Patent Application
20060185819
It is well known that excessive moisture in buildings causes considerable problems. Drywall and flooring absorb moisture and are readily damaged if the excessive moisture condition persists for any length of time. Interior elements such as insulation, studs, and joists can eventually be affected as well. Furthermore, mold begins to form on the damp building materials, and can remain in the structure even after it has dried, causing breathing problems for persons occupying the building.
At the extreme, such excessive moisture conditions are exemplified by a flooded building. U.S. Pat. No. 6,457,258 to Cressy et al., “Drying Assembly and Method of Drying for a Flooded Enclosed Space”, discloses an apparatus for drying flooded buildings that overcomes problems in the prior art. Such prior art is said to require stripping wall and floor coverings and using portable dryers to circulate air to dry out the exposed floor boards, joists and studs. The methods were slow and allowed mold to form on the interior framing, which could then go unnoticed and be covered up and then later present a health hazard to occupants.
The solution proposed by Cressy is to introduce very hot and dry air into the building, indicated as being at 125° F. and 5% relative humidity, in order to dry the building very quickly to prevent mold growth and allow an early return to occupants. In the apparatus of Cressy et al., outside air is heated by a furnace and the heated air is blown into the building where it picks up moisture and then is exhausted back outside. In Cressy heat from the warmer exhaust air is transferred to the cooler outside air prior to heating by the furnace, thereby increasing the efficiency of the system.
While the method proposed by Cressy can be effective, it is not practical to use such a system where the building being dried must be occupied. The very hot dry air moving through the building is not conducive to occupancy by persons, nor to effective work output of occupants. Thus no drying can take place during business hours for example, and considerable time may also be required for the building's conventional air conditioner to return the interior air from the high temperatures involved during drying to conditions suitable for occupancy.
Prior art systems for drying flooded buildings also include desiccant dehumidifiers that use a desiccant material with a high affinity to water to absorb water from the air, and refrigerant dehumidifiers that condense water out of the air by cooling it. In both of these systems, the water must be disposed of in some manner. The water absorbed by the desiccant material is removed by subsequently drying the material. The water condensed by the refrigerant system is collected in a reservoir that must be emptied from time to time or piped to a disposal area. Such systems are relatively costly to manufacture and operate, and are relatively slow to remove moisture from the subject building.
It is an object of the present invention to provide a system for drying occupied buildings that overcomes problems in the prior art.
Co-pending United States Published Patent Application 2005/0145109 of the present inventors discloses a controlled system for maintaining a desired humidity level in buildings and for drying buildings. Portable heat exchanger units comprise a fluid coil and a fan drawing air from an inlet through the coil and out an outlet. The coil is connected by conduits to a fluid heater or fluid cooler such that the air passing through the coil can be either heated or cooled. By drawing in outside air and heating it, the relative humidity of the air is reduced, and the drier air is directed into the building. A vent is provided, typically somewhere opposite the intake, so that the drier air moves through the building and picks up moisture from building and carries it out through the vents.
Again, such a system as disclosed in Dancey et al. is not conducive to use in occupied buildings in warm climates, since the air passing through the building has a higher temperature than the outside air, which will be very uncomfortable where the outside air is already excessively warm. By connecting the fluid coil to a fluid cooler, the air inside the building can be cooled as well to allow occupancy, however no drying will take place when cooled air is circulating.
The present invention provides, in a first embodiment, a portable heat exchanger unit comprising at least one fan operative to create an air stream by drawing air from an intake and discharging the air stream through an outlet. A first temperature adjusting element is located in the air stream, and a second temperature adjusting element is located in the air stream downstream from the first temperature adjusting element. The portable heat exchanger unit is configured such that a temperature of the air stream can be changed by at least one of the first and second temperature adjusting elements.
Conveniently the temperature adjusting elements can be provided by fluid coils connected to receive hot or cold circulating fluid from a fluid heater or cooler, such that either element can be used to increase or decrease the temperature of the air stream, add in versatility to the apparatus. Alternatively the temperature adjusting elements can be provided by refrigerant coils, electric heating elements, or the like.
The present invention provides, in a second embodiment, a system for removing moisture from an occupied building interior using the portable heat exchanger unit. In the system the first temperature adjusting element is operative to cool the air stream, and the second temperature adjusting element is operative to heat the air stream. The intake is oriented such that the fan draws ambient air from outside the building and the outlet is oriented to direct the air stream into the building interior.
The present invention provides, in a third embodiment, a method for removing moisture from an occupied building interior comprising with at least one fan, creating an air stream by drawing air from an intake located outside the building and discharging the air stream through an outlet located in the building interior; with a first temperature adjusting element, cooling the air stream to a temperature below the dew point and condensing water out of the air stream; directing the air stream leaving the first temperature adjusting element to pass through a second temperature adjusting element, and with the second temperature adjusting element, heating the air stream to a desired temperature; providing a vent in the building such that the air stream can flow from the outlet through the building interior and out through the vent.
Compared to prior art desiccant and refrigerant dehumidifiers for drying occupied buildings, the present invention provides a system and method that are relatively economical to build and operate. Outside air is first cooled to condense at least some water out of the air, and then re-heated to a desired temperature for directing into the building interior at a reduced relative humidity. The air at a reduced relative humidity absorbs excess moisture from the building interior at an increased rate.
While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:
In
Alternatively the first temperature adjusting element, operative to cool the air stream 5, can be provided by a refrigerant coil connected to a conventional refrigeration unit, and the second temperature adjusting element, operative to heat the air stream 5, can be provided by an electrical heating element. However use of fluid coils 11, 13 provides added versatility in that each coil can be used to either heat or cool the air stream 5.
The illustrated embodiment of
In the illustrated use for removing moisture from an occupied building interior 21, the system 20 is configured such that the intake 7 of the portable heat exchanger unit I is oriented such that the fan 3 draws ambient air from outside the building 29 and the outlet 9 is oriented to direct the air stream 5 into the building interior 21. A vent 31 is provided in the building 29 to allow air to exit the building interior 21.
The method for removing moisture from the occupied building interior 21 comprises, with the fan 3, creating the air stream 5 by drawing air from the intake 7 located outside the building 29 and discharging the air stream 5 through the outlet 9 located in the building interior 21. The fluid cooler 23 is connected to the first fluid coil 11 located in the air stream 5 and cooled fluid is circulated through the first fluid coil 11 to at a flow and temperature sufficient to cool the air stream 5 to a temperature below the dew point and thereby condense water out of the air stream 5.
For example, where the outside air has a temperature of 80° F. and a relative humidity of 60%, cooled fluid will be circulated through the first fluid coil 11 such that the temperature of the air stream 5 as it exits the first fluid coil will be 62° F., which is below the dew point of the outside air in the air stream 5, such that some water will condense out of the air stream 5 and such that the relative humidity of the air will be 100%. Relative humidity is a measure of the water holding capacity of the air. Therefore at 100% relative humidity, air is saturated and can hold only so much water, and any excess water in the air will condense into liquid form.
The water holding capacity of air decreases with temperature, such that the relative humidity increases as temperature decreases. Conversely raising the temperature of air will increase the water holding capacity thereof such that the relative humidity decreases as the temperature increases. The relationship is known to be such that raising the temperature of air by 18° F. will reduce the relative humidity of the air stream by one half, and conversely decreasing the temperature by 18° F. will double the relative humidity.
In contrast, the term “grains of moisture per pound of dry air” (GPP) is used to measure the actual weight of the water in a volume of air. The GPP of air at 80° F. and a relative humidity of 60% is greater than the GPP of air at 62° F. and a relative humidity of 100%, and thus water must condense out of the air stream when the temperature thereof is reduced to 62° F. As the water condenses out of the air stream, the GPP of the air stream is decreased somewhat and the relative humidity of the air stream 5 as it exits the first fluid coil at 62° F. will be 100%.
The fluid heater 25 is connected to the second fluid coil 13 that is located in the air stream 5 between the first fluid coil 11 and the outlet a 9, and heated fluid is circulated through the second fluid coil 13 to heat the air stream 5 to a desired temperature. In the present example the temperature of the air stream 5 leaving the first fluid coil can be raised 18° F. from 62° F. back up to 80° F., the same as the outside temperature, thus reducing the relative humidity by one half to 50%. Because the GPP of the air stream 5 has been reduced by condensation, the relative humidity of the air stream 5 as it leaves the second fluid coil 13 and enters the building interior 21 through the duct 9 will thus be 50%, instead of the 60% relative humidity of the outside air, even though it is at the same temperature as the outside air.
Thus the water holding capacity of the air stream 5 entering the building interior 21 has been increased compared to the outside air by removing some water from the air stream 5. As the relative humidity is decreased, the moisture gradient between the wet building surfaces and the air increases such that water is absorbed at a faster rate, as well as in greater quantities.
As the air stream circulates through the building interior 21 to the vent 31, it absorbs moisture and dries the building interior 3. The air stream 5 will absorb an increased amount of moisture from the building interior 21, and will absorb moisture at an increased rate, compared to simply drawing in and circulating the outside air through the building interior 3. The temperature of the air stream can be selected such that the building interior 3 is fairly comfortable for those occupying the building, and yet at least some improved drying can take place during the hours the building must be occupied.
Where practical, the rate of drying in the building interior 21 can be further increased by locating the second portable heat exchanger unit 101 inside the building interior to remove moisture from interior air.
The above illustrates the principal of the operation of the invention, with values given as examples only. Decreasing the temperature of the incoming outside air by a greater amount will result in the condensation of an increased amount of water, thus lowering the GPP of the air further, such that when the temperature is increased at the second fluid coil the relative humidity will be further reduced, and the rate of drying further increased. For example decreasing the tm of the air exiting the first fluid coil to 60° F. instead of 62° F. will result in more water condensing out of the air, such that when it is raised again to 80°0 F. at the second fluid coil, the relative humidity will be about 47.5%. The reduction in relative humidity is thus increased by one quarter from a 10% drop to a 12.5% drop, which demonstrates that small temperature differences can cause a significant change in the resulting operation of the system 20.
Similarly increasing the temperature of the air stream as it enters the building will also decrease the relative humidity. The system can also be conveniently adjusted to correlate with changing outside air configurations. For example as the outside temperature and relative humidity vary, flow to the coils 11, 13 may be varied to suit the existing conditions. Typically a control will be incorporated to maintain the temperature of the air stream 5 entering the building interior 21 at the desired temperature.
The system 20 also allows for conveniently increasing the rate of removing moisture when the building interior is temporarily unoccupied, such as after business hours. By ceasing to circulate the cooled fluid through the first fluid coil 11 at the beginning of an unoccupied period, while continuing to circulate heated fluid through the second fluid coil 13 the temperature of the air stream 5 can be raised for example by 18° F. to 98° F., which will reduce the relative humidity thereof by half to 30% and further increase the water holding capacity of the air stream 5, and thus the rate of water absorption from the building interior. The valve and conduit arrangement 27 can be automated so that the system 20 will change the fluid flows and system configuration at desired times corresponding to the projected unoccupied period. Automatic adjustments can be made as well to adjust the operation of the system 20 for changes in outside temperature, which may fall at night when the building is unoccupied, outside relative humidity, and like variables.
Further heat could be added to increase the temperature and further reduce the relative humidity, either by increasing the temperature of the heated fluid circulating in the second fluid coil, or by also connecting the first fluid coil to the fluid heater 25 and circulating heated fluid therethrough.
Prior to the end of the unoccupied period cooled fluid can again be circulated through the first fluid coil 11 such that the temperature of the air in the building interior 21 at the end of the unoccupied period is reduced from the temperature of the building interior 21 during the unoccupied period when the air temperature is higher and increased drying is taking place. Faster cooling can be achieved by stopping the flow of heated fluid through the second fluid coil, and further by circulating cooled fluid through both the first and second fluid coils 11, 13.
A container 33 can be positioned under the first fluid coil 11 to collect condensed water dripping from the first fluid coil 11. Alternatively where the portable heat exchanger unit 1 is located outside the building as illustrated in
If the portable heat exchanger unit 1 is located inside the building 29, with only the intake 7 located outside, the condensed water can be directed from the container 33 out of the building 29 or into a floor drain though a conduit 35 to prevent same from evaporating inside the building and contributing to the moisture problem being addressed by the system 20.
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable changes or modifications in structure or operation which may be resorted to are intended to fall within the scope of the claimed invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2,537,015 | Feb 2006 | CA | national |
This application is a continuation-in-part (CIP) of U.S. patent application Ser. No. 10/751,455 “METHOD AND APPARATUS FOR CONTROLLING HUMIDITY AND MOLD”, filed Jan. 6, 2004, the disclosure of which is hereby incorporated herein by reference. This invention is in the field of drying building interiors that have become flooded or otherwise have excessive moisture accumulated therein, and in particular with drying building interiors where the buildings must be occupied for at least a portion of time.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10751455 | Jan 2004 | US |
| Child | 11404015 | Apr 2006 | US |
