U.S. patent application number 13/054773 was filed with the patent office on 2011-06-09 for device and method for drying an air stream.
This patent application is currently assigned to Mentus Holding AG. Invention is credited to Reto Holzner, Gustav Hans Weber, Urs A. Weidmann.
Application Number | 20110133349 13/054773 |
Document ID | / |
Family ID | 41061218 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110133349 |
Kind Code |
A1 |
Weidmann; Urs A. ; et
al. |
June 9, 2011 |
DEVICE AND METHOD FOR DRYING AN AIR STREAM
Abstract
A device for dehumidifying an air stream includes at least one
first module including at least one Peltier element and at least
one second module including at least one Peltier element. The
entirety of the first module forms a first zone for cooling the air
stream. The entirety of the second module forms a second zone for
dehumidifying the air stream. The entirety of the first and the
second modules forms an air channel for the air stream. A water
discharge channel is disposed below the entirety of the second
module and receives water accumulating during the dehumidifying of
the air stream in the second zone. At least one sensor for
measuring a temperature and/or a moisture of the air stream
provides at least one output signal. A control unit including at
least one controller controls the Peltier elements based on the at
least one output signal of the at least one sensor.
Inventors: |
Weidmann; Urs A.; (Zug,
CH) ; Weber; Gustav Hans; (Freienstein, CH) ;
Holzner; Reto; (Zuerich, CH) |
Assignee: |
Mentus Holding AG
Cham
CH
|
Family ID: |
41061218 |
Appl. No.: |
13/054773 |
Filed: |
July 8, 2009 |
PCT Filed: |
July 8, 2009 |
PCT NO: |
PCT/EP09/58653 |
371 Date: |
January 18, 2011 |
Current U.S.
Class: |
261/128 ;
261/130 |
Current CPC
Class: |
F24F 5/0007 20130101;
F24F 2013/221 20130101; F24F 5/0042 20130101; F24F 11/30 20180101;
F24F 13/22 20130101; F24F 3/153 20130101; F24F 13/30 20130101; F24F
2003/144 20130101; F24F 2110/10 20180101 |
Class at
Publication: |
261/128 ;
261/130 |
International
Class: |
F24F 3/14 20060101
F24F003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2008 |
CH |
1138/08 |
Claims
1-8. (canceled)
9. A device for dehumidifying an air stream comprising an air
channel having an inlet through which the air to be dehumidified is
supplied and an outlet through which the dehumidified air is
released, the air channel divided into at least two zones, a
plurality of Peltier elements for cooling the air channel, at least
one sensor measuring a temperature and/or humidity of the air
flowing in the air channel, and a control unit comprising at least
one first and at least one second controller, the control unit
configured to calculate a relevant dew point temperature from the
temperature and humidity measured by the at least one sensor, the
at least one first controller controlling the Peltier elements of
the first zone in such a manner that the air stream at the end of
the first zone is cooled to the dew point temperature or to a
temperature which is higher than the dew point temperature by a
small amount, and the at least one second controller controlling
the Peltier elements of the second zone in such a manner that the
air stream in the second zone releases moisture in the form of
water.
10. The device according to claim 9, wherein a material and/or a
surface structure of walls defining the air channel are configured
differently in the first zone and in the second zone.
11. The device according to claim 9, wherein the air channel is
divided into at least four zones, wherein the control unit is
further configured to control a temperature in the third zone in
such a manner that the air stream in the third zone releases
moisture in the form of water, and wherein waste heat accumulating
in the third zone is supplied to the air stream in the fourth
zone.
12. The device according to claim 10, wherein the air channel is
divided into at least four zones, wherein the control unit is
further configured to control a temperature in the third zone in
such a manner that the air stream in the third zone releases
moisture in the form of water, and wherein waste heat accumulating
in the third zone is supplied to the air stream in the fourth
zone.
13. The device according to claim 11, wherein a temperature in the
third zone is controlled by means of at least one Peltier element,
whose cold side during operation cools the third zone and whose
warm side during operation heats the fourth zone.
14. The device according to claim 12, wherein a temperature in the
third zone is controlled by means of at least one Peltier element,
whose cold side during operation cools the third zone and whose
warm side during operation heats the fourth zone.
15. A method for dehumidifying an air stream comprising: making the
air stream flow through at least a first zone and a second zone of
an air channel, measuring a temperature and/or a humidity of the
air stream, calculating a relevant dew point temperature from the
measured temperature and humidity, cooling the air stream in the
first zone by means of Peltier elements to such an extent that a
temperature of the air stream at the end of the first zone reaches
a value which corresponds to the calculated dew point temperature
or is higher than the calculated dew point temperature by a small
amount, and cooling the air stream in the second zone by means of
Peltier elements to such an extent that water condenses.
16. The method according to claim 15, further comprising making the
air stream flow through a third zone and a fourth zone of the air
channel, cooling the air stream in the third zone by means of
Peltier elements to or below a local dew point temperature of the
air stream so that water condenses, heating the air stream in the
fourth zone by heat accumulating in the third zone.
17. The method according to claim 16, wherein said cooling is
effected by at least one Peltier element whose cold side cools
walls of the air channel forming the third zone and whose warm side
heats walls of the air channel forming the fourth zone.
18. The method according to claim 15, further comprising
configuring a material and/or a surface structure of walls defining
the air channel differently in the first zone and in the second
zone.
19. The method according to claim 16, further comprising
configuring a material and/or a surface structure of walls defining
the air channel differently in the first zone and in the second
zone.
20. The method according to claim 17, further comprising
configuring a material and/or a surface structure of the walls of
the air channel differently in the first zone and in the second
zone.
Description
TECHNICAL FIELD
[0001] The invention relates to a device and a method for
dehumidifying an air stream.
[0002] Such a device can be used in an air conditioner to
dehumidify one or a plurality of air streams circulating in such a
device. An air conditioning system should also be understood by the
term air conditioner.
BRIEF DESCRIPTION OF THE INVENTION
[0003] It is the object of the invention to develop a device for
dehumidifying an air stream, whose operation is as energy-efficient
as possible.
[0004] The said object is solved according to the invention by the
features of claims 1 and 5. Advantageous embodiments are obtained
from the dependent claims.
[0005] A device for dehumidifying an air stream comprises an air
channel having an inlet through which the air to be dehumidified is
supplied and having an outlet through which the dehumidified air is
released. According to the invention, the air channel is divided
into at least two zones, wherein a temperature in the first zone
can be controlled in such a manner that the air stream at the end
of the first zone is cooled to a dew point temperature
corresponding to the air stream or to a temperature which is higher
than the dew point temperature by a small amount and wherein a
temperature in the second zone can be controlled in such a manner
that the air stream in the second zone releases moisture in the
form of water.
[0006] The material and/or the surface structure of the walls
defining the air channel are preferably configured differently in
the first zone and in the second zone.
[0007] The air channel is, for example, divided into at least four
zones, wherein a temperature in the third zone can be controlled in
such a manner that the air stream in the third zone releases
moisture in the form of water and wherein waste heat accumulating
in the third zone is supplied to the air stream in the fourth
zone.
[0008] The temperature in the third zone is preferably controlled
by means of at least one Peltier element, whose cold side during
operation cools the third zone and whose warm side during operation
heats the fourth zone.
[0009] The temperature of the walls of the air channel is
preferably controlled by means of Peltier elements, which are
controlled by a control unit comprising at least two controllers,
wherein the first controller controls the Peltier element or the
Peltier elements of the first zone in such a manner that the air
stream in the first zone is cooled without condensing water and
wherein the second controller controls the Peltier element or the
Peltier elements of the second zone in such a manner that the air
stream releases water in the second zone.
[0010] The method according to the invention for dehumidifying an
air stream accordingly comprises the steps:
a) making the air stream flow through a first zone in which the air
stream is cooled to such an extent that its temperature at the end
of the zone reaches a value which corresponds to the dew point
temperature or is higher than the dew point temperature by a small
amount, and b) making the air stream flow through a second zone in
which the air stream is cooled to such an extent that water
condenses. In order to achieve this, the temperature of the walls
of the first zone must be higher than the dew point temperature of
the air stream, which is associated with its current temperature
and current relative humidity, whereas the temperature of the walls
of the second zone must lie below the "local" dew point temperature
of the air stream. In this context, it should be noted that the dew
point temperature of the air stream decreases along the second zone
because the air stream condenses moisture in the form of water. The
dew point temperature in the second zone is location-dependent and
is therefore designated as "local" dew point temperature.
[0011] The method advantageously comprises the additional step of
making the air stream flow through a third zone which is cooled to
or below the local dew point temperature so that water condenses,
and then making the air stream flow through a fourth zone in which
the air stream is heated by the heat accumulating in the third
zone.
[0012] The invention is explained in detail hereinafter with
reference to an exemplary embodiment and with reference to the
drawings. The figures are schematic and are not drawn to scale.
DESCRIPTION OF THE FIGURES
[0013] FIG. 1 shows a schematic diagram which illustrates both the
structure of a device according to the invention for dehumidifying
an air stream and also a method according to the invention for
dehumidifying an air stream,
[0014] FIG. 2 shows a Mollier diagram,
[0015] FIG. 3 shows an enlarged section of the Mollier diagram from
FIG. 2 and an example of a dehumidification process,
[0016] FIG. 4 shows in perspective schematic view an exemplary
embodiment of a device for dehumidifying an air stream,
[0017] FIG. 5 shows individual parts of a first module,
[0018] FIG. 6 shows details of the first module in side view,
[0019] FIG. 7 shows the first module in perspective view,
[0020] FIG. 8 shows individual parts of a second module,
[0021] FIG. 9 shows the second module in perspective view,
[0022] FIG. 10 shows an individual part of the second module in
another embodiment, and
[0023] FIG. 11 shows a circuit diagram for controlling the device
from FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0024] FIG. 1 shows a schematic diagram which illustrates the
structure of a device according to the invention for dehumidifying
an air stream on the one hand and a method according to the
invention for dehumidifying an air stream on the other hand. The
device comprises an air channel having an inlet 1 through which the
air to be dehumidified is supplied and having an outlet 2 through
which the dehumidified air is released. The air stream is shown by
an arrow 3. The air channel is either divided into two zones 4 and
5 or, as shown, into four zones 4, 5, 6A, and 6B, wherein the zones
are either directly adjacent to one another or are somewhat spaced
apart from one another. The first zone 4 is used to cool the
supplied air stream, wherein the air stream at the end of the first
zone 4 is cooled to the dew point temperature or to a temperature
which is higher than the dew point temperature by a small amount.
The dew point temperature is that temperature of the moist air at
which this is saturated with water vapor so that in the event of a
further lowering of temperature, water would condense. The dew
point temperature is therefore that temperature of moist air at
which the relative air humidity, phi, is 100 percent. In the first
zone 4 the air is consequently cooled predominantly without water
condensing. It is possible that at the end of the first zone 4,
some water has already condensed without this disturbing the
operation. This is the case, for example, when the temperature is
below the dew point temperature, which naturally can occur since
the temperature must be regulated. The second zone 5 is used to
further cool and dehumidify the air stream, i.e. to extract
moisture from the air stream and condense this in the form of
water. The water passes into a water discharge channel. The
temperature in the second zone 5 must therefore be below the local
dew point temperature of the air stream everywhere. The third zone
6A and the fourth zone 6B are optional and serve to heat the cold
dehumidified air stream efficiently to a desired temperature.
Whether these two zones are used or not depends on the operating
mode of the air conditioner.
[0025] The device is additionally equipped with at least one sensor
in order to operate said device in accordance with the method
according to the invention described hereinafter. The at least one
sensor is used to measure the temperature and/or the relative
humidity of the air stream.
[0026] The method according to the invention for dehumidifying an
air stream accordingly comprises the steps
a) making the air stream flow through a first zone 4 in which the
air stream is cooled to such an extent that its temperature at the
end of the zone 4 reaches a value which corresponds to the dew
point temperature or is higher than the dew point temperature by a
small amount, b) making the air stream flow through a second zone 5
in which the air stream is cooled to such an extent that water
condenses, and c) optionally making the air stream flow through a
third zone 6A which is cooled to or below the local dew point
temperature so that water condenses, and then making the air stream
flow through a fourth zone 6B in which the air stream is heated by
the heat accumulating in the third zone 6A.
[0027] In this context, the following should be noted:
[0028] the dew point temperature of the air depends on various
factors, in particular on the temperature of the air, the water
content of the air, and the pressure of the air. The relative
humidity phi, given in %, designates the ratio of the instantaneous
water vapor content in the air to the maximum possible water vapor
content at the same temperature.
[0029] The dew point temperature in zones 5 and 6A decreases along
the zones since water condenses in these zones, which means that
the water content of the air stream and therefore the relative
humidity phi decrease continuously.
[0030] The dew point temperature of the air stream at any position
in zones 5 and 6A can be determined, for example, by measuring the
temperature and the relative humidity phi of the air stream by
means of sensors and then determining the associated dew point
temperature. The dew point temperature T.sub.p1 can be determined,
for example, by calculations using the equation
T p 1 = 241.2 * ln ( phi 100 ) + 4222.03716 * T 241.2 + T 17.5043 -
ln ( phi 100 ) - 17.5043 * T 241.2 + T ( 1 ) ##EQU00001##
where the dimensional unit of the temperatures T and T.sub.p1 is
degrees Celsius and the relative air humidity phi should be
inserted in percent. The dew point temperature T.sub.p1 can,
however, also be determined by means of a Mollier diagram.
[0031] The Mollier diagram is also suitable for representing the
dehumidification process of the air stream and deducing from this
how the temperature should be regulated in zones 4 and 5 or 4, 5,
and 6A. FIG. 2 shows a Mollier diagram. The diagram contains a
family of curves which represent the behavior of the dew point
temperature T.sub.p1 as a function of the water content X and the
temperature T of the air for various values of the relative air
humidity phi. The dehumidification process is explained in detail
hereinafter with reference to an example having randomly selected
values of the temperature T and the relative humidity of the air
stream by reference to FIG. 3 which shows an enlarged section of
the Mollier diagram from FIG. 2. The process of dehumidifying the
air stream is shown by four arrows, which adjoin one another. One
of the zones 4, 5, 6A, and 6B of the device for dehumidifying the
air stream is associated with each of the four arrows. On entry of
the air stream into the first zone 4, i.e. at the inlet 1, the air
stream in this example has a temperature T=30.degree. and a
relative air humidity phi=50%. On leaving the zone 6B, i.e. at the
outlet 2 of the device for dehumidifying the air stream, the air
stream in this example should have reached a temperature
T=22.degree. and a relative air humidity phi=30%. In the first zone
4 the air stream is only cooled without water being separated. The
first arrow therefore runs perpendicularly and points downward. In
the first zone 4 the air stream must be cooled to a temperature
T.sub.1, which approximately corresponds to its dew point
temperature, T.sub.p1, of T.sub.p1=18.5.degree. C. in the example.
If no water is to be condensed in the first zone 4, the temperature
T.sub.1 must lie above the dew point temperature T.sub.p1. If,
however, water may be condensed in the first zone 4, in particular
in the region of the end of the first zone 4, the temperature
T.sub.1 of the air stream in the region of the end of the first
zone 4 may then also reach a value lying below the dew point
temperature T.sub.p1. In the second zone 5, the air stream is
continuously dehumidified. Since it thereby loses water, the dew
point temperature diminishes continuously along the second zone 5,
as is clearly apparent in the Mollier diagram. In the third zone
6A, the air stream is also continuously dehumidified, consequently
the dew point temperature also diminishes continuously along the
third zone 6A. In the example, the air stream must have reached the
temperature T.sub.2=3.5.degree. C. at the end of the third zone 6A.
In the fourth zone 6B, the air stream is heated to the desired
temperature of 22.degree. C. in the example, where it then also
reaches the desired relative air humidity phi=30%.
[0032] The two zones 6A and 6B are coupled to one another in such a
manner that the heat accumulating in zone 6A and to be removed, is
supplied to zone 6B to heat the air stream to the desired
temperature. The dew point temperature at the transition from the
second zone 5 to the third zone 6A should be adjusted or regulated
in accordance with this requirement.
[0033] The invention relates in its main aspect to the cooling and
dehumidification of an air stream, wherein the cooling takes place
in the first zone 4, in which no water is yet condensed from the
air stream, wherein the relative air humidity on leaving the first
zone 4 is ideally approximately 100%, and wherein the
dehumidification only takes place in the subsequent second zone 5.
This division makes it possible to optimize the material and the
surface structure of the walls of the air channel defining the
first zone 4 for optimal heat transfer without condensation, and to
optimize the material and the surface structure of the walls of the
air channel defining the second zone 5 for optimal heat transfer
with condensate or droplet formation and rapid drainage of the
condensed water. It is optimal if a monolayer of water forms on the
walls of the second zone 5 since such an extremely thin layer on
the one hand effects the rapid drainage of the water and on the
other hand offers only a low heat resistance. A possible embodiment
of the walls of the second zone 5 is that they are coated with a
material having a fraction of hydrophobic and hydrophilic effect
which varies from top to bottom in the direction of gravity,
wherein the hydrophobic fraction predominates in the upper region
and the hydrophilic fraction predominates in the lower region.
[0034] When the air flow leaves the second zone 5, it is cold and
relatively dry. It can now be supplied, for example, directly to a
room to be air conditioned or mixed with fresh air and supplied to
the room or mixed with exhaust air removed from the room and
returned to the room, or heated and supplied to the room as
prepared supply air. The invention relates in a further aspect to a
device in which the air channel is divided into at least four zones
4, 5, 6A, and 6B, wherein a temperature in the third zone 6A can be
controlled in such a manner that the air stream in the third zone
6A releases moisture as water and wherein waste heat accumulating
in the third zone 6A is supplied to the air stream in the fourth
zone 6B. This is advantageously accomplished by means of at least
one Peltier element which is used such that on the one hand, its
cold side cools the walls of the third zone 6A to the required
temperature and on the other hand, its warm side heats the walls of
the fourth zone 6B.
[0035] FIG. 4 shows a possible exemplary embodiment of a device for
dehumidifying an air stream. The first zone 4 is formed by at least
one module 7 of a first type, in the example, two modules 7 are
disposed consecutively. The second zone 5 is formed by at least one
module 8 of a second type, in the example, five modules 8 are
disposed consecutively. The modules 7 and 8 have a similar
structure and only differ in certain details.
[0036] FIG. 5 shows the individual parts of which the module 7 is
composed. These individual parts are a frame 10, a first perforated
plate 11, a second perforated plate 12, a Peltier element 13, and a
cooling element 14. The frame 10, the first perforated plate 10,
and the second perforated plate 12 have the same outer contour. The
perforated plates 11 and 12 contain a plurality of holes, which in
the example are circular. The holes of the first perforated plate
11 are disposed in an offset manner with respect to the holes of
the second perforated plate 12. A plurality of frames 10, first
perforated plates 11, and second perforated plates 12 are connected
to one another in the sequence frame 10, first perforated plate 11,
frame 10, second perforated plate 12, frame 10, first perforated
plate 11, frame 10, second perforated plate 12, etc., so that they
form a channel for the air stream. FIG. 6 illustrates this
structure: it shows in side view the frames 10, first perforated
plates 11, and second perforated plates 12, wherein FIG. 6 was
stretched in the horizontal direction so that the individual parts
can be better identified. FIG. 7 shows the module 7 in perspective
view. In this example, six Peltier elements 13 are mounted on each
side wall 16 of the channel, of which two are shown in FIG. 6. The
channel has a base 15, two side walls 16, and a cover 17. At least
one Peltier element 13 is mounted on at least one of the two side
walls 16, preferably on both side walls 16. During operation of the
module 7, a current flows through the Peltier elements 13, which
cools the side of the Peltier elements 13 facing the channel and
heats the side of the Peltier elements 13 facing away from the
channel. This heat must be removed to the surroundings. This can be
accomplished in various ways, for example, by air cooling or water
cooling. In the example, a cooling element 14 is mounted on the
Peltier elements 13, which is cooled with water or another medium
which circulates in a circuit and releases the heat absorbed by the
Peltier elements 13 to the surroundings at a suitable point. In the
example shown in FIG. 7, six Peltier elements 13 and two cooling
elements 14 (of which one is omitted) are mounted on each side wall
of the channel.
[0037] The perforated plates 11 and 12 are flow obstacles which are
disposed transversely to the direction of the air stream or the
channel. The air flowing through the channel either impinges on the
perforated plate or flows unhindered through the holes of the
perforated plate. Since the holes of the first perforated plates 11
are disposed in an offset manner with respect to the holes of the
second perforated plates 12, the air is continuously deflected
inside the channel of the module 7 so that it continuously comes in
contact with the perforated plates and thereby cools.
[0038] FIG. 8 shows the individual parts of which the module 8 is
composed. These individual parts are the frame 10, a certain number
of different plates with tips, in this example, four different
plates, i.e. a first sawtooth plate 18, a second sawtooth plate 19,
a third sawtooth plate 20, a fourth sawtooth plate 21, the Peltier
element 13, and the cooling element 14. FIG. 9 shows the module 8
in perspective view. A plurality of frames 10, first sawtooth
plates 18, second sawtooth plates 19, third sawtooth plates 20, and
fourth sawtooth plates 21 are connected to one another in the
sequence frame 10, first sawtooth plate 18, frame 10, second
sawtooth plate 19, frame 10, third sawtooth plate 20, frame 10,
fourth sawtooth plate 21, frame 10, first sawtooth plate 18, frame
10, second sawtooth plate 19, frame 10, third sawtooth plate 20,
frame 10, fourth sawtooth plate 21, etc. so that they form a
channel for the air stream. The frame 10 and the four sawtooth
plates 18 to 21 per se have the same external contour but the
sawtooth plates 18 to 21 are open at the bottom, i.e. on the side
facing the base 15 of the channel so that the base 15 of the
channel of the assembled module 8 contains a plurality of slots,
which are each formed between neighboring frames 10. The sawtooth
plates 18 to 21 comprises a surface 22, whose edge 23 facing the
base 15 of the channel of the module is provided with tips and
typically is configured in a sawtooth form. Peltier elements 13 and
cooling elements 14 are mounted in the same way as in the module 7.
The three sawtooth plates 18 to 21 differ in respect of the
distance at which the surface 22 is disposed from the base of the
channel of the module 8.
[0039] The sawtooth plates 18 to 21 are flow obstacles which are
disposed transversely to the direction of the air stream or the
channel of the module 8. The air flowing through the channel of the
module 8 impinges on the surface 22, whereby moisture contained in
the air condenses in the form of water on the surface 22 and flows
downward as a result of gravity, accumulates at the tips of the
edge 23, becomes detached there, drops downward, and passes through
the slots in the base of the channel of the module 8 into the water
discharge channel 9 mounted in the zone 5 underneath the module 8
(FIG. 4). The water discharge channel 9 is sealed with respect to
the surroundings. The water discharge channel 9 has an opening
through which the water passes preferably by means of a siphon or a
long thin tube with correspondingly great friction in order to
prevent air flowing through the air channel from being able to
escape into the surroundings through the slots in the base 15 of
the channel and the opening in the water discharge channel 9. In
the example, the water discharge channel 9 extends over all three
zones 4 to 6A.
[0040] In this example, the frames 10, perforated plates 11, 12,
and sawtooth plates 18, 19, 20 are provided with holes so that
these can be screwed together by means of screws to the module 7 or
8 or also to the entire air channel. The frames 10, perforated
plates 11, 12, and sawtooth plates 18, 19, 20 consist of a very
good heat-conducting material. The lower the thermal conductivity,
the thicker are these frames and plates. The Peltier elements 13
are mounted on the outer wall of the channel formed by the frames
10 and perforated plates 11, 12 or frame 10 and sawtooth plates 18
to 21 and consequently are in thermal communication with the
perforated plates 11, 12 and sawtooth plates 18 to 21 to be cooled.
The cooling elements 14 are mounted on the Peltier elements 13.
[0041] The third zone 6A of the device according to the invention
for dehumidifying an air stream is, as has already been mentioned,
optional. Said zone also comprises modules 8 of the second type and
is configured in such a manner that the air stream flows through
the inside of these modules 8 and then in a channel formed on the
outside of the modules 8 flows past the warm sides of the Peltier
elements 13 of these modules 8 and is thereby heated. The inside of
the modules 8 forms the third zone 6A which is not visible in FIG.
4, the outside of the modules 8 forms the fourth zone 6B.
[0042] The modules 7 and 8 can also be constructed in a different
manner. An example of a different design is illustrated in FIG. 10
by reference to the sawtooth plate 19. The sawtooth plate 19 here
consists of two different materials, i.e. a material suitable for
forming the outer frame 24 and a good heat-conducting material for
the surface 22 having the tips which must cool the air and bring it
to the moisture separation point. Respectively one Peltier element
25 is mounted on the left and right edge of the surface 22, which
elements cool the surface 22 to the desired temperature during
operation. Mounted on the side of the Peltier elements 25 opposite
the surface 22 in this example is a lamella 26, via which the
accumulating heat is released to the surroundings. The lamellas 26
are preferably cooled by means of a separate air stream, which
consists either of outside air or exhaust air and is released to
the surroundings as outgoing air. In this example, the lamellas 26
therefore form the cooling elements 14 (FIG. 4). This embodiment is
additionally suitable for combining the sawtooth plate 19 with the
frame 10 (FIG. 8) to form a single component, by configuring the
frame 24 accordingly. The same design is also applied to the other
sawtooth plates 18, 20, 21 (FIG. 8) so that the module 8 can be
formed by continuously stringing together such sawtooth plates 18
to 21 without interposed frames 10. This design affords two
important advantages since good heat-conducting material is only
used where it is needed and since the temperature of each sawtooth
plate can be regulated individually because each sawtooth plate is
assigned its own Peltier elements 25. The thermal conductivity of
the surface 22 can be increased by mounting at least one heat pipe
27 on the surface 22. (A heat pipe is also called Warmerohr in
German). Likewise, the thermal conductivity of the lamellas 26 can
be increased by means of at least one heat pipe 28. In this
example, the lamellas 26 form the cooling elements 14 (FIG. 4).
[0043] The perforated plates 11, 12 (FIG. 5) can be constructed in
a similar manner to the sawtooth plate 19 described with reference
to FIG. 10, so that individual Peltier elements are also assigned
to each perforated plate.
[0044] If the modules 7 and 8 are assembled to form a device, as
shown for one example in FIG. 4, the individual channels of the
modules 7 and 8 together then form the air channel for the air
stream to be dehumidified. The device according to the invention
further comprises a control unit 29 for controlling the Peltier
elements 13 of the modules 7 and 8 and at least one sensor 30,
which measures the temperature T and/or the humidity, preferably
the relative humidity phi of the air. FIG. 11 shows a circuit
diagram of this control unit. The output signal or the output
signals of the at least one sensor 30 are supplied to the control
unit 29 and used for control of the Peltier elements 13 of the
modules 7 and 8. In the example, the control unit 29 comprises a
first controller 31 for controlling the Peltier elements 13 of the
module 7 of the zone 4 and a second controller 32 for controlling
the Peltier elements 13 of the modules 8 of the zone 5. The control
of the temperatures of the modules 7, 8 of the two zones 4 and 5 is
complex. The basic principles of the control are explained
hereinafter.
[0045] Such a sensor 30 is placed, for example, at the inlet of the
air channel and measures the temperature T and the relative
humidity phi of the air stream to be dehumidified. The sensor 30
can, however, also be placed at another suitable position, for
example, as shown in FIG. 4 between the two zones 4 and 5. The
control unit calculates the relevant dew point temperature T.sub.p1
from the measured values of T and phi, for example, using Equation
(1) or by reference to the Mollier diagram (FIG. 2), which is
stored in the control unit 29, for example, as a function, curve
family, or table. The controller 31 regulates the current flowing
through the Peltier elements 13 of the modules 7 of the zone 4 in
such a manner that at least the perforated plate located nearest to
the outlet of the zone 4 is cooled to the temperature T.sub.1,
wherein the temperature T.sub.1 is either the calculated dew point
temperature T.sub.p1 or a temperature a small amount higher than
the dew point temperature T.sub.p1. The temperature T.sub.1 is
advantageously selected so that no condensed water accumulates in
zone 4 and/or condensate eventually formed evaporates again in the
air stream. The relative humidity of the air stream at the inlet of
the zone 5 is now at least approximately 100%.
[0046] In zone 5 moisture is removed from the air stream. The water
content and therefore the relative humidity of the air stream
decrease. The dew point temperature varies along zone 5; at the
outlet of zone 5 this temperature is lower than at the inlet of
zone 5. In order that moisture can be condensed from the air stream
in the form of water, the temperature of the sawtooth plates at any
point in zone 5 must be lower than the local dew point
temperature.
[0047] On leaving, the dehumidified air stream should have a
predetermined temperature T.sub.2 and a predetermined relative
humidity phi.sub.2. The dew point temperature T.sub.p2 which the
sawtooth plates of that module 8 located nearest to the outlet of
the air channel must have, can be calculated by means of Equation
(1) or the Mollier diagram.
[0048] The controller 32 regulates the current flowing through the
Peltier elements 13 of the modules 8 of the zone 5 and possibly the
zone 6 in such a manner that the temperature of the sawtooth plates
of the modules 8 is lower than the local dew point temperature so
that moisture contained in the air stream is separated in the form
of water.
[0049] The controller 31 advantageously contains a plurality of
subordinate controllers 33, the controller 32 advantageously
contains a plurality of subordinate controllers 34 so that the
currents flowing through the modules 7, 8 can be regulated
individually.
[0050] The efficiency of a Peltier element 13 depends on various
factors, in particular on the temperature difference between its
warm and its cool side. The controllers 33 and the controllers 34
operate the Peltier elements of the associated modules 7, 8
preferably in the optimal working range, wherein it can well occur
that only some of the modules 7, 8 are operating and that some of
the modules 7, 8 are switched off.
[0051] The dew point temperature which must be reached so that
moisture can be extracted from the air flowing into the device
having the temperature T and the relative humidity phi can be
determined by reference to the Mollier diagram shown in FIG. 2.
Likewise, for each individual module 8 of the zone 5 and optionally
of the zone 6 its individual dew point temperature can also be
determined by reference to the Mollier diagram.
* * * * *