Patent Application
20140123578
The present invention is directed to using fluidic and microfluidic structures incorporated in the panes of windows for optical and thermal conditioning.
Buildings transfer a significant amount of thermal energy through windows, in the summer (heat gain) or winter (heat loss). In fact windows often represent the most important feature of buildings to cost energy due to this thermal loss or gain. Yet windows are obviously a necessary feature of architecture, and in fact, increasing amounts of glass seem to be used in many modern designs.
Low-emissivity (low-e) glass is designed to include a metal oxide layer that reflects or absorbs light in the IR range, but allows transmission of the visible. This development in the 1970s has increased the energy efficiency of buildings significantly. Such windows are designed to reflect IR back into the room in the winter, and reflect IR from entering the building in the summer. However, in hot climates (and summer months of extreme northern and southern climates) thermal heating of the window itself is still an issue, which contributes to thermal conduction through the window to the room.
This invention involves the application of fundamental design principles that living organisms use to control heat exchange as a novel way to minimize heat exchange across the window surfaces of habitable structures (e.g., buildings), boats, vehicles, tents, or any other structure. The invention involves the application of one or more microfluidic heat exchanger layers applied to a surface of a window or window pane. Each heat exchange layer can include a plurality of fluidic or microfluidic channels extending over the surface of the window. In some embodiments of the invention, the channels can be arranged in a patterned network of channels and resemble a capillary network. Each heat exchange layer can include at least one inlet port and at least one outlet port to enable a fluid to flow into the heat exchange layer and out the outlet port. The fluid can include any flowable medium, including solid particles, liquids and gases as well as combinations of any of the materials. Examples of the fluid can include, water, oil and air, as well as suspensions of materials and particles in water or air. In some embodiments of the invention, the heat exchange layer can be transparent to visible light and can block undesirable wavelengths of the electromagnetic spectrum including all or portions of the ultraviolet and infrared spectrum.
While the invention is generally discussed in relation to a building, it is to be understood that invention can used in any structure. For example, the invention can be used for any structure comprising a window. Amenable structures include, but are not limited to, buildings, tents, cars, boats, ships, airplanes, submarines, military vehicles or tanks, and the like. The invention can also be employed to control color, heat, or condensation in lights, cameras, and the like.
In accordance with one embodiment of the invention, the heat exchange layer can be employed in a system for cooling the surface of a window in a building to improve the energy efficiency of the building by feeding the fluid, at a lower temperature than the window, into the heat exchange layer to convectively cool the window and control the transfer of heat energy between the outside and the inside of the building through the window.
In an alternative embodiment of the invention, the system can be used as part of a solar energy harvesting system that supplies heated water to an existing hot water system or to a heat storage system that can be used for warming the building as needed at other times of the day.
In accordance with another embodiment of the building, the heat exchange layer can be employed in a system for heating the surface of a window in a building to improve energy efficiency of the building by feeding the fluid, at a higher temperature than the window, into the heat exchange layer to convectively warm the window and control the transfer of heat energy between the inside and the outside of the building through the window.
In accordance with other embodiments of the system, the fluid that flows through the heat exchange layer can include colored dyes or other materials that change the light transmission properties of the fluid to modulate the light energy that is transferred into a room and further improve energy efficiency, as well as esthetic value. In some embodiments of the invention, different fluids can be selectively fed into the heat exchange layer to modulate light and heat transfer in response to changes in environmental conditions. For example, bright sunlight can be diffused using, a more opaque or light diffusing or scattering fluid that has high heat absorbing properties to reduce the brightness and lower the temperature in the room.
In some embodiments, the fluid can be fed and pushed through the heat exchange layer using gravity, capillary action or an active pressure source such as a pump or an elevated reservoir. The fluid can be fed in the top of the window and gravity can be used draw the fluid down through the heat exchange layer to one or more outlet ports at the bottom of the window. Alternatively, the fluid can be fed in the bottom of the window and the head pressure or capillary action can be used push the fluid up through the heat exchange layer to one or more outlet ports at the top of the window. In other embodiments, channels can be configured to enable the fluid to flow horizontally from one side to the other.
In some embodiments of the invention, the channels on the inside surface of the window can be convection heated or cooled to room temperature by ambient room air that is heated/cooled by the central heating/air conditioning functions of the building. And the exposed surface area of channels distributed across the outside surface of the window would similar be heated or cooled by external environmental conditions, convection and solar energy. These parallel heat exchange layers at the inner and outer surface layers of the window can be connected by channels with fluids flowing in the opposite direction through a central insulating layer so that heat can be exchanged across their walls and the invention can be used to increase the insulating efficiency of the window. The efficiency is derived from the use of a counter current heat exchanger design that mimics designs utilized for similar thermal stabilization effects in living organisms.
These and other capabilities of the invention, along with the invention itself, will be more fully understood after a review of the following figures, detailed description, and claims
The present invention is directed to a system and method for controlling heat exchange and for reducing heat exchange through the windows of buildings and habitable structures. The invention concerns the application of one or more microfluidic heat exchanger layers applied to one or more surfaces of a window or window pane. The heat exchange layers can be applied on the inside surface, the outside surface and the inner (in-between) surface of multi-pane (or multi-layer) windows. Each heat exchange layer can include a plurality of fluidic or microfluidic channels extending over the surface of the window. In some embodiments of the invention, the channels can be arranged in a patterned network of channels and resemble a capillary network. The heat exchange layers can be used to add or remove heat from the surface of the window to which it is applied.
In accordance with one embodiment, as shown in
In accordance with some embodiments of the invention, more than one set or array of channels can be provided in one or more heat exchange layers adhered to the window 100. In some embodiments of the invention, two or more separate arrays of channels can be provided in a single heat exchange layer to provide heating or cooling or light filtering of a portion of the window, for example, to allow the top and bottom of the window to be treated separately. In some embodiments of the invention, two or more heat exchange layers can be adhered to the window 100, either as layers built up on one side of the window 100 or on both sides of the window 100.
As shown in
While the window 100 is described as comprising two layers (110 and 120), it is to be understood that the window can comprise more than two layers. Without limitations, a window can comprise one or more of the first layers 100 and one or more of the second layers 120 arranged in any order desirable. For example, the second layer 120 can be positioned between two first layers 110, i.e. a window comprising three layers in the order 110-120-110. In another example, the second layer 120 can be positioned next to a second layer 120 which is then positioned next to a second first layer 110, i.e. a window comprising four layers in the order 110-120-120-110. In yet still another example, the window can comprise five layers in the order 110-120-110-120-110.
In accordance with some embodiments of the invention, the channels of the heat exchange layer can be etched or otherwise formed (such as by molding or machining) into the surface of the first layer 110 and the etched surface can be covered by the second layer 120 of transparent material. In some embodiments, the second layer 120 can include additional well known and desirable properties, for example, blocking or reflecting all or select portions of the electromagnetic spectrum, for example, ranging from infrared to ultraviolet. In addition, the second layer 120 can also include a pattern that matches or is complementary to the pattern of channels etched into the first layer 110. For example, with regard to the diamond pattern shown in
In accordance with some embodiments of the invention, an additional layer of a material can be positioned between the first layer 110 and the second layer 120 as desired to improve the thermal transfer characteristics of the window. This additional layer of a material can be selected to provide additional thermal insulating or conducting properties to the design of the window to decrease or increase the transfer of energy from the window surface. In one aspect of this embodiment, the second layer 120, including the patterned array of channel, would not be in direct contact with the surface of the first layer 110 of the window. In some aspects of this embodiment, the additional layer of material can include light blocking or reflecting properties, such as the Mylar films used to block or reflect all or select portions of the electromagnetic spectrum, for example ranging from infrared to ultraviolet. In accordance with some embodiments of the invention, the first layer 110 can be bonded or laminated to the second layer to form a transparent window pane using a transparent adhesive, such as a silicone or PDMS based adhesive that provides a conformal seal, or using heat bonding or other adhesives, plastics or polymers.
In accordance with some embodiments of the invention, the second layer 110 can include a patterned array of channels 130 which when bonded to the first layer produce channels and/or microchannels that permit a fluid 160 to flow over predefined areas of the surface of the first layer. As shown in
In accordance some embodiments of the invention, the channels can be arranged or configured in the form a networked array of channels, for example as show in
In accordance with the invention, one or more fluids can be caused to flow through the channels of the heat exchange layer. As used herein, the term fluid includes any flowable medium, including solid particles, liquids and gases as well as mixtures or combinations of any of the foregoing materials. Examples include, water and air, as well as suspensions of materials and particles in water or air. Examples of fluids can include water, ethylene glycol, oil, silicone oil, hydrocarbons, nitrogen-containing compounds, oxygen-containing compounds, sulfur-containing compounds, fluorinated compounds, carbonyl compounds, alcohols, acids, bases, anhydrides, thiols, esters, heterocyclic compounds, sulfides, organosilicates, organometallic compounds, halogenated derivatives, as well as mixtures or combinations of any of the materials disclosed herein. Further examples of fluids can include vapors comprising air, steam, acetone, acetylene, alcohol, ammonia, argon, benzene, butane, carbon dioxide, ethane, ether, ethylene, Freon, helium, hexane, hydrogen, hydrogen chloride, hydrogen sulfide, hydroxyl, methane, methyl chloride, Neon, nitric oxide, nitrogen-containing compounds, oxygen-containing compounds, halogenated compounds, oxygen, nitrogen, pentane, propylene, sulfur dioxide, as well as mixtures or combinations of any of the materials disclosed herein. These and other materials can be selected and used to formulate a fluid that provides a high heat capacity and high heat transfer rate.
In addition, the fluid can include colored dyes or other materials that change the light transmission properties of the fluid to modulate the light energy that penetrates the window. The fluid can have light absorbing, scattering, blocking or reflecting properties that enable the fluid to prevent some or all of the light from being transmitted through the window. In addition, the fluid can be selected or formulated to absorb, scatter, block or reflect a portion of the light transmitted, for example, absorbing, scattering, blocking or reflecting, either partially or entirely, a specific wavelength, range of wavelengths or predetermined portion of the electromagnet spectrum. In some embodiments of the invention, the fluid can include a suspension of nanoparticles including TiO2, quantum dots, gold, aluminum, nickel, cadmium, antimony, barium, buckminsterfullerenes, carbon, copper, lithium, silica, as well as mixtures or combinations of any of the materials disclosed herein. In some embodiments of the invention, the fluid can include a suspension of particles including carbon black, barium, apatite, beryl, bismuth, calcite, cement, chalk, coal, clay, coke, glass, plastic, stone, mineral, rubber, or organic compounds or polymers, as well as mixtures or combinations of any of the materials disclosed herein. These and other materials can be selected and used to formulate a fluid having the desired index of refraction. In some embodiments, the index of refraction of the fluid can be selected to match that of the first and second layer to maximize optical transparency. In other embodiments, the index of refraction of the fluid can be selected to maximize light diffusion or absorption, either broadly or in one or more narrow bands.
In some embodiments of the invention, the fluid can be fed into the heat exchange layer using gravity, such as by locating the reservoir holding the fluid at an elevation above the level of the window. In some embodiments, the fluid can be fed in the top of the window and gravity can be used draw the fluid down through the heat exchange layer to one or more outlet ports at the bottom of the window. Alternatively, the fluid can be fed in the bottom of the window and the head pressure can be used push the fluid up through the heat exchange layer to one or more outlet ports at the top of the window. In other embodiments, channels of the heat exchange layer can be sized and configured to enable capillary action to draw the fluid through the heat exchange layer, either up from the bottom of the window or across, from one side of the window to the other side of the window. In other embodiments of the invention, a pump can be used to pump the fluid into the window or a pressurized container or up to an elevated reservoir in order to provide the pressure necessary to flow the fluid at the desired flow rate through the channels 130 of the window 100.
In some embodiments of the invention, the flow rate of the fluid through the channels can be in the range from 0.1 mL/min to over 20 mL/min. The flow rate of the fluid can be selected according to the desired heat transfer of the system, taking into account the physical dimensions of the channels and the heat transfer characteristics of the fluid and window materials. In some embodiments of the invention, the Tin and Tout can be monitored and flow rate can be increased or decreased to achieve the desired heat transfer. A computer or microcontroller can be used to receive Tin and Tout data and control a variable speed pump to increase or decrease the flow rate maintain a predefine level of system performance.
In accordance with one embodiment of the invention, where the window is installed in a hot, sunny environment, the fluid flow can be used to convectively cool the inside window surface, absorbing thermal energy from the glass surface, such that Tout>Tin. This convective heat transfer can be used to effectively decrease the temperature of the inner window surface, preventing the heat from entering the building and decrease the energy associated with air conditioning the building. Therefore, this cooling function can be used to increase the insulating efficiency and the overall energy efficiency of the building itself.
In accordance with one embodiment of the invention, the heat exchange layer can be employed in a system for cooling the surface of a window in a building to improve the energy efficiency of the building. The fluid at a lower temperature than the window can be fed into the heat exchange layer to convectively cool the window and control the transfer of heat energy from the outside to the inside of the building through the window. The warmed fluid received from the heat exchange layer can be cooled, either directly or indirectly, by the existing cooling system of the building before being fed back into the heat exchange layer. Alternatively, the warmed fluid can be fed outside where it is allowed to evaporate away.
In an alternative embodiment of the invention, the system can be used as part of a solar energy harvesting system that supplies heated water to the existing hot water system or to heat storage system that can be used for warming the building when the outside temperature drops, such as in the evenings.
In accordance with another embodiment of the building, the heat exchange layer can be employed in a system for heating the surface of a window in a building to improve energy efficiency of the building during the colder seasons. The fluid at a higher temperature than the window can be fed into the heat exchange layer to convectively warm the window and control the transfer of heat energy from the inside to the outside of the building through the window. The cooled fluid received from the heat exchange layer can be re-heated by the existing heating system of the building before being fed back into the heat exchange layer.
In accordance with other embodiments of the invention, the fluid that flows through the heat exchange layer can include colored dyes or other materials that change the light transmission properties of the fluid to modulate the light energy that is transferred into a room and further improve energy efficiency, as well as to provide esthetic control. In this embodiment, different fluids can be selectively fed into the heat exchange layer in response to environmental conditions, for example, by cooperating with the lighting, heating and cooling systems of the building with the goal of providing maximum energy efficiency. A fluid manifold, under thermostatic, electro-optical or computer control can be used to select appropriate solenoid valves to allow the desired fluid to provide more optimum use of energy for the room and the building. For example, where bright sunlight is beaming into a window, a more opaque or light diffusing fluid that has high heat absorbing properties can be selected reduce the brightness in the room and collect the excess heat to control the temperature in the room. The heated fluid can be stored in an insulated container until the sun goes down and then used to warm the window and provide some privacy in the evening hours. Without wishing to be bound by a theory, a steady state thermal transport model can be used to estimate the effect of fluid flow rate on the window temperature.
In some embodiments of the invention, the fluid can be heated or cooled by the ambient air in the room adjacent to the window before the fluid is returned to the channels in the window. For example, during the winter time, the ambient heat in the room adjacent to the window will rise to the ceiling and can be used to warm the fluid in ceiling mounted heat exchange tubing or microfluidic channels. The warmed fluid can be pumped or driven by gravity into the heat exchange layer of the window to warm the window.
In some embodiments of the invention, the heat exchange layer can be provided on one of the surfaces of a multi-pane window. In multi-pane windows, two or more glass panels are provided in a spaced-apart configuration. The space or gap between the glass panels is typically filled with a low energy transferring gas. In some embodiments of the invention, a heat exchange layer can be provided on one or both of the glass panel surfaces in the gap to heat or cool the inside or outside glass panel of the window.
In some embodiments, an outer heat exchange layer can be provided on the outside of the window and an inner heat exchange layer can be provided on the inside of the window. During the cold seasons, solar energy can be used to heat the fluid in the outer heat exchange layer that can flow through the window or window frame and into the inner heat exchange layer and warm the inside of the window. In this embodiment, counter-current flows within an insulating medium separating the panes can be used to enhance heat transfer.
In some embodiments of the invention, the exposed surface area of channels across the inside surface of the window can be convection heated or cooled to room temperature by ambient room air that is heated/cooled by the central heating/air conditioning functions of the house or building. And the exposed surface area of channels distributed across the outside surface of the window would similar be heated or cooled by external environmental conditions, convection and solar energy. These parallel ‘capillary plexuses’ at the inner and outer surface layers of the window can be connected by channels with fluids flowing in opposite direction that are closely juxtaposed to one another so that heat can exchange across their walls. By continuously flowing small volumes of fluids through these channels, the invention can be used to increase the insulating efficiency of the window, sustain the temperature differential across their width, and be maintained at a relatively constant temperature regardless of the temperature differential across the window, thereby minimizing thermal gain in summer and heat loss in winter. The efficiency of this response can be based on incorporation of a counter current heat exchanger design including an insulating layer into the device that mimics configurations that are utilized for similar thermal stabilization effects in living organisms.
In one embodiment of the invention, using a flow rate of 2.0 mL/min of a fluid at room temperature can be used to cause a temperature drop of around 7 to 10° C. for windows according to the invention. This amount of cooling would be significant for a building in which windows represent a majority of the thermal transfer losses.
In an alternative embodiment, the thermal convective cooling (or heating) of windows can be used to heat water, exiting the windows, as a source of solar heated water for household use.
In some embodiments of the invention, an optically-absorbing or cloudy (light scattering) dye or particle suspension could be incorporated into the fluid to actively change the optical absorption/transmission spectrum (i.e.; transparency) of the window as a whole.
In one embodiment of the invention, the window can utilize a closed loop flow system driven by a small electric pump that could be located within the window frame. Alternatively, it could involve use of evaporative pumping and require a water reservoir that requires connection to a continuous source or refilling by the user. The heating can be done by the internal surface of the window that contacts the heated room air in winter, and by the external glass surface that contacts the heated external environment in summer. In both cases, the counter current heat exchanger would minimize heat transfer across the insulated layer. These fluidic channels also could be incorporated in the window frame and window seals to further prevent heat loss along the window edges.
Additional descriptions of the principles of the invention and further embodiments of the invention are described in the attached Appendix A, which is hereby incorporated by reference in its entirety.
In accordance with the invention, standard principles for thermal heat exchangers can be applied to this kind of transparent window heat exchange design. For example, the design of the channel network can be made such that the path length of flow is equal across the area of the network. Therefore, there would be uniform heat transfer across the area of the PDMS layer.
Furthermore, in accordance with another embodiment of the invention, ‘smart’ switching of the channels could allow for variable flow of the fluid within the fluidic network, similar to the vascular network of blood flow or in plant leaves. Manual or temperature-sensitive valves could be incorporated to increase flow to increased numbers of channels covering greater surface area on the outside of the window at night to cool buildings in summer or on the inside of the windows to warm windows in winter.
Other embodiments are within the scope and spirit of the invention. For example, due to the nature of software, functions described above can be implemented using software, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Controllers, pumps and valves also can be located within the material surface layer, within a surrounding window frame or at a distance if linked by fluid-bearing channels.
The invention can be described by any of the following numbered paragraphs:
Further, while the description above refers to the invention, the description may include more than one invention.
Unless stated otherwise, or implicit from context, the following terms and phrases include the meanings provided below. Unless explicitly stated otherwise, or apparent from context, the terms and phrases below do not exclude the meaning that the term or phrase has acquired in the art to which it pertains. The definitions are provided to aid in describing particular embodiments, and are not intended to limit the claimed invention, because the scope of the invention is limited only by the claims. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.
As used herein the term “comprising” or “comprises” is used in reference to compositions, methods, and respective component(s) thereof, that are useful for the invention, yet open to the inclusion of unspecified elements, whether useful or not.
The singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term “about.” The term “about” when used in connection with percentages may mean±5% of the value being referred to. For example, about 100 means from 95 to 105.
Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The term “comprises” means “includes.” The abbreviation, “e.g.” is derived from the Latin exempli gratia, and is used herein to indicate a non-limiting example. Thus, the abbreviation “e.g.” is synonymous with the term “for example.”
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow. Further, to the extent not already indicated, it will be understood by those of ordinary skill in the art that any one of the various embodiments herein described and illustrated may be further modified to incorporate features shown in any of the other embodiments disclosed herein.
All patents and other publications identified in the specification and examples are expressly incorporated herein by reference for all purposes. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.
This application claims benefit under 35 U.S.C. §119(e) of the U.S. Provisional Application No. 61/447,872, filed Mar. 1, 2011, the content of which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2012/027253 | 3/1/2012 | WO | 00 | 1/13/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61447872 | Mar 2011 | US |
