EP2609245B1 - Method for drying textiles and laundry dryer - Google Patents

Description

The present invention relates to a process for drying textile goods according to the preamble of claim 1, as well as a tumble dryer.

In view of the continuously growing relevance of environmental and energy policy issues in recent years and an increased energy awareness on the part of the population, the energy efficiency of electrical appliances is becoming increasingly important today. As a significant proportion of the energy produced in the industrialized countries is used for laundry drying, numerous development efforts have also focused on improving the efficiency of tumble dryers.

Thus, for example, tumble driers are known in which the pressure in the laundry containers is reduced so that the moisture evaporates already at a relatively low temperature and consequently the energy consumption is reduced. Such clothes dryers are eg from the documents DE 1 432 869 . DE 1 585 916 . US 3,030,712 such as US 3,238,750 known. A disadvantage of these clothes dryers is in particular that they still have a relatively low efficiency and a relatively complex structure. The DE 2 218 440 suggests a clothes dryer in which the pressure in the laundry container is reduced and, as an additional measure to increase the efficiency of the air stream for drying the laundry via the heat exchanger of a heat pump is circulated. Another disadvantage is that the Device has a relatively complicated structure and a relatively low efficiency.

In the FR 1 201 674 . DE 31 16 697 and DE 36 44 077 devices are again proposed for dehumidifying wet laundry, in which the space containing the textile material is evacuated and thus evaporated at low temperature moisture is removed. In addition, in the devices proposed in these publications, the withdrawn moisture is compressed, which undergoes an increase in temperature. The elevated temperature and the condensation energy are utilized in a heat exchanger to heat the material to be dried in the device. The placement of an additional heat exchanger has not been proven, which is why the proposed devices have never been further developed to production maturity.

In view of the above mentioned drawbacks has been in the WO2007 / 093073 proposed a method for drying textile good or operating a tumble dryer, which is characterized by a higher efficiency compared to the prior art. characterized by reduced energy consumption.

It is proposed that for drying a textile material in a designated receptacle initially the interior of the receptacle is evacuated with the material entered therein and heated. By reducing the pressure and heating the moisture is evaporated from the material, whereupon the water is withdrawn from the interior. By discharging the withdrawn water to the environment or by compression of the withdrawn water to ambient pressure, this is heated and at least a portion of the energy of the water vapor we supplied to further heating of the drum on the outside, wherein the water vapor thereby at least partially condensed.

In the DE 4104989 For example, a method and apparatus for evacuating and dehumidifying a space filled with one or more vaporizable fluids and one or more non-vaporizable fluids is described, wherein the space is dehumidified by first increasing the pressure of the fluid to be aspirated by means of a turbo-engine.

The object of the present invention is based on the mentioned WO2007 / 093073 to propose a further improvement in the operation of a tumble dryer.

These objects are achieved for a method by the features of the characterizing part in particular of claim 1 and for the tumble dryer by the features of the characterizing part of claim 5.

According to the invention it is proposed that the textile material to be dried is placed in a designated receptacle, and that the pressure in the recording with the entered good to be dried compared to the ambient pressure by means of a multi-stage radial turbocompressor is reduced, whereby the evaporation temperature of the moisture in the estate accordingly is reduced, whereupon the evaporated moisture is removed from the recording. It is proposed that the pressure in the receptacle, such as a drying room and / or a laundry drum, first reduced and heated together with the material to be dried therein at least such that an evaporation at reduced pressure begins, whereupon the evaporated moisture, preferably continuously withdrawn from the receptacle, such as the drying room and / or the laundry drum. The withdrawn moisture is different than in the WO2007 / 093073 not with a conventional compressor / vacuum pump compressed to ambient pressure, but by means of a turbo compressor.

Contrary to the solutions proposed in the prior art, the increased heat and the heat of condensation is not used via a separate heat exchanger, but at least a portion of the heated moisture is fed directly to the outer wall of the receptacle, such as the drying room and / or the laundry drum and condenses there at least in part, to heat these and in particular arranged therein to be dried Good.

Turbocompressors are usually suitable for very large volume flows, since high peripheral speeds are necessary for an efficient machine, which results in very high speeds being required for small machines. Radial turbocompressors typically require a peripheral speed of 270m / s. This results in high pressure ratios (typically 2-3) with good efficiency (about 70%). Turbocompressors require a large volume flow in relation to the size, otherwise the gap losses destroy the efficiency. This means that the small flow rate results in extremely fast rotating machines for which until recently no electric drives or generators were available. However, one finds also in the previous technology very small radial turbomachinery. So in cryotechnology as a throttle body on expansion turbines and in the exhaust gas turbocharger for piston engines. In both cases Speeds up to 300,000 revolutions per minute usual. In all applications, the turbocompressor is driven by a turbine and not directly electrically or mechanically.

The limits of the use of directly electrically driven turbomachinery are today at the speed of an electric motor or a generator. More recently, the answer to the question of the feasibility of a direct-drive turbocompressor for the application defined here according to the invention would clearly have had to be answered "no". Today electric motors are available, which can be used up to 1'000'000 revolutions per minute. All of them are all electronically consulted, as brushes are hardly conceivable under the operating conditions. This was made possible by fast and cost-effective power electronics, with which one is able to drive motors accordingly high-frequency.

By now recently possible dimensionally small turbocompressors can be achieved by the inventive proposed combination with a tumble dryer a significant increase in efficiency, at the same time extremely compact design by the turbocompressor latest generation dimensionally can be kept relatively small.

In conclusion, it follows that the use of a min. 2-stage radial turbocompressor has to be considered as a key to the fact that in a dryer proposed as in US Pat WO2007 / 093073 a significant increase in efficiency at the same time at least constant sizing is made possible.

The invention has the advantage that due to the favorable energy balance of the process, the costs for the drying of the material to be dried, such as the laundry or the like, are reduced. The clothes dryer according to the invention moreover has the advantage of a simplified construction in comparison with known clothes dryers, which contributes to a reduction in the production costs. Another advantage is that tumble dryers can be operated more economically than known dryers.

In addition, the laundry is dried much more gently thanks to the lower drying temperature.

Essence of the invention is that the water to be extracted from the laundry is used as a working medium for an open heat pump process.

Fig. 1

eine Trommel und zu dieser benachbarte Bauteile eines erfindungsgemässen Wäschetrockners, schematisch in einem Schnitt senkrecht zur Trommelachse,

Fig. 2

die Trommel und zu dieser benachbarte Bauteile eines erfindungsgemässen Wäschetrockner, schematisch in einem Schnitt entlang der Trommelachse,

Fig. 3

Laufrad eines radialen Truboverdichters mit und ohne Deckscheibe,

Fig. 4

Schnitt längs der Wellenachse durch einen 2-stufigen Turboverdichter mit Elektromotor und Lagerung, wobei beide Verdichterstufen am selben Wellenende angeordnet sind,

Fig. 5

Schnitt längs der Wellenachse durch einen 2-stufigen Turboverdichter mit Elektromotor und Lagerung, wobei die beiden Verdichterstufen je an einem Wellenende angeordnet sind,

Fig. 6

Schnitt längs der Wellenachse durch einen 2-stufigen Turboverdichter mit Elektromotor und Lagerung, wobei die beiden Verdichterstufen je an einem Wellenende angeordnet sind, wobei zwischen den Verdichterstufen ein Wärmetauscher als Zwischenkühler angeordnet ist.

The invention will be explained in more detail by means of embodiments with reference to the accompanying figures. Show it:

Fig. 1

a drum and adjacent components of a tumble dryer according to the invention, schematically in a section perpendicular to the drum axis,

Fig. 2

the drum and, to this adjacent components of a tumble dryer according to the invention, schematically in a section along the drum axis,

Fig. 3

Impeller of a radial trolley compressor with and without cover disk,

Fig. 4

Section along the shaft axis through a 2-stage turbocompressor with electric motor and bearing, wherein both compressor stages are arranged on the same shaft end,

Fig. 5

Section along the shaft axis through a 2-stage turbocompressor with electric motor and storage, wherein the two compressor stages are each arranged at a shaft end,

Fig. 6

Section along the shaft axis through a two-stage turbo compressor with electric motor and storage, wherein the two compressor stages are each arranged at a shaft end, wherein between the compressor stages, a heat exchanger is arranged as an intercooler.

In the Fig. 1 schematically illustrated arrangement, which comprises a drum 1 and to these adjacent components is housed inside a chassis (not shown) of the clothes dryer. The airtight sealable drum 1 is used to hold eg laundry and is surrounded by an example cylindrical insulation housing 2 of good thermal insulation material, such as insulation wool, polystyrene, foamed polyurethane, etc. The drum 1 consists of a good heat-conducting material, such as stainless steel, aluminum, etc. Of course, both drum and insulation housing also spherical, egg-shaped, etc. may be formed, it is essential that the shape resp. the Construction allows the evacuation of the interior. In the lower area, the insulation housing 2 is provided with a liquid, for example ball-shaped or cylindrical collecting vessel 5, for collection. A heating device (not shown) for heating the drum interior 4 is provided on the tumble dryer, wherein the heating device can be, for example, a heating coil (10), as shown, or an infrared heat radiator arranged at a distance from the drum 1 in the insulation housing. At the tumble dryer, a control device can be provided, by means of which the temperature in the drum interior 4 can be controlled in a conventional manner by means of the heating device mentioned. In this case, the pressure in the drum, the so-called temperature indicator, as long as there is sufficient water or moisture in the system, such as the laundry, is present.

For the pressure reduction in the drum 4, as now proposed according to the invention, a turbocompressor 3 is provided which, for example, draws air-water vapor mixture from the interior of the drum via a discharge line provided centrally in the drum axis. Subsequent to the turbo compressor, a return line 9 is provided to guide at least a portion of the compressed air-water vapor mixture into the interior of the insulating housing 2 to the outer wall of the drum 1.

Fig. 2 shows the drum 1 and to this adjacent components of a laundry dryer according to the invention, schematically in a section along the drum axis. The For example, cylindrical drum 1 is pressure-resistant and is rotatably supported by (not shown) means in a known manner in the insulating housing 2 and driven by a (not shown motor). As the access to the loading of the drum 1 or to remove laundry 11 from the drum 1 is done via a closable by the door 6 access opening, which is provided in the front region of the drum 1.

Between the drum 1 and the insulating housing 2, a gap 7 remains.

The following is the description of the drying process. At the beginning, a location-dependent external air pressure of approximately 1 bar prevails in the drum interior 4. After the drum interior 4 is charged with moist laundry 11 and the door 6 is closed, a temperature of, for example, 60 ° C is produced in the drum interior 4, in which the laundry is spared and, above all, does not shrink. At the same time, the interior space 4 is successively evacuated by means of the turbo-compressor 3 to a pressure of approximately 0.2 bar, whereby the vapor pressure of the moisture in the laundry is increased and evaporation of the moisture commences. Subsequently, water vapor-air mixture containing vaporized steam from the laundry, from the turbo compressor 3 from the drum interior 4 in the outer area A, which is outside the drum interior 4, promoted, wherein the originating from the laundry moisture is discharged from the drum interior 4 , Since the drum 1 is largely hermetically sealed, the negative pressure remains during the removal of the water vapor-air mixture in the drum interior 4 is obtained.

From physics it is known that due to the decrease in pressure without further heating of the drum interior 4, the temperature in the drum interior 4 decrease and therefore the evaporation intensity (for example, defined as the amount of moisture that evaporates out of the laundry per unit time) would decrease or the evaporation would come to a halt. It could possibly come to the freezing of the water in the laundry. Therefore, it is necessary that at least as much heat is supplied to the drum interior 4 during the drying process, for example, by the mentioned heating means that the evaporation process is kept in motion. The pumping of the water vapor-air mixture is carried out until the mentioned predetermined negative pressure of, for example, has reached almost 0.2 bar. It has been shown that a gentle and energy-efficient drying results if the temperature in the drum interior 4 during the pumping, for example, at 60 ° C holds constant and the pressure by pumping the water vapor-air mixture to about 0.2 bar reduced. For further details on the physical processes that take place during the drying process in the drum interior 4, reference is made to the technical literature.

As already mentioned above, the pumped-off steam-air mixture is fed to an outer area A, which lies outside of the drum interior 4 and prevails in the atmospheric pressure. Since during the pumping of the Water vapor-air mixture from the drum interior 4 is a pressure in the drum interior 4 is generated, which is less than the atmospheric pressure is compressed in an outdoor area A steam-air mixture in the outer area A and thereby heated by itself. In one possible embodiment of the method, at least part of the compressed and heated water vapor-air mixture is passed back into the intermediate region 7 within the insulating housing 2 and fed to the outside of the drum 1.

Due to the good thermal conductivity of the wall of the drum 1, a transfer of the heat of the water-steam mixture from the outside of the drum takes place in the drum interior 4, so that the cooled in the interior in consequence of evacuation and evaporation of the moisture cooled material is reheated. In this case, the amount of guided to the outside water-steam mixture can be chosen such that the previously mentioned and desired internal temperature of about 60 ° can be maintained.

Due to this cooling output to the drum 1 condenses, the outside of the drum 1 supplied water vapor. Thus, a heat recycling takes place, in which the drum 1 serves as a kind of heat exchanger. Thus, the further heating of the drum by the above-mentioned heater or otherwise required in addition to the drum 1 arranged heat exchanger is obsolete, thereby reducing the structural and operational costs of the inventive drying device and thus reduce their manufacturing and operating costs.

By choosing a particularly good thermal insulation material for the insulation housing 2, the energy losses can be reduced and thus improve the efficiency of the drying process. The precipitated in the condensation water runs down along the outside of the drum 1 and finally enters the collecting container. 5

The big advantage of the present invention, compared with the dryer as proposed in the WO2007 / 093073 , lies in the use of a turbo compressor or a small turbo compressor for generating the vacuum in the drying chamber. The use of the turbo-compressor brings a significant increase in efficiency of the dryer with at the same time reduced operating costs. By enabling small turbocompressors, the dryer can also be dimensioned analogously to a dryer, as known in the art.

For example, proposed is a radial turbocompressor with at least 2 stages as in Fig. 4 . 5 or 6 is shown, wherein the wheels (15,21,23) with or without cover discs (13, Fig. 3 ) can be performed. A multi-stage turbocompressor with one or more coolers between the individual compressor stages ( Fig. 6 ) can be energetically advantageous. The turbocompressor and the possible intercooler (39), for example, arranged so that they are in the condensation chamber (7) or at least give off their waste heat in this.

In the in the Fig. 1 to 6 Of course, schematically illustrated embodiments are only to possible embodiments, which can be modified in any manner, modified or supplemented by other elements. In particular, has been dispensed with the representation of the usually used in drying equipment additional units and housing parts, since these are best known analog conventional devices. The Fig. 1 to 6 Concentrate on the essential elements of the illustrated embodiments. In particular, in the

Figures represented shape of the drum can of course be changed x-arbitrarily, depending on, for example, at which vacuum conditions and temperatures to operate the drying device. The operating conditions described are only for example and it is of course possible to work at lower or higher negative pressure, which of course also change the temperature conditions. It is also possible to move the drum with the moist, textile material or leave it alone, depending on whether a gentle drying is required. Known, a large part of the damage to the laundry by the mechanical movement and less by the drying process itself. So it is for example possible for wool to provide a special drying process in which the drum is little or no move.

Preferred operating conditions result from the textile material to be dried in each case and the optimization of the drying device proposed according to the invention is not in itself an object of the present invention.

In addition, it should be pointed out again that instead of just a laundry drum as shown in the Fig. 1 and 2 It is also possible to provide an evacuable and heatable drying space in which a rotatable laundry drum is arranged. The advantage of this solution could be that the evacuation of a stationary drying space is structurally simpler than the evacuation of a rotatable laundry drum.

Claims (13)

1. A process for drying a textile good in a reception for that purpose, wherein the pressure in the reception (1) with the textile good to be dried (11) is reduced with respect to the environmental pressure, whereby the evaporation temperature is reduced respectively and the evaporated humidity is removed from the interior of the reception, wherein the evaporated and removed humidity is compressed to environmental pressure through compression by means of a compressor (3) and at least a part of the heated humidity is supplied to the outer wall of the reception, where the humidity condensates at least partially, in order to heat it, characterized in that the compression is performed by a multi-stage radial turbo compressor, which is, for example, 2- or 3-stage, with or without covering disks.
2. The process according to claim 1, characterized in that the interior (4) of the reception (1) is reduced to a pressure < 0,5 bar, preferably in a range of 0,4 to 0,2 bar and the heating of the interior or of the good to be dried respectively takes place by means of heating correspondingly to a temperature of at least 40 °, preferably 50 to 65 °C, as especially approximately 60 °C.
3. The process according to one of claims 1 or 2 for operating a laundry dryer with a drying room or a drum (1) as reception and a heating device, at which steam is removed from the room interior or the drum interior (4) respectively and is supplied to an outside area (A), which is located outside of the drum interior (4), wherein the pressure in the room interior or the drum interior (4) respectively is reduced by evacuating and therefore by removing the steam, characterized in that the temperature in the room interior or the drum interior (4) is held at a temperature, that is at least almost as high, that the humidity evaporates from the laundry at least over a part of the duration of the removal of the steam.
4. The process according to one of claims 1 to 3, characterized in that compression is performed by means of a multi-stage radial turbo compressor, which is at least 2-stage and wherein one or more cooler are provided between the individual compressor stages.
5. A laundry dryer at least comprising:

   - a reception for a textile good to be dried, wherein the reception is designed as drying room, evacuatable drum or laundry room,

   - a heating device (10) for the heating of the reception, for example the drum (1), or the laundry (11) arranged therein respectively,

   - a compressor (3) for the evacuation of the room interior (4) of the reception and for the removal of the humidity from the reception, for example from the drum (1), as well as

   - a recirculation (9) of the removed humidity to the outer wall of the reception, for example of the drum (1), characterized in that, the compressor (3) is designed as a multi-stage radial turbo compressor (3).
6. The laundry dryer according to claim 5, characterized in that the turbo compressor is a multi-stage radial turbo compressor comprising at least two stages with one or more cooler between the individual compressor stages.
7. The laundry dryer according to one of claims 5 or 6, characterized in that the drive motor of the turbo compressor is arranged on the high pressure side, and is provided with a permanent magnet rotor, which typically comprises a fluid bearing, wherein, for example, the fluid can be water.
8. The laundry dryer according to claim 7, characterized in that a free floating sleeve is arranged at the fluid bearing, in order to reduce the sheer forces in the bearing.
9. The laundry dryer according to one of claims 7 or 8, characterized in that, the motor comprises an electric power of typically 500 Watt to 1 Kilowatt at revolution speeds from 300'000 to 700'000 revolutions/minute, preferably approximately 550'000 revolutions/minute.
10. The laundry dryer according to one of claims 5 to 9, characterized in that the recirculation (9) opens into the interspace and in that a reception (5) for the condensed humidity from the interspace is further provided.
11. The laundry dryer according to one of claims 5 to 10, characterized in that an evacuatable drying room is provided with a rotatable laundry drum arranged therein.
12. The laundry dryer according to one of claims 5 to 11, characterized in that the evacuatable drum (1) is a cylindrical drum with concave closures or concave side walls respectively.
13. The laundry dryer according to claim 12, characterized in that an opening is provided in one of the concave closures, which is covered with a largely transparent material, such as for example a window from quartz glass, and in that an additional heating device for the heating of the good to be dried is provided, like for example a halogen spot light, which is arranged in the region of the opening or the quartz glass window respectively.

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