segments help to make the gas expand in the evaporator and make it cool more efficiently. Compound evaporators and condensers may be used, and fins on both aid in heat transfer. 
     The capillary and expansion valve function as expansion devices and can be combined. Both adjust the refrigerant pressure. One important difference is that the capillary capacity for adjusting the pressure is static and the expansion valve capacity is dynamic. Once a capillary is brazed in the system, its capacity is fixed by its length and inside diameter, those factors cannot be adjusted during operation. The expansion valve may have a variable aperture or it may be opened to a single fixed diameter in a series of pulses. Using a single open diameter, the valve is controlled by pulses in a similar principle as controlling a step motor. The expansion valve controls the evaporator temperature according to the detected environmental temperature and humidity, through the PLC program. The PLC sends a pulse to the expansion valve, with more pulse, the valve opens more; less pulse and the expansion valve opens less. 
     When the evaporator is very cold, frost accumulates on the exterior surface and fins of the evaporator. 
     The flow path of working fluid is changed to defrost the evaporator. The flow path may have a bypass directly from the condenser routing hot working fluid through the evaporator. Alternately, the flow path through the system may be reversed. The frost is melted from the fins and then the cycle is restated. The evaporator is again cooled until frost forms. The cooling cycle continues so that more frost accumulates on the evaporator fins. The rate of frost accumulation may slow as the frost obstructs airflow. The valves then redirect warm working fluid through the evaporator and frost is melted and then the cooling cycle starts again. 
     To efficiently collect water from the humidity of air, the evaporator surface temperature must be about 2° C. to about 3° C. lower than the dew point or frost point. Dew point is related to environment temperature, humidity, and pressure. Generally, when the environment temperature is lower than about 15° C. and the humidity is lower than about 40%, the dew point is near, or lower than about 0° C. When the dew point or frost point nears about 0° C., the evaporator surface temperature is reduced to near or below about 0° C. Then, frost, rather than condensate forms on the evaporator. In many embodiments, one or more sensors are used to measure environment temperature and humidity. The approximate frost point or dew point is calculated and the evaporator temperature is adjusted accordingly to run in either the condensate mode or in the frost and defrost cycle mode. 
     In some embodiments, a sensor mounted on the evaporator measures its surface temperature. If the temperature is lower than about −2° C., the system will start defrosting automatically after a set period of time. The frost time may be set at approximately 30 minutes. At which point the frost thickness is thick enough and the system will start defrosting, melting the frost and generating water. In some embodiments the frost period may be shortened to as short as about 5 minutes in response to higher humidity or lengthened to as long as about two hours in response to lower humidity. In other embodiments, a sensor detects frost thickness and initiates the melting cycle. In embodiments that detect frost thickness, the melting cycle is initiated when the sensor detects a predetermined frost level. The frost level will generally be set at a frost thickness of at least about 1 mm and less than about one half of the distance between evaporator fins. In many embodiments, a desired range will be between about 2 mm to about 6 mm of frost. 
     In another embodiment, the condenser and evaporator may switch functionality by reversing the flow of refrigerant through the system. Both the condenser and evaporator are heat exchangers. Essentially the system comprises a loop: heat exchanger→compressor→other heat exchanger→expansion device, and back to the beginning. By selectively routing refrigerant from one of the heat exchangers to the compressor, and then to the other heat exchanger, using a four-way valve to switch the sequence, the system can melt ice from one heat exchanger while frosting or promoting condensate on the other. 
     In other embodiments, a bypass valve may work in parallel with the expansion valve. In such cases, the bypass valve operates during the defrosting process thereby increasing the efficiency of the frosting/defrosting process. 
     The fans may be placed anywhere along the air flow path such that the fans perform either by sucking or by blowing air past the evaporator. A single fan or a large fan assembly may be used. In some embodiments, a tubular fan assembly promotes efficient air flow. The fans are arranged parallel to the evaporator with all fans in the assembly equidistant from the evaporator. The tubular fan is one kind of cross flow fan, which has a long and narrow shape, so it is relatively easy to mount, it sits close to the condenser surface, and several in parallel may be located to nearly-uniformly direct air past a large area of a heat exchanger. Other types and configurations of fans may be used including cross flow fans, centrifugal blowers, and axial flow fans. 
     Many embodiments of the system incorporate an integrated filtration system. Filtration may include reverse osmosis filters, carbon filters, resin filters, and particulate filters. Water processing may include re-mineralization, pH adjustment, chlorination, and fluoridation. The filtration system is fully optional for systems designed to provide water to livestock. 
     Some additional features may include carbonation for sparkling water, heated water, chilled water, and water with flavorings and nutrients. Flavorings and nutrients may include broth, tea, coffee, herbal extracts, minerals, and vitamins. Optional features may be included at or just prior to dispensing. Heating and chilling features may be efficiently designed to take advantage of the heat properties of the evaporator and condenser. 
     The system may incorporate a power generation unit, such as solar panels, a wind turbine, or a diesel generator. The system may include a bottling feature. Some embodiments are designed to be self-contained units within a standard size shipping container. These embodiments are particularly useful for quickly responding to a humanitarian crisis because they are self-contained and require minimal set-up. They also require no water or power infrastructure. 
     Some embodiments may produce potable water from either atmospheric moisture or by filtering available liquid water sources. Such sources may include, grey-water, surface water such as that from lakes or streams, and compromised municipal water. These dual-use systems utilize the same filtration system. These dual input systems are designed to permit addition of liquid water into the collection vessel. 
       FIG. 11  illustrates how moisture content increases with temperature. The shading depicts the area in which the disclosed system may generate water.  FIG. 12  is a typical chart showing the relationship between dew point and temperature for several levels of relative humidity and illustrates the conditions at which the disclosed system may generate water. 
     While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations therefore. It is therefore intended that the following appended claims hereinafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations are within their true spirit and scope. Each apparatus embodiment described herein has numerous equivalents. 
     The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the subjection matters claimed. Thus, it should be understood that although the present systems and methods have been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this subject matter as defined by the appended claims. Whenever a range is given in the specification, all intermediate ranges and sub-ranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and sub-combinations possible of the group are intended to be individually included in the disclosure. 
     Although the disclosed device and method have been described with reference to disclosed embodiments, numerous modifications and variations can be made and still the result will come within the scope of the disclosure. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.