Abstrict A dehumidification system for dehumidifying a conditioned space.
The system is comprised of a motionless desiccant block for dehumidifying
air within the conditioned space. The system is configured to operate
in one of two modes. In a first dehumidifying mode the system draws
air from the conditioned space, dehumidifies the air, and returns
the air to the conditioned space. In a second regeneration mode
the system draws air from outside the conditioned space, heats the
air, passes the heated air through the desiccant to dry the desiccant,
and expels the air back outside the conditioned space. The system
is configured with pivoting dampers to select air source and air
destination for the two modes of the system. The system includes
blowers in order to motivate the flow of air and a regenerative
heater for use during regeneration mode. By utilizing a motionless
desiccant block the system avoids the expense and maintenance of
desiccant wheels and wheel motors.
Claims We claim:
1. A dehumidifier utilizing a motionless desiccant block comprising:
a unit housing having a front end and a back end, the front end
of the unit housing defining a front intake aperture and a front
exhaust aperture, the back end of the unit housing defining a back
intake aperture and a back exhaust aperture;
a motionless desiccant block disposed within the unit housing and
acting with the unit housing to define front and back chambers,
the desiccant block extending laterally across the unit housing
along a majority of a width of the unit housing;
a back damper pivotally mounted to the back end of the unit housing,
the back damper having at least two positions, wherein when the
back damper is in a first position it closes the back exhaust aperture
leaving the back intake aperture open, and when the back damper
is in a second position it closes the back intake aperture leaving
the back exhaust aperture open;
a front damper pivotally mounted to the front end of the unit housing,
the front damper having at least two positions, wherein when the
front damper is in a first position it closes the front intake aperture
leaving the front exhaust aperture open, and when the front damper
is in a second position it closes the front exhaust aperture leaving
the front intake aperture open;
a regenerative heater disposed within the front chamber to increase
regeneration of the desiccant block;
a blower system disposed within the unit housing between the front
and back dampers for blowing air from the back intake aperture through
the desiccant block and through the front exhaust aperture, and
also for blowing air from the front intake aperture through the
desiccant block and through the back exhaust aperture;
wherein, when the front and back damper are in their first positions,
the air blower system propels an air current from the back intake
aperture, through the desiccant block where the air current loses
moisture, and through the front exhaust aperture, whereby the system
works in a first mode as a dehumidifier;
and further wherein, when the front and back damper are in their
second positions the air blower system propels an air current from
the front intake aperture, through the front chamber where the air
current is heated by the regenerative heater, through the desiccant
block where the air current adsorbs moisture from the block, and
through the back exhaust aperture, whereby the system works in a
second mode to reactivate the desiccant block.
2. The dehumidifier of claim 1 wherein the blower system is a reversible
blower.
3. The dehumidifier of claim 1 wherein the blower system comprises
a first blower for blowing air from the back intake aperture through
the front exhaust aperture, and a second blower for blowing air
from the front intake aperture through the back exhaust aperture.
4. The dehumidifier of claim 1 further comprising a humidity sensor
for measuring the humidity both inside and outside the conditioned
space.
5. The dehumidifier of claim 4 further comprising a humidity sensor
for detecting when the desiccant requires reactivation.
6. The dehumidifier of claim 5 further comprising a control logic
unit that automatically selects to operate the system either in
a first mode as a dehumidifier or in a second mode reactivating
the desiccant.
7. The dehumidifier of claim 1 further comprising a humidity sensor
for detecting when the desiccant requires reactivation.
8. The dehumidifier of claim 1 wherein the first and second positions
of the front damper are separated by an angle of approximately 90
degrees.
9. The dehumidifier of claim 1 wherein the first and second positions
of the back damper are separated by an angle of approximately 90
degrees.
Description BACKGROUND OF THE INVENTION
The present system relates to air dehumidification and an improved
air dehumidification system.
Dehumidifying systems have been used in residential as well as
commercial spaces to regulate indoor air quality to provide greater
comfort. High humidity levels are not only uncomfortable but can
also increase health risks. Living organisms such as bacteria, mold
and mildew, thrive on the damp air in air conditioning ducts. For
this reason, reducing humidity levels is not only a comfort concern
but also a health concern. Homeowners can reduce their exposure
to harmful bacteria, mold and mildew by regulating the humidity
level within their homes. There exists a need for smaller, less
complex, less expensive dehumidification systems that are appropriate
for residential use.
Many dehumidifiers currently in use rely on refrigerated cooling
coils and compression elements to dehumidify. U.S. Pat. No. 5179998
assigned to Deschamps Laboratories, Inc., is one such example using
refrigerated coils to aid in dehumidification. Refrigerating coils
increase the complexity and expense of the units as well as the
input energy necessary to operate the system. Dehumidification can
be achieved with less expense by using desiccant materials. Desiccant
materials can either adsorb or absorb moisture and then expel that
moisture without the need for cooling coils.
Desiccant dehumidifiers of the prior art typically use desiccants
in the shape of a wheel. Such a configuration requires a motor to
rotate the wheel, adding expense, complexity, and maintenance costs
to the system. There exists a need for less complex and less expensive
desiccant dehumidifiers.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a dehumidification
system for dehumidifying a conditioned space. The system is comprised
of a unit housing containing a desiccant block, regenerative heater,
and blower system. The unit housing acts with the desiccant block
to define front and back chambers. In the front end of the unit
housing are a front intake aperture and a front exhaust aperture.
In the back end of the housing are a back intake aperture and a
back exhaust aperture. Each end of the housing also contains a pivoting
damper. The dampers move between two positions so that either the
intake or exhaust aperture is open while the other is covered by
the damper. The system dehumidifies by drawing air from the conditioned
space, passing the air through the desiccant block where the block
adsorbs moisture from the air and then returning the air back to
the conditioned space. When the desiccant block becomes saturated
with moisture the system reverses the direction of the air flow
and pivots the two dampers so that outside air is drawn into the
system, heated by the regenerative heater, then passed through the
desiccant block where it removes moisture from the block, and finally
expelled back outside. By alternating between these two modes the
system economically dehumidifies a conditioned space.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic diagram of one embodiment of the system.
DETAILED DESCRIPTION
Referring to the drawings, FIG. 1 shows one embodiment of the system
for dehumidifying a conditioned space. The system comprises a unit
housing 1 typically made of sheet metal or plastic, having both
a back panel 5 and a front panel 3. The unit housing 1 is generally
rectangular with a front end 4 and a back end 6 making up opposite
ends of the rectangular unit housing 1. The front end 4 of the unit
housing is separated from the back end 6 by a desiccant block 15.
The back end 6 which includes the back panel 5 as well as portions
of the side walls, defines two apertures, the back intake aperture
11 and the back exhaust aperture 13. The back intake aperture 11
is in fluid communication with other piping or ductwork which is
itself in communication with inside air. The back exhaust aperture
13 is in fluid communication with other piping or ductwork which
is itself in communication with outside air. The back intake aperture
11 is a port through which inside air in need of dehumidification
is supplied to the system. The back exhaust aperture 13 is a port
through which moisture laden air is discharged to the outside after
regenerating the desiccant block 15.
Similarly, the front end 4 which includes the front panel 3 as
well as portions of the side walls, defines two apertures, the front
intake aperture 7 and the front exhaust aperture 9. The front intake
aperture 7 is in fluid communication with outside air or other ductwork
which is itself in communication with outside air. The front exhaust
aperture 9 is in fluid communication with inside air or other ductwork
which is itself in communication with inside air. The front intake
aperture 7 is a port through which outside air is drawn into the
system in order to regenerate the desiccant block 15. The front
exhaust aperture 9 is a port through which the system supplies dehumidified
air to the conditioned space.
A front damper 23 is pivotally mounted to the unit housing so that
it can close either the front intake aperture 7 or the front exhaust
aperture 9. A simple electric motor powers the front damper between
a first position which closes the front intake aperture 7 and a
second position which closes the front exhaust aperture 9. FIG.
1 shows one embodiment of the system configured so that the front
damper 23 rotates only 90.degree. between first and second positions.
A back damper 21 is pivotally mounted to the unit housing so that
it can close either the back intake aperture 11 or the back exhaust
aperture 13. A simple electric motor powers the back damper between
its first position which closes the back exhaust aperture 13 and
its second position which closes the back intake aperture 11. FIG.
1 shows one embodiment of the system configured so that the back
damper 21 rotates only 90.degree. between first and second positions.
The unit housing contains a motionless desiccant block 15. The
desiccant block 15 conforms to the size and shape of the unit housing
so that the interior of the unit housing is divided by the desiccant
block 15 into front and back chambers 17 and 19. The desiccant block
acts to dehumidify a current of air as it passes through small passages
within the block. Desiccants are typically formed of a substrate
on which desiccant material has been coated or impregnated. Examples
of substrate materials include fiberglass, paper, aluminum, and
titanium. In one preferred embodiment the substrate is formed of
fiberglass. The desiccant may comprise a silica gel. Desiccant materials
are commercially available from Munters Corporation.
A stationary block desiccant simply adsorbs moisture from the air
stream until the block adsorbs its moisture capacity. At that point
the block would need to be dried or regenerated before it could
operate to dehumidify again. For this reason desiccants known in
the art are shaped like a wheel. Such wheels continually transfer
moisture between two air streams, constantly adsorbing moisture
in one stream, rotating to the second, less humid air stream, and
there releasing the moisture to the air stream. The present system,
however, by using a fixed block desiccant avoids the substantial
cost, reliability and maintenance issues that accompany the use
of motors to spin the desiccant wheels.
A blower system 27 may be placed in the back chamber 19 to motivate
an air current either from the back intake aperture 11 through
the desiccant block 15 and out the front exhaust aperture 9 or
alternatively from the front intake aperture 7 through the desiccant
block 15 and out the back exhaust aperture 13. The blower system
27 may be configured as two oppositely oriented blowers or a single
reversible one. Examples of blower system 27 include squirrel cage
blowers, axial fans, propellers and other devices capable of creating
a current of air.
A regenerative heater 25 is placed within the front chamber 17
near enough the desiccant block 15 in order to regenerate or dry
the desiccant block when in operation. By heating the air before
it passes through the desiccant block 15 more moisture is expelled
from the desiccant block 15 to the out-flowing stream of air. The
regenerative heater 25 may be configured as an electric heating
element, hot water elements, or in one preferred embodiment as a
natural gas burner such as is commonly found in clothes dryers.
The system may be configured to operate in two modes. The first
mode is the dehumidifying mode. In the dehumidifying mode, the blower
system 27 drives the air current from the back end 6 toward the
front end 4 of the unit housing 1. When dehumidifying, the back
and front dampers 21 and 23 are pivoted so as to leave the back
intake aperture 11 and the front exhaust aperture 9 OPEN, while
the back exhaust aperture 13 and the front intake aperture 7 are
CLOSED. In such a configuration, inside air is drawn from the back
intake aperture 11 dehumidified by the desiccant block 15 and
then returned to the inside space via the front exhaust aperture
9.
The second mode is the block regenerating mode used to reactivate
the desiccant block 15 after it has adsorbed its capacity of moisture.
In this mode the blower system 27 drives the air current from the
front end 4 toward the back end 6 of the unit housing 1. The dampers
21 and 23 are pivoted so that the front intake aperture 7 and the
back exhaust aperture 13 are OPEN, and the front exhaust aperture
9 and the back intake aperture 11 are CLOSED. In such a configuration,
outside air is drawn from the front intake aperture 7 heated by
the regenerative heater 25 forced through the desiccant block 15
where it removes moisture from the block, and expelled outside through
the back exhaust aperture 13.
In order to detect when the desiccant block requires reactivation,
sensors 8 and 10 may be configured to measure the humidity of the
air before entering the desiccant block and after exiting the desiccant
block. When the change in humidity between the two sensors becomes
relatively small, the block would require regeneration. The sensors
8 and 10 may also be configured to include thermistors.
The present system may be configured to include a control panel
which would enable the user to select the desired mode from the
above modes by turning the blower system, regenerative heater and
dampers either on or off or to the appropriate positions and directions.
Another embodiment of the system includes both thermisters and
RH sensors to measure the temperature and humidity inside or outside
the conditioned space. The system may also or alternatively be electrically
connected to the home thermostat for monitoring indoor air conditions.
When coupled to a controller logic unit 12 the system then may be
configured to select automatically the preferred operating mode
that will most efficiently achieve desired temperature and humidity
levels.
Acceptable thermisters and RH sensors are commercially available
and can be ordered from Stetron International, Inc. and TDK USA
Corp.. The controller logic unit could be any programmable microprocessor
such as a Motorola HC705 JP7 micro-controller.
The above specification, examples and data provide a description
of the manufacture and use of the invention. Many embodiments of
the invention can be made without departing from the spirit and
scope of the invention as defined by the claims below. |