EP2069566B1 - Apparatus and process for drying items of laundry, using a heat pump and a heat exchanger - Google Patents

Abstract

An apparatus for drying laundry including a process air system for guiding a process air stream along a process air path having a treatment chamber therealong at which the process air stream contacts laundry, a first fan for moving the process air stream, a cooling location of a heat exchanger, a heating location of a heat pump downstream of the heat exchanger, and a heater in addition to the heat pump for heating the process air stream; and a secondary air system for guiding a secondary air stream along a secondary air path, the secondary air path including a second fan for imparting motion to the secondary air stream, a heating location of the heat exchanger, and a cooling location of the heat pump, and, within the secondary air path, the cooling location of the heat pump is located downstream of the heating location of the heat exchanger.

Description

The invention relates to a device for drying laundry, comprising a substantially closed first channel system for guiding the process air acting on the laundry, in which first channel system, a treatment chamber for receiving the laundry, a first fan for driving the process air stream, a first cooling channel of a heat exchanger and a second heating channel of a heat pump are arranged, wherein the second heating channel along the process air flow is behind the first cooling channel, and an open second channel system for guiding a secondary air flow, in which second channel system a second fan for driving the secondary air flow, a first heating channel of the heat exchanger and a second cooling channel of the heat pump are arranged.

Likewise, the invention relates to a method for drying laundry, by means of a guided in a substantially closed first channel system and the laundry in a treatment chamber acting process air stream which cooled in a heat exchanger by a guided in an open second channel system secondary air flow and then by a heat pump Cooling of the secondary air flow is heated.

Such a method and apparatus will be apparent from the DE 43 30 456 C1 , There circulates a process air flow through the laundry to be dried to absorb moisture, the heat exchanger for cooling and condensation of moisture and the heat pump and optionally an additional heater for heating. An open secondary air flow first flows through the heat pump, where it is cooled, and then through the heat exchanger to cool the process air flow. Finally, the secondary air flow returns to an environment of the device from which it was previously removed. With this method and this device, the purpose is pursued to improve the condensation performance of the heat exchanger and therefore to additionally cool the secondary air flow by means of the heat pump. This is also a more compact and thus easier to handle especially for cleaning heat exchanger be achieved. The heat pump works with a circulating, cyclically alternately vaporized and liquefied refrigerant.

In the EP 1 342 828 A2 a device is described which has two circuits for air flows, which are coupled together via a thermoelectric heat pump on the one hand and an air-to-air heat exchanger on the other hand for the exchange of heat. A self-contained closed loop process air stream is heated in the heat pump and cooled in the heat exchanger, a self-contained or open cooling air flow is cooled in the heat pump and heated in the heat exchanger. Apart from any blowers for driving the air streams, no further functional components are provided.

A tumble dryer also results 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 conventional 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. 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 required additional facilities several alternatives are shown; In particular, an electric heating device for heating a used for drying laundry Air flow and a simple heat exchanger for cooling the heated air flow may be provided after applying the laundry, 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 extract device for drying laundry, which in turn corresponds to the type described input 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.

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-Peltierelementen.pdf and http://www.quick-ohm.de/waerme/download/Einbau.pdf were downloadable.

The input described apparatus and method according to EP 1 342 828 A2 have a disadvantage in that only the heat pump is available for heating the circulating process air flow. Also, the heat pump must pump the heat from its cooling channel to its heating channel via a significant temperature difference - at the outlet of the cooling channel prevails a temperature that is less than the temperature of the environment of the device is. With the corresponding cooling of the secondary air flow, it may optionally come to condensation of moisture in the secondary air flow, which may lead to a burden of the device with unwanted moisture and hygienic problems under certain circumstances.

An object of the invention to be disclosed below is to provide the apparatus and method according to the EP 1 342 828 A2 be further developed so that an improved heating of the process air flow and a better operating point of the heat pump can be achieved.

To achieve this object according to the invention, a device for drying laundry, comprising a substantially closed first channel system for guiding a process air flow acting on the laundry, in which first channel system a treatment chamber for receiving the laundry, a first fan for driving the process air flow, a first Cooling channel of a heat exchanger and a second heating channel of a heat pump are disposed, wherein the second heating channel along the process air flow is behind the first cooling channel, and an open second channel system for guiding a secondary air flow, in which second channel system, a second fan for driving the secondary air flow, a first heating channel of the heat exchanger and a second cooling channel of the heat pump are arranged, and in which device in the first channel system, a heater for heating the process air stream is arranged, and the second cooling channel along the Seku the air flow is behind the first heating channel.

For solving this problem according to the invention, a method for drying laundry is also carried out by means of a process air stream guided in a substantially closed first channel system and acting on the laundry in a treatment chamber, which is cooled in a heat exchanger by a secondary air flow guided in an open second channel system and thereafter is heated by a heat pump with cooling of the secondary air flow, in which method the process air flow is heated by a heater arranged in the first channel system and the cooling of the secondary air flow takes place behind the heat exchanger.

According to the invention, therefore, the process air flow is heated not only by the heat pump, but also by a special heater, which according to conventional practice can be designed as an electrical resistance heater. In addition, the heat pump is inserted into the second channel system for the secondary air flow so that it does not cool the secondary air flow until it has absorbed heat from the process air flow in the heat exchanger and thus lost relative humidity. Therefore, the heat exchanging components of the heat pump are exposed to moisture exposure only to a small extent, resulting in a particularly low tendency to corrosion and, accordingly, an advantage of extended life.

In addition - according to the invention - a sufficiently good efficiency of the heat exchanger assumed - the process air flow and the secondary air flow with a particularly low temperature difference in the corresponding channels heat pump, so that they can work at relatively low, averaged over their entire active volume temperature difference and thus particularly favorable conditions. This ensures a good efficiency of the heat pump.

The heat introduced by the heater into the process air flow is no longer or less completely lost in the secondary air flow in the device according to the invention or in the method according to the invention, but is recovered with the heat pump and returned to the process air flow. Even if this recovery is not complete, but can be achieved by suitable design of the heater, the heat exchanger and the heat pump that the device meets the requirements of the known energy consumption class A.

A preferred embodiment of the device is characterized in that the heater along the process air flow is arranged immediately in front of the treatment chamber. Such an undesirable loss of heat is kept low.

With further preference, the first fan along the process air flow is located immediately in front of the heater; so that the thermal load of the fan remains very small.

In another preferred refinement of the device, in the second channel system, in which the secondary air which cools the process air flow is guided, the second fan is arranged along the secondary air flow in front of the first heating channel. This arrangement is particularly favorable for the construction of the device.

The preferred arrangements of the first and second blowers should be noted that they have proven themselves in prior art devices, but are not necessarily mandatory for the functional success of the device according to the invention. Other arrangements, for example, the first fan behind instead of in front of the drum or the second blower behind instead of before the first heating channel, are conceivable and, in particular depending on the arrangement of the components of the device in a conventional housing for a corresponding domestic appliance, also advantageous.

In a particularly preferred development of the device, the first channel system has a separator on the outlet side of the first cooling channel for separating moisture from the process air stream; This can be easily separated and disposed of in a simple and convenient way resulting in the heat exchanger condensate from the process air stream. The separator can be constructively connected to the heat exchanger according to current practice. However, as far as possible separation of the condensate from the process air flow is an important criterion for achieving high efficiency, since in the process air flow remaining condensate must be evaporated again in the subsequent heating of the process air flow, which requires additional energy and thus the efficiency impaired the device during operation.

Also particularly preferred is a Weitebildung in which the treatment chamber is rotatable and in particular configured as a drum.

Furthermore, a further development of the device is particularly preferred in that the heater and the heat exchanger are set up for drying the laundry without using the heat pump. This development is favorable because it allows operation even without the heat pump as at least unusual component, albeit with some loss in terms of the energy to be used. The device thus achieves reliability as it would for a conventional clothes dryer is usual, without it depends on the characteristics of the heat pump used.

Preferably, the heater is designed for a maximum heating power of at most 2700 W, in particular about 2000 W.

Preferably, the heat exchanger has a cooling capacity of at least 1000 W, in particular about 1500 W.

For the heat pump of the device, a power consumption between 200 W and 800 W, in particular of about 500W, is preferred.

A particularly preferred development of the device has a heat pump with a thermoelectric pump unit. Such a pumping unit is very compact and simple, and therefore particularly suitable for use in a device designed as a tumble dryer. The particularly low load on the heat exchanging components has a particularly advantageous effect in such a heat pump, since in this case the problem of avoiding an impairment of the electrical components, the concept of the heat exchange components are immediately adjacent, to a much lesser extent than in such a heat pump in a device of the prior art.

Preferably, a thermoelectric pumping unit to be used in accordance with the invention has a power consumption of about 500 W, the heater in the corresponding apparatus being arranged for optional operation at a high level with a power consumption of about 2000 W and at a low level with a power consumption of about 500 W, and wherein the heater and the pumping unit are arranged to control such that the pumping unit is operated in unison with the heater.

The fact that the heat pump is operated simultaneously with the heater is generally a preferred development of the method and a preferred mode of operation of the device. Thus, at each stage where heat is supplied to the process air stream, heat is recovered which would otherwise be lost via the secondary air flow.

Fig. 1

eine Vorrichtung zum Trocknen von Waschgut mit einer Wärmepumpe und einem Wärmetauscher;

Fig. 2

einen Ausschnitt aus einer solchen Vorrichtung, umfassend eine Kompressor-Wärmepumpe;

Fig. 3

einen Ausschnitt aus einer Vorrichtung gemäß Figur 1, umfassend eine thermoelektrische Wärmepumpe.

Embodiments of the invention are explained below with reference to the drawing. The figures of the drawing are to be regarded as sketches; For the realization of the associated teaching in concrete embodiments, reference is made to the more extensive knowledge of a relevant skilled person and the cited documents of the prior art. In detail show:

Fig. 1

a device for drying laundry with a heat pump and a heat exchanger;

Fig. 2

a section of such a device, comprising a compressor heat pump;

Fig. 3

a section of a device according to FIG. 1 comprising a thermoelectric heat pump.

The device 1 for drying laundry 2 according to FIG. 1 is a substantially closed first channel system 3, in which a process air stream 4 (symbolized by a straight arrow outside the channel system 3) circulates. For receiving the laundry 2, a treatment chamber 5 in the form of a rotatable drum 5 is provided. The laundry 2 is introduced into the drum 5 and there acted upon by the process air stream 4. The process air stream 4 is driven by a first blower 6, which is part of the first duct system 3. After the process air stream 4 has been enriched in the treatment chamber 5 with moisture, it passes into a first cooling channel 7 of a heat exchanger 7, 8. There it is cooled, so that the entrained moisture condenses and by means which in FIG. 1 are not shown, separated from the process air stream 4 and discharged. A first heating channel 8 in the heat exchanger 7, 8 is acted upon by a secondary air flow 13 (likewise symbolized by a straight arrow) guided into an open second channel system 12, which is driven by a second fan 14. The secondary air stream 13 absorbs heat from the process air stream 4 in the heat exchanger 7, 8.

Behind the heat exchanger 7, 8, the process air stream 4 and the secondary air stream 13 to a heat pump 9, 10, 11, comprising a second heating channel 9, in which the process air stream 4 passes, a second cooling channel 11, in which the secondary air flow 13 passes, and a pump unit 10, which internal heat exchanger of the heat pump 9, 10, 11, which are arranged in the channels 9 and 11 and heat or cool the flowing air flows, applied. In the second heating channel 9 of the heat pump 9, 10, 11 of the cooled in the heat exchanger 7, 8 process air stream 4 is reheated, by heat, which is taken according to the bent arrow the secondary air stream 13 in the second cooling channel 11, and in addition the waste heat, the is generated during operation of the heat pump 9, 10, 11. Thus, the process air stream 4 in the heat pump 9, 10, 11 is reheated. He then passes to the first fan 6 and from this to a conventional heater 15. There, it is further heated and finally returns to the treatment chamber 5.

The secondary air stream 13 is taken from an environment of the device 1 and passes back into this environment, after he has passed through the second channel system 12. In the heat exchanger 7, 8, it is first heated by heat, which is taken from the process air stream 4. In the heat pump 9, 10, 11, the secondary air stream 13 is cooled again, so that the heat that was taken from the process air stream 4 in the heat exchanger 7, 8, this at least partially re-flows.

FIG. 2 shows a section of the in FIG. 1 recognizable device. Shown are the heat exchanger 7, 8, the heat pump 9, 10, 11 and a separator 16 for separating condensate, which has formed in the process air stream 4 after flowing through the first cooling channel 7. The heat pump 9, 10, 11 comprises two internal heat exchangers, which form the second heating channel 9 and the second cooling channel 11, and a pump unit 10, which contains a compressor and a throttle. Accordingly, the heat pump 9, 10, 11 a compressor heat pump, as it is known from a conventional refrigerator or freezer.

The configuration according to FIG. 3 differs from the configuration according to FIG. 2 , which is hereby incorporated by reference, by a thermoelectric heat pump 9, 10, 11, the pump unit 10 includes a circuit with Peltier elements, which are to be understood as special electronic components. A Peltier element has two poles between which a temperature difference arises when an electric current flows from one pole to the other pole. The integration of such Peltier elements in a pump unit 10 is basically known and requires this point no explanation. In the second heating channel 9 and in the second cooling channel 11 are heat conducting body 17, which are thermally conductive connected to the pump unit 10 and provide for the exchange of heat between the channels 9 and 11 via the pump unit 10.

LIST OF REFERENCE NUMBERS

1

Device, tumble dryer

2

laundry

3

First channel system

4

Process air flow

5

Treatment chamber, drum

6

First blower

7

Heat exchanger, first cooling channel

8th

Heat exchanger, first heating channel

9

Heat pump, second heating channel

10

Heat pump, pump unit

11

Heat pump, second cooling channel

12

Second channel system

13

Secondary air flow

14

Second blower

15

stoker

16

separators

17

thermal conductors

Claims (14)

1. Device (1) for drying laundry (2), comprising a substantially closed first channel system (3) for conducting a process air flow (4) acting on the laundry (2), in which first channel system (3) a treatment chamber (5) for receiving the laundry (2), a first fan (6) for driving the process air flow (4), a first cooling channel (7) of a heat exchanger (7, 8) and a second heating channel (9) of a heat pump (9, 10, 11) are arranged, wherein the second heating channel (9) along the process air flow (4) lies behind the first cooling channel (7), as well as an open second channel system (12) for conducting a secondary air flow (13), in which second channel system (12) a second fan (14) for driving the secondary air flow (13), a first heating channel (8) of the heat exchanger (7, 8) and a second cooling channel (11) of the heat pump (9, 10, 11) are arranged, wherein a heater (15) for heating the process air flow (4) is arranged in the first channel system (3), characterised in that the second cooling channel (11) along the secondary air flow (13) lies behind the first heating channel (8).
2. Device (1) according to claim 1, in which the heater (15) along the process air flow (4) is arranged directly in front of the treatment chamber (5).
3. Device (1) according to claim 2, in which the first fan (6) along the process air flow (4) is arranged directly in front of the heater (15).
4. Device (1) according to any one of the preceding claims, in which the second fan (14) along the secondary air flow (13) is arranged in front of the first heating channel (8).
5. Device (1) according to any one of the preceding claims, in which the first channel (3) has downstream of the first cooling channel (7) a separator (16) for separation of moisture from the process air flow (4).
6. Device (1) according to claim 1, in which the treatment chamber (5) is rotatable and, in particular, formed as a drum (5).
7. Device (1) according to any one of the preceding claims, in which the heater (15) and the heat exchanger (7, 8) are equipped for drying the laundry (2) without use of the heat pump (9, 10, 11).
8. Device (1) according to any one of the preceding claims, in which the heater (15) is designed for a maximum heat output of at most 2700 W, particularly approximately 2000 W.
9. Device (1) according to any one of the preceding claims, in which the heat exchanger (7, 8) has a cooling output of at least 1000 W, particularly approximately 1500 W.
10. Device (1) according to any one of the preceding claims, in which the heat pump (9, 10, 11) has a power consumption between 200 W and 800 W, particularly approximately 500 W.
11. Device (1) according to any one of the preceding claims, in which the heat pump (9, 10, 11) comprises a thermoelectric pump unit (10).
12. Device (1) according to claim 11, in which the pump unit (10) has a power consumption of approximately 500 W and in which the heater (15) is equipped for selectable operation at a high step with a power consumption of approximately 2000 W and at a low step with a power consumption of approximately 500 W, wherein the heater (15) and the pump unit (10) are equipped for control in such a manner that the pump unit (10) is operated in common with the heater (15).
13. Method of drying laundry (2) by means of a process air flow (4), which is conducted in a substantially closed first channel system (3) and acts on the laundry (2) disposed in a treatment chamber (5) and which is cooled in a heat exchanger (7, 8) by a secondary air flow (13) conducted in an open second channel system (12) and thereafter heated by a heat pump (9, 10, 11) under cooling of the secondary air flow (13), wherein the process air flow (4) is heated by a heater (15) arranged in the first channel system (3), characterised in that the cooling of the secondary air flow (13) is carried out behind the heat exchanger (7, 8).
14. Method according to claim 13, in which the heat pump (9, 10, 11) is operated at the same time as the heater (15).

Images