EP2565321B1 - Dryer with a cross-flow heat exchanger and method for operating same - Google Patents

Description

The invention relates to a dryer, comprising a control device, a process air duct in which a heater, a drying chamber for objects to be dried, a fan and a cross-flow heat exchanger are arranged, wherein the process air duct comprises a supply air duct in front of the drying chamber and an exhaust duct between the drying chamber and crossflow heat exchanger, and a preferred method of operating this dryer.

Under dryer in the present case is a pure dryer, which is used only for drying certain items, but also a washer dryer, which is intended for drying certain items, usually laundry. In particular, the dryer is thus a tumble dryer or a washer-dryer, ie a combination of a washing machine and a tumble dryer.

Usually in a dryer air (so-called "process air") by means of a blower through a drying chamber, which contains the objects to be dried, passed. The process air absorbs moisture from the objects to be dried. Since warm air is able to absorb more moisture, the process air is heated before it enters the drying chamber. After exiting the drying chamber, the warm moist process air is cooled in a heat exchanger, wherein the heat exchanger, a filter, in particular a lint filter, may be upstream. The cooling of the process air in the heat exchanger generally condenses the moisture contained in the process air and can be removed as condensate. The dehumidified process air is then usually reheated and fed again to the objects to be dried (circulating air dryer) or the storage room of the dryer supplied (exhaust air dryer).

Since the drying process is very energy intensive, it is desirable for environmental and economic reasons to reduce the energy consumption of the dryer. This can be achieved by increasing the efficiency of the heat exchanger.

It is known to increase the efficiency of a heat exchanger in a dryer in that the most uniform possible distribution of the process air flow over the surface of the heat exchanger is ensured. This plays a role in particular because process air ducts in dryers often have bends due to the design, as a result of which the process air flow enters the heat exchanger unevenly.

So revealed the DE 196 44 711 A1 a dryer with a curved at least in a partial region process air duct in which are arranged in front of the entrance to the heat exchanger flow guide so that the flow is more uniform.

The EP 1 050 618 B1 describes a staggered arrangement of heat exchanger plates, whereby the flow losses of the gas stream is reduced and the heat exchange performance is increased.

Furthermore, it is known to increase the efficiency of an air-air heat exchanger by improving the heat dissipation on the cooling air side. On the cooling air side is due to the existing dry air there is a significantly poorer heat transfer than on the process air side, as on the process air side a very good heat transfer is favored by the condensation taking place there. For this reason, measures on the cooling air side have a strong effect on the efficiency of the heat exchanger.

In this context, the DE 30 27 900 C2 an air-cooled heat exchanger for a domestic laundry dryer, wherein in the cooling air area air guide body are provided to improve the heat transfer and design-related improved sealing is achieved.

The EP 1 729 078 A2 describes a heat exchanger for a condensation clothes dryer, which has a plurality of lamellar structures in the cooling air area, whereby a larger surface for the heat transfer is achieved and the cooling air is introduced as a turbulent flow in the heat exchanger. This leads to an improved heat transfer and thus a higher efficiency of the heat exchanger.

In order to increase the efficiency of the heat exchanger by improved heat dissipation, the use of materials with improved conductivity is also known. The font EP 0 982 427 B1 discloses a crossflow heat exchanger for a condensation clothes dryer with plates of a highly conductive metal or thermoplastic. The DE 10 2009 046 680 A1 discloses a heat exchanger constructed of a composite material including thermoplastic and carbon nanotubes.

By such measures, the efficiency of the heat exchanger is increased mainly in terms of improved cooling performance, whereby an improved separation efficiency of the moisture in the moist, warm process air from the drying chamber (dehumidification) can be achieved.

It is also known to use the energy used in a dryer efficiently by using a heat pump. Dryers with a heat pump are for example from the DE 10 2008 044 277 A1 and the DE 10 2008 043 920 A1 known. A heat pump is generally associated with a comparatively high construction-related outlay, which can have an unfavorable economic effect (costs, maintenance).

It is against this background object of the present invention to provide a dryer with an efficient heat exchanger, in particular, the separation efficiency is improved with respect to moisture from moist warm process air from the drying chamber, an increase in cooling capacity can be avoided.

The object is achieved according to this invention by a dryer with the features of the corresponding independent claim and the method of the corresponding independent claim. Preferred embodiments of the dryer according to the invention are listed in corresponding dependent claims. Preferred embodiments of the dryer according to the invention correspond to preferred embodiments of the method according to the invention and vice versa, although this is not explicitly stated herein.

The invention thus relates to a dryer, comprising a control device, a process air duct, in which a heater, a drying chamber for drying Objects, a fan and a cross-flow heat exchanger are arranged, wherein the process air duct comprises a supply air duct in front of the drying chamber and an exhaust duct between the drying chamber and crossflow heat exchanger, and wherein the exhaust duct and / or cross-flow heat exchanger is / are such that a larger proportion p * M a process air amount M passing through the exhaust duct into the crossflow heat exchanger, where p> 0.5, being directed to a cooling flow entrance side of the cross flow heat exchanger. In this case, preferably p ≥ 0.6, and more preferably p ≥ 0.7.

"Extraction duct" in the sense of the invention means the part of the process air duct between the drying chamber and cross-flow heat exchanger, ie the part in which generally the moist, warm process air flows from the drying chamber to the crossflow heat exchanger. In this sense, an exhaust duct can be present both in a circulating air and in an exhaust air dryer.

In a heat exchanger, thermal energy is generally transferred from one material stream to another. In this case, a heat exchanger is usually well sealed to the outside and between the streams. In the case of a cross-flow heat exchanger, the material flows are guided in such a way that their directions intersect, essentially at right angles. Thus, the warmer material flow is cooled and the cooler stream, hereinafter also called cooling stream, heated. In a cross-flow heat exchanger in a dryer, the warmer material flow is usually the process air flow. Since the directions of the process air flow and the cooling flow intersect, the greatest temperature differences are thus found in the process air area of the heat exchanger at the side facing the cooling flow inlet, i. the cooling flow inlet side.

According to the exhaust duct and / or cross-flow heat exchanger are designed such that a larger proportion of the process air is passed to the cooling flow inlet side of the crossflow heat exchanger, at which the cooling flow occurs. As a result, a larger volume fraction of the process air flows through the region of the greater temperature difference in the heat exchanger. Surprisingly, it has been found that this leads above all to a higher separation of the moisture from the moist, warm process air and thus to an increased dehumidification of the process air, without an increased cooling of the process air takes place. Thus, the process air has the desired lower water loading, without the process air should be heated more by simultaneously increased cooling below. A dryer according to the invention, in which the cooling air side is more strongly flown in the process air area of the cross-flow heat exchanger, is thus more efficient due to its higher separation efficiency.

wobei Q den Volumenstrom [m³/s], V das Volumen [m³] und t die Zeit [s] darstellt. Der Volumenstrom lässt sich beispielsweise durch Durchflusssensoren bestimmen. Weiterhin gilt für den Volumenstrom: $$\mathrm{Q}=\mathrm{c}*\mathrm{A}$$

wobei c die mittlere Strömungsgeschwindigkeit [m/s] und A die durchströmte Fläche [m²] darstellt. Folglich kann ein größerer Anteil der Prozessluft, der erfindungsgemäß zur Kühlstromeintrittsseite des Wärmetauschers geleitet wird, beispielsweise durch eine vergrö-ßerte Eintrittsfläche des zur Kühlstromeintrittsseite zu leitenden Prozessluftanteils in den Wärmetauscher (mehr als 50 % der Prozesslufteintrittsfläche) oder durch Erhöhung der Strömungsgeschwindigkeit in dem zur Kühlstromeintrittsseite zu leitenden Prozessluftanteil erreicht werden.A larger proportion of the process air here usually means more than 50% by volume of the process air. In this case, the reference volume (100%) is that volume of the process air which flows through the entire process air inlet surface of the heat exchanger in the same time unit (for example 1 s). In general, the volume of a medium moving through a cross-section in a unit of time is referred to as a volumetric flow with: $$\mathrm{Q}=\mathrm{dV}/\mathrm{dt}$$

where Q represents the volume flow [m ³ / s], V the volume [m ³ ] and t the time [s]. The volume flow can be determined, for example, by flow sensors. Furthermore, the following applies to the volume flow: $$\mathrm{Q}=\mathrm{c}*\mathrm{A}$$

where c represents the average flow velocity [m / s] and A represents the area [m ² ] which is traversed. Consequently, a larger portion of the process air, which is passed according to the invention to the cooling flow inlet side of the heat exchanger, for example, by an enlarged inlet surface of the process to the Kühlstromeintrittsseite to conductive process air fraction in the heat exchanger (more than 50% of the process air inlet surface) or by increasing the flow velocity in the cooling flow inlet side to conductive process air content can be achieved.

Accordingly, "cooling flow inlet side" of the crossflow heat exchanger generally refers to a volume fraction of the heat exchanger. The heat exchanger can be divided, for example, in a volume half, which faces the cooling flow inlet and in another volume half, which faces away from the cooling flow inlet. "Cooling flow inlet side" thus refers to the volume half of the heat exchanger facing the cooling flow inlet. At least 60% by volume is preferred the process air passed to the side of the cross-flow heat exchanger, where the cooling flow occurs.

Since there is usually little room for a change in the geometry of the process air channels in a dryer due to the structural conditions, the attachment of at least one flow guide in the relevant process air stream, i. in the exhaust air part channel and / or in the cross-flow heat exchanger, preferably. By introducing one or more flow guide bodies, a larger proportion of the process air is thus brought to the cooling flow inlet side. The respective number, design and arrangement of the flow guide body depends on the geometry of the exhaust air duct and the geometry of the crossflow heat exchanger itself, on the type of flow and on the distribution of the flow velocities over the cross section.

In a preferred embodiment of the dryer, at least one flow guide body is arranged in the exhaust air duct and / or cross flow heat exchanger, wherein the position of the flow guide is fixed or changeable. In general, the flow guide body, e.g. a baffle, a first baffle surface and a second baffle surface, which differ in their location with respect to the cooling flow inlet side. In this case, the flow guide body can generally be flowed around by the process air from the drying chamber.

A flow guide according to the invention may generally be any type of body that is capable of directing the process air flow according to the invention. In a preferred embodiment of the dryer according to the invention, the at least one flow guide body is a guide plate. Here, "baffle" generally means a relatively thin body, the generally uniform thickness of which is relatively small compared to its length. With regard to the material, preference is given to those materials whose properties are not impaired by the contact with the moist, warm process air. This material is preferably a non-corrosive metal, such as aluminum, or a plastic. For improved flow conduction, the flow guide body, in particular the guide plate, can have a correspondingly structured surface such as a guide profile, which is then preferably located on the upstream side of the guide plate.

It is inventively preferred that the at least one flow guide is arranged in the exhaust duct. In this case, the at least one flow guide body is preferably arranged in the exhaust air duct in the inflow region of the crossflow heat exchanger. In this case, inflow region generally means the section of the exhaust air duct through which the process air stream flows immediately before entry into the crossflow heat exchanger.

In a further preferred embodiment of the dryer according to the invention, at least one flow guide body is arranged in the crossflow heat exchanger. In this case, the at least one flow guide body preferably divides a process air area in the crossflow heat exchanger into at least two separate process air portions, of which a first process air portion faces the cooling flow inlet side and a second process air portion of the cooling flow inlet side faces away from the side of the cooling flow outlet. In this case, the at least one flow guide body is arranged largely in the flow direction of the process air flow in the process air region of the heat exchanger.

It is particularly preferred that a baffle divides the process air area in the cross-flow heat exchanger into two separate process air subregions, of which a first process air portion faces the cooling flow inlet side and a second process air part region faces away from the cooling flow inlet side. In this case, the area of the process stream inlet is preferably smaller than the area of the process stream outlet in the first process air partial area, whereas in the second process air partial area the corresponding area ratio is preferably reversed. The volume fractions of the two process air subregions are preferably not greatly different, ie the volume fraction of one of the two process air subregions at the corresponding total process air range does not exceed 70%, more preferably not 60%, particularly preferably not 55%. The corresponding proportions, based on the total process air range, depending on the design of the cross-flow heat exchanger are determined differently, for example in a plate heat exchanger based on the respective plate gap. This is important in that, in the case of a plate heat exchanger, the arrangement of the at least one flow guide body can be configured differently in different plate interspaces of the process air area.

With the present invention, the heat exchange in the cross-flow heat exchanger and in particular the heat exchange accompanied by condensation of the heat exchange accompanied by the moist, warm process air in the heat exchanger can be made efficient. Preferably, in this case, the heat exchange via the position of the flow guide be optimally adjusted.

Preferably, therefore, in the dryer according to the invention a position of the flow guide in the exhaust duct and / or in the crossflow heat exchanger can be adjusted by means of the control device. This makes it possible in particular for the temperature and moisture content of the moist warm process air originating from the drying chamber to be taken into account.

For example, preferably, the position of the flow guide can be adjusted depending on parameters of a drying process.

Alternatively or in addition to this, in a dryer according to the invention, a wall of the exhaust air duct can be designed such that a larger proportion p * M of the process air quantity M, where p> 0.5, is conducted to a cooling flow inlet side of the crossflow heat exchanger in the process air flowing in the exhaust air duct , For this purpose, the wall of the exhaust duct, for example, contain correspondingly shaped ribs, which direct the flow of process air in the direction of the cooling flow inlet side of the crossflow heat exchanger, or the wall itself may have a suitable slope or other shape. This is in particular possible by means of curvatures in the exhaust air duct, which can cause, for example, different flow velocities over the duct cross section.

In a further preferred embodiment of the invention, the exhaust air duct may comprise a plurality of partial exhaust air ducts, which differ with respect to the flow of the cooling flow inlet side of the crossflow heat exchanger. For example, these may be separate pipes, each of which represents a partial exhaust air duct.

In a preferred embodiment of the dryer according to the invention, the at least one flow guide body divides the exhaust air duct upstream of the crossflow heat exchanger in at least two separate exhaust air ducts. In this case, the at least one flow guide body is generally arranged substantially in the flow direction of the process air flow in the exhaust duct upstream of the heat exchanger, ie, generally along the exhaust passage, whereby at least two separate exhaust air ducts are formed. Of these, one of the cooling flow inlet side of the heat exchanger faces and the other facing away from this. The number of exhaust air partial ducts thus formed is thus determined as a rule from the number of flow guide. For example, a baffle can be introduced along the flow direction into the exhaust air duct, so that now two separate Ablufteilkanäle arise through which the cross-flow heat exchanger is flown, with an exhaust air duct facing the cooling flow inlet side and the other side facing the cooling flow outlet. In this case, preferably, the entire surface of the heat exchanger which is flowed through by the process air is subdivided in such a way that a maximum of one third of the total area of the crossflow heat exchanger which is flown by the process air is occupied by the exhaust air part channel facing the cooling flow inlet side.

The crossflow heat exchanger is not limited by its type and design. So it may be an air-gas or air-liquid heat exchanger. For example, it may be the heat sink of a heat pump or an air-to-air heat exchanger. As a cooling medium can thus serve, for example, a refrigerant of a heat pump. Likewise, can serve as a cooling medium cold air of an air-to-air heat exchanger. According to the invention, a dryer is preferred in which the cross-flow heat exchanger is an air-air heat exchanger.

Furthermore, various types of cross-flow heat exchanger can be used, for example, tube bundle heat exchanger and plate heat exchanger. Preferably, the heat exchanger has a suitable shape and / or surface structure to assist the heat exchange. In this case, the shape and / or surface structure are suitably selected so that the heat exchange between an optionally loaded with lint moist warm process air and a coolant or refrigerant optimally.

According to the invention, a plate heat exchanger is advantageous in this case. A plate heat exchanger consists of several plates, which are composed so that in each successive spaces alternately once the heat-emitting and once the cooling stream flows. Thus, the areas through which the process air flows alternate with the areas of the cooling flow. If, in a plate heat exchanger, the at least one flow guide body is arranged in the heat exchanger, its arrangement can take place in all process air intermediate spaces ("process air areas") in an identical manner or vary. A variation of the arrangement of the at least one flow guide body over the different process air intermediate spaces is preferred in particular for different admission of the different interspaces with process air, but also with different loading of the various spaces with coolant such as cooling air.

According to the invention, a larger proportion of the process air is conducted to the side of the crossflow heat exchanger, at which the cooling flow occurs. In the case of a plate heat exchanger, for example, this means that the volume over all process air gaps is considered as a whole with regard to the "side of the crossflow heat exchanger at which the cooling flow occurs". Thus, in a plate heat exchanger, it may be sufficient that in a single process air gap more than 50% by volume of the process air of this gap is directed to the side of the crossflow heat exchanger where the cooling flow occurs.

The invention also relates to a method for operating a dryer, comprising a control device, a process air duct, in which a heater, a drying chamber for objects to be dried, a fan and a cross-flow heat exchanger are arranged, wherein the process air duct a supply air duct in front of the drying chamber and an exhaust duct between drying chamber and cross-flow heat exchanger, and wherein the exhaust duct and / or cross-flow heat exchanger is / are such that a larger proportion p * M of a process air amount M flowing through the exhaust duct into the cross-flow heat exchanger, where p> 0.5, to a cooling flow inlet side the cross-flow heat exchanger is passed, wherein in the method, the moist, warm process air from the drying chamber in the exhaust duct is divided and divided so that a larger proportion p * M of a process air amount M, which flows through the exhaust duct in the cross-flow heat exchanger where p> 0.5, is passed to a cooling flow inlet side of the cross-flow heat exchanger.

The invention has the advantage that a dryer is provided with an efficient heat exchanger, thereby enabling energy saving. This is the case in particular because, with a dryer according to the invention, the separation efficiency for the moisture from the moist, warm process air is improved, whereas an increase in the cooling capacity is unnecessary. Thus, despite more efficient heat exchanger no amplified power supply is needed to supply lost thermal energy in the heat exchanger process air. In embodiments of the dryer according to the invention, in which the cross-flow heat dryer is an air-to-air heat exchanger, there is the advantage that it costs less and less maintenance compared to dryers with heat pump by fewer components.

• Fig. 1 zeigt einen vertikalen Schnitt durch einen Trockner gemäß einer ersten Ausführungsform, bei welcher der Trockner als Umlufttrockner ausgestaltet ist.
• Fig. 2 zeigt eine dreidimensionale Ansicht eines relevanten Ausschnitts aus einer zweiten Ausführungsform eines erfindungsgemäßen Trockners, bei dem ein Luft-Luft-Wärmetauscher als Kreuzstromwärmetauscher und angrenzende Prozessluftkanäle, Zuluft- und Abluftkanal, sichtbar sind.
• Fig. 3 zeigt eine dreidimensionale Ansicht eines relevanten Ausschnitts aus einer dritten Ausführungsform eines erfindungsgemäßen Trockners, bei dem ein Luft-Luft-Wärmetauscher als Kreuzstromwärmetauscher und angrenzende Prozessluftkanäle, Zuluft- und Abluftkanal, sichtbar sind. Dabei ist ein Leitblech im Prozessluftbereich des Kreuzstromwärmetauschers angeordnet.

Further details, features and advantages of the invention will become apparent from the following description of non-limiting embodiments of a dryer according to the invention with reference to the FIGS. 1 to 3 ,

• Fig. 1 shows a vertical section through a dryer according to a first embodiment, in which the dryer is designed as a circulating air dryer.
• Fig. 2 shows a three-dimensional view of a relevant section of a second embodiment of a dryer according to the invention, in which an air-air heat exchanger as a cross-flow heat exchanger and adjacent process air ducts, supply air and exhaust air duct, are visible.
• Fig. 3 shows a three-dimensional view of a relevant section of a third embodiment of a dryer according to the invention, in which an air-air heat exchanger as a cross-flow heat exchanger and adjacent process air ducts, supply air and exhaust air ducts are visible. In this case, a baffle is arranged in the process air area of the crossflow heat exchanger.

Fig. 1 shows in particular a vertically cut dryer 1 according to a first embodiment, in which the dryer 1 is designed as a circulating air dryer, which is equipped with a cross-flow heat exchanger 14. The cross-flow heat exchanger 14 is designed here as an air-to-air heat exchanger. The dryer 1 has a drum 3 rotatable about a horizontal axis as a drying chamber 3, within which Carrier 4 are attached to the movement of laundry during a drum rotation. Process air is conducted by means of a blower 15 through a supply air duct 12 as part of the process air duct and a heater 16 in the drum 3 and through an outlet 13 in an exhaust duct 2 and through a cross-flow heat exchanger 14 in a closed circuit (process air circuit 2, 12). After passing through the drum 3 in this case passes the moist, warm process air in the cross-flow heat exchanger 14, where it is cooled and dehumidified and then heated by the heater 16 again. The heated process air is from the rear, ie from the door 5 opposite side of the drum 3, passed through the perforated bottom in the drum 3, comes there with the laundry to be dried (not shown) into contact and flows through the filling opening of the drum 3, the process air flow in the door 5 is deflected downward and guided in the exhaust duct 2 to the cross-flow heat exchanger 14, where it is cooled and dehumidified. For this purpose, a cooling air flow into the dryer 1, which leaves it at the cooling air outlet 18, enters the crossflow heat exchanger 14 at the cooling air inlet 17.

In the wall 29 of the exhaust duct 2 is a rib 30, which ensures that the air flowing in the exhaust duct 2 process air flows mainly in the direction of a cooling flow inlet side 24 in the cross-flow heat exchanger 14 and there contributes to an efficient heat exchange.

The part of the process air channel 2,12 from the heat exchanger 14 to the drum 3 is thus also referred to as supply air duct 12 and the part of the process air duct 2,12 from the drum 3 to the heat exchanger 14 as the exhaust duct 2.

The drum 3 is in the in Fig. 1 shown embodiment at the rear bottom by means of a pivot bearing and front mounted by means of a bearing plate 7, wherein the drum 3 rests with a brim on a sliding strip 8 on the bearing plate 7 and is held at the front end.

The control of the dryer 1 via a control device 11 (also denoted by program control), which regulated by the user via an operating unit 9 can be. By means of a display device 10 different states of the dryer 1 can be displayed visually or acoustically.

Fig. 2 shows a three-dimensional view of a relevant section of a second embodiment of a dryer 1 according to the invention, in which an air-air heat exchanger as a cross-flow heat exchanger 14 and adjacent process air ducts 2,12, supply air and exhaust duct, are visible. Here, a baffle is arranged as a flow guide 22 in the inflow region 23 of the cross-flow heat exchanger 14.

In this embodiment, the cross-flow heat exchanger 14 is formed as an air-to-air heat exchanger with heat exchanger plates 19. The hot, moist process air supplied via the supply air channel 2 to the crossflow heat exchanger 14 is guided through the intermediate spaces of the heat exchanger plates 19, which are designed as process air regions 20. The process air regions 20 are arranged alternately in the cross-flow heat exchanger 14 with separate cooling air regions 21, through which cooling air flows, which is passed from the cooling air inlet 17 to the cross-flow heat exchanger 14 and from there via the cooling air outlet 18 from the dryer 1 passes.

In the exhaust duct 2, a baffle 22 is arranged as a flow guide 22 in the inflow region 23 of the crossflow heat exchanger 14 such that a larger proportion of the process air is passed to the cooling flow inlet side 24 of the crossflow heat exchanger 14. By the guide plate 22 of the exhaust duct 2 is divided into two separate process air duct areas 25 and 26 respectively.

Fig. 3 shows a three-dimensional view of a relevant section of a third embodiment of a dryer 1 according to the invention, in which an air-air heat exchanger 14 as a cross-flow heat exchanger and adjacent process air ducts, supply air duct 12 and exhaust duct 2, are visible. In this case, a baffle 22 is arranged in the process air region of the cross-flow heat exchanger 14.

In this embodiment, the cross-flow heat exchanger 14 is also formed as an air-to-air heat exchanger with heat exchanger plates 19. However, herein a baffle 22 is arranged as a flow guide 22 in the process air area 20 of the cross-flow heat exchanger 14, so that a larger proportion of the process air to the cooling flow inlet side 24 of the cross-flow heat exchanger 14 is passed. By the baffle 22 of the crossflow heat exchanger 14 is divided into two separate process air sections 27,28. In this case, a first process air part region 27 faces the cooling flow entry point 24 and a second process air part region 28 faces away from the cooling flow entry point 24.

The difference between the in Fig. 2 shown second embodiment of a dryer 1 according to the invention and in Fig. 3 shown third embodiment of a dryer according to the invention therefore consists in the different arrangement of the baffle 22. In Fig. 2 is the baffle 22 in the exhaust duct 2 in the upstream region 23 of the cross-flow heat exchanger 14, whereas in Fig. 3 the guide plate 22 is arranged in the crossflow heat exchanger 14 itself.

LIST OF REFERENCE NUMBERS

1

Dryer, condensation dryer

2

Process air duct, exhaust duct

3

Drying chamber, drum

4

takeaway

5

door

6

lint

7

end shield

8th

lubricating strip

9

operating unit

10

display device

11

Control device, program control

12

Process air duct, supply air duct

13

drum exit

14

Cross-flow heat exchanger

15

fan

16

heater

17

Cooling air inlet

18

Cooling air outlet

19

heat exchanger plates

20

Process air area

21

The cooling air

22

Guide plate, flow guide

23

Flow area of the cross-flow heat exchanger

24

Cooling flow inlet side

25

First exhaust air duct

26

Second partial exhaust air duct

27

First process air section in cross flow heat exchanger

28

Second process air section in the crossflow heat exchanger

29

Wall of the exhaust duct

30

Rib in wall of the exhaust duct

Claims (15)

1. Dryer (1), comprising a control device (11), a process air channel (2, 12), in which a heater (16), a drying chamber (3) for articles to be dried, a fan (15) and a crossflow heat exchanger (14) are arranged, wherein the process air channel (2, 12) comprises a feed-air channel (12) upstream of the drying chamber (3) and an exhaust-air channel (2) between the drying chamber (3) and crossflow heat exchanger (14), characterised in that the exhaust-air channel (2) and/or the crossflow heat exchanger (14) is or are constructed in such a manner that a larger proportion p*M of a process air quantity M flowing through the exhaust-air channel (2) into the crossflow heat exchanger (14), wherein p > 0.5, is conducted to a cooling flow inlet side (24) of the crossflow heat exchanger (14).
2. Dryer (1) according to claim 1, characterised in that p ≥ 0.6.
3. Dryer (1) according to claim 1 or 2, characterised in that at least one flow guidance body (22), the position of which is fixed or variable, is arranged in the exhaust-air channel (2) and/or crossflow heat exchanger (14).
4. Dryer (1) according to claim 3, characterised in that the at least one flow guidance body (22) is arranged in the exhaust-air channel (2).
5. Dryer (1) according to claim 4, characterised in that the at least one flow guidance body (22) is arranged in the exhaust-air channel (2) in the incident flow region (23) of the crossflow heat exchanger (14).
6. Dryer (1) according to any one of claims 3 to 5, characterised in that at least one flow guidance body (22) is arranged in the crossflow heat exchanger (14).
7. Dyer (1) according to any one of claims 3 to 6, characterised in that a position of the flow guidance body (22) in the exhaust-air channel (2) and/or in the crossflow heat exchanger (14) is set by means of the control device (11).
8. Dryer (1) according to any one of claims 3 to 7, characterised in that the position of the flow guidance body (22) can be set in dependence on parameters of a drying process.
9. Dryer (1) according to any one of claims 1 to 8, characterised in that a wall (29) of the exhaust-air channel (2) is so designed that when the process air is flowing in the exhaust-air channel (2) a larger proportion p*M of the process air quantity M, wherein p > 0.5, is conducted to a cooling flow inlet side (24) of the crossflow heat exchanger (14).
10. Dryer (1) according to any one of claims 1 to 9, characterised in that the exhaust-air channel (2) comprises a plurality of exhaust-air sub-channels which differ with respect to the incident flow of the cooling flow inlet side (24) of the crossflow heat exchanger (14).
11. Dryer (1) according to any one of claims 3 to 10, characterised in that the at least one flow guidance body (22) is a guide plate.
12. Dryer (1) according to any one of claims 3 to 11, characterised in that the at least one flow guidance body (22) divides the exhaust-air channel (2) upstream of the crossflow heat exchanger (14) into at least two separate exhaust-air sub-channels (25, 26).
13. Dryer (1) according to claim 8, characterised in that the at least one flow guide body (22) divides the process air region (20) in the crossflow heat exchanger (14) into at least two separate process air sub-regions (27, 28), of which a first process air sub-region (27) faces the cooling flow inlet side (24) and a second process air sub-region (28) faces away from the cooling flow inlet side (24).
14. Dryer (1) according to any one of claims 1 to 13, characterised in that the crossflow heat exchanger (14) is an air-air heat exchanger.
15. Method of operating a dryer (1), comprising a control device (11), a process air channel (2, 12), in which a heater (27), a drying chamber (3) for articles to be dried, a fan (15) and a crossflow heat exchanger (14) are arranged, wherein the process air channel (2, 12) comprises a feed-air channel (12) upstream of the drying chamber (3) and an exhaust-air channel (2) between the drying chamber (3) and crossflow heat exchanger (14), and wherein the exhaust-air channel (2) and/or the crossflow heat exchanger (14) is or are constructed in such a manner that a larger proportion p*M of a process air quantity M flowing through the exhaust-air channel (2) into the crossflow heat exchanger (14), wherein p > 0.5, is conducted to a cooling flow inlet side (24) of the crossflow heat exchanger (14), characterised in that the humid process air is conducted out of the drying chamber (3) into the exhaust-air channel (2) and so divided up that a greater proportion p*M of a process air quantity M flowing through the exhaust-air channel 92) into the crossflow heat exchanger (14), wherein p > 0.5, is conducted to a cooling flow inlet side (24) of the crossflow heat exchanger (14).

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