Note: Descriptions are shown in the official language in which they were submitted.
CA 02537015 2006-02-20
- Page 2 -
DRYING OCCUPIED BUILDINGS
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.
BACKGROUND
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. United States Patent Number 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
CA 02537015 2006-02-20
- Page 3 -
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
fumace, 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 rnust 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
CA 02537015 2006-02-20
-Page4-
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 gubject building.
United States Published Patent Application 2005/0145109 of the present
inventors
Dancey et al. discloses a controlled system for maintaining a desired humidity
level in
buildings and for drying bnildings. 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.
As with the apparatus of Cressy et al., 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
CA 02537015 2006-02-20
- Page 5 -
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.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a system for drying
occupied buildings
that overcomes problems in the prior art.
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 tempera.ture
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.
CA 02537015 2006-02-20
- Page 6 -
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 streant. 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
CA 02537015 2006-02-20
,Page7-
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.
DESCRIPTION OF THE DRAWINGS:
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:
Fig. 1 is a schematic view of an embodiment of a portable heat exchanger unit
of
the invention, and a system for removing moisture from a building interior;
Fig. 2 is a schematic view of an alternate embodiment of a portable heat
exchanger unit of the invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS:
Fig. I schematically illustrates a portable heat exchanger unit 1 comprising a
fan 3
operative to create an air stream 5 by drawing air from an intake 7 and
discharging the air
stream through an outlet 9. A first temperature adjusting element, illustrated
as first fluid
coil 11, is located in the air stream 5, and a second temperature adjusting
element,
CA 02537015 2006-02-20
- Page 8 -
illustrated as second fluid coil 13, is located in the air stream 5 downstream
from the first
fluid coil 11. The portable heat exchanger unit I is configured such that a
temperature of
the air stream 5 can be changed by a fluid circulating through either of the
first and
second fluid coils 11, 13. The first and second fluid coils 11, 13 are adapted
for
connection to a source of pressurized fluid.
Fig. 2 illustrates an alternate embodiment of the portable heat exchanger unit
201
comprising a first fan 203 operative to create an air stream 205 by drawing
air from the
intake 207 through the first fluid coil 211, and a second fan 203A operative
to draw the
air stream 205 from the first fluid coil 211 through the second fluid coil 213
and
discharge the air stream 205 through the outlet 209. The embodiment of Fig. 2
can thus
be provided by connecting the discharge duct of a heat exchanger that has a
single coil
and a single fan to the intake of another single fan and coil heat exchanger
such as may
be conveniently available. The coils 211 and 213 can be connected to a fluid
heater or
cooler in a manner similar to the embodiment of Fig. 1.
In Fig. 1, the portable heat exchanger unit 1 is used in a system 20 for
removing moisture
from an occupied building interior 21. The system 20 comprises the portable
heat
exchanger unit 1. A fluid cooler 23 operatively is connected to the first
fluid coil 11 and
is operative to circulate pressurized cooled fluid through the first fluid
coil 11. A fluid
heater 25 is operatively connected to the second fluid coil 13 and is
operative to circulate
CA 02537015 2006-02-20
- Page 9 -
pressurized heated fluid through the second fluid coil 13. The pressures are
selected to
satisfactorily circulate the fluids through the first and second fluid coils
11, 13. Typically
the fluid cooler will be provided by an absorption chiller, or the like, and
the fluid heater
will be provided by a water heater or the like.
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 Fig. 1 comprises a valve and conduit arrangement
27
connected to the fluid cooler 23, fluid heater 25, and fluid coils 11, 13 and
configured
such that the fluid cooler 23 can be selectively connected to the first and
second fluid
coils 11, 13 and such that the fluid heater 25 can also be selectively
connected to the first
and second fluid coils 11, 13. Such a valve and conduit arrangement 27 can be
readily
configured by those skilled in the art and conveniently allows either the
fluid cooler 23,
or heater 25 to be connected to either or both of the first and second fluid
coils 11, 13 so
that the temperature of the air stream 5 can be changed upward or downward by
either of
the fluid coils 11, 13. Versatility for a variety of possible uses of the
system 20 is thus
conveniently and economically provided. Temperature and/or flow controls can
be
CA 02537015 2006-02-20
-Page 10-
provided to control the volume and temperature of fluid flowing through the
coils 11, 13
and thus the temperature of the air stream 5, and can be incorporated in the
valve and
conduit arrangement 27, or as otherwise might be convenient.
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 1 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.
Fig. I also illustrated the use of a second portable heat exchanger unit 101
located inside
the building interior 21 such that the intake 107 is oriented such that the
fan 103 draws air
from inside the building, the first fluid coil 111 cools the air inside the
building to the
dew point and condenses water out of the air stream, and the second fluid coil
113 heats
the air stream to a desired temperature and discharges the air stream 105
through the
outlet 109 back into the building interior 21. In the illustrated system 20,
the second
portable heat exchanger unit 101 is connected to the valve and conduit
arrangement 27 to
receive cooled and heated fluid from the same sources 23, 25 as supply the
portable heat
exchanger unit 1. Adding the second portable heat exchanger unit 101 removes
further
moisture from the air inside the building, further increasing the rate of
drying in the
building interior.
CA 02537015 2006-02-20
- Page 11 -
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
CA 02537015 2006-02-20
-Page12-
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 OF and a relative
humidity of 100%,
and thus water must condense out of the air stream when the temperature
thereof is
reduced to 62 T. 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
CA 02537015 2006-02-20
- Page 13 -
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.
CA 02537015 2006-02-20
- Page 14 -
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 fiuther 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
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
CA 02537015 2006-02-20
-Page15-
ceasing to circulate the cooled fluid through the first fluid coil l 1 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
CA 02537015 2006-02-20
- Page 16 -
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 I 1 to collect
condensed water
dripping from the first fluid coil 11. Altematively where the portable heat
exchanger unit
I is located outside the building as illustrated in Fig. 1, the water may be
allowed to drip
onto the ground. By positioning the portable heat exchanger unit I outside the
occupied
building 29, the occupants will not be exposed to the noise of the fan 3.
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
CA 02537015 2006-02-20
- Page 17 -
structure or operation which may be resorted to are intended to fall within
the scope of
the claimed invention.