A laundry machine with heat pump system and a method for operating the laundry machine

Abstract

 The present invention relates to laundry machine with heat pump system. The heat pump system comprises an air stream circuit (10) and a closed refrigerant circuit (12) for a refrigerant. The air stream circuit (10) includes a condenser (18) and an evaporator (20). The air stream circuit (10) is associated to a drum for receiving laundry to be dried. The refrigerant circuit (12) includes at least one compressor (14), the condenser (18), at least one expansion device (16) and the evaporator (20). The air stream circuit (10) and the refrigerant circuit (12) are thermally coupled by the condenser (18) and the evaporator (20). The condenser (18) is a heat exchanger and provided for heating up the air stream in the air stream circuit (10) and cooling down the refrigerant in the refrigerant circuit (12). The evaporator (20) is a heat exchanger and provided for cooling down the air stream in the air stream circuit (10) and heating up the refrigerant in the refrigerant circuit (12). The heat pump system includes at least one additional heat exchanger (22) between the refrigerant coming from an outlet of the condenser (18), the refrigerant coming from an outlet of the evaporator (20) and air in a further air stream (28). Further, the present invention relates to a method for operating the laundry machine.

Description

[0001] The present invention relates to a laundry machine with heat pump system according to the preamble of claim 1. Further, the present invention relates to a method for operating the laundry machine according to the preamble of claim 13.

[0002] The heat pump technology is an efficient way to save energy in a laundry machine for example in tumble dryers, washer-dryers or washing machines. The following description will refer particularly to a tumble dryer but the invention is clearly applicable to other household appliances.

[0003] Usually the tumble dryer comprises an open or closed air stream circuit and a closed refrigerant circuit. The air stream circuit and the refrigerant circuit are coupled by at least two heat exchangers, e.g. an evaporator and a condenser.

[0004] In the air stream circuit hot dry air is blown into the drum containing wet laundry. Then warm humid air leaves the drum and is cooled down in the evaporator. The water vapour of the humid air is condensed and deposited in the evaporator, while a refrigerant in the refrigerant circuit evaporates and is heated up in the evaporator. Thus, the humid air is dehumidified by the condensation of the water vapour. Then cold dry air in the air stream circuit is blown to a condenser, in which said dry air is heated up, while the refrigerant condenses and is cooled down in the condenser. At last hot dry air is blown into the drum again.

[0005] In the refrigerant circuit the refrigerant is compressed and heated by a compressor. Then the refrigerant condenses and is cooled down in the condenser, in which the air stream is heated up. Between the condenser and the evaporator the refrigerant passes an expansion device, in which said refrigerant is cooled down. In the evaporator the refrigerant is heated up and the air stream is cooled down, wherein the water vapour of the air stream condenses. Then the refrigerant is compressed and heated up again by the compressor.

[0006] As the expansion device a capillary device is used, e.g. an expansion valve or a throttling device. The safe work of the compressor may not be impeded by the capillary tube design. The necessary superheating at the outlet of the evaporator must be realized and maintained. The efficiency is not optimum, because a portion of the evaporator is dedicated to overheat instead of dehumidify the air stream.

[0007] It is an object of the present invention to provide a heat pump system for a tumble dryer, which allows the compressor to work in safe way. Further, it is an object of the present invention to provide a corresponding method for operating said heat pump system.

[0008] The object of the present invention is achieved by the heat pump system according to claim 1.

[0009] According to the present invention the heat pump system includes at least one additional heat exchanger between the refrigerant coming from an outlet of the condenser, the refrigerant coming from an outlet of the evaporator and air in a further air stream.

[0010] The core of the present invention is the exchange of heat between two different points of the refrigerant circuit on the one hand and between the further air stream and at least one of said points on the other hand. The additional heat exchanger has a double function. A part of the additional heat exchanger act as an auxiliary condenser. Another part of the additional heat exchanger act as a regenerative heat exchanger. The auxiliary condenser is provided for that refrigerant, which comes from the outlet of the condenser. The regenerative heat exchanger is provided for that refrigerant, which comes from the outlet of the evaporator.

[0011] The auxiliary condenser keeps the superheating phase out of the evaporator. The expansion device may be reduced, e.g. a shorter capillary tube can be used. The present invention improves the heat pump performances. The regenerative heat exchanger preserves the compressor from failure due to entering of liquids. The time for drying the laundry is reduced. The energy consumption is also reduced.

[0012] According to a preferred embodiment of the present invention the additional heat exchanger comprises a first refrigerant channel interconnected between an outlet of the condenser and an inlet of the expansion device. Preferably, the first refrigerant channel within the further air stream works as the auxiliary condenser.

[0013] Further, the additional heat exchanger may comprise a second refrigerant channel interconnected between an outlet of the evaporator and an inlet of the compressor.

[0014] In particular, the second refrigerant channel is thermally coupled to the first refrigerant channel so as to works as the regenerative heat exchanger.

[0015] For example, the expansion device is or includes a capillary tube and/or an expansion valve.

[0016] Preferably, the condenser comprises a serpentine pipe for the refrigerant, wherein said serpentine pipe is arranged within the air stream circuit.

[0017] In a similar way, the evaporator may comprise a serpentine pipe for the refrigerant, wherein said serpentine pipe is arranged within the air stream circuit.

[0018] Further, the first refrigerant channel may comprise a serpentine pipe for the refrigerant, wherein said serpentine pipe is arranged within the further air stream.

[0019] Similarly, the second refrigerant channel may comprise a serpentine pipe for the refrigerant, wherein said serpentine pipe is thermally coupled to the first refrigerant channel.

[0020] For example, the further air stream is generated by at least one fan.

[0021] Further, the present invention relates to a corresponding tumble dryer with the heat pump system as described above.

[0022] The object of the present invention is further achieved by the method for operating the heat pump system according to claim 13.

[0023] According to the present invention there is an exchange of heat between the refrigerant coming from the condenser, the refrigerant coming from the evaporator and air within an air stream by an additional heat exchanger.

[0024] The main idea of the present invention is the exchange of heat between two different points of the refrigerant circuit and the air stream. The additional heat exchanger acts as an auxiliary condenser as well as a regenerative heat exchanger. The auxiliary condenser is provided for that refrigerant coming from the outlet of the condenser. The regenerative heat exchanger is provided for that refrigerant coming from the outlet of the evaporator.

[0025] The auxiliary condenser keeps the superheating phase out of the evaporator. The expansion device may be reduced, so that a shorter capillary tube can be used. The present invention improves the heat pump performances. The regenerative heat exchanger preserves the compressor from failure due to a liquid entering. The time for drying the laundry is reduced, so that the energy consumption is also reduced. Preferably, the method is performed by the heat pump system and/or the tumble dryer as described above.

[0026] The novel and inventive features believed to be the characteristic of the present invention are set forth in the appended claims.

[0027] The invention will be described in further detail with reference to the drawings, in which

FIG 1

illustrates a schematic diagram of a heat pump system for a tumble dryer according to a preferred embodiment of the present invention, and

FIG 2

illustrates a schematic view of an additional heat exchanger for the heat pump system according to the preferred embodiment of the present invention.

[0028] FIG 1 illustrates a schematic diagram of a heat pump system for a tumble dryer according to a preferred embodiment of the present invention. The heat pump system comprises an air stream circuit 10 and a refrigerant circuit 12.

[0029] The air stream circuit 10 includes a drum, a condenser 18 and an evaporator 20. The drum is not shown in FIG 1. The drum is integrated within the air stream circuit 10 and provided for receiving laundry to be dried. Additionally, the air stream circuit 10 may include a fan. The air stream circuit 10 may be formed as a closed or an open loop. FIG 1 shows only a portion of the air stream circuit 10.

[0030] The condenser 18 and the evaporator 20 are air-fluid heat exchangers and form the interconnections between the air stream circuit 10 and the refrigerant circuit 12. The condenser 18 is provided for heating up the air stream in the air stream circuit 10. The evaporator 20 is provided for cooling down the air stream in the air stream circuit 10 for condensing the water vapour in said air stream.

[0031] The refrigerant circuit 12 includes a compressor 14, the condenser 18, an additional heat exchanger 22, an expansion device 16 and the evaporator 20. The refrigerant circuit 12 forms a closed loop. The air stream circuit 10 and the refrigerant circuit 12 are thermally coupled by the condenser 18 and the evaporator 20. The additional heat exchanger 22 is also an air-fluid heat exchanger.

[0032] A refrigerant flows in the refrigerant circuit 12. The refrigerant is compressed and heated by the compressor 14. Then, the heated refrigerant reaches the condenser 18. In the condenser 18 the refrigerant condenses and is cooled down. At the same time, the air stream in the air stream circuit 10 is heated up.

[0033] The additional heat exchanger 22 comprises a first refrigerant channel 24 fluidly connecting the outlet of the condenser 18 to the inlet of the expansion device 16. In the first refrigerant channel 24 of the additional heat exchanger 22 the refrigerant is additionally cooled down by the air in the air stream 28 and by the refrigerant coming from the evaporator 20.

[0034] Then the refrigerant is expanded and cooled down by the expansion device 16. In the evaporator 20 the refrigerant is heated up and the air stream in the air stream circuit 10 is cooled down.

[0035] The additional heat exchanger 22 comprises a fan 30 generating the air stream 28. At least the first refrigerant channel 24 is arranged within the air stream 28. The fan 30 takes the air from outside the apparatus. It is not necessary that the air stream 28 requires an air-tight channel. The only channel of the heat pump system can be the air stream circuit 10 which is preferably a closed circuit, in which the condenser 18, the evaporator 20 and the drum are arranged. In this example, the fan 30 blows only at the first refrigerant channel 24, but not at the second refrigerant channel 26.

[0036] The additional heat exchanger 22 comprises a second refrigerant channel 26 fluidly connecting the outlet of the evaporator 20 to the inlet of the compressor 14. In the second refrigerant channel 26 of the additional heat exchanger 22 the refrigerant is additionally heated up by the refrigerant coming from the condenser 18. At last, the refrigerant is compressed and heated up again by the compressor 14.

[0037] The additional heat exchanger 22 removes heat from the first refrigerant channel 24, whereas due to the arrangement of the first refrigerant channel 24 and the second refrigerant channel 26 a superheating of the outlet of the evaporator 20 is improved. The additional heat exchanger 22 comprises a plurality of fins 32 allowing a heat exchange between the first refrigerant channel 24 and the second refrigerant channel 26.

[0038] Thus, in the additional heat exchanger 22 a first heat exchange between the first refrigerant channel 24 and the air blown by the fan 30 is performed. In a similar way, a second heat exchange between the first refrigerant channel 24 and the second refrigerant channel 26 is performed in the additional heat exchanger 22.

[0039] FIG 2 illustrates a schematic view of the additional heat exchanger 22 for the heat pump system according to the preferred embodiment of the present invention. The additional heat exchanger 22 is an air-fluid heat exchanger and is arranged within the air stream 28.

[0040] FIG 2 clarifies the arrangement of the first refrigerant channel 24, the second refrigerant channel 26 and the fins 32. The fins 32 allow the heat exchange the first refrigerant channel 24 and the second refrigerant channel 26.

[0041] The additional heat exchanger 22 comprises a first refrigerant channel 24 and a second refrigerant channel 26. The first refrigerant channel 24 and the second refrigerant channel 26 are formed as serpentine pipes in the additional heat exchanger 22. In this example, the first refrigerant channel 24 comprises a plurality of straight channel sections (preferably five) and the second refrigerant channel 26 comprises a plurality of straight channel sections (preferably two).

[0042] The auxiliary condenser keeps the superheating phase out of the evaporator. The additional heat exchanger 22 improves the heat pump performances. The regenerative heat exchanger preserves the compressor from failure due to the entering of liquids. The time for drying the laundry and the energy consumption are reduced.

[0043] Although an illustrative embodiment of the present invention has been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to that precise embodiment, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.

List of reference numerals

[0044] 

10

air stream circuit

12

refrigerant circuit

14

compressor

16

expansion device

18

condenser

20

evaporator

22

additional heat exchanger

24

first refrigerant channel

26

second refrigerant channel

28

air stream

30

fan

32

fins

Claims

1. A laundry machine with heat pump system, wherein:

- the heat pump system comprises an air stream circuit (10) and a closed refrigerant circuit (12) for a refrigerant,

- the air stream circuit (10) includes a condenser (18) and an evaporator (20),

- the air stream circuit (10) is associated to a drum for receiving laundry to be dried,

- the refrigerant circuit (12) includes at least one compressor (14), the condenser (18), at least one expansion device (16) and the evaporator (20),

- the air stream circuit (10) and the refrigerant circuit (12) are thermally coupled by the condenser (18) and the evaporator (20),

- the condenser (18) is a heat exchanger and provided for heating up the air stream the air stream circuit (10) and cooling down the refrigerant in the refrigerant circuit (12), and

- the evaporator (20) is a heat exchanger and provided for cooling down the air stream in the air stream circuit (10) and heating up the refrigerant in the refrigerant circuit (12),

characterized in that
the heat pump system includes at least one additional heat exchanger (22) between the refrigerant coming from an outlet of the condenser (18), the refrigerant coming from an outlet of the evaporator (20) and air in a further air stream (28).

2. The laundry machine according to claim 1, characterized in that
the additional heat exchanger (22) comprises a first refrigerant channel (24) interconnected between an outlet of the condenser (18) and an inlet of the expansion device (16).

3. The laundry machine according to claim 2,
characterized in that
the first refrigerant channel (24) within the further air stream (28) acts as an auxiliary condenser.

4. The laundry machine according to any one of the preceding claims,
characterized in that
the additional heat exchanger (22) comprises a second refrigerant channel (26) interconnected between an outlet of the evaporator (18) and an inlet of the compressor (14).

5. The laundry machine according to claim 4,
characterized in that
the second refrigerant channel (26) thermally coupled to the first refrigerant channel acts as a regenerative heat exchanger.

6. The laundry machine according to any one of the preceding claims,
characterized in that
the expansion device (16) is or includes a capillary tube and/or an expansion valve.

7. The laundry machine according to any one of the preceding claims,
characterized in that
the condenser (18) comprises a serpentine pipe for the refrigerant, wherein said serpentine pipe is arranged within the air stream circuit (10).

8. The laundry machine according to any one of the preceding claims,
characterized in that
the evaporator (20) comprises a serpentine pipe for the refrigerant, wherein said serpentine pipe is arranged within the air stream circuit (10).

9. The laundry machine according to any one of the preceding claims,
characterized in that
the first refrigerant channel (24) comprises a serpentine pipe for the refrigerant, wherein said serpentine pipe is arranged within the further air stream (28).

10. The laundry machine according to any one of the preceding claims,
characterized in that
the second refrigerant channel (26) comprises a serpentine pipe for the refrigerant, wherein said serpentine pipe is thermally coupled to the first refrigerant channel.

11. The laundry machine according to any one of the preceding claims,
characterized in that
the further air stream (28) is generated by at least one fan.

12. The laundry machine according to any one of the preceding claims,
characterized in that
in the additional heat exchanger 22 a first heat exchange between the first refrigerant channel 24 and the air blown by the fan 30 is performed and a second heat exchange between the first refrigerant channel 24 and the second refrigerant channel 26 is performed in the additional heat exchanger 22.

13. A method for operating laundry machine with heat pump system, said method comprises the steps of:

- compressing and heating up a refrigerant in a closed refrigerant circuit (12) by a compressor (14),

- condensing and cooling down the refrigerant by a condenser (18), wherein an air stream in an air stream circuit (10) is heated up by said condenser (18),

- expanding and cooling down the refrigerant by an expansion device (16),

- heating up the refrigerant by an evaporator (20), wherein the air in the air stream circuit (28) is cooled down, and

- compressing and heating up again the refrigerant by the compressor (14).

characterized in, that
there is an exchange of heat between the refrigerant coming from the condenser (18), the refrigerant coming from the evaporator (20) and air within an air stream (28) by an additional heat exchanger (22).

14. The method according to claim 13,
characterized in, that
the method is performed by a laundry machine according to any one of claims 1-12.

Drawing