Patent Application
20120186285
Proper hydration is important for general health, as well as for improving athletic performance. Poor hydration affects multiple body systems. Although the importance of hydration is known, it is usually less appealing to drink warm liquids as the ambient temperature rises. Insulation has been used to slow warming of liquids in containers, but is ineffective for long periods of time.
A device to cool drinking water that is small and lightweight, cools water to below ambient temperature, can be retrofitted with existing equipment packs, is low cost, has a hands free operation, is quiet and is compatible with potable water is needed.
Provided is a liquid cooler that cools liquid by evaporative cooling. In an aspect of the invention the liquid cooler includes a liquid inlet and outlet, one or more liquid reservoirs, a porous material (also referred to herein as “evaporative element”) forming one or more surfaces of the liquid reservoir for evaporative cooling and a fan that forces air across the surface of the evaporative element to enhance the cooling effect. A housing which surrounds the liquid reservoirs is used in an embodiment to protect the device, as well as provide the air channels for air to flow across the surface of the evaporative element. Also provided is a method of cooling water by evaporative cooling using a device as described herein. As will be apparent from the description and other materials provided herein such as the figures, the evaporative element is attached to the reservoir(s) and forms a portion of the reservoir surface and is in fluid contact with at least a portion of the contents of the reservoir. In an embodiment, the liquid reservoirs are in fluid communication with each other and one reservoir has a liquid inlet and another reservoir has a liquid outlet.
As used herein, “evaporative element” is a porous material attached to the liquid reservoir and which forms one or more surfaces of the liquid reservoir for evaporative cooling. “Evaporative element” and “porous material” and other forms of the phrases are used interchangeably herein unless otherwise specified by the context or language.
Some specific aspects and embodiments of the invention are provided here. In an aspect of the invention, provided is a liquid cooling system comprising: a liquid inlet and outlet; one or more liquid reservoirs in fluid communication with the liquid inlet and outlet; an evaporative element in fluid communication with a liquid reservoir; and a fan with airflow in flowable communication with a surface of the evaporative element.
In an aspect of the invention, the system further comprises a housing surrounding the one or more liquid reservoirs. In an aspect of the invention, there is an exterior housing which holds the reservoirs/evaporative elements, fan, and fan power source (sources include batteries and/or solar panel(s)) and protects the reservoirs/evaporative elements. In an embodiment this housing also defines the airflow channel geometry with the shape of its inner surfaces. In an aspect of the invention, these airflow channels are shaped such that pressure drop through the airflow channels is minimized, which maximizes the airflow provided by the fan.
The housing is preferably made of lightweight material which can withstand the force of the intended use. The housing is used to protect the reservoir(s) and provide airflow channels in one embodiment. The housing can be machined to provide airflow channels by having one portion of the housing with more or less thickness to create grooves, for example. In an aspect of the invention, the housing is ruggedized. The term “ruggedized” means the housing is able to withstand a force, impact, or other load that it is expected to undertake during normal operation or if the unit is dropped or if an object of reasonable size is dropped on the unit.
In an embodiment the housing material is a polymer. In an embodiment the housing is clear or transparent so the evaporative element can be seen, for test and development purposes. In an embodiment the housing is any desired color or pattern. In an embodiment, the housing provides and defines the desired airflow channels for the airflow across the evaporative element. In the case of multiple reservoirs, the housing also defines the airflow channel between the reservoirs. The amount of airflow to provide the desired cooling is easily determined by one of ordinary skill in the art using the information provided herein as well as the information known in the art, and depends on such factors such as surface area of the evaporative element, airflow velocity, air temperature, and desired cooling efficiency.
In an aspect of the invention, the system further comprises a power source. The power source is one or more selected from the group consisting of: one or more DC batteries, one or more solar panels, one or more rechargeable batteries, an AC power source and combinations thereof. In an aspect of the invention, a solar panel is used in conjunction with another power source. In an aspect of the invention, the solar panel is used in conjunction with one or more rechargeable batteries. In an aspect of this embodiment, the solar panel can be used to recharge a rechargeable battery. This allows the device to function when the solar power is insufficient to completely power the device, on a cloudy day, for example.
The evaporative element is a porous material in fluid or gaseous communication with a portion of the liquid reservoir. In an aspect of the invention, the porous material is selected from one or more of: expanded polytetrafluoroethylene (ePTFE), porous (e.g., sintered) plastic, ultra high molecular weight polyethylene (UHMWPE), micro-porous ceramic membrane, or a multi-layer laminate material made up of one or more of the above materials. In an aspect of the invention the porous material forms a surface of a liquid reservoir and is attached to a liquid reservoir. The porous material is attached to a surface of the liquid reservoir using any suitable method, such as adhesive, thermal bonding, mechanical attachment, or others providing sufficient adhesion to prevent liquid leakage between the reservoir and porous material. In an aspect of the invention one side of the porous material is attached to a side of a liquid reservoir and another side of the porous material is surrounded by a material which acts to provide structural support, such as a wire mesh, grid or clamp. All layers of the evaporative element should be attached to the reservoir or each other to prevent leakage. At least one layer is attached to the reservoir. The embodiment of the invention using a wire mesh or grid is useful to prevent deflection or displacement of the evaporative element, for example, if the evaporative element itself is not structurally capable of doing so.
In an aspect of the invention, the liquid reservoir contains one or more a baffles or internal ribs positioned to direct the liquid flow through the liquid reservoir. This aspect prevents liquid which is warm as compared to the cooled liquid from flowing directly from the inlet and outlet and allows sufficient residence time in the device for the desired cooling. The baffle or internal rib may occupy any suitable area of the liquid reservoir. In a specific embodiment of this aspect of the invention, in a generally rectangular liquid reservoir, the baffle is positioned approximately half way on the height of the reservoir and extends less than the full length of the reservoir. In an embodiment of this aspect of the invention, the baffle is an integral part of the reservoir (i.e., the reservoir and baffle are one piece). In an embodiment of this aspect of the invention, the baffle is attached to the reservoir using any suitable method, such as glue, thermal bonding, or other method known to one of ordinary skill in the art without undue experimentation.
In an embodiment where there is more than one liquid reservoir, the liquid reservoirs are attached together in any suitable method using any suitable material. In an aspect of the invention, the liquid reservoirs are attached together using a tube. In an aspect of the invention, the liquid reservoirs are attached together using a flange or other aspect which is positioned on each liquid reservoir at an opposite end from the liquid inlet or outlet. This flange or other attachment means can be any suitable material, such as metal, plastic, polymer, or other material which are suitable for the desired purpose. When there is more than one reservoir in an aspect of the invention, the liquid flow between the reservoirs can be designed to minimize the air present in the reservoirs.
As is known in the art, the reservoir can be any desired shape, including rectangular cuboid, ovoid, cylindrical (including cylinders hollowed out axially to create additional evaporative surface area, one or more of these channels may be hollowed out along the cylinder length, for example), toroidal, tubular or teardrop. As is known in the art, different shapes may be more desired for different applications or may be more desired from other perspectives, such as cost or ease of manufacturing. It is generally advantageous to cooling performance to have a large evaporative surface area relative to the amount of fluid in the reservoir, particularly if a quick cooldown is desired. However, a shape with high volume-to-surface area, the extreme example of which is a sphere, will also provide cooling, albeit more slowly than a reservoir with the same volume and a different shape allowing for greater evaporative surface area. These aspects are included in the invention. Any shape that provides a high enough surface area to volume to provide the desired cooling of the liquid is suitable. The surface area to volume determination to determine if a shape is suitable is easily performed using the information provided herein and known to the art.
In an aspect of the invention, a reservoir is generally rectangular cuboid in shape. It is understood there are two length×width faces of a rectangular cuboid. In an aspect of the invention, the porous material forms at least a portion of a length×width face of a rectangular cuboid liquid reservoir. In an aspect of the invention, the porous material forms at least a portion of both length×width faces of a rectangular cuboid liquid reservoir. As is understood, if the porous material forms more surface area of the reservoir the cooling rate is generally increased, providing that sufficient airflow is provided.
In an aspect of the invention, the porous material forms at least 50% of the surface area of a reservoir. In an aspect of the invention, the porous material forms up to 100% of the surface area of a reservoir and any percentage thereof. In an aspect of the invention, the porous material forms a percentage of the surface area of a length×width face of a rectangular reservoir between 10% and 100%. In an aspect of the invention, the porous material forms less than 50% of the surface area of a reservoir. In an aspect of the invention, the porous material on one of the length×width face of the rectangular cuboid is different than the evaporative element on the other length×width face of the rectangular cuboid. In an aspect of the invention, the evaporative element on one of the length×width face of the rectangular cuboid is the same as the evaporative element on the other length×width face of the rectangular cuboid. Surface area of the reservoir which does not include porous material can be enclosed using any other suitable material such as the same material making up the reservoir, for example. In an embodiment it may be desirable to cover only a portion of the available surface area of the reservoir with evaporative element, for various reasons, such as cost and structural strength. When the term “attached to” is used in conjunction with the porous material and reservoir, it is intended to indicate the porous material forms a portion of the overall shape of the reservoir. It should be clear that a porous material placed over a solid surface will not function as an evaporative element. In an aspect of the invention, a liquid reservoir can be fabricated as an entire shape, such as a rectangle, and the portion of the shape which is desired to be evaporative element can be removed, using a laser cutter or knife, for example. In other aspects, a liquid reservoir can be fabricated to not include the portion which is intended to be evaporative element. For example, if the liquid reservoir is a generally rectangle shape where the front surface area is intended to be evaporative element, the rectangle can be fabricated to not include the front surface area or to include a flange, for example for ease of positioning and/or attaching the evaporative element, or the rectangle can be fabricated with the front surface area and the desired area can then be removed.
In an aspect of the invention, an evaporative element is a multi-layer laminate material where the layers may be the same or different materials. In an aspect of the invention, the evaporative element is a single-layer porous hydrophobic material where the inner surface is treated to create a hydrophilic layer. In an aspect of the invention, when a multiple-layer evaporative element is used, the hydrophobic layer is a membrane. In an aspect of the invention, the inner layer of the multi-layer laminate is hydrophilic. In an aspect of the invention, the inner surface of a single-layer evaporative element or the inner layer of a multi-layer evaporative element is plasma treated to create a hydrophilic surface. Other treatments to create a hydrophilic surface are useful, as is known in the art. Naturally-hydrophilic materials are also useful and do not require a plasma or other treatment to form a hydrophilic surface. It is known in the art that some treatments of materials to create a hydrophilic surface are permanent and other treatments of materials to create a hydrophilic surface are not. If a treatment is not permanent, or for other reasons, the performance of the evaporative element in particular and the system in general may be reduced over time. In this event, the evaporative element may be replaced if desired.
As is known in the art, hydrophilic and hydrophobic are relative terms and are not intended to be limiting to a particular polarity or characteristic. As is recognized, the hydrophilicity and hydrophobicity of the evaporative element is useful to prevent the passage of liquid from one surface of the evaporative element to another, in an embodiment. This aspect is discussed further herein.
In an aspect of the invention, the device is modular or partially modular. As used herein, modular means that any element can be removed and replaced with the same or similar element. For example, in an embodiment of the liquid cooler which includes two reservoirs, a modular device allows removal and replacement of one or both reservoirs. In an embodiment of a modular device, one or more of the evaporative elements used on a reservoir may be replaced with the same type of evaporative element or a different type of evaporative element, for example. This is useful in the event of element failure or fouling, for example. Other components and elements of the device are also replaceable. In an embodiment of a modular device, one or more of the reservoirs may be replaced, for example. The elements or components can clip in to a frame for ease of replacement for example. As is typical for systems for water, mold and mildew may be a concern and the modularity provides a useful and efficient way to provide a clean system when desired.
As used herein, “device” and “system” are used synonymously unless otherwise indicated by the language or context.
As is apparent to one of ordinary skill in the art, the device can have one, two, three or other numbers of reservoirs of varying size and shape to provide the desired water supply, liquid cooling rate and consumption amount. The physical and fluid attachments of the reservoirs together are made in any suitable manner, as will be appreciated by one of ordinary skill in the art. In an aspect of the invention, the system comprises two liquid reservoirs. In an aspect of the invention, the system comprises a plurality of liquid reservoirs. In an aspect of the invention, the system further comprises a gas source in gaseous communication with the evaporative element. Although the word “air” is typically used herein to describe the substance that flows over the evaporative element, it is apparent to one of ordinary skill in the art that other gaseous substances can be used. These other gaseous substances are intended to be included in the invention to the same extent as if they were individually listed. In an aspect of the invention, the gas is not air. In an example, helium, nitrogen or other gas can be used to create the desired airflow across the evaporative element. Generally, any gas with a lower vapor pressure of the liquid to be cooled than the vapor pressure of the liquid itself within the reservoir is suitable to create cooling. For example, dry air is better than moist or humid air for cooling water, warm water is more easily cooled than cool water, dry bottled gases are very effective for cooling water since they contain less moisture than ambient air, and any ambient airstream, regardless of humidity, is effective at cooling process liquids whose vapors are not present in the atmosphere such as solvents. All of these aspects are included in the invention.
In an aspect of the invention, the system further comprises a switch in electrical communication with the fan. In an aspect of the invention, the switch is operated by the user to allow cooling of the water upon demand. In an embodiment of the invention the switch is located on or near the housing. In an embodiment of the invention the switch is located remotely from the device, so the user can easily access the switch while walking, for example. In an embodiment of the invention the switch is wireless. In an embodiment of the invention the switch is electrically connected to the device using a wire or other electrical connection.
In an aspect of the invention, the system further comprises airflow channels on one or both sides of the reservoir and/or evaporative elements. These airflow channels may be provided by a housing, in one embodiment. The airflow channels may also be fabricated into the reservoir and/or evaporative elements. In an aspect of the invention, the airflow channels are sized and scaled to meet water/liquid cooling/consumption requirements. In an aspect of the invention, there is a screen or filter positioned adjacent to an evaporative element to prevent fouling of the evaporative element. This is particularly useful in an environment where there is no housing.
As is apparent to one of ordinary skill in the art, the power requirements of the fan can vary depending on the desired airflow and other considerations such as size of the device. In an aspect of the invention, the fan draws between 0.25-1 W of power and all ranges and values therein. Of course, as will be apparent to one of ordinary skill in the art, if the device is scaled to a larger size, a larger fan will be required to meet the airflow requirements. In this case, the fan may draw more than 1 W power.
As will be apparent to one of ordinary skill in the art from the disclosure herein, the apparatus and method can be used to cool any suitable liquid. In an aspect of the invention, the liquid is water. In an aspect of the invention, the liquid is drinking water. In an aspect of the invention, the liquid is suitable for human or animal consumption and the surfaces of the cooling system which contact the liquid are approved for potable water systems. The liquid cooled using the system and methods described here can also be a fluid used in industry. In an embodiment, the liquid is an organic solvent. In an embodiment, the liquid is an inorganic solvent.
In an aspect of the invention, the system is inserted into the liquid supply line of a hydration system between the bladder and mouth piece. This insertion can be performed by merely cutting the liquid supply line and inserting a suitable coupling piece, or in other ways as will be appreciated by one of ordinary skill in the art.
The performance of the system and methods provided can vary depending on the desired use and components used. In an aspect of the invention, in operation, the liquid is cooled by at least 8° F. in 5 minutes. In an aspect of the invention, in operation, the liquid is cooled by at least 10° F. in 5 minutes. In an aspect of the invention, in operation, the liquid is cooled by at least 15° F. in 5 minutes. In an aspect of the invention, in operation, the liquid is cooled by at least 15° F. in 10 minutes. In an aspect of the invention, in operation, the liquid is cooled by at least 20° F. in 10 minutes. In an aspect of the invention, in operation, the liquid is cooled by at least 36° F. in 5 minutes. In an aspect of the invention, in operation, the liquid is cooled by at least 36° F. in 10 minutes. Other temperature reductions in various times are included in the invention.
Also provided is a liquid cooling system comprising: one or more liquid reservoirs having a liquid inlet and a liquid outlet; and one or more evaporative element(s) in liquid communication with the one or more liquid reservoirs, wherein gas passes over the evaporative element(s) and cools liquid in a reservoir. In this embodiment, there is no fan or power supply, and the airflow which augments evaporation is provided either by the system being in motion or by ambient airflow/breezes. In this embodiment, there may be a housing which protects the evaporative elements and defines the airflow channels and is designed to minimize blockage of airflow over the evaporative element(s). This configuration can be used by bicyclists, for example. In another embodiment, the flow augmenting cooling can be provided by bottled gas(es). This configuration can be used in laboratory or manufacturing settings, for example.
Also provided is a method to cool liquids comprising providing: a liquid cooling system comprising: a liquid inlet and outlet; one or more liquid reservoirs; and an evaporative element; and providing airflow over the evaporative element.
Also provided is a method of cooling liquid comprising: providing a liquid cooling system comprising: a liquid inlet and outlet, one or more liquid reservoirs, a porous evaporative element attached to one or more surfaces of the liquid reservoir for evaporative cooling, and a fan that forces air across the surface of the evaporative element; providing liquid in the liquid reservoir; activating the fan; and allowing evaporation to occur, whereby liquid in the liquid reservoir is cooled. The system configurations described elsewhere are useful in the methods described herein. Any aspect of the invention which is described as a device can be used in a method for cooling water.
In an aspect of the invention, the method comprises drawing the liquid through the reservoir at a constant rate. A constant rate may also be thought of as a continuous flow for a certain period of time. This embodiment is useful for a larger scale operation where there is sufficient cooling provided so that the liquid withdrawn from the device is cooler than the liquid provided to the device, for example. In an aspect of the invention, the method comprises drawing the liquid through the reservoir at a variable rate, determined by a user withdrawing the liquid or an external mechanical system. A variable rate may also be thought of as a discrete volume flow. In the constant-flow embodiment, the flow rate may be low relative to the volume of liquid being cooled so that desired cooling can occur before the liquid exits the reservoir. An example of a variable-reservoir-flow embodiment where cooling of a constant flow of liquid can take place is a large community water source where the cooled exit flow is used to fill water bottles. In this embodiment, the flow rate during bottle filling is the maximum flow rate, and the inlet water temperature is elevated relative to a preferred temperature for consumption (e.g., ambient temperature in a hot environment). The flow rate drops to zero between bottle filling, during which time the reservoir water in this embodiment is cooled and held at or near the ambient wet-bulb temperature through evaporative cooling. An embodiment with purely variable flow is a “batch-cooling” embodiment where one or multiple reservoirs collectively comprise a batch of water to be cooled via evaporation of a small portion of the water within the reservoirs. Once this batch of water is cooled to the desired temperature, it is consumed and replaced with a new batch of warm water which is then cooled, and so on. The batch size can be scaled to fit the desired application. All variations on the constant and variable flow rate embodiments are included here.
Also provided is a device comprising: one or more porous liquid reservoirs; and a battery-powered fan; wherein the device cools the liquid in the liquid reservoirs by evaporative cooling of the fan or flow over the porous liquid reservoirs.
Any device described here can include an optional solar panel with accompanying wiring and physical connections to the device as will be known to one of ordinary skill in the art. The solar panel can be used to power the device alone or in conjunction with one or more batteries or AC power sources. In an embodiment, the solar panel is used to recharge rechargeable batteries.
The device can be fabricated to any desired pressure specifications. In an embodiment, the device operates at an internal pressure of at least 1 psig without leaking water and a negative pressure of at least 1 psig without leaking air into the liquid reservoir. In an embodiment, the device operates at an internal pressure of at least 2 psig without leaking water and a negative pressure of at least 2 psig without leaking air into the liquid reservoir. In an embodiment, the device operates at an internal pressure of less than 2 psig without leaking water and a negative pressure of less than 2 psig without leaking air into the liquid reservoir. Any individual value or range within the ranges supplied are intended to be included to the same extent as if they were individually listed.
In an aspect of the invention, a portion of the liquid reservoirs comprise a porous material or layered porous materials such that the evaporative cooling effect provides desired cooling performance. In an aspect of the invention, the porous material or layered porous material comprises one or more of: expanded polytetrafluoroethylene (ePTFE), sintered porous plastic, and metallic and non-metallic screen to provide needed structural support. In an aspect of the invention, the device operates for over 12 hours with 4 CR123A batteries. In an aspect of the invention, the device operates for >12 hours with ≦4 CR123 A batteries or a solar panel. In an aspect of the invention, the device cools a small volume (2-3 oz) of water, initially at 120° F. in 120° F. air temperature/15% humidity, to below body temperature in less than 10 minutes.
In general, the terms and phrases used herein have their art-recognized meaning, which can be found by reference to standard texts, journal references and contexts known to those skilled in the art. As to the embodiments of the invention, it is understood that any embodiment having a combination of components which is not able to be made is not included in the invention. Although Applicant does not wish to be bound by theory, the description herein is provided to aid in understanding of the invention. The following description is provided to illustrate specific embodiments of the invention. It is understood that all aspects of the invention which are described using a specific embodiment or embodiments referred to in the alternative (one or more liquid reservoirs, for example) are applicable to other embodiments and are intended to be disclosed herein to the same extent as if they were specifically listed.
As will be appreciated, the drinking water cooler can have a variety of configurations.
In an aspect of the invention, the apparatus size is such that will provide an adequate amount of cooled water but will take up as small an amount of space as possible. In certain uses, the device is as quiet as possible. In an embodiment, the device weighs as little as possible. In an embodiment, the device costs as little as is feasible to manufacture. As will be appreciated, there is a tradeoff between the size, weight, noise, volume and power needed with the cost and reliability of the device. One of ordinary skill in the art will understand the tradeoffs required for the desired purpose. The liquid cooler can be any suitable size to provide the desired amount of cooled liquid. If a greater amount of cooled liquid is required, the system can be scaled up appropriately.
In an embodiment, exemplary dimensions of the system are approximately (L×W×H): 14.7×6.9×4.0 cm; system volume of 299 cm3 (18 in3); input power of 0.5 W @ 12 VDC (continuous operation); noise 22 dBA (normally determined by the specifications of the fan); and dry weight 8.2 oz. It is appreciated by one of ordinary skill in the art that the provided dimensions and specifications are exemplary and may change. All changes are intended to be incorporated herein.
In an exemplary system, the input power is ≦0.5 W, ≦22 dBA, total reservoir volume is approximately 2.3 oz. In testing of an exemplary embodiment, it was shown that a 0.5 W fan was statistically as effective as a 1.0 W fan at providing evaporative cooling airflow. The inherent reduction in airflow provided by a lower power fan did not negatively affect unit performance. In a further test, a reduction in fan input power to 0.25 W did not detrimentally affect performance. These results show a doubling of DWC operation time if four batteries are used, or a reduction in number of batteries used (i.e., from four to two) with no net effect on operation time. In an aspect of the invention a two-battery system creates a 6-V power source for a fan designed for a 5-V power source, which may shorten the fan lifetime. In addition, depending on the components, the fan noise is reduced to as low as 13 dBA from 22 dBA by use of a 0.25 W fan.
In an aspect of the invention the input power is a 1 W fan. In an aspect of the invention the input power is a <1 W fan. In an aspect of the invention the input power is a 0.5 W fan. In an aspect of the invention the input power is a <0.5 W fan. In an aspect of the invention the input power is a 0.25 W fan.
In an aspect of the invention a solar panel is used as an alternative or supplemental power source. The solar panel is designed so that the solar panel will re-charge spent or degraded rechargeable batteries. The rechargeable batteries may be used as backup power in cloudy, shaded, or nighttime conditions.
As known in the art, the specifications of the system and components thereof can vary, depending on many factors, including the overall desired size and/or weight of the system, the amount of cooling desired, the cost of the system, the specifications of the “off-the-shelf” components, manufacturing requirements, and other considerations which are well-understood by one of ordinary skill in the art. As known in the art, materials used for the components such as switch components, batteries, tubing, housing materials, fan, methods of attaching components together and reservoir frame materials may vary, depending on the factors discussed herein and other factors known in the art of designing systems. All such modifications are intended to be included herein.
Although the invention is described in detail using the term “drinking water” it is understood that other liquids may be cooled using the invention. As known in the art, the DWC system can be used to cool most liquids, including water, sports drinks, alcoholic beverages, coffee, tea, and any other desired beverage. These embodiments are well understood by one of ordinary skill in the art using the description and teachings described herein without undue experimentation, and are intended to be included herein.
As is apparent to one of ordinary skill in the art, some liquids will damage the reservoir materials before sufficient cooling of some extreme example liquids will occur. For example, an evaporative cooler that cools liquid tungsten is impossible to make since all potential reservoir materials would melt/burn/evaporate before the tungsten melts. Materials that become fluids at extremely high temperatures are generally not feasible for cooling with this unit.
A class of liquids that can be cooled using the methods and apparatus described herein are process liquids such as methyl ethyl ketone (MEK) or acetone. In operation, it is desired that the vapors from an evaporative cooler cooling such liquids be contained as necessary for safety reasons such as vapor flammability or toxicity. In this embodiment, it is likely that the air or other gas used to enhance evaporation will come from a bottled or otherwise contained source. The methods and apparatus described herein are a viable way to provide cooling of these industrial fluids if it is needed in a manufacturing process or for other uses.
In one example of operation, the DWC is inserted in a hydration pack water line (such as a Camelbak or similar system) at any suitable location between the hydration bladder and the mouth piece. The reservoir of the DWC is filled with the desired liquid (in one embodiment, this filling occurs when the user withdraws liquid from the reservoir which is replaced by water remaining in the hydration pack). For this exemplary description, water is used as the liquid, although the principles of operation will be the same for any other liquid used. A small portion of the stored water in the reservoir evaporates through the evaporative element that is in contact with the reservoir or a portion thereof. This evaporation cools the remaining water in the reservoir. The cooled water is consumed and replaced with water from the hydration pack, which is then cooled, and so on representing a batch-cooling process. In an embodiment, air is forced across the evaporative element to increase the evaporative cooling. This air flow can be produced using a fan or other device which increases air flow.
In operation, the reservoir volume remains near-constant during cooling (assuming the DWC water pressure remains constant). Water evaporated from the reservoir during cooling is replaced by water from the hydration pack (or by water from the tubing connecting the hydration pack and the DWC). Since this is a small amount of water compared to the reservoir volume (because of water's high heat of vaporization), this does not have a significant detrimental affect on cooling performance. In a system cooling a fluid with a low heat of vaporization, the reduction in temperature, or the time needed to reach a desired temperature, may be detrimentally affected since a larger proportion of liquid must evaporate to provide desired cooling.
In an embodiment, exemplary parameters of the system are based on the following consumption profile: water consumption takes place in sets of sips, three to five sips taken with 1-2 seconds between sips. In an embodiment, the reservoir capacity (combined) is 2.3 oz. In this embodiment, a six-minute consumption (cooldown) interval maintains an overall consumption rate of approximately 23 oz/hour.
Other parameters may be used, such as larger or smaller reservoir capacities, different reservoir geometries, different numbers of reservoirs, and larger or smaller time interval for desired cooling effect.
Cooling is provided by the evaporation of water. The heat of vaporization of a small portion of water in the reservoir is used to cool the remaining drinking water within the reservoir. This is the same process as sweating that cools the body. The proportion of reservoir liquid needed to evaporative in order to cool the liquid remaining in the reservoir depends on the liquid's heat of vaporization and heat capacity. For example, it is feasible to cool a reservoir of water by 36° F. by evaporating as little as 3.5% of the water therein due to water's relatively high heat of vaporization. The refrigerant R134a requires over 15% of the liquid to evaporate to produce the same effect. A device having any amount of liquid evaporation is included in the invention as long as the liquid is not 100% evaporated before it reaches the liquid output.
In an embodiment, evaporation can be enhanced via forcing air around the reservoirs with the use of a fan or other method known in the art. The fan can be powered by one or any combination of: batteries, a solar panel, a wall outlet, or other suitable source of power.
The evaporative element can be made of a number of materials. The internal surface of the evaporative element in contact with the water in the reservoir must be a hydrophilic porous material that absorbs water like a blotter and prevents passage of air when pressure in reservoir is below that on air-side of the evaporative element, as may occur due to suction created to draw the liquid to the user during consumption. The external evaporative surface in contact with air must be a material that allows passage of water vapor (i.e., evaporation), but prevents the passage of liquid water and remains dry at the surface (hydrophobic). These requirements can be achieved by a single porous hydrophobic material having a conventional surface treatment (such as plasma or corona discharge treatment, chemical etching, or an applied coating) to make one surface (and a portion of the total material thickness) hydrophilic. Alternatively, a multi-layer laminate may be used. The layers in the multi-layer laminate may be the same or different, and may be comprised of one or more of the materials listed below or other suitable materials. Some specific materials useful for the evaporative element include: expanded polytetrafluoroethylene (ePTFE), porous (e.g., sintered) plastic including ultra high molecular weight polyethylene (UHMWPE), or micro-porous ceramic membrane and other suitable materials.
In an embodiment, the reservoir assembly (including evaporative element(s)) can easily be disconnected from the water inlet and outlet lines, and the housing can be opened so that the reservoir assembly can be removed and replaced with a new reservoir assembly if needed due to evaporative element degradation and/or soiling. This represents a modular reservoir assembly design.
The reservoir(s) may be designed such that the presence of air bubbles is minimized during the initial filling of the reservoir(s), and such that consumption of water within the system is conducive to purging existing air bubbles within the reservoir(s).
The reservoirs may include baffles to direct the flow of water within the reservoirs during consumption in a way that mitigates potential mixing of warm water from the hydration system with cooled water before all or a significant majority of the cooled water is consumed.
In an embodiment comprising a multiple-reservoir system, the reservoirs may be connected with a section of tubing. This tubing section may run between barb or other suitable types of fitting integrated into the individual reservoirs. Other suitable connection methods known in the art, including but not limited to quick-connect fittings or plumbing fittings, may be used if desired.
As is known in the art, there are different suitable methods of attaching the laminate layers both to each other and to the reservoir frame. The layers can be attached to each other either at the outside edges via adhesive(s), thermal bonding, ultrasonic welding, stitching, and/or other means, or over some or all of their surfaces in contact with one another by adhesive(s), thermal bonding, ultrasonic welding, stitching, and/or other means. The attachment method should not detrimentally affect the transport of liquid through the hydrophilic layer or the transport of vapor though the hydrophobic layer to the point where cooling performance is compromised. The evaporative element can be attached to the reservoir frame by adhesive(s), thermal bonding, ultrasonic welding, stitching, and/or other means. In the case of a drinking water (or other beverage) cooling system, substances in contact with the water/beverage (i.e., reservoir, evaporative element, and any adhesives/other bonding agents) must be approved for use with potable water systems. These methods are known in the art and are selected by considerations such as the desired use and the materials available and other considerations such as cost and performance.
In an embodiment, the evaporative element has the following characteristics:
As is known in the art, the characteristics above may vary, depending on the desired application and other factors known in the art. For example, water or air leakage may occur, although the amount of water of air leakage is desired to be minimized. In addition, the specified limit for water or air leakage may be higher or lower, depending on various aspects of the system as described herein and known to the art.
An exemplary DWC system was fabricated and operated to demonstrate the cooling performance at simulated hot desert conditions. For initial testing, reservoirs were fabricated by epoxy bonding porous ePTFE to reservoir frames both with and without sintered porous plastic.
For the laminate assembly: 25-mil thick porous UHMWPE sintered plastic (DeWAL Industries #492P), Tetratex® (ePTFE/polypropylene mat laminate-Donaldson Company product # 6502), and 0.25×0.25″ stainless steel wire mesh (0.028″ diameter) were layered and only bonded at the perimeter of the reservoir housing. This layered assembly was bonded to both sides of a plastic reservoir frame such that it would contain water without leakage. Pressure testing confirmed no water leakage at 24 in of water and no air leakage at up to 15 in negative water pressure within the reservoir. For one example Tetratex (product #6502) was bonded alone to both sides of the reservoir for performance comparison testing. This material alone provides resistance to water leakage, but no resistance to air leakage. Tetratex product #6502 is an ePTFE membrane laminated to a thin, open polypropylene scrim. These two reservoir assemblies are shown in
In an embodiment of a laminate material, Tetratex 6502 is used with a 40-mil (0.040-in) thick porous plastic plasma treated for hydrophilicity. This porous plastic has a slightly smaller pore size which allows for air intrusion prevention to a reservoir vacuum level of at least 31 inches of water when it is saturated.
The example system also contains the cooling fan, batteries, and switch needed for operating the cooler. Two different fan power levels were used for the tests: ½ watt and 1 watt. Both fans are 35×35×10 mm generally used for electronics cooling. For the example system, SUNON fan models GM1235PFV1-8 (0.5 W) and GM1235PFV2-8 (1.0 W) were used. Four CR123A batteries provide the nominal 12-V fan power. As known in the art, these components and their specifications may change depending on the availability, size and cost of the items, among other factors recognized and known in the art.
Cooling performance with respect to time for the laminate reservoir described above (but without the wire mesh) is shown in
In lab testing in the same environmental chamber, water contained in the Tetratex only reservoir cooled by 23.4 and 30.9° F. at 5 and 10 minutes respectively at 120° F./15% relative humidity conditions indicating that the performance penalty associated with the 25-mil thick porous plastic addition was small.
The degree of cooling described in the description herein and in the claims are necessarily affected by the ambient conditions, including temperature and humidity, as known by one of ordinary skill in the art and illustrated in
All such variables are contemplated and all degrees of performance are intended to be included in the invention.
It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a reservoir” includes a plurality of such reservoirs and equivalents thereof known to those skilled in the art, and so forth. As well, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably. The expression “of any of claims XX-YY” (wherein XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form, and in some embodiments is interchangeable with the expression “as in any one of claims XX-YY.”
Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods and materials are now described. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.
All references throughout this application, for example patent documents including issued or granted patents or equivalents; patent application publications; unpublished patent applications; and non-patent literature documents or other source material; are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in this application (for example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference). In addition, any aspect described herein is intended to be described to such an extent so that it may be included or excluded from the claims.
Where the terms “comprise”, “comprises”, “comprised”, or “comprising” are used herein, they are to be interpreted as specifying the presence of the stated features, integers, steps, or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component, or group thereof. Separate embodiments of the invention are also intended to be encompassed wherein the terms “comprising” or “comprise(s)” or “comprised” are optionally replaced with the terms, analogous in grammar, e.g.; “consisting/consist(s)” or “consisting essentially of/consist(s) essentially of” to thereby describe further embodiments that are not necessarily coextensive. For clarification, as used herein “comprising” is synonymous with “having,” “including,” “containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, “consisting of” excludes any element, step, component, or ingredient not specified in the claim element. As used herein, “consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim (e.g., not affecting an active ingredient). In each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.
The invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention. It will be appreciated by one of ordinary skill in the art that methods, devices, device elements, materials, optional features, procedures and techniques other than those specifically described herein can be applied to the practice of the invention as broadly disclosed herein without resort to undue experimentation. All art-known functional equivalents of methods, devices, device elements, materials, procedures and techniques described herein; and portions thereof; are intended to be encompassed by this invention. Whenever a range is disclosed, all subranges and individual values are intended to be encompassed. This invention is not to be limited by the embodiments disclosed, including any shown in the drawings or exemplified in the specification, which are given by way of example or illustration and not of limitation.
This application claims priority to U.S. provisional patent application Ser. No. 61/181,943, filed May 28, 2009, which is incorporated by reference in its entirety.
This invention was made with government support under grant M67854-08-C-6511, awarded by the Department of the Navy. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US10/36399 | 5/27/2010 | WO | 00 | 4/12/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61181943 | May 2009 | US |
