EP2029804B1 - Device and method for drying laundry - Google Patents

Description

The invention relates to a device for drying laundry, comprising a substantially closed channel system for guiding an air stream acting on the laundry, in which channel system a treatment chamber for receiving the laundry, a fan for driving the air flow, a heater for heating the air flow before the application of the laundry and a cooler for cooling the air flow after the loading of the laundry are arranged.

Likewise, the invention relates to a method for drying laundry by means of a guided in a substantially closed channel system, the laundry to be acted upon air flow, in which channel system, a treatment chamber for receiving the laundry, a blower for driving the air flow, a heater for heating the air flow before the Loading the laundry and a cooler for cooling the air flow after the loading of the laundry are arranged.

Such a method and apparatus will be apparent from each of the documents EP 0 477 554 B1 and EP 1 108 812 B1 , the disclosure of which is fully attributable to this disclosure. The duct system in which the air flow is guided is substantially closed - this means that the air flow circulates in the normal operation substantially without leaks, but does not assume a much higher pressure than air in the vicinity of the device. The treatment room for receiving the laundry is designed as a rotatable drum.

From the EP 0 467 188 B1 , the disclosure of which is fully attributable to the disclosure, a device for drying laundry emerges in which a heat pump is provided instead of the arrangement of cooler and heater. In this case, an evaporator takes the place of the cooler, and in place of the heater, a condenser for a circulating in an associated cycle of the heat pump working fluid. The evaporator can be referred to as a "cold branch" of the heat pump because it extracts heat from the flowing air stream; as can the Condenser be referred to as a "warm branch", as the heat flowing through the air stream. If desired, the channel system in which the air flow circulates can be brought into contact with the environment by opening a flap, in particular to discharge part of the air stream heated during operation from the device and to replace it with relatively cool ambient air ,

From the DE 14 10 206 A is a washing machine, in which laundry not only washed, but also can be dried. For the additional facilities required for this, the document shows several alternatives; In particular, an electric heating device for heating an air stream used for drying laundry and a simple heat exchanger for cooling the heated air stream after the loading of the laundry may be provided, alternatively, a heat pump may be provided. This heat pump can be designed like the one in the EP 0 467 188 B1 It may also be a heat pump that uses Peltier elements to utilize the thermoelectric effect.

From the DE 19 738 735 C2 goes out a device for drying laundry of the type described input, in which a heat pump is used, which operates on an absorber principle.

One from one in the "Patent Abstracts of Japan" data collection JP 08 057 194 A proper English short summary resulting device for drying laundry, which in turn corresponds to the input described type contains in its channel system in addition to a thermoelectric heat pump with cold and warm branch upstream of the cold branch additional heat exchanger for cooling the discharged air from the laundry and a warm Branch downstream additional heater for further heating of the air flow before applying the laundry.

Also from the DE 35 09 549 A1 shows a device for drying laundry, which in addition to a heat pump has a further heating device and additional heat transport devices such as gravitation heat pipes.

The document DE-C1-4330456 discloses a method and an apparatus for drying laundry, comprising a substantially closed duct system for guiding an air stream to be washed, in which duct system a treatment chamber for receiving the laundry, a fan for driving the air flow, a heater for heating the air flow before Loading the laundry and a cooler are arranged for cooling the air flow after the loading of the laundry, and with a arranged in the channel system heat pump comprising a pumping unit and a cold branch and a warm branch.

All of the devices described in the prior art have in common that their components required for drying the laundry are arranged one behind the other in the channel system provided for guiding the air flow. Such an arrangement has specific requirements for implementation in a suitable and suitable for use in a normal household device. These requirements may be due to only limited space available that components of the duct system must be relatively small and therefore run with relatively high flow resistance for the air flow; this can significantly affect the effect of the drying process taking place in the device, since in this case an airflow with limited volume throughput must be driven by a channel system that may cause considerable frictional and throttling losses. This problem is particularly pronounced when a heat pump is used in the device, in particular a thermoelectric heat pump. Especially in such a case, in a device which is used in a household tumble dryer with conventional outer dimensions, the duct system must be folded several times.

Details on the basics, function and application of Peltier elements can be found in documents published on 25 November 2005 from the Internet addresses http://www.quick-ohm.de/waerme/download/Erlaeuterung-zu-Poltierelemonten.pdf and http://www.quick-ohm.de/waerme/download/Einbau.pdf
were downloadable.

An object of this invention is the further development of the device mentioned in the introduction as well as the method mentioned in the introduction to the extent that a drying of the laundry is possible with a relation to the possibilities of the prior art reduced use of energy.

This task can also be seen against the background of the EP 0 467 188 B1 and other documents mentioned above known use of a heat pump. In principle, the heat pump provides the recovery of at least a portion of the heat energy, which is supplied to an air stream, before it acts on the laundry and extracted moisture, and this air stream is subsequently withdrawn to condense the extracted and entrained from the laundry moisture and separate. However, a conventional heat pump for use in a tumble dryer is comparatively expensive and expensive, which limits the use of a heat pump to distinctly expensive dryers. Also, a conventional heat pump takes a relatively long time to achieve a steady state operation after its commissioning, so that this drying of laundry is relatively tedious. From this complex of problems to be remedied with the invention.

To achieve the object according to the invention an apparatus for drying laundry, comprising a substantially closed channel system for guiding an air stream acting on the laundry, in which channel system, a treatment chamber for receiving the laundry, a fan for driving the air flow, a heater for heating the Air stream are arranged before the loading of the laundry and a cooler for cooling the air flow after the loading of the laundry, wherein a arranged in the channel system heat pump is provided, which comprises a pumping unit and a cold branch and a warm branch, wherein the cold branch and the warm branch are connected in parallel to each other and can be flowed through in parallel by corresponding parts of the air flow.

Also, to achieve the object, a method for drying laundry by means of a guided in a substantially closed channel system, the laundry to be acted upon air stream, in which channel system, a treatment chamber for receiving the laundry, a fan for driving the air flow, a heater for heating the Air flow before applying the laundry and a cooler for cooling the air flow after the application of the laundry are arranged, wherein the air flow through a heat pump comprising a pumping unit and a cold branch and a warm branch, wherein the cold branch and the warm branch of corresponding parts flow through the air flow in parallel.

According to the invention, therefore, a heat pump is provided in a designed in the manner of a known circulating air dryer, a heat pump, with which part of the heat energy expended for heating the air flow is recoverable. From the realization that in a heat pump always a Using energy is required to operate the desired pumping process, according to the invention, the known arrangement of a conventional heater and a conventional radiator is not simply replaced by a heat pump, but these components are retained. They should be designed to handle the drying of one kilogram of wet laundry from a standard washing process in a maximum of 30 minutes. The additionally used heat pump serves to reduce the expenditure of energy to such an extent that a given limit for the energy consumption, for example a limit defined by the generally known energy consumption class A, is exceeded. The heat pump should be designed to reduce the energy consumption of the device per kilogram of wet laundry used by at least 0.1 kWh, in particular about 0.13 kWh.

According to the invention, a heat pump is used, which differs substantially from the heat pumps described above. With this heat pump, removal of heat from an air stream and supply of heat to an air stream are not sequential, with the air stream passing through respective components of the heat pump sequentially, but simultaneously at two parts into which the air stream is split in front of the heat pump. In accordance with the invention, there is thus a departure from a paradigm derived from a functional consideration of the drying process. Thus, the invention opens up a great advantage in that the parallel arrangement of the cold and the warm branch makes a substantially doubled flow cross section at substantially halved flow length available for the air flow and thus a resulting in the flow through the heat pump pressure loss compared to any corresponding device of the state the technology significantly reduced; This reduction is also particularly large, that the cold and the warm branch of the heat pump no longer need to be flowed through one another with the addition of their flow resistance. The use of the heat pump improves the performance of the dryer by the pumping power of the Peltier elements, which is currently between 50% and 70% of their electrical connection capacity. With an electrical connection power of 500 W (see also below), a pump power between 250 W and 350 W is therefore to be expected.

Preferably, the channel system in the device downstream of the radiator comprises a separator for separating moisture from the air flow. Through this Separator can moisture, which has been condensed in the cooler or in the cold branch of the heat pump from the air stream, removed from the air flow and fed to a suitable collecting container.

The treatment chamber of the device is preferably rotatable and in particular designed as a drum for receiving the laundry, wherein the drum is provided on the inside with strip-like drivers. In such a drum, the laundry can be moved and shaken in the impinging air flow, which is conducive to a uniform dehumidification of the laundry while largely avoiding wrinkling in the laundry.

It is particularly preferred that the heater and the cooler are set up for drying the laundry without using the heat pump. In particular, in this context, the heater is preferably designed for a maximum heating power of at most 2700 W, in particular about 2000 W. Accordingly, the cooler is designed in particular for a cooling capacity of at least 1000 W, in particular about 1800 W. These and the following performance specifications apply in particular a device designed to dry 7 kg wet laundry from a conventional washing process.

The heat pump is preferably designed for a power consumption between 200 W and 800 W, in particular about 500 W. In this design, the heat pump can reduce the energy consumption of a conventional dryer of energy efficiency class C so far that the supplemented by this heat pump dryer can be assigned energy efficiency class A. , In this case, the pump power of the heat pump is in particular between 200 W and 300 W, wherein the pump power corresponds to that power with which heat energy is pumped from the cold branch to the warm branch of the heat pump.

The pump unit of the heat pump is preferably a thermoelectric pump unit, that is, a pump unit which functions with Peltier elements as functional components. In this connection, the pump unit preferably has a power consumption of about 500 W; the heater is set up for optional operation at a high level with a power consumption of about 2000 W and on one In particular, the heater and the pump unit are arranged to control such that the pump unit is operated in conjunction with the heater. The heater contains in the simplest case a preferably electrically operable heating element; In order to be able to flexibly adapt its heat output to the requirements of the drying process, it may be advantageous if the heater has two or more heating elements or heating stages.

A configuration according to the previous paragraph is shown in particular such that the heater contains two independently operable heating elements, the first of which together with an associated switch or relay connected in series with the heat pump and the second is connected in addition to the associated switch or relay in parallel to this series circuit. So it is particularly possible to use the full power output of the heater and the heat pump to heat the device quickly after their commissioning and thus to create the conditions for effective drying of the laundry in a largely quasi-stationary operation. If the device is sufficiently warmed up, the power output of the heater can be reduced if necessary, whereby the further operated heat pump at least partially compensates for the reduced power of the heater and additionally improves the dehumidification of the airflow flowing from the treatment chamber and saturated with moisture.

Preferably, the device in the duct system in front of the heat pump includes a first divider through which the air flow is divisible into a first part passed through the cold branch and a second part led through the warm branch, the first part being between about 20% and about 50%. , in particular between 25% and 50%, of the total air flow. This corresponds to a distribution which is particularly well adapted to the operating requirements.

Further preferably, the heat pump is arranged in the air flow between the radiator and the heater. With additional preference, the duct system in front of the radiator contains a second divider, by means of which the air flow is divisible into a third part guided through the radiator and a fourth part guided through a secondary duct connected in parallel to the radiator. This leads to a further saving of energy, since instead of the entire air flow only the third part enters the cooler, and only this energy is withdrawn. It is particularly preferred that the secondary channel is additionally connected in parallel with the heat pump, or alternatively the secondary channel opens into a first branch of the heat pump, preferably the cold branch, and a second branch of the heat pump, preferably the warm branch, is connected to the cooler.

A preferred embodiment of the method according to the invention is that the heat pump is operated during drying for a period of 65% to 95% of a period of drying. With further preference, the heat pump is put out of operation, when in the laundry a residual moisture between 15% and 5%, in particular about 7%, is reached.

Fig. 1

ein Ausführungsbeispiel einer Vorrichtung zum Trocknen von Waschgut mit einer thermoelektrischen Wärmepumpe;

Fig. 2, 3, 4 und 5

jeweils ein Ausführungsbeispiel einer Weiterbildung der Vorrichtung gem. Fig. 1; und

Fig. 6 und Fig. 7

jeweils ein Schaltbild betreffend die Versorgung eines Heizers und einer Wärmepumpe mit elektrischer Energie.

Embodiments of the invention are explained below with reference to the drawing. The figures of the drawing show topologies of tumble dryers and are by no means to be understood as true-to-scale reproductions of real objects. In detail show:

Fig. 1

an embodiment of an apparatus for drying laundry with a thermoelectric heat pump;

FIGS. 2, 3, 4 and 5

in each case an embodiment of a development of the device gem. Fig. 1 ; and

Fig. 6 and Fig. 7

in each case a circuit diagram relating to the supply of a heater and a heat pump with electrical energy.

Fig. 1 shows a device for drying laundry 1, which has a substantially closed channel system 2 for guiding a laundry 1 impinging air stream 3. Disposed in the duct system 2 are a treatment chamber 4 for receiving the laundry 1, a fan 5 for driving the airflow 3, a heater 6 for heating the airflow 3 before the laundry 1 is charged, and a cooler 7 for cooling the airflow 3 after being charged of the laundry 1. The air flow 3 is represented by arrows, which are drawn next to the channel system 2 in the figure and in each case the direction of the circulating in the channel system 2 Indicate air flow 3. The air flow 3 circulates without substantial exchange with air from the environment of the device, wherein within the device but at no point a significant pressure difference to the environment occurs. For this reason, the channel system 2 is referred to herein as "substantially closed".

First, it should be noted that the heater 6 and the radiator 7 are designed so that they are suitable for drying the laundry 1 within a normal time for a conventional household tumble dryer without the use of other, previously unlisted components in the duct system 2. For this purpose, the heater 6 and the cooler 7 have specific power values which have been mentioned above and to which reference is hereby made.

The treatment chamber 4 is formed according to conventional practice as a rotatable drum 4; by their rotation, the laundry 1 is moved in the air stream 3, which supports a uniform absorption of moisture in the air stream 3. In the cooler 7, the moisture carried by the air stream 3 out of the drum 4 is condensed out and separated from the air stream 3 by means of a separator 8.

The device in Fig. 1 is characterized by a arranged in the channel system 2 heat pump 9, 10, 11 comprising a thermoelectric pump unit 9 and two heat exchangers 10 and 11, one of which, the "cold branch" 10, the cooling air flowing through, and the other, the " warm branch "11, which serves to warm air flowing through. The pump unit 9 receives as a functionally essential component semiconductor components, which cause by utilizing the Peltier effect temperature differences when they are flowed through by electric current. Such Peltier elements are known per se and in the present case require no further explanation in addition to a reference to documents cited above relating to the relevant prior art.

The heat pump 9, 10, 11 is designed in departure from a common paradigm so that its cold branch 10 and its warm branch 11 are not sequentially flowed through by the air flow 3, but in parallel. For this purpose, the air stream 3 is divided at a first divider 12 into a first part 13, which flows through the cold branch 10, and a second part 14, which flows through the warm branch 11. The Both parts 13 and 14 are united behind the heat pump 9, 10, 11 back to the air stream 3 and pass through the fan 5 and the heater 6 back to the drum 4. It is understood that the cold branch 10 has a separator 8 to separate moisture condensed out of the first part 13. It is further understood that the separator 8 of the radiator 7 and the cold branch 10 suitably cooperate as much as possible.

By means of the heat pump 9, 10, 11 on the one hand the action of the cooler 7 is supported by further separation of moisture from the air stream 3 and the first part 13, and also the action of the heater 6 due to the taking place in the warm branch 11 additional heating of the air flow For this purpose, energy is supplied only to the extent in which this is necessary for the operation of the pump unit 9, and in particular the thermal performance of the heater 6 can be reduced. So there is a significant saving of energy in an extent that is sufficient in any case to assign the device of energy efficiency class A. The device does not have the disadvantages of a conventional household clothes dryer with heat pump; In particular, it is possible to bring the device relatively quickly to its operating temperature, and the heat pump 9, 10, 11 can be switched off towards the end of the drying process, when only a small amount of moisture can be condensed from the air stream.

Fig. 2 shows a development of the device according to Fig. 1 , In this development, a second divider 15 is provided in the duct system 2 in front of the radiator 7, from which a secondary duct 16 starts. Only a third part 17 of the air flow 3 reaches the radiator 7 and the heat pump 9, 10, 11, and a fourth part 18 of the air flow passes through the sub-channel 16 around the radiator 7 and the heat pump 9, 10, 11 around to the blower 5, where he is reunited with the third part 17 only. This embodiment results in a further saving of energy, because it is no longer necessary to cool the entire air stream 3 so far that the desired condensation of moisture contained can take place. Rather, the condensation takes place exclusively from the third part 17. Incidentally shows Fig. 2 also the interaction of the separator 8 of the cooler 7 and the cold branch 10th

A particularly preferred embodiment is Fig. 3 refer to. Again, located in the duct system 2 in front of the radiator 7, a second divider 15, from which a fourth part 18 of the air flow 3 is guided in a side channel 16. This sub-channel 16 leads past the radiator 7 and directly to the cold branch 10 of the heat pump 9, 10, 11. A third part 17 of the air flow 3 passes through the radiator 7 and from there to the warm branch 11 of the heat pump 9, 10, eleventh In this embodiment condensation of moisture takes place from the entire air stream 3, whereby the distribution of this condensation on the cooler 7 and the cold branch 10 is a matter of the dimensioning of the performance values of these components.

In any case, the particularly low flow resistance of the specific heat pump used 9, 10, 11 is used to relieve the conventional heater 6 and the conventional cooler 7 and energy that would be lost without the use of the heat pump 9, 10, 11, for drying the Laundry 1 to make usable. Preferred performance values for the components just discussed are listed above, and are incorporated herein by reference.

Fig. 4 shows another embodiment of the device according to FIG. 1 , Compared to the training according FIG. 3 the secondary duct 16 leads from the second branch 15 to the warm branch 11 of the heat pump 9, 10, 11, and the radiator 7 is followed by the cold branch 10.

Still another embodiment of the device according to FIG. 1 can be found in FIG. 5 , this training is in accordance with the training FIG. 4 essentially differs in that the arrangement comprising the heat pump 9, 10, 11, the heater 6 and the side channel 16 designed the same, but is traversed in the reverse direction of the air stream 3 and its parts 12 and 13. Functionally, this has at best little influence; It is clear that the present teaching is not limited to a particular order of the components of the device in the air stream. 3

In the developments according to FIG. 4 and FIG. 5 Condensation takes place only from the first part 13 of the air flow 3, which, however, has the advantage that only this first part 13 must be cooled so far that condensation can take place, and As a result, a reduction of the airflow 3 necessarily to be withdrawn energy is achieved.

Fig. 6 shows a circuit diagram for the supply of the heater 6 and the pump unit 9 with electrical energy. As stated above, it is advantageous to operate the heater 6 without operation of the pump unit 9 with approximately four times the electrical power than during operation of the pump unit 9. For this purpose, it is advantageous to perform the heater 6 and the pump unit 9 with the same connection resistances , as shown in Fig. 4 to electrically connect in series and connect to a single power supply 19. A switch 20 is additionally provided, with which the pump unit 9 is bridged when it should not work. If the heater 6 and the pump unit 9 are operated together, then half of the output voltage of the power supply 19 is applied to each of these components 6, 9, and a current flows which is half as large as if the heater 6 were supplied alone when the switch 20 is closed would. Accordingly, the power of the heater 6 operated alone is as desired four times as high as the power of the heater 6 when at the same time the pumping unit 9 is operated with the switch 20 open.

In the circuit according to FIG. 7 the heater 6 is designed with two electrical and independently operable heating elements 21 and 22. Whose first heating element 21 is connected in addition to an associated and upstream switch (or relay) 20 to the pump unit 9 in series. Whose second heating element 22 is connected in addition to associated and upstream switch (or relay) 20 parallel to this series arrangement. This circuitry comes with two switches or relays 20 to operate the heater 6 and the pumping assembly 9 together, either with only the first heating element 21 or with both heating elements 21 and 22 together. It also opens up the possibility of generating the required DC voltage in the power supply 19 by simply rectifying the mains supply voltage of, in particular, 230 V and without using a step-down converter or the like. By appropriate choice of the first heating element 21, taking into account the internal switching structure of the pumping unit 9, the compatibility of the series arrangement can be made with such a DC voltage, and by suitable selection of the second heating element 22, the desired performance of the heater 6 can be produced.

LIST OF REFERENCE NUMBERS

1

laundry

2

channel system

3

airflow

4

Treatment chamber, drum

5

fan

6

stoker

7

cooler

8th

separators

9

Heat pump, pump unit

10

Heat pump, cold branch

11

Heat pump, warm branch

12

First divider

13

First part of the airflow

14

Second part of the airflow

15

Second divider

16

secondary channel

17

Third part of the airflow

18

Fourth part of the airflow

19

power supply

20

Switch or relay

21

First heating element

22

Second heating element

Claims (18)

1. Device for drying laundry (1), comprising an essentially closed channel system (2) for conveying an airflow (3) acting on the laundry (1), in which channel system (2) a treatment chamber (4) for receiving the laundry (1), a fan (5) for driving the airflow (3), a heater (6) for heating the airflow (3) before it acts on the laundry (1) and a cooler (7) for cooling the airflow (3) after it acts on the laundry (1) are arranged, characterised by a heat pump (9, 10, 11) arranged in the channel system (2), comprising a pump unit (9) as well as a cold branch (10) and a warm branch (11), which are connected in parallel to one another and through which corresponding parts of the airflow (3) acting on the laundry (1) can flow in parallel.
2. Device according to claim 1, in which the channel system (2) has a separator (8) downstream of the cooler (7) for separating the moisture from the airflow (3).
3. Device according to claim 1, in which the treatment chamber (4) is rotatable and is in particular embodied as a drum (4).
4. Device according to one of the preceding claims, in which the heater (6) and the cooler (7) are set up for drying the laundry (1) without using the heat pump (9, 10, 11).
5. Device according to one of the preceding claims, in which the heater (6) is set up for a maximum heating power of at most 2700 W, in particularly approximately 2000 W.
6. Device according to one of the preceding claims, in which the cooler (7) has a cooling power of at least 1000 W, in particular approximately 1500 W.
7. Device according to one of the preceding claims, in which the heat pump (9, 10, 11) has a power consumption of between 200 W and 800 W, in particular approximately 500 W.
8. Device according to one of the preceding claims, in which the pump unit (9) is a thermoelectric pump unit (9).
9. Device according to claim 8, in which the pump unit (9) has a power consumption of approximately 500 W, and in which the heater (6) is set up to optionally operate at a high level with a power consumption of approximately 2000 W and at a low level with a power consumption of approximately 500 W, wherein the heater (6) and the pump unit (9) are set up for control purposes such that the pump unit (9) is operated together with the heater (6).
10. Device according to claim 9, in which the heater (6) contains two heater elements (21, 22) which can be operated independently of one another, the first (21) of which is connected in series with the heat pump (9, 10, 11) in addition to an associated switch (20), and the second (22) of which is connected in parallel to this series circuit (9, 21) in addition to the associated switch (20).
11. Device according to one of the preceding claims, in which the channel system (2) contains a first divider (12) upstream of the heat pump (9, 10, 11), by means of which the airflow (3) can be divided into a first part (13) conveyed through the cold branch (10) and a second part (14) conveyed through the warm branch (11), with the first part (13) amounting to between approximately 20% and approximately 50%, in particular between 25% and 50%, of the whole airflow (3).
12. Device according to one of the preceding claims, in which the heat pump (9, 10, 11) is arranged in the airflow (3) between the cooler (7) and the heater (6).
13. Device according to claim 12, in which upstream of the cooler (7) the channel system (2) contains a second divider (15), by means of which the airflow (3) can be divided into a third part (17) conveyed through the cooler (7) and a fourth part (18) conveyed through an auxiliary channel (16) which is connected in parallel to the cooler (7).
14. Device according to claim 13, in which the auxiliary channel (16) is also connected in parallel to the heat pump (9, 10, 11).
15. Device according to claim 13, in which the auxiliary channel (16) opens into a first branch (10, 11) of the heat pump (9, 10, 11), preferably the cold branch (10), and a second branch (10, 11) of the heat pump (9, 10, 11), preferably the warm branch (11), is connected to the cooler (6).
16. Method for drying laundry (1) by means of an airflow (3) acting on the laundry (1) and conveyed in an essentially closed channel system (2), in which channel system (2), a treatment chamber (4) for receiving the laundry (1), a fan (5) for driving the airflow (3), a heater (6) for heating the airflow (3) before it acts on the laundry (1) and a cooler (7) for cooling the airflow (3) after it acts on the laundry (1) are arranged, characterised in that the airflow (3) flows through a heat pump (9, 10, 11) comprising a pump unit (9) and a cold branch (10) and a warm branch (11), with the cold branch (10) and the warm branch (11) being flowed through in parallel by corresponding parts of the airflow (3) acting on the laundry (1).
17. Method according to claim 16, in which the heat pump (9, 10, 11) is operated during the drying process for a period of 65% to 95% of a duration of the drying process.
18. Method according to claim 17, in which the heat pump (9, 10, 11) is taken out of operation if a residual humidity of between 15% and 5%, in particular approximately 7%, is reached in the laundry (1).

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