Condensing dryer with heat pump and circulating air assembly and method of operation thereof

Abstract

The invention relates to a condenser dryer (1) having a drum (2) for receiving laundry to be dried, an air inlet duct (3), an air outlet duct (4) from which a recirculation air duct (5) branches off which opens into the air inlet duct (3) upstream of a drum inlet (6), a fan (7), a heat pump (8, 9, 10, 11) having a condenser (8) which is arranged in the air inlet duct (3), an evaporator (9) which is arranged in the air outlet duct (4), a throttle device (10) and a compressor (11), and a control device and a heating device, wherein the condenser dryer (1) is set up in such a way that in a drying program carried out in the condenser dryer, the warm, moist process air from the drum (2) flows in the same direction as the incoming air in an inlet region (13) of the air inlet duct (3) which contains the condenser (8) in a part of the air outlet duct (12) which is delimited downstream by the evaporator (9) and the process air leaving the drum (2) has a relative air humidity F rel , which applies for this relative air humidity F rel min ≤ F rel ≤ F rel max , wherein F rel min is a predetermined minimum value and F rel max is a maximum value of the relative air humidity which can be achieved in the drying program. Furthermore, the invention also relates to a preferred method for operating a condenser dryer (1).

Description

Technical Field

[0001] This invention relates to a condenser dryer with a heat pump and a circulating air assembly, and a method of operating the same. In particular, the invention relates to a condenser dryer comprising: a drum for receiving clothes to be dried; an air inlet; an exhaust duct from which a circulating air duct branches, the circulating air duct opening into the air inlet upstream of the drum inlet; a fan; a heat pump having a condenser arranged in the air inlet; an evaporator arranged in the exhaust duct; a throttling device and a compressor; and a control device and a heating device. The invention also relates to a preferred method for operating the condenser dryer. Background Technology

[0002] Generally, clothes dryers operate as either vented dryers or condenser dryers. Condenser dryers function by condensing moisture evaporated from clothes using warm process air, thus recovering energy from the heated process air, for example, through the use of a heat pump. The condensate produced in a condenser dryer is collected, either pumped away or disposed of by manually emptying the collection container.

[0003] On the other hand, in exhaust-type dryers, the air loaded with moisture after passing through the clothes drum is usually drawn out of the dryer. Heat recovery is typically not performed here.

[0004] However, exhaust-type dryers with heat recovery are also known. For example, publication DE 30 00 865A1 describes a dryer with heat recovery. This clothes dryer consists of a container for receiving and moving clothes, into which an inlet airflow heated by a heating element enters, while the humid, warm air is discharged as exhaust through an outlet. A heat exchanger is disposed upstream of the heating element in the inlet airflow, and this heat exchanger is traversed by the warm, humid exhaust from the container.

[0005] Publication DE 197 31 826 A1 describes a clothes dryer with a heat recovery system (such as a heat pump), wherein a substantially closed air passage can exchange circulating air with indoor air at two predetermined points through two openings in order to maintain the drying temperature and condensation temperature at predetermined values.

[0006] Publication EP 2037034 B1 describes an exhaust dryer with a heat pump and an evaporator cleaning device.

[0007] Exhaust dryers with heat recovery are also described in publications US2012 / 0030960 A1 and DE 10 2008 055 087 A.

[0008] Publication DE 40 23 000 C2 describes a clothes dryer with a heat pump circuit, wherein an air inlet is provided in the process air passage between the condenser and the evaporator, and the air inlet can be closed by a controllable sealing device.

[0009] Publication DE 43 06 217 B4 describes a programmable clothes dryer with a clothes drum, wherein process air is delivered through the clothes drum by a fan in a closed process air duct, the process air duct having a sealing device. Furthermore, the clothes dryer also has a heat pump circuit consisting of an evaporator, a compressor, and a condenser for removing moisture from the process air from the clothes drum. The sealing device is arranged such that the generation of process air depends on the process stage.

[0010] In an exhaust-type dryer with a heat pump, the evaporator of the heat pump extracts heat from the exhaust gas from the drying chamber (usually a drum), and this heat is then supplied to the intake gas via the condenser. Because the exhaust-type dryer is an open system, it recovers both latent and sensible heat, unlike condensing dryers which use a closed process gas path. Therefore, even though the condensation efficiency may be, for example, less than 50%, the energy consumption of an exhaust-type dryer with heat recovery is still lower than that of a condensing dryer.

[0011] Depending on the efficiency of the heat pump, heat is coupled in from the surrounding environment. To improve operating efficiency, higher condensation efficiency is desirable.

[0012] To achieve condensing efficiency exceeding 80% in open-air systems, a heat exchanger (desuperheater or subcooler) is added to the refrigeration loop, as described in the prior art. In closed systems, the continuous input of compressor power causes the dryer temperature to rise steadily. If the input power is not balanced with energy losses (e.g., due to component heating, radiation, convection, or leakage), the system overheats, reducing the heat pump's efficiency. As a countermeasure, the use of an auxiliary heat exchanger with active cooling in the refrigeration loop or an air-to-air heat exchanger in the process air is well-known. In open systems, the temperature of the intake air from the installation chamber remains almost constant and does not exceed ambient temperature, thus preventing overheating under normal installation conditions for condensing dryers. The constant low temperature necessitates a high efficiency heat pump.

[0013] In contrast, a disadvantage of exhaust-type dryers is the overall energy balance of the installation site, as warmer indoor air typically exchanges with cooler outdoor air multiple times. This disadvantage is eliminated in open-air guided systems with a condensation efficiency greater than 80%, since the exhaust does not need to be routed out of the installation chamber.

[0014] Furthermore, it is well known that the energy efficiency of exhaust-type dryers can be improved through a recirculating air system. In this case, the process air loaded with moisture from the clothes in the drying chamber is partially returned to the drying process via a heating device.

[0015] Publication DE 103 49 712 A1 describes a method for drying clothes in a clothes dryer with a programmable control unit, a drying chamber and a process air duct, wherein a fan and a heating device for conveying drying air through the drying chamber are arranged in the process air duct, wherein the process air duct is constructed with a fresh air supply device and an exhaust exhaust device, wherein a device for separating the drying airflow into an exhaust component and a recirculated air component is arranged in the process air duct.

[0016] Publication DE 34 46 468 A1 describes a method for drying clothes in a clothes dryer, the clothes dryer having a driveable clothes drum, a fan, a heater arranged in the drying airflow path, and a cooled condenser, wherein the drying airflow exiting the clothes drum is guided to the condenser, wherein the drying airflow exiting the clothes drum is separated into two sub-airflows. One sub-airflow is supplied to the condenser, and the other sub-airflow bypasses the condenser and mixes with the sub-airflow exiting the condenser.

[0017] Publication DE 34 19 743 C2 describes a clothes dryer having a clothes drum, a heating element with an air inlet, and an exhaust outlet, wherein various auxiliary devices can be arranged in a switchable manner between the air inlet and exhaust outlet of the heating element, and these auxiliary devices determine the operating mode of the dryer. In one embodiment of the dryer, a circulation section is connected between the air inlet and exhaust connections, and an air control device is provided in this circulation section, thereby allowing the intake and exhaust ratio of the dryer to be changed.

[0018] Publication DE 10 2007 042969 A1 describes a dryer having a drying chamber for the object to be dried and a process air duct. The process air duct includes a heater for heating the process air, a fan for guiding the heated process air from an inlet through the drying chamber to an outlet, and at least one heat exchanger. The heat exchanger is arranged between the drying chamber and the outlet. A recirculating air duct branches off from the process air duct behind the drying chamber, through which a portion of the process air can be guided to the heating device. The at least one heat exchanger may consist of an evaporator and a condenser of a heat pump. Summary of the Invention

[0019] Against this backdrop, the objective of this invention is to provide a condensing dryer with an open air system and a heat recovery heat pump, which exhibits high energy efficiency. Here, a portion of the warm, humidified process air from the drum can be used as circulating air. Furthermore, the objective of this invention is to provide a method for operating the condensing dryer.

[0020] According to the present invention, the above-mentioned tasks are solved by a condenser dryer having the present invention and its operating method. Preferred embodiments of the condenser dryer and the method of the present invention are listed in the corresponding technical solutions of the present invention. The preferred embodiments of the condenser dryer of the present invention correspond to the preferred embodiments of the method of the present invention, and vice versa, even if not explicitly stated herein.

[0021] Therefore, the subject of this invention is a condenser dryer comprising: a drum for receiving clothes to be dried; an air inlet; an exhaust duct from which a circulating air duct branches, the circulating air duct opening into the air inlet upstream of the drum inlet; a fan; a heat pump having a condenser arranged in the air inlet; an evaporator arranged in the exhaust duct; a throttling device and a compressor; and a control device and a heating device, wherein the condenser dryer is configured such that, in the drying process performed in the condenser dryer, warm and humid process air from the drum flows substantially in the same direction as the intake air in the inlet region of the air inlet containing the condenser in an exhaust duct portion downstream of the evaporator boundary, and the process air leaving the drum has a relative humidity F. rel For this relative air humidity, F is applicable. rel min ≤F rel ≤F rel max , where F rel min It is the predetermined minimum value, F rel max It is the maximum relative air humidity that can be achieved during the drying process.

[0022] In other words, the applicant found that increasing the relative humidity of the process air at the drum outlet can improve the drying efficiency and / or drying speed of a condenser dryer. The air conditions at the drum outlet are affected by the volumetric airflow, the temperature inside the drum, the relative humidity of the process air at the drum inlet, the air guiding through the drum, and the load and type of clothing.

[0023] Relative air humidity is an indirect measure of the proportion of sensible heat in process air. Although sensible heat can be recovered as energy and thus increase drying speed in open-air systems with heat pumps (which are present in the condenser dryer of this invention), the proportion of sensible heat should be relatively small relative to latent heat in order to achieve higher condensation efficiency.

[0024] In this way, the size of the additional heat exchanger (such as a subcooler) used to meet the condensation efficiency requirement can be reduced. In any case, the present invention improves the efficiency of the condensing dryer.

[0025] Due to the introduction of air components with higher moisture content, the moisture content of the process air before and after the condenser will increase. The relative humidity of the air at the drum inlet will increase, and the relative humidity of the process air at the drum outlet will also increase.

[0026] In a preferred embodiment of the condenser dryer of the present invention, the circulating air passage is introduced into the air intake passage downstream of the condenser along the air intake flow direction.

[0027] In a more preferred embodiment of the condenser dryer of the present invention, the circulating air passage is introduced into the air intake passage upstream of the condenser or at the condenser along the air intake flow direction, thereby resulting in an increase in the airflow through the condenser.

[0028] According to the present invention, flow measurement devices are preferably arranged upstream and downstream of the condenser in the air intake duct. This allows for the determination of the proportion of circulating air introduced from the drum.

[0029] According to the invention, it is particularly preferred that the exhaust duct portion of the condenser dryer and the condenser share a common wall having a plurality of holes that form a circulating air passage. Here, it is also preferred that the plurality of holes be located in the inlet region of the condenser.

[0030] The shape and number of holes are not limited, as long as the desired circulating air ratio according to the invention can be achieved through multiple holes.

[0031] Preferably, in any case, the multiple orifices of the condenser dryer are designed to cooperate with the fan during the drying process to form a volumetric airflow through the condenser, such that 15% to 50% by volume, preferably 20% to 40% by volume, of this airflow consists of recirculated air. Compared to the evaporator, the volumetric airflow through the condenser is significantly increased, thereby additionally improving the efficiency of the heat pump. With the efficiency remaining constant, the size of the heat exchanger, especially the auxiliary heat exchanger, can be smaller. However, if the volumetric airflow through the condenser is not increased, the intake and exhaust flow rates will be reduced, thereby lowering the noise level of the condenser dryer without increasing efficiency.

[0032] According to the present invention, increasing the proportion of recirculated air can be achieved, for example, by increasing the fan power and thus increasing the fan's delivery power. Increasing the fan power leads to an increase in underpressure in the intake duct and an increase in overpressure in the exhaust duct. This, in turn, increases the pressure difference between the process air entering the intake duct from the drum or exhaust duct, particularly entering the condenser inlet region.

[0033] In embodiments with multiple holes in a shared wall, the number, location, and size of the holes are typically fixed and therefore cannot be changed. However, a condenser dryer can advantageously have a device that allows control over the total effective opening area of ​​the multiple holes. For example, such a device can be designed to completely or partially cover some of the holes, where, for example, coverage can be achieved using a partially permeable foam material that impedes air passage. Another possibility for coverage is the use of adjustable louvers.

[0034] In an advantageous embodiment of the condenser dryer of the present invention, the heat pump includes an additional cooler, also known as a subcooler. This allows for better control of the heat pump's function, and in particular, prevents overheating of the heat pump.

[0035] However, the present invention can precisely avoid the use of an auxiliary cooler. When the proportion of process air in the circulating air duct (which, in embodiments of the invention, directly reaches the condenser) is sufficiently high, the use of an auxiliary cooler can be avoided. Therefore, in another preferred embodiment of the invention, the heat pump does not include an auxiliary cooler.

[0036] Furthermore, according to the present invention, the condenser dryer preferably stores the fan speed u and the air flow rate V in the condenser in the control device. C and the air velocity V in the evaporator E The relationship between the ratios r and r. This allows for better control of the circulating air ratio in the condenser dryer of this invention.

[0037] Finally, the condenser dryer preferably also has a humidity sensor at the drum outlet to determine the relative humidity F of the process air leaving the drum. rel Because although this invention can be implemented based on empirical values ​​of relative humidity and its relationship with various parameters, relative humidity F... rel More accurate results can be obtained through measurement. In this case, it is advantageous to use an additional temperature sensor at the roller outlet.

[0038] Adjustable sealing devices can be incorporated into various passageways, such as the intake, recirculated air, and exhaust passageways, to improve airflow control, particularly the control of the intake air ratio in the airflow passing through the condenser. For example, valves can be used as adjustable sealing devices, and these valves can open to different degrees independently or in relation to each other.

[0039] The dryer preferably includes an electric heating device, so that the process air can be heated not only through the condenser but also through the electric heating device. Since the energy required for drying decreases as the dryness of the clothes in the condenser dryer increases, it is advantageous to adjust the heating device accordingly, i.e., reduce its heating power as the dryness increases. Furthermore, in the condenser dryer of the present invention, if the evaporator inlet temperature is too high, the proportion of circulating air can be reduced according to the temperature.

[0040] By using a circulating air duct or by supplying hot circulating air loaded with moisture to the heating device through a circulating air duct, the air temperature upstream of the heater is typically increased. However, due to the increased airflow through the heating device, the drum inlet temperature can still be kept within the allowable range.

[0041] To accelerate the heating of process air after the condenser dryer is started, a controllable sealing device can be used to control the air intake in the intake duct, thereby stopping the air intake at the initial stage of the drying process and using only recirculated air as process air.

[0042] According to a preferred embodiment of the invention, exhaust, intake, and / or refrigerant are guided through the respective heat exchangers in a cross-flow or counter-flow manner.

[0043] The evaporator of a heat pump is located in the exhaust duct to extract heat from the warm, humid air in the drum, which typically flows into the installation chamber through the exhaust duct.

[0044] In a condensing dryer equipped with a heat pump, the cooling of the hot, humid process air takes place primarily in the evaporator of the heat pump, where the transferred heat is used to evaporate the refrigerant used in the heat pump circuit. The refrigerant, which evaporates due to heating in the heat pump, is supplied to the condenser of the heat pump via a compressor, where heat is released due to the condensation of the gaseous refrigerant. This heat is used to heat the process air or intake air before entering the drying chamber.

[0045] In the dryer of the present invention, the fan is preferably arranged directly after the condenser or directly before the condenser.

[0046] Furthermore, another aspect of the present invention is a method for operating a condenser dryer, the condenser dryer comprising: a drum for receiving clothes to be dried; an air inlet; an exhaust duct from which a recirculating air duct branches, the recirculating air duct opening into the air inlet upstream of the drum inlet; a fan; a heat pump having a condenser arranged in the air inlet; an evaporator arranged in the exhaust duct; a throttling device and a compressor; and a control device and a heating device, wherein the condenser dryer is configured such that, during a drying process performed in the condenser dryer, warm, humid process air from the drum flows substantially in the same direction as the intake air in the inlet region of the air inlet containing the condenser in an exhaust duct portion downstream of the evaporator, and the process air exiting the drum has a relative humidity F. rel For this relative air humidity, F is applicable. rel min ≤F rel ≤F rel max , where F rel min It is the predetermined minimum value, F rel max This is the maximum relative humidity achievable during the drying process, where the fan is controlled by a control unit to ensure that the process air leaving the drum has a relative humidity F. rel For this relative air humidity, F is applicable. rel min ≤F rel ≤F rel max .

[0047] Here, the phrase "flowing substantially in the same direction" should take into account the fact that the circulating air portion, that is, the process air portion flowing through multiple holes in one embodiment of the circulating air passage used according to the invention, flows laterally or even perpendicularly to that direction and thus affects the flow in the exhaust passage and the circulating air passage.

[0048] In a preferred embodiment of the method of the present invention, the fan is controlled by a control device to make the circulating air consist of 15% to 50% by volume, preferably 20% to 40% by volume, of the air volume flow through the condenser.

[0049] Furthermore, according to the present invention, the air flow rate V in the condenser C With air velocity V in the evaporator E Methods where the ratio r is greater than 1, preferably greater than 1.2, are preferred.

[0050] Finally, the method of the present invention is preferably carried out after the process air leaving the drum has reached a predetermined minimum temperature. At this time, the relative air humidity F at the drum outlet is... rel Typically very high, preferably even reaching the highest relative humidity F rel max This invention allows for the maintenance of such high relative humidity. Therefore, the method of this invention is preferably carried out during the main drying stage.

[0051] However, during the drying process, especially at the end of the main drying stage when most of the moisture in the clothes is removed, the relative humidity F of the process air leaving the drum... rel It will decrease. Therefore, even in the final stage of the drying process after the main drying stage, for example by increasing the fan speed u to increase the relative humidity F of the air at the drum outlet. rel It is very advantageous.

[0052] As mentioned earlier, the amount of clothing loaded will also affect the relative humidity of the process air. rel This has an impact. Therefore, it is preferable that the load of clothes in the drum can also be determined in a known way. Therefore, it is advantageous to correlate the load with F rel min or F rel max The relationships between them are stored in the control device so that these values ​​can be set more specifically.

[0053] The advantages of the condenser dryer and the method of the present invention are that the condenser dryer can operate with high condensation efficiency in an energy-saving manner. In particular, in the condenser dryer of the present invention, the efficiency and / or noise level of the condenser dryer can be improved by using an open air system, a heat pump for heat recovery, and separating a portion of the process air after the drum outlet and returning it as circulating air before or after the condenser. Attached Figure Description

[0054] Further details of the invention will emerge from the following description of non-limiting embodiments of the condenser dryer and the method of using the condenser dryer. Reference is made herein to... Figures 1 to 7 .

[0055] Figure 1 A perspective view of a prior art condenser dryer with a heat pump is shown, wherein an air intake duct for partially returning process air from the drum is not used.

[0056] Figure 2 Show Figure 1 A vertical cross-sectional view of a condenser dryer, showing the air guidance through the inlet, drum, and exhaust ducts.

[0057] Figure 3 A vertical cross-sectional view of a condenser dryer according to a first embodiment of the present invention is shown, in which a portion of the process air from the drum is supplied to a condenser in the air inlet via a circulating air passage.

[0058] Figure 4 picture Figure 3 The diagram shows a vertical cross-sectional view of a condenser dryer according to a first embodiment of the invention. In this first embodiment, a portion of the process air is supplied from the drum to the condenser in the inlet duct via a circulating air passage. Figure 3 The difference is that, for clarity, there are no arrows here indicating the airflow in a condenser dryer.

[0059] Figure 5 A schematic diagram (thick arrows) shows the process air flow through the condenser, drum, evaporator and subcooler of a condenser dryer according to a second embodiment of the present invention, wherein thin arrows indicate the refrigerant flow through the heat pump assembly used.

[0060] Figure 6 A schematic diagram (thick arrows) shows process air flowing through the condenser, drum, evaporator and subcooler of a condensing dryer according to a third embodiment of the present invention, wherein thin arrows indicate refrigerant flowing through the heat pump assembly used.

[0061] Figure 7 A perspective top view of the lower part of the condenser dryer used according to the invention is shown, in particular a common wall separating the condenser from the exhaust duct is visible, the wall having a plurality of holes in the inlet area of ​​the condenser that can be used as circulating air ducts. Detailed Implementation

[0062] Figure 1 This is a perspective view of a prior art condenser dryer 1 with a heat pump, showing the condenser 8 and evaporator 9. In this condenser dryer, no inlet duct is used to partially return process air from the drum 2. Arrows indicate the airflow direction through the condenser dryer. Light-colored arrows indicate air intake from the condenser dryer's mounting chamber, which is conveyed in inlet duct 3 due to the use of a fan (not shown). This air intake is heated in the condenser 8, and the heated process air is then further guided into the drum 2. The warm, humid process air exits the drum 2 at drum outlet 18. Here, the process air has a relatively high temperature, indicated by the black arrows. The warm, humid process air is cooled in the evaporator 9 (with moisture condensation, not shown) and conveyed into the mounting chamber of the condenser dryer 1 in exhaust duct 4. 17 refers to the subcooler in the heat pump circuit.

[0063] Figure 2Show Figure 1 A vertical sectional view of the condenser dryer 1, showing air guidance through the inlet duct 3, drum 2, and exhaust duct 4. The meanings of the reference numerals in the figure are as follows: Figure 1 same.

[0064] Figure 3 A vertical cross-sectional view of a condenser dryer 1 according to a first embodiment of the present invention is shown, wherein a portion of the process air from the drum 2 is supplied to the condenser 8 in the inlet duct 3 via a recirculating air passage 5. The recirculating air passage 5 is located in the inlet portion 13 of the inlet duct 3. 12 indicates an exhaust passage in which the flow direction of the process air is substantially the same as the flow direction in the inlet duct, particularly in the condenser 8. The forked thick arrows illustrate how a portion of the warm, humid process air from the drum 2 enters the condenser 8 as recirculating air after the drum outlet 18.

[0065] Figure 4 picture Figure 3 This is shown as a vertical cross-sectional view of a condenser dryer 1 according to a first embodiment of the present invention, wherein a portion of the process air from the drum 2 is supplied to the condenser 8 in the inlet duct 3 via a circulating air passage 5. Figure 3 The difference is that, for clarity, there are no arrows indicating airflow in condenser dryer 1. The meanings of other reference numerals are the same as... Figure 3 same.

[0066] Figure 5 A schematic diagram (thick arrows) shows process air flowing through the condenser 8, drum 2, evaporator 8, and subcooler 17 of a condensing dryer 1 according to a second embodiment of the present invention, where thin arrows indicate refrigerant flow through the heat pump components used. The refrigerant is guided in a refrigerant circuit, which also includes a throttling device 10 and a compressor 11. The curved thick arrows indicate that a portion of the process air from the drum 2 returns after the condenser 8 to the air inlet duct (not shown) containing the condenser 8.

[0067] Figure 6 A schematic diagram is shown, in which thick arrows represent the process air flow passing through the condenser 8, drum 2, evaporator 9, and subcooler 17 of the condensing dryer 1 according to a third embodiment of the present invention, while thin arrows represent the refrigerant flow passing through the heat pump components used. The refrigerant is guided in a refrigerant circuit, which here also includes a throttling device 10 and a compressor 11. Here, the curved thick arrows indicate... Figure 5 In contrast, a portion of the process air from the drum 2 is preferably returned upstream of or at the condenser 8 to the intake duct containing the condenser 8 (not shown).

[0068] Figure 7 A perspective top view of the lower part of the condenser dryer used according to the invention is shown, in particular the common wall 14 separating the condenser 8 from the exhaust duct (not shown here), which has a plurality of holes 15 in the inlet region 16 of the condenser 8. 13 refers to the inlet portion of the air intake duct, which is also not shown here.

[0069] List of reference numerals 1. Condensing dryer 2. Drum for receiving clothes to be dried 3. Air intake 4. Exhaust duct 5. Circulating air duct 6. Roller Inlet 7 fans 8. Condenser 9. Evaporator 10 Throttling device 11 Compressor 12. Exhaust passage section 13. (Intake duct) Inlet area 14. Common wall of condenser and recirculating air duct section More than 15 holes (on a common wall) 16. Condenser inlet area 17. Additional coolers, subcoolers (in heat pumps) 18 Outlet (for process air from the drum), drum outlet.

Claims

1. A condenser dryer (1) comprising: a drum (2) for receiving clothes to be dried; an air inlet (3); an exhaust duct (4) from which a circulating air duct (5) branches, the circulating air duct opening into the air inlet (3) upstream of the drum inlet (6); a fan (7); a heat pump having a condenser (8) arranged in the air inlet (3); an evaporator (9) arranged in the exhaust duct (4); a throttling device (10) and a compressor (11); and a control device and a heating device. in, The condenser dryer (1) is configured such that, during the drying process performed in the condenser dryer, the warm, humid process air from the drum (2) flows in the same direction in an exhaust duct section (12) downstream of the evaporator (9) as the intake air in the inlet region (13) of the intake duct (3) containing the condenser (8) and exits the process air from the drum (2) has a relative humidity F. rel For this relative air humidity, F is applicable. rel min ≤F rel ≤F rel max , where F rel min It is the predetermined minimum value and F rel max It is the maximum relative air humidity that can be achieved in the drying process, wherein the circulating air passage (5) is introduced into the air intake passage (3) upstream of the condenser (8) located in the inlet area of ​​the air intake passage or at the condenser located in the inlet area of ​​the air intake passage in the direction of air intake flow, and the exhaust passage portion (12) and the condenser (8) have a common wall (14) having a plurality of holes (15) forming the circulating air passage (5).

2. The condenser dryer (1) according to claim 1, characterized in that, The circulating air passage (5) enters the intake passage (3) downstream of the condenser (8) in the direction of air flow.

3. The condenser dryer (1) according to claim 1 or 2, characterized in that, Flow measurement devices are arranged upstream and downstream of the condenser (8) in the intake duct (3).

4. The condenser dryer (1) according to claim 1 or 2, characterized in that, The plurality of holes (15) are located in the inlet region (13) of the condenser (8).

5. The condenser dryer (1) according to claim 1 or 2, characterized in that, The plurality of holes (15) are designed to interact with the fan (7) during the drying process implemented in the condenser dryer (1) such that 15% to 50% of the volume percentage of the air volume flow through the condenser (8) consists of circulating air.

6. The condenser dryer (1) according to claim 5, characterized in that, 20% to 40% of the volume of air flowing through the condenser (8) consists of circulating air.

7. The condenser dryer (1) according to claim 1 or 2, characterized in that, The condenser dryer has a device that allows control over the total effective opening area of ​​the plurality of holes (15).

8. The condenser dryer (1) according to claim 1 or 2, characterized in that, The heat pump includes an additional cooler (17).

9. The condenser dryer (1) according to claim 1 or 2, characterized in that, The control device stores the fan (7) speed u and the air velocity V in the condenser (8). C and the air velocity V in the evaporator (9) E The relationship between the ratios r between them.

10. The condenser dryer (1) according to claim 1 or 2, characterized in that, A humidity sensor is arranged at the outlet (18) of the drum (2) to determine the relative humidity F of the process air leaving the drum (2). rel .

11. A method for operating a condenser dryer (1), the condenser dryer comprising: a drum (2) for receiving clothes to be dried; an air inlet (3); an exhaust duct (4) from which a circulating air duct (5) branches, the circulating air duct being introduced into the air inlet (3) upstream of the drum inlet (6); a fan (7); a heat pump having a condenser (8) arranged in the air inlet (3); an evaporator (9) arranged in the exhaust duct (4); a throttling device (10) and a compressor (11); and a control device and a heating device, wherein the condenser dryer (1) is configured such that, in a drying process performed in the condenser dryer, warm, humid process air from the drum (2) flows in the same direction in an exhaust duct portion (12) downstream of the evaporator (9) and in the inlet air of the air inlet duct (3) containing the condenser (8) and exits the process air of the drum (2) having a relative humidity F. rel For this relative air humidity, F is applicable. rel min ≤F rel ≤F rel max , where F rel min It is the predetermined minimum value and F rel max It is the maximum relative humidity that can be achieved during the drying process. Its features are, The fan (7) is controlled by a control device to ensure that the process air leaving the drum (2) has a relative humidity F. rel For this relative air humidity, F is applicable. rel min ≤F rel ≤F rel max The circulating air passage (5) is introduced into the intake passage (3) upstream of the condenser (8) in the intake passage or at the condenser in the intake passage in the direction of air flow. The exhaust passage portion (12) and the condenser (8) have a common wall (14) with a plurality of holes (15) forming the circulating air passage (5).

12. The method according to claim 11, characterized in that, The fan (7) is controlled by a control device to make 15 to 50% of the volume percentage of the air volume flow through the condenser (8) consist of circulating air.

13. The method according to claim 12, characterized in that, 20 to 40 percent of the volume of air flowing through the condenser (8) consists of circulating air.

14. The method according to any one of claims 11 to 13, characterized in that, Air velocity V in condenser (8) C With the air velocity V in the evaporator (9) E The ratio r between them is greater than 1.

15. The method according to any one of claims 11 to 13, characterized in that, This method is implemented after the process air leaving the drum (2) reaches a predetermined minimum temperature.

16. The method according to claim 14, characterized in that, Air velocity V in condenser (8) C With the air velocity V in the evaporator (9) E The ratio r between them is greater than 1.2.

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