ARCHITECTURAL HEAT AND MOISTURE EXCHANGE
An architectural heat and moisture exchanger. The exchanger defines an interior channel which is divided into a plurality of sub-channels by a membrane configured to allow passage of water vapor and to prevent substantial passage of air. In some embodiments, the exchanger includes an opaque housing configured to form a portion of a building enclosure, such as an exterior wall, an interior wall, a roof, a floor, or a foundation.
Latest ARCHITECTURAL APPLICATIONS P.C. Patents:
This application is a continuation of U.S. patent application Ser. No. 13/942,376, filed Jul. 15, 2013, which is a continuation of U.S. Patent Application Serial No. 13/747,218, filed Jan. 22, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 13/185,439, filed Jul. 18, 2011, which claims priority from U.S. Provisional Patent Application Ser. No. 61/365,173, filed Jul. 16, 2010, each of which are incorporated herein by reference. This application also incorporates by reference in its entirety for all purposes the following: U.S. Pat. No. 6,178,966, issued Jan. 30, 2001 and U.S. Patent Publication No. 2007/0151447 to Merkel, published Jul. 5, 2007.
INTRODUCTIONIn centrally heated or cooled buildings, fresh air or “makeup air” is typically added continuously to the total volume of circulated air, resulting in some previously heated or cooled air being exhausted from the building space. This can result in an undesirable loss of energy and humidity from the building. Heat exchangers are commonly used in the exhaust air and makeup airflow paths of these systems to recover some of the energy from the exhaust air and to induce warmer makeup air during heating processes and cooler makeup air during cooling processes.
Materials used for heat exchangers commonly include metal foils and sheets, plastic films, paper sheets, and the like. Good heat exchange is generally possible with these materials, but significant moisture exchange cannot easily be performed. Desiccants, or moisture adsorbing materials, are occasionally employed to transfer moisture. With this method, the desiccant merely holds the moisture. To effectively transfer moisture between gas streams, the desiccant must be relocated from the gas stream of higher moisture content to the gas stream of lower moisture content, requiring an additional input of mechanical energy. With many desiccant materials, satisfactory performance can be achieved only with the input of additional thermal energy to induce the desiccant to desorb the accumulated moisture.
Heat and moisture exchange are both possible with an exchange film made of paper. However, water absorbed by the paper from condensation, rain, or moisture present in the air can lead to corrosion, deformation, and mildew growth, and, hence, deterioration of the paper exchange film.
The various types of heat and moisture exchangers in common usage are generally contained within an opaque metal housing and located at or near the building air-handling units in the mechanical room, basement, or rooftop of the building. The nature of moisture exchange requires a very large surface area in contact with the gas stream, and, consequently, so-called total heat exchangers are often very large in size when compared to heat-only exchangers. A larger exchanger in the conventional locations requires additional mechanical room space and/or additional load-bearing capacity of the roof in the case of a roof-top unit.
Porous polymeric or ceramic films are capable of transferring both heat and moisture when interposed between air streams of differing energy and moisture states. A system for heat and moisture exchange employing a porous membrane is described in Japanese Laid-Open Patent Application No. 54-145048. A study of heat and moisture transfer through a porous membrane is given in Asaeda, M., L. D. Du, and K. Ikeda. “Experimental Studies of Dehumidification of Air by an Improved Ceramic Membrane,” Journal of Chemical Engineering of Japan, 1986, Vol. 19, No. 3. A disadvantage of such porous composite film is that it also permits the exchange of substantial amounts of air between the gas streams, as well as particles, cigarette smoke, cooking odors, harmful fumes, and the like. With respect to building indoor air quality, this is undesirable. In order to prevent this contamination of make-up air, the pore volume of a porous film is preferably no more than about 15%, which is difficult and expensive to achieve uniformly. Furthermore, a porous film made to a thickness of 5 to 40 micrometers in order to improve heat exchange efficiency tears easily and is difficult to handle.
U.S. Pat. No. 6,178,966 to Breshears addressed the shortcomings described above by describing an improved apparatus for enabling heat and moisture exchange between makeup and exhaust air streams in the heating and air conditioning system of a structure. The apparatus included a rigid frame for holding a pair of light transmitting panes, the frame and panes collectively defining an interior cavity within the apparatus. The apparatus could be integrated into the exterior walls of a building. The light transmitting properties of the panes allow incident solar radiation to permeate the panels, creating a more natural ambient environment in the interior of the structure adjacent with the panel, as well as raising the temperature of the air stream and the water vapor permeable barrier to further enhance the exchange of moisture through the barrier.
In the prior art Breshears apparatus, a water-vapor-permeable barrier was provided within the apparatus, to divide the interior of the apparatus into sub-channels for receiving makeup and exhaust air streams, respectively. The barrier was described as a composite film made of porous polymeric membrane having applied thereto a water-vapor-permeable polymeric material so as to form a non-porous barrier to block the flow of air and other gas.
Despite overcoming some of the shortcomings of preexisting systems, the prior art Breshears apparatus was limited in some ways. For example, the disclosed apparatus was limited to transparent structures configured to be integrated into the exterior of a building. Furthermore, the polymeric membranes described by Breshears were limited to certain particular membrane materials.
The present teachings relate to improved methods and apparatus for recovering energy and/or moisture as air is added to and exhausted from an enclosed space. These teachings may be combined, optionally, with apparatus, methods, or components thereof described in U.S. Pat. No. 6,178,966 to Breshears. However, the present teachings expand upon the prior art teachings by disclosing novel improvements such as an exchanger incorporated into an opaque exterior building element. These and other aspects of the present teachings are described in detail in the sections below.
This description discusses some of the basic features of heat and moisture exchangers according to aspects of the present teachings, and focuses particularly on incorporating exchangers into various external building elements, such as walls, foundations, roofs, and slab floors configured to divide an enclosed space from the ambient exterior and collectively referred to as a building enclosure system. See
In the embodiment of
Barrier 18, which divides interior channel 16 into sub-channels 20 and 22, is generally permeable to water vapor and substantially impermeable to the constituent gases of air, which principally include nitrogen and oxygen. Various types of barriers may be suitable for use with the present teachings, including microporous polymeric membranes with appropriate characteristics. One particularly suitable type of polymeric membrane is described in U.S. Patent Publication No. 2007/0151447 to Merkel, which is hereby incorporated by reference into the present disclosure for all purposes.
In a manner described in more detail below, source and exhaust gas streams, respectively denoted throughout the drawings as gas stream A and gas stream B, are directed through adjacent sub-channels 20 and 22 within exchanger 10. Due to the proximity of the air streams, heat may be conducted from the hotter gas stream through barrier 18 and into the cooler gas stream, and moisture may be transported from the gas stream of higher moisture content through barrier 18 and into the gas stream of lower moisture content. Various barrier configurations and resulting geometries of sub-channels may be chosen depending on the desired heat transfer, moisture transfer, and pressure drop characteristics. The following paragraphs include descriptions of various such arrangements, with barriers and sub-channels that function in a manner similar to those described above.
Similar arrangements having odd numbers of barriers with corresponding even numbers of sub-channels are possible, such as disposing five barriers within channel 86 to form six sub-channels evenly divided between gas stream A and gas stream B. Alternatively, some examples may have any number of barriers forming any corresponding number of sub-channels, divided unevenly between gas streams A and B. For example, four barriers may be used to form five sub-channels, with three devoted to gas stream A and two to gas stream B. In yet other examples, the barrier arrangements of exchangers 40 and 80 may be combined to produce parallel pleated or corrugated barriers, or even alternating corrugated and flat barriers, in any case forming sub-channels with corresponding shapes.
For example,
More specifically, The following description discusses some of the basic methods of configuration and integration of the heat and moisture exchangers into elements of the building according to the present teachings. See
The subsequent description also contemplates a heat and moisture exchanger for integration into a portion of the building enclosure. In this example certain portions of the exchanger may be transparent to various spectra of radiation, resulting in transfers of radiant energy between elements of the exchanger system. In this embodiment, the transmissivity of the radiation-transmitting elements and the geometry of the radiation-absorbing objects may be configured to control the fraction of heat- or light-energy incident on the exchanger housing that is transmitted through the exchanger to the building interior. The absorptivity and emissivity properties of the material from which the elements are made may be determined and selected to enhance the transmission of radiation within the desired spectra and simultaneously to maximize the absorption of radiation outside the desired spectra. These teachings expand upon the prior art teachings to address shortcomings by disclosing a radiation-energy transferring exchanger in which the energy-absorbing objects may be of various geometries and materials and may be configured within one gas stream or the other in order to best exploit the absorbed energy that is re-emitted as heat via convection into that gas stream.
Exchanger 10 is an apparatus for enabling heat and moisture exchange between air streams while simultaneously enabling transfer of radiant energy incident on the exchanger surface to certain other elements within the assembly. An exchanger housing, generally indicated at 12, includes exterior walls 320 which may be transmissive to incident radiation over certain spectra. These walls define an interior channel 16 through which a gas may pass. A barrier 324 which is also transmissive to certain wavelengths of radiation is disposed within interior channel 16 and partitions interior channel 16 into sub-channels 20 and 22, each of which is adapted to receive a gas stream, such as a source air stream A and an exhaust air stream B, respectively. Channel 16, and thus sub-channels 20 and 22, may be in fluid communication with gas stream sources via suitably located openings in housing exterior wall 320 such as openings 24 and 26 shown in
In the embodiment of
Barrier 324, which divides interior channel 16 into sub-channels 20 and 22, is generally permeable to water vapor and substantially impermeable to the constituent gases of air, which principally include nitrogen and oxygen. Various types of barriers may be suitable for use with the present teachings, including microporous polymeric membranes with appropriate characteristics. One particularly suitable type of polymeric membrane is described in U.S. Patent Publication No. 2007/0151447 to Merkel, which is hereby incorporated by reference into the present disclosure for all purposes.
In the configuration represented in
The present teachings relate to improved methods and apparatus for recovering energy and/or moisture as air is added to and exhausted from an enclosed space. The heat and moisture exchangers described in the present teachings may induce some change in temperature and humidity of incoming ventilation air as it passes through the exchanger by transfer to an outgoing air stream also passing though the exchanger. In cases where further alteration of the temperature or humidity of the incoming air stream is desired beyond what is induced by the exchanger, the exchanger may be interconnected and configured to operate with a separate apparatus or device providing additional heating, cooling, dehumidification or humidification to the airstream. This heating, ventilating and air conditioning device (which may be referred to herein as simply “HVAC”) may be an apparatus of various types or functions. An incoming gas stream, designated as A, is directed through the heat and moisture exchanger and at some point on its path of travel may also be processed by the HVAC in order to alter its temperature and/or humidity. An outgoing gas stream, designated as B, may be directed from the interior space to the exterior by passing through the heat and moisture exchanger. The descriptions that follow relate to methods in which a system of heat and moisture exchangers and HVAC devices may be configured to alter the temperature and humidity of an air stream as it is added to an enclosed space. See
An enclosed space 410 is depicted in
An enclosed space 410 is depicted in
In
The disclosure set forth herein encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. Each example defines an embodiment disclosed in the foregoing disclosure, but any one example does not necessarily encompass all features or combinations that may be eventually claimed. Where the description recites “a” or “a first” element or the equivalent thereof, such description includes one or more such elements, neither requiring nor excluding two or more such elements. Further, ordinal indicators, such as first, second or third, for identified elements are used to distinguish between the elements, and do not indicate a required or limited number of such elements, and do not indicate a particular position or order of such elements unless otherwise specifically stated.
Claims
1. An apparatus for enabling heat and moisture exchange within a building, comprising:
- an exchanger housing including an exterior wall which is substantially transparent to radiation within a spectrum, the housing defining an interior channel configured to be disposed within a building, to receive an incoming air stream from an environment outside the building, to pass the incoming air stream into an environment inside the building, to receive an outgoing air stream from the environment inside the building, and to exhaust the outgoing air stream to the environment outside the building;
- a membrane, permeable to water vapor and substantially impermeable to constituent gases of air, disposed within the housing and dividing the interior channel into a first sub-channel through which the incoming air stream may pass and a second sub-channel through which the outgoing air stream may simultaneously pass; and
- at least one radiation absorbing element disposed within one of the sub-channels and configured to absorb radiation passing through the exterior wall of the exchanger and to transfer heat by convection to the air stream passing through the sub-channel within which the radiation absorbing element is disposed.
2. The apparatus of claim 1, wherein the radiation absorbing element is further configured to absorb radiation passing through the membrane.
3. The apparatus of claim 1, wherein the radiation absorbing element is disposed within the first sub-channel and is configured to transfer heat to the incoming air stream by convection.
4. The apparatus of claim 1, wherein the radiation absorbing element is disposed within the second sub-channel and is configured to transfer heat to the outgoing air stream by convection.
5. The apparatus of claim 4, wherein the membrane is substantially transparent to radiation within the spectrum, and wherein the radiation absorbing element is configured to absorb radiation passing through both the exterior wall of the exchanger and the membrane.
6. The apparatus of claim 1, wherein the exchanger housing, the membrane and the radiation absorbing element are collectively configured to allow a desired fraction of radiation incident on the exchanger housing to be transmitted to the building interior.
7. A system for enabling heat and moisture exchange between air streams entering and leaving a building, comprising:
- a heat and moisture exchanger including exterior walls constructed at least partially from radiant energy transmitting enclosure material and which define an interior channel;
- a membrane, permeable to water vapor and substantially impermeable to constituent gases of air, disposed within the interior channel and dividing the interior channel into a first sub-channel through which a source air stream may pass and a second sub-channel through which an exhaust air stream may simultaneously pass;
- a first opening in the exterior walls configured to allow ingress of the source air stream from an external environment into the first sub-channel;
- a second opening in the exterior walls configured to allow ingress of the exhaust air stream from an interior enclosure of the building into the second sub-channel; and
- at least one radiation-absorbing element disposed within one of the sub-channels;
- wherein the energy transmitting enclosure material has a transmissivity, the radiation-absorbing element has a geometry, and the transmissivity and the geometry are collectively configured to control a fraction of energy incident on the exterior walls that is transmitted through the exchanger to the interior enclosure of the building.
8. The system of claim 7, wherein the at least one radiation-absorbing element includes a plurality of discrete radiation-absorbing elements.
9. The system of claim 7, wherein the at least one radiation-absorbing element includes a plurality of interconnected radiation-absorbing elements.
10. The system of claim 7, wherein the exchanger is configured to be coupled with an HVAC unit and to direct the source air stream into the HVAC unit after the source air stream passes through the exchanger.
11. A heat and moisture exchanger system, comprising:
- an exchanger housing including exterior walls defining an interior channel;
- a barrier disposed within the interior channel and partitioning the interior channel into a first sub-channel adapted to receive a source air stream and a second sub-channel adapted to receive an exhaust air stream; and
- a plurality of radiation-absorbing elements disposed within one of the sub-channels and each configured to absorb radiant energy incident upon a surface of the radiation-absorbing element, and to re-emit at least a fraction of the absorbed energy by convection.
12. The system of claim 11, wherein at least one of the exterior walls is transparent to radiation within a first spectrum.
13. The system of claim 12, wherein the barrier is transparent to radiation within the first spectrum.
14. The system of claim 12, wherein the barrier is transparent to radiation within a second spectrum.
15. The system of claim 12, wherein the radiation-absorbing elements are transparent to radiation within the first spectrum.
16. The system of claim 12, wherein the radiation-absorbing elements are disposed within the first sub-channel.
17. The system of claim 12, wherein the radiation-absorbing elements are disposed within the second sub-channel.
18. The system of claim 11, wherein the radiation-absorbing elements are discrete.
19. The system of claim 11, wherein the radiation-absorbing elements are interconnected.
20. The system of claim 11, wherein first sub-channel is further adapted to direct the source air stream toward a building interior, wherein the exterior walls have a transmissivity, wherein the radiation-absorbing elements have a geometry, and wherein the transmissivity and the geometry are collectively configured to control a fraction of energy incident on the exchanger housing that is transmitted through the exchanger to the building interior.
Type: Application
Filed: Oct 15, 2013
Publication Date: Feb 6, 2014
Applicant: ARCHITECTURAL APPLICATIONS P.C. (Portland, OR)
Inventor: John Edward BRESHEARS (Portland, OR)
Application Number: 14/053,921
International Classification: F28D 21/00 (20060101);