DEVICE AND METHOD FOR DRYING AN AIR STREAM
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.
Latest Mentus Holding AG Patents:
- Arrangement for air conditioning rooms and heat pump unit for use in the arrangement
- Room air conditioner having a liquid-to-air heat exchanging device with peltier elements
- Method For Operating A Liquid-To-Air Heat Exchanger Device
- Room Air Conditioner Having a Liquid-To-Air Heat Exchanging Device With Peltier Elements
- Arrangement For Air Conditioning Rooms And Heat Pump Unit For Use In The Arrangement
The invention relates to a device and a method for dehumidifying an air stream.
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 INVENTIONIt is the object of the invention to develop a device for dehumidifying an air stream, whose operation is as energy-efficient as possible.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
In this context, the following should be noted:
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.
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.
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 Tp1 can be determined, for example, by calculations using the equation
where the dimensional unit of the temperatures T and Tp1 is degrees Celsius and the relative air humidity phi should be inserted in percent. The dew point temperature Tp1 can, however, also be determined by means of a Mollier diagram.
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.
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.
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.
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.
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.
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 (
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.
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
The modules 7 and 8 can also be constructed in a different manner. An example of a different design is illustrated in
The perforated plates 11, 12 (
If the modules 7 and 8 are assembled to form a device, as shown for one example in
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
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.
On leaving, the dehumidified air stream should have a predetermined temperature T2 and a predetermined relative humidity phi2. The dew point temperature Tp2 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.
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.
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.
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.
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
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.
Type: Application
Filed: Jul 8, 2009
Publication Date: Jun 9, 2011
Applicant: Mentus Holding AG (Cham)
Inventors: Urs A. Weidmann (Zug), Gustav Hans Weber (Freienstein), Reto Holzner (Zuerich)
Application Number: 13/054,773
International Classification: F24F 3/14 (20060101);