EP2203586B1 - Laundry dryer having a distributor for condensate, and a method of operating the same - Google Patents

Description

The invention relates to a dryer with a drying chamber for the objects to be dried and a process air duct in which a blower for driving process air through the drying chamber and a heat exchanger assembly are, through which heat exchanger arrangement of the effluent from the drying chamber process heat heat extracted and the drying chamber on the inflowing Process air can be supplied, wherein the process air duct has a Zuluftöffnung for drawing process air from an environment of the dryer, an exhaust port for expelling process air in the environment of the dryer and an exhaust duct part through which process air to the exhaust port is feasible and which a distributor, through which Condensate, which was deposited in the heat exchanger assembly from the process air, in the flowing process air can be distributed, has.

The invention also relates to a method for operating such a dryer.

Such a dryer and such a method are apparent from the non-prepublished German patent application 10 2007 011 809.2 or the parallel, also not previously published International patent application PCT / EP2008 / 052259 , In the dryer described there, the heat exchanger arrangement may be a simple heat exchanger or a heat pump. WO 2008/013382 Also shows a next state of the art according to Art 54 (3) EPC.

A dryer with heat recovery is apparent from the DE 30 00 865 A1 , There, a so-called exhaust air dryer is described which once heated an air flow in an open channel and passes through the laundry to be dried, and then ejects it from the channel. The heat recovery takes place by means of a simple heat exchanger in which heat is transferred from the process air to be discharged to newly inflowing process air. The heated process air in the heat exchanger is further heated by a heater and then passes to the laundry to be dried.

From the WO 2004/059070 A1 goes out a dryer, in which a nebulizer, in particular ultrasonic nebulizer, is provided, with the in the drying or to be treated objects to be treated supplied process air, a liquid can be distributed.

In general, a tumble dryer is operated as a vented dryer or as a condensation dryer. An exhaust air dryer passes heated air once through the laundry to be dried and carries this moisture-laden air through an exhaust hose from the exhaust air dryer and from the room in which it is placed. A condensation dryer whose operation is based on the condensation of moisture evaporated from the laundry by means of warm process air does not require an exhaust hose and allows energy recovery from the heated process air, for example by using a heat pump. However, with such a condensation dryer it is generally necessary to collect the accumulated condensate and either pump it off or dispose of it by manually emptying collection containers.

In the DE 40 23 000 C2 a tumble dryer is described with a heat pump circuit, which is basically designed as a condensation dryer and in which a supply air opening is arranged in the process air duct between a condenser and an evaporator of the heat pump circuit, which is closable with a controllable closure device.

In the case of an exhaust air dryer, the air laden with moisture after the passage through the drum with the laundry items is generally led out of the dryer. Compared to a condensation dryer, an exhaust air dryer can be made simpler and thus cheaper. An exhaust air dryer draws air from its environment during operation and uses it directly for drying.

Like in the DE 30 00 865 A1 A heat recovery is basically possible in an exhaust air dryer, but any such heat recovery implies a cooling of the exhaust air, whereby condensate from the exhaust air can fail and should be disposed of. In this case, ambient air (of, for example, 20 ° C. and 60% relative humidity, so-called supply air) flows over heat exchanger surfaces of the air-to-air heat exchanger and is heated there by cooling the warm process air coming from the drying chamber. Depending on the cooling capacity or the heat exchange arises Condensate collected or pumped in a container. In the first case an emptying is necessary, and in the second case a connection to the sewage network. The amount of accumulating condensate is a measure of the heat energy emitted in the heat exchanger and thus a measure of the improvement of energy efficiency.

For disposal accumulating condensate already during a drying process and without the need for caching and otherwise disposal of the condensate is provided according to the above-unpublished patent application to pass a portion of the discharged from the dryer process air to the heat exchanger assembly and an evaporator, which Verdunster the accumulating condensate is supplied so that it evaporates in the overflowing process air and can be discharged with this. However, this necessarily means that part of the heat present in the process air to be removed is no longer available for recycling in the drying process.

Object of the present invention is therefore to provide a dryer of the type mentioned, in which it is unnecessary to use the heat of a portion of the discharged process air to dissipate condensate incurred. It is also intended to provide a corresponding generic method.

The solution of this object is achieved according to this invention by a dryer with the features of claim 1 and the method having the features of claim 7.

Preferred embodiments of the dryer according to the invention and of the method according to the invention are listed in the dependent claims. In general, preferred embodiments of the dryer according to the invention correspond to preferred embodiments of the method according to the invention and vice versa, even if it is not referred to in detail below.

The invention thus relates to a dryer with a drying chamber for the objects to be dried and a process air duct in which a blower for driving process air through the drying chamber and a heat exchanger assembly are, through which heat exchanger assembly of the drying chamber The process air duct has a Zuluftöffnung for drawing process air from an environment of the dryer, an exhaust port for expelling process air into the environment of the dryer and an exhaust duct part through which process air to the exhaust port is feasible and which has a manifold through which condensate, which was deposited in the heat exchanger assembly from the process air, in the throughflowing process air can be distributed, wherein the manifold is a nebulizer.

The condensate separated during drying in this dryer is a measure of the return of heat energy in the drying process. Starting from the energy balance of an exhaust air dryer without recirculation of heat, the return of heat in particular be sized and adjusted by appropriate design of the dryer that a predetermined improvement in energy balance is achieved, for example, an improvement by which a classification of the dryer in a desired , compared to the exhaust air dryer, which is expected to be better energy consumption class according to the usual system in the European Union would be possible. In this context, it may be disregarded to seek a deposition of a maximum of moisture in the heat exchanger assembly. To improve an energy consumption class from C for the simple exhaust air dryer to B for the heat recovery exhaust air dryer, it may be sufficient to strive to deposit no more than 10 grams of condensate per minute. This poses the problem of storing a larger amount of condensate as in the condensation dryer not. Incidentally, it would also be conceivable to allow a fan of the dryer arranged behind the heat exchanger arrangement to continue after completion of a drying process in order to create an air flow for distributing any remaining condensate. Also a small separate blower for this application would be conceivable. Finally, depending on the design of the dryer for distributing any remaining condensate and a draft can be exploited, resulting in, for example, by a chimney effect, in the unused dryer. This spreading may, but not necessarily, be assisted by the nebulizer. In operation, in particular the drying chamber must be sealed against the environment of the dryer to allow undisturbed proper flow of process air. For this purpose the drying chamber is by means of a corresponding one Door closed. Apart from such use, this door is usually open and thus also opens the process air duct to the environment of the dryer. A draft of air through the process air duct, including the subchannel and the open door, can effectively aid the distribution of residual condensate.

In a preferred embodiment of the dryer according to the invention, the nebulizer is an ultrasonic nebulizer. Ultrasonic nebulizers are known and available as compact, integrated and effective components, and can be integrated into a tumble dryer without requiring much space. They are used in many applications, for example in humidifiers and inhalers.

Also, in view of the fact that the invention in principle does not make any special demands on the type and configuration of the heat exchanger assembly, a particularly preferred embodiment of the invention is characterized in that the heat exchange arrangement comprises a heat sink and a heat source of a heat pump cycle, that is, the dryer according to this development a heat pump circuit for supplying and removing heat to or from the process air flow uses. Basically any heat pump can be used. An advantage of the heat pump is that temperature levels for cooling or heating the process air can be selected with some independence from each other. By adjusting the pumping factor of the heat pump, which is to be understood as meaning the ratio between the pumped heat output and the power used for this purpose, any additional heating of the process air which may be necessary can also be effected; the inevitable fact of the limited efficiency of a heat pump is thus used as a further advantage.

The heat exchanger arrangement in the dryer according to the invention preferably has an evaporator and a condenser of a known heat pump circuit, wherein such a heat pump circuit is designed according to the principle of the compressor heat pump. Such a heat pump cycle includes a self-contained piping for circulating refrigerant therein, in which piping the heat sink as the evaporator for the refrigerant, a compressor for compressing the evaporated refrigerant, the heat source as a condenser for the compressed refrigerant and a throttle for expanding the liquefied refrigerant are arranged. When Refrigerants come in accordance with known practice in particular fluorinated ethane derivatives and propane and carbon dioxide into consideration. In a dryer equipped with such a heat pump, the cooling of the warm, moisture-laden process air essentially takes place in the evaporator of the heat pump, where the heat transferred is used to evaporate the refrigerant. The refrigerant vaporized due to the heating is supplied to the condenser via the compressor, where heat is released due to the condensation of the gaseous refrigerant and used to heat the process air. The refrigerant circulates in a closed circuit in which it passes from the condenser via a throttle back to the evaporator.

An embodiment of the dryer in which the exhaust air duct part is set up for storing condensate is also preferred. It is assumed that the absorption capacity of the exhaust air duct part flowing through during operation of the dryer process air for additional moisture is not always the same. At the beginning of the drying process, when the objects to be dried first have to heat up, the process air flow in the drying chamber still absorbs little moisture and can therefore take up and remove condensate that is left over from a previous drying process. In the middle of the drying process, the process air flow removes a relatively large amount of moisture from the objects to be dried and therefore can absorb less condensate; So it is advantageous if condensate that can not be distributed evenly, initially can remain stored. Towards the end of a drying process, when the objects to be dried have already released a relatively large amount of moisture, the process air flow again becomes drier and at the same time warmer, and can therefore absorb and remove more condensate again. If not all accumulated condensate can be distributed, a certain amount can remain stored until a subsequent drying process or be distributed separately, as described above.

Preferably, the exhaust air duct part to a collecting vessel for collecting the condensate. This collecting vessel may further preferably simply be a depression of the exhaust air duct part. According to this depression, the exhaust air duct part may, with further preference, have at least one wall region which is inclined towards the recess and which may be designed in particular as a groove or duct.

Particularly preferred is a development of the dryer, in which the collecting vessel is arranged below the heat exchanger assembly, so that accumulating condensate can instantly drip. The collecting vessel can more preferably also be designed as a type of bypass of the exhaust air duct part in order to selectively guide a part of the process air stream for collecting condensate, which is additionally nebulized by the nebulizer, through the collecting vessel. For this purpose, the collecting vessel has a respect to the process air flow upstream first opening to the exhaust duct part and a respect to the process air flow downstream second opening to the exhaust duct part and the heat exchanger assembly, in particular the heat sink, at least partially bridged in the exhaust duct.

Also preferably, in the dryer according to the invention, a fill level sensor is assigned to the collecting vessel. In this case, the collecting vessel can be designed so that it can be removed for the purpose of cleaning or otherwise disposal of condensate from the dryer.

Particularly preferred is an embodiment of the dryer, wherein the process air duct is an open channel leading from the supply air opening to the exhaust air opening. Such is the dryer according to the invention, in which an at least partial circulation of the process air would not be excluded in principle, perfected as exhaust air dryer.

Also preferred is an embodiment of the dryer in which the process air duct has a heater. Depending on the size of the pumping power of the heat pump circuit, this heating may merely be provided for heating the corresponding components of the dryer and the wet objects inserted into the drum at the beginning of a drying process, the drying process continuing after the heating has been carried out without the use of the heating. It is also possible to design the heat pump circuit only with a relatively small pumping power and at least to introduce the heat necessary for the drying process to a substantial extent via the permanently operated heating. In any case, the heater provides further considerable flexibility in the design of the dryer according to the invention and in particular the option to optimize the dryer under a variety of economic aspects.

The heater may in particular be an electric heating element or a burner for oil or gas according to conventional practice.

The invention also relates to a method for operating a dryer with a drying chamber for the objects to be dried and a process air duct in which there are a fan for driving process air through the drying chamber and a heat exchanger arrangement, through which heat exchanger arrangement of the effluent from the drying chamber process air heat withdrawn and the process air supplied to the drying chamber is supplied, wherein the process air duct has a Zuluftöffnung for drawing process air from an environment of the dryer, an exhaust port for expelling process air into the environment of the dryer and an exhaust duct part through which process air is fed to the exhaust port and in which is distributed through a manifold condensate, which was deposited in the heat exchange arrangement of the process air in the flowing process air, wherein the distribution of the condensate by misting erfo lgt.

Preferred embodiments of the method provide that the atomization takes place by the action of ultrasound, or that the removal of heat from the process air flowing from the drying chamber and the supply of heat to the process air flowing to the drying chamber are effected by a heat pumping process running in the heat exchanger arrangement. Corresponding explanations emerge from the above corresponding statements, to which reference is hereby made.

• Fig. 1 eine Skizze für ein Ausführungsbeispiel eines Trockner mit Verteiler für Kondensat;
• Fig. 2 eine Skizze für eine erste Ausführungsform des Abluftkanalteils eines solchen Trockners mit dem Verteiler für Kondensat; und
• Fig. 3 eine Skizze für eine zweite Ausführungsform des Abluftkanalteils.

Further details of the invention will become apparent from the following description of preferred, non-limiting embodiments of the dryer and the method used to operate this dryer. In detail show:

• Fig. 1 a sketch for an embodiment of a dryer with manifold for condensate;
• Fig. 2 a sketch for a first embodiment of the exhaust duct part of such a dryer with the manifold for condensate; and
• Fig. 3 a sketch for a second embodiment of the exhaust duct part.

The in Fig. 1 Dryer 1, shown as a sketch, has a process air channel 2 and a drying chamber 3, which is a drum 3 rotatable about an axis 4 shown as a small cross. Process air flowing in the process air stream is guided by means of a blower 5 through the drum 3 and laundry items (not shown) located therein; behind the drum 3, the process air passes through a lint filter 6, which in the simplest case is a lattice-shaped sieve 6, to lint, ie small fibers, which process air entrains the entrained by the rotation of the drum 3 against each other laundry pieces and entrains. This is important for a sufficiently long trouble-free operation of the downstream of the process air stream 2 components of the dryer 1, since it prevents lint from settling on these components. The process air is drawn through a supply air opening 7 in the process air duct 2 and pushed out through an exhaust port 8. In the supply air opening 7 air passes directly from an environment of the dryer 1. To the exhaust port 8 is connected an exhaust hose 9, with which the exhaust air from the dryer 1 away and from a building in which it is placed, is discharged. In that regard, the dryer 1 in construction and function corresponds to a conventional exhaust air dryer.

In addition, a heat exchange arrangement 10, 11 is present; in her or the associated heat source 11, the retracted through the supply air opening 7 process air is heated. The heated process air is passed into the drum 3, where it comes into contact with the laundry to be dried and then flows to the lint filter 6. Then the moist, warm and freed of any fluff process air is cooled in the heat sink 10. The heat withdrawn from the process air is conducted from the heat sink 10 to the heat source 11 in a heat pump circuit 10 to 14, whose components include the heat sink 10 and the heat source 11, and is supplied there to the freshly introduced process air. That according to the specifications of thermodynamics more heat to the process air than this is removed in the heat sink 10, this heat pumping process does not bother - a portion of the heat supplied is required to evaporate moisture from the laundry in the drum 3, and therefore not be recovered anyway. In addition, condensate precipitates from the cooling process air at the heat sink 10. This condensate must be removed from the dryer 1, which is explained in detail below.

The heat pump circuit 10 to 14 is formed by an evaporator 10, which acts as a heat sink 10, and the condenser 11, which acts as a heat source 11, and a throttle 12 and a compressor 13, all of which via a closed line system 14 to a circuit with each other In the circuit circulates, driven by the compressor 13, a cyclically to be evaporated, to be compressed, to be liquefied and to be expanded refrigerant. This is a fluorinated Äthanderivat, for example, under the name R134a pertinent known compound, propane or carbon dioxide. Gas refrigerant leaving the evaporator 10 is compressed and heated by the compressor 13; It passes to the condenser 11, where it liquefies by giving off heat to the process air. Subsequently, it flows in the line system 14 through the throttle 12, where it is expanded to a lower pressure, and reaches the evaporator 10, where it evaporates while absorbing heat from the process air. From the evaporator, it flows in the line system 14 back to the compressor 13, so that the circuit closes. The heat pump 10 to 14 allows a relatively free adjustment of the temperature levels in the evaporator 10 and the condenser 11, wherein the setting includes the choice of the refrigerant and the pressure levels in the evaporator 10 and liquefier 11. It also offers options for optimizing the energy balance of the dryer 1.

To remove the condensate occurring in the evaporator 10, the process air flow is used, in which the condensate is distributed in an exhaust duct part 15 of the process air duct 2 immediately in front of the exhaust port 8 - see also Figures 2 and 3 with accompanying explanation. Condensate, which is obtained at the evaporator 10, passes through a corresponding conduit or channel or a correspondingly inclined wall portion 16 to a manifold 17, which is an ultrasonic atomizer 17. For the transport of the condensate is expediently a natural gradient, which can be formed by appropriate construction of the exhaust duct part 15, exploited. In the exhaust air duct part 15, the process air stream takes on atomized condensate and discharges it through the exhaust air opening 8 and the exhaust air hose 9. Means for controlling the nebulizer 17 are not shown, as well as means for driving other components of the dryer 1. Such means are basically known, it is therefore unnecessary to go into detail here.

A particular advantage of the nebuliser 17 is that it allows the condensate to be distributed in the process air without the process air having to fulfill specific thermodynamic requirements, in particular having a certain elevated temperature and a certain reduced relative humidity in order to evaporate condensate present as a liquid and to be able to record like that. The removal of the condensate takes place as a mist, that is as a dispersion of liquid in gas. The limited life of a mist is of lesser importance - it is quite sufficient that the mist substantially exists until it has come out of the dryer 1 and through the exhaust hose 9 from the vicinity of the dryer 1.

In the FIG. 1 between the fan 5 and the drum 3 shown heater 18, in this case an electric heating element 18 may be provided depending on the size of the pump power of the heat pump cycle 10 to 14 only for heating the corresponding components of the dryer 1 and the inserted into the drum 3 wet objects Beginning of a drying process, wherein the drying process continues after heating without using the heater 18; It is also possible to design the heat pump cycle 10 to 14 only with a relatively small pumping power and to introduce the heat required for the drying process into a more or less significant proportion via the permanently operated heater 18. The specific design of the dryer 1 between these extremes is a matter of consideration, which also takes into account economic aspects - the heat pump cycle 10 to 14 is a major cost factor for the dryer 1, the price of which remains smaller the smaller the heat pump cycle 10 to 14 is. Ultimately, there is a trade-off between an acceptable price and an acceptable level of heat recovery in the dryer 1.

FIG. 2 shows a simple embodiment for the exhaust duct part 15. Condensate, which drips from the heat sink 10, passes according to the given by the inclined wall portion 16 slope to the collecting vessel 18, which is only a recess 18 containing the ultrasonic atomizer 17. The condensed by the ultrasonic atomizer 17 condensate enters the symbolized by a thick arrow process air stream after it has passed through the heat sink 10, and is discharged from this from the exhaust air duct part 15.

According to FIG. 3 is in the exhaust duct part 15 a separate, possibly for the purpose of cleaning or otherwise disposal of any remaining condensate removable collecting vessel 18 is provided. The collecting vessel forms a bypass, through which a part of the process air flow is guided past the heat sink 10. This part enters the collecting vessel 18 at the first opening 19 on the upstream side of the heat sink 10 (based on the process air stream symbolized by thick arrows) and leaves it again after receiving atomized condensate through the second opening 20 which, downstream of the latter, flows in relation to the process air flow Heat sink 10 is arranged. In this way, a pressure loss over the heat sink 10 in the process air stream is made usable for forming a partial flow which is not cooled in the heat sink 10 and thus can absorb the condensate better than cooled air. Associated with the collection vessel 18 is also a fill level sensor 21. This is used to detect any excess condensate that may be present and to display it to a user in order to enable the user person to take appropriate action, for example to otherwise dispose of the excess condensate.

Although the embodiments of the invention show exhaust air dryer, it should be noted that the invention is not limited to exhaust air dryers, but in particular includes those dryers that circulate the process air in any case in part. In any case, an inventive dryer allows at least partial recovery of heat energy that would otherwise be lost to the drying process, without accumulation of condensate, which would have to be separately and specially disposed of. Therefore, the invention is also attractive from an economical point of view, especially, but not exclusively, in an exhaust air dryer.

Claims (16)

1. Drier (1) with a drying chamber (3) for articles to be dried and a process air channel (2) in which a fan (5) for driving process air through the drying chamber (3) as well as a heat exchanger arrangement (10, 11) are disposed, by which heat exchanger arrangement (10, 11) the heat can be extracted from process air flowing away from the drying chamber (3) and can be fed to the process air flowing to the drying chamber (3), wherein the process air channel (2) has an air feed opening (7) for the intake of process air from an environment of the drier (1), an air exhaust opening (8) for expulsion of process air into the environment of the drier (1) and an air exhaust channel part (15), through which process air can be guided to the air exhaust opening (8) and which comprises a distributor by which condensate which has been separated in the heat exchanger arrangement (10, 11) from the process air can be distributed in the process air flowing through, characterised in that the distributor (17) is an atomiser (17).
2. Drier (1) according to claim 1, in which the atomiser (17) is an ultrasonic atomiser (17).
3. Drier (1) according to one of the preceding claims, characterised in that the heat exchange arrangement (10, 11) comprises a heat sink (10) and a heat source (11) of a heat pump circuit (10, 11, 12, 13, 14).
4. Drier (1) according to claim 3, in which the heat pump circuit (10, 11, 12, 13, 14) comprises a duct system (14), which is closed in itself, for a refrigerant able to be circulated therein, in which duct system (14) the heat sink (10) as an evaporator (10) for the refrigerant, a compressor (13) for compressing the evaporated refrigerant, the heat source (11) as condenser (11) for the compressed refrigerant and a choke (12) for expansion of the condensed refrigerant are arranged.
5. Drier (1) according to any one of the preceding claims, in which the air exhaust channel part (15) is equipped for storing condensate.
6. Drier (1) according to claim 5, in which the air exhaust channel part (15) comprises a collecting vessel (18) for collecting the condensate.
7. Drier (1) according to claim 6, in which the collecting vessel (18) is a depression of the air exhaust channel part (15).
8. Drier (1) according to claim 7, in which the air exhaust channel part (15) has at least one wall region (16) inclined towards the depression (18).
9. Drier (1) according to claim 6, in which the collecting vessel (18) is arranged below the heat exchanger arrangement (10, 11).
10. Drier according to claim 9, in which the collecting vessel (18) has a first opening (19), which is at the inflow side with respect to the process air flow, to the air exhaust channel part (15) and a second opening (19), which is at the outflow side with respect to the process air flow, for the air exhaust channel part (15) and at least partly bridges over the heat exchanger arrangement in the air exhaust channel part (15).
11. Drier according to any one of claims 6 to 10, in which a filling state sensor (210 is associated with the collecting vessel (18).
12. Drier (1) according to any one of the preceding claims, in which the process air channel (2) is an open channel (2) leading from the air feed opening (7) to the air exhaust opening (8).
13. Drier (1) according to any one of the preceding claims, in which the process air channel (2) comprises heating means (18).
14. Method of operating a drier (1) with a drying chamber (3) for articles to be dried and a process air channel (2) in which a fan (5) for driving process air through the drying chamber (3) as well as a heat exchanger arrangement (10, 11) are disposed, by which heat exchanger arrangement (10, 11) the heat is extracted from process air flowing away from the drying chamber (3) and is fed to the process air flowing to the drying chamber (3), wherein the process air channel (2) has an air feed opening (7) for the intake of process air from an environment of the drier (1), an air exhaust opening (8) for expulsion of process air into the environment of the drier (1) and an exhaust air channel part (15), through which process air is guided to the air exhaust opening (8) and in which condensate, which was separated in the heat exchanger arrangement (10, 11) from the process air, is distributed by a distributor (17) in the process air flowing through, characterised in that the distribution of the condensate takes place by atomisation.
15. Method according to claim 14, wherein the atomisation is carried out by the action of ultrasound.
16. Method according to one of claims 14 and 15, in which the extraction of heat from the process air flowing away from the drying chamber (3) and the feed of heat to the process air flowing to the drying chamber (3) is carried out by a heat pump process running in the heat exchanger arrangement (10, 11).

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