EP2732090A1

EP2732090A1 - Vented laundry drying having an additional heater and heat exchanger unit

Info

Publication number: EP2732090A1
Application number: EP12732611.4A
Authority: EP
Inventors: Frank Höfler; Uwe-Jens Krausch; Günter Steffens; Andreas Stolze
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2011-07-11
Filing date: 2012-06-26
Publication date: 2014-05-21
Anticipated expiration: 2032-06-26
Also published as: DE102011078922A1; CN103649405B; RU2564601C2; US20140165420A1; CN103649405A; EP2732090B1; RU2014101766A; US9708750B2; WO2013007506A1; PL2732090T3

Abstract

The invention relates to a vented laundry dryer 1, comprising an air inlet duct 3, an air outlet duct 5, a heat recovery system 8-11 for transferring heat from the air outlet duct 5 to the air inlet duct 3, and an additional heater 7, wherein the heat recovery system 8-11 is a heat pump comprising an evaporator 8, a liquefier 9, a condenser 10, and a relaxation unit 11, wherein the liquefier 9 is thermally coupled to the air inlet duct 3, and the evaporator 8 is thermally coupled to the air outlet duct 5, and a relaxation property of the relaxation unit 11 can be adjusted depending on at least one parameter that is connected to an activity of the additional heater 7. A method is used to operate a vented heat dryer 1 comprising an additional heater 7 and a heat pump 8-11 having a relaxation unit 11, wherein the method comprises the following steps: (a) monitoring at least one parameter that is connected to an activity of the additional heater 7; and (b) changing a relaxation property of the relaxation unit 11 depending on the at least one parameter.

Description

Exhaust air drying with additional heating and

heat exchanger assembly

The invention relates to an exhaust air dryer having an air inlet duct leading from the outside to a heatable laundry treatment room, an air outlet duct leading from the laundry treatment room to the outside, a heat recovery unit for transferring heat from the air outlet duct to the air inlet duct and an auxiliary heater disposed on the air inlet duct , The invention further relates to a method for operating such an exhaust air dryer.

For example, from DE 197 37 075 A1 an exhaust air dryer of the type mentioned is known in which the heat recovery unit is an air / air heat exchanger, which is on the one hand with air of the air inlet channel and on the other hand with air of the air outlet channel flows. The air / air heat exchanger is arranged in terms of flow before an additional heating.

DE 10 2007 062 776 A1 discloses an exhaust air dryer with a drying chamber, a process air duct in which a heating for heating the process air is located and the heated process air can be guided by means of a blower in the drying chamber, a motor and a controller, which dryer is set up for operating by picking up an electric power never exceeding a predetermined value Pmax. The exhaust air dryer has means which are set up in such a way that, during operation, the dryer receives at least in phases the electrical power corresponding to the predetermined value Pmax. The dryer may include a heat pump cycle with an evaporator, a liquefier, a compressor, and an expansion valve or throttle valve.

By replacing the air / air heat exchanger by a heat pump, an efficiency of the exhaust air laundry dryer can be further increased. The efficiency depends on a predetermined design or tuning of the heat pump, the efficiency is the higher, the better the heat pump to a temperature or a temperature difference of the process air and thus the Air ducts is adjusted. Conversely, the efficiency is reduced when fluctuations in the performance of the exhaust air dryer, especially in its temperature or temperature differences, occur. Such fluctuations may occur, for example, as a function of a load and a humidity of the laundry located in the laundry treatment room, as well as due to an operation of the additional heating. In particular, due to an additional heat input generated by the additional heating, overheating of the evaporator can become so high that the efficiency drops significantly. It is the object of the present invention to provide a possibility for exhaust air drying laundry with a heater (hereinafter called "auxiliary heater") and a heat exchanger unit, which at least partially overcomes the disadvantages of the prior art and in particular a high efficiency over a wider range of Operating conditions, especially temperature changes, can maintain.

This object is achieved according to the features of the independent claims. Preferred embodiments are particularly apparent from the dependent claims and the following description.

The object is thus achieved by an exhaust air dryer, comprising an air inlet duct leading from outside to a heatable laundry treatment room, an air outlet duct leading from the laundry treatment room to the outside, a heat recovery unit for transferring heat from the air outlet duct to the air inlet duct and an arranged additional heating the air inlet duct. The heat recovery unit is a heat pump with an evaporator, a condenser, a compressor and a expansion device, wherein the condenser is thermally coupled to the air inlet channel and the evaporator is thermally coupled to the air outlet channel. A relaxation characteristic of the expansion device can be set as a function of at least one parameter associated with an activity of the additional heating. Due to the fact that the evaporator is thermally coupled to the air outlet duct, heat is extracted from the air outlet duct or the warm, moist process air (exhaust air) located in the air outlet duct and transferred to the evaporator. Conversely, by thermally coupling the condenser to the air inlet duct, heat can be transferred from the condenser to the air inlet duct or to the process air (fresh air) located in the air inlet duct. Due to the temperatures or temperature differences (and analogous to the pressures or pressure differences) on the evaporator and the condenser, the heat pump cycle is operable. Efficiency of the heat pump depends on these temperatures or temperature differences and can be optimized by design of the elements of the heat pump to the temperatures or temperature differences for given boundary conditions. By changing the relaxation characteristic as a function of the activity of the additional heating, the heat pump, in particular its optimal operating point, can be adapted in a simple manner to a particularly strong displacement of the operating point of the heat pump due to the additional heating.

The exhaust air dryer may be an exhaust air dryer or a pure exhaust air dryer.

The laundry treatment room may in particular be a rotatable laundry drum. The exhaust air dryer may be in particular a front loader.

The additional heater may be, for example, a power-driven or a gas-powered auxiliary heater.

The additional heating can be an autonomously operable auxiliary heating for even lower energy consumption, eg operated by solar cells. A parameter associated with an activity of the additional heating may in particular be an operating parameter of the additional heating. It is therefore also an embodiment that the relaxation property of the expansion device is adjustable in dependence on at least one operating parameter of the additional heating. Thus, an adaptation to the operation of the additional heating can be done immediately. It is a preferred embodiment that the relaxation property of the expansion device is adjustable in dependence on a current heating power of the auxiliary heater. The associated with the activity of the additional heating parameters is thus the heating power. This heat output can thus be regarded in particular as an operating parameter of the additional heater. The heating power can be represented, for example, by an electrical power currently consumed by the additional heater, which can be measured, for example, by means of a current sensor. Alternatively, the heating power may be represented by a desired power of the additional heater, which can be dispensed with a current sensor. A relationship between the heating power and the relaxation characteristic, for example the flow cross section required for an optimized efficiency, may have been determined experimentally, for example. In addition, it is a preferred embodiment that the expansion characteristic of the expansion device is adjustable as a function of a switch-on state of the additional heater. The parameter associated with the activity of the additional heating is thus the switch-on state ("on" or "off" or the like) of the additional heating. The switch-on state can therefore also be regarded as an operating parameter of the additional heater. Thus, an improvement in the efficiency can be achieved with particularly simple means. In particular, the expansion device can thus be switched between a first operating position, which corresponds to an off additional heater, and a second operating position, which corresponds to an activated additional heater. For example, a flow cross section between a smallest flow cross section in the case of an off additional heater and a largest flow cross section in the case of an activated additional heater can be switched. In particular, the expansion device only needs to have these two operating positions. It is a preferred embodiment that the expansion device is an expansion valve (also called a throttle valve) and a flow cross-section of the expansion valve (as a size influencing the expansion characteristic) is adjustable in dependence on the at least one parameter. This allows the adaptation of the heat pump in a particularly simple and inexpensive way to reach. The expansion valve may in particular be a remotely controllable, in particular a controllable, expansion valve. The expansion valve may in particular be an electronic expansion valve. For operation of the heat pump, the flow cross section of the adjustable expansion valve may be adjustable, in particular, between a smallest flow cross section and a largest flow cross section, with both flow cross sections being greater than zero, ie, the expansion valve is not closed even at the smallest flow cross section.

It is still a preferred embodiment that the expansion device comprises a group of a plurality of fluidly connected in parallel capillaries, of which at least one capillary depending on the at least one parameter is either obvious and closed. A flow cross section of the expansion device is then determined by the number of open capillaries, whereby the expansion device consequently has a stepwise adjustable flow cross section. In particular, a capillary can be present as an expansion valve with a flow cross-section fixed in the open state. In particular, all capillaries or all capillaries except a first capillary may optionally be visible and closable. It is also a preferred embodiment that the expansion device is adjustable in such a way that it (only) between a first operating position and a second operating position is switchable. In this case, therefore, the expansion device has only two adjustable flow cross sections. Such a relaxation device may be particularly simple and inexpensive ausgestaltbar, e.g. by providing only two capillaries.

It is also a preferred embodiment that the expansion device is multistage or continuously adjustable, which can be achieved even more accurate adjustment of the heat pump. For example, the expansion valve may change its flow cross-section gradually or continuously. To operate the heat pump, the flow cross section of the adjustable expansion valve may be adjustable, in particular stepwise or stepwise, between a smallest flow cross section and a largest flow cross section. Also a The total flow cross-section of the group of several fluidically connected capillaries is simply adjustable in stages or in multiple stages.

It is still a preferred embodiment that the expansion characteristic, in particular the flow cross-section of the expansion device in response to a temperature difference and / or a pressure difference is adjustable. The associated with the activity of the additional heating at least one parameter thus includes a temperature difference and / or a pressure difference. The temperature difference and / or a pressure difference may be a difference in the air duct or the process air. The temperature difference and / or the pressure difference may alternatively or additionally be a difference in the refrigeration cycle or the refrigerant. This embodiment allows a particularly accurate adaptation of the heat pump.

It is particularly preferred that the relaxation characteristic be adjustable in response to a temperature difference and / or a pressure difference across the evaporator (i.e., between an inlet temperature and an outlet temperature of the refrigerant at the evaporator).

The adjustment of the relaxation characteristic, in particular the flow cross-section, depending on the actual heating power, the temperature difference, the pressure difference and / or another parameter of the exhaust air dryer, which may take several values, may be proportional (ie, linearly proportional or non-linearly proportional ) are set to this parameter, if necessary only within a predetermined value range of the parameter.

The adjustment can be made alternatively or additionally with reaching or exceeding / falling below one or more threshold values of at least one parameter of the exhaust air laundry drying device. Thus, an adjustable expansion valve may be opened or closed in stages, if corresponding threshold values of the heating power and / or the temperature difference at the evaporator are reached.

The object is also achieved by a method for operating an exhaust air dryer with an additional heater and a compression heat pump with a relaxation device, the method comprising at least the following steps: (a) monitoring at least one associated with an activity of the additional heating parameter (eg, a power of additional heating and / or a temperature difference on an evaporator) and (b) changing a relaxation property of the expansion device depending on the at least one parameter. The method has the same advantages as the described exhaust air dryer and can be configured in an analogous manner.

In particular, monitoring can include determining a desired value and / or measuring an actual value.

For example, the expansion device may be an adjustable expansion valve and the method may include at least the following steps: (a) monitoring a booster state (on / off) of the booster heater, and (b) expanding a flow diameter of the expansion valve with the booster heater turned on and narrowing the flow diameter of the expansion valve a switched-off additional heating.

In another example, the expansion device may be an expansion valve and the method may comprise at least the following steps: (a) monitoring a temperature difference and / or a pressure difference (in particular the coolant, in particular between an inlet temperature and an outlet temperature of the coolant at the evaporator); (B) expanding a flow diameter of the expansion valve with increasing temperature difference and / or pressure difference and (c) reducing the flow diameter of the expansion valve with decreasing temperature difference and / or pressure difference. Expanding and contracting can be carried out continuously or stepwise (in particular by means of threshold values). Within the scope of yet another example, the expansion device may comprise a group of capillaries connected in fluidic manner, of which at least one capillary is optionally open and closable depending on the at least one parameter, and the method comprises at least the following steps: (a) monitoring a heating power the additional heating and (b) opening at least one previously closed capillary with increasing heating power and (c) closing at least one previously opened capillary with decreasing heating power.

In yet another example, the expansion device may comprise a group of fluidically connected capillaries, of which at least one capillary is selectively open and closed depending on the at least one parameter, and the method comprises at least the following steps: (a) monitoring a temperature difference and / or a pressure difference (in particular of the coolant, in particular between an inlet temperature and an outlet temperature of the coolant at the evaporator) and (b) opening at least one previously closed capillary with increasing temperature difference and / or pressure difference and (c) closing at least one previously opened capillary with decreasing temperature difference and / or pressure difference. Expanding and contracting is done step by step.

In the following figures, the invention will be described schematically with reference to exemplary embodiments. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity. 1 shows a sketch of an exhaust-air laundry drying apparatus according to a first embodiment;

FIG. 2 shows a sketch of an exhaust-air laundry drying device according to a second embodiment; FIG.

3 shows a sketch of an exhaust-air laundry drying apparatus according to a third embodiment; and

4 shows a sketch of an exhaust air laundry drying device according to a fourth embodiment.

1 shows a sketch of an exhaust air drying device 1 according to a first embodiment. The exhaust air drying apparatus 1 is a front loader with a rotary laundry drum 2 as a laundry treatment room. From an exterior space A, an air inlet duct 3 leads to the laundry drum 2. At the air inlet duct 3 is a blower 4 for conveying air L (then still as fresh air) from the outside space A to the laundry drum 2 and further (as exhaust air) from the laundry drum 2 over one Air outlet channel 5 again in the outer space A. As it flows through the laundry drum 2, the air L moisture absorbs therein laundry W to dry the laundry W. For heating the air L in the air intake duct 3 in an energy-saving manner, the exhaust air drying apparatus 1 comprises a compression heat pump 8 to 11 having an evaporator 8, a condenser 9, a compressor 10, and expansion means in the form of an expansion valve 1 1 on. The condenser 9 is thermally coupled to the air inlet duct 3, and the evaporator 8 is thermally coupled to the air outlet duct 5. As a result, heat is removed from the air outlet duct 5 or the warm, moist air (exhaust air) L located in the air outlet duct 5 and transferred to the evaporator 8. Conversely, by virtue of the fact that the condenser 9 is thermally coupled to the air inlet duct 3, heat can be transferred from the condenser 9 to the air inlet duct 3 or to the air (fresh air) L present in the air inlet duct 3. Due to the temperatures or temperature differences on the evaporator 8 and the condenser 9, the heat pump 8 to 1 1 is operable. An operation of the heat pump 8 to 1 1 is basically well known and need not be further elaborated here. At the air inlet duct 3, an additional heater 7 is further arranged to heat the laundry W even more and to accelerate their drying. The blower 4 may alternatively be arranged on the air outlet channel 5.

An efficiency of the heat pump 8 to 1 1 depends on these temperatures or temperature differences and can be optimized by a design, for example by dimensioning the elements of the heat pump 8 to 1 1 for predetermined boundary conditions. In order to keep the efficiency high even for changing boundary conditions, especially in an operation of the exhaust air dryer 1 optionally with and without the additional heater 7, a relaxation property of the expansion valve 1 1 can be set depending on at least one associated with an activity of the auxiliary heater 7 parameters become. The expansion valve is for this purpose designed as an (adjustable) expansion valve 1 1, whose flow cross-section is adjustable in dependence on the at least one parameter. To set the expansion valve 1 1 8 and 1 1 before and after the evaporator 8 temperature sensor 12 and 13 are provided in the heat pump or refrigeration cycle of the heat pump, which sense an inlet temperature and an outlet temperature of the coolant to the evaporator 8. The temperature sensors 12 and 13 are coupled to a serving as an evaluation device controller 14, as indicated by the associated dashed lines. For example, the controller 14 may also control the operation of other components (such as the laundry drum 2 and the auxiliary heater 7). In the control device 14, the sensed by the temperature sensors 12 and 13 sensor signals or temperature values are linked to a temperature difference.

The control device 14 thus monitors the temperature difference and can continuously adjust the flow cross-section of the expansion valve 11 as a function of the temperature difference, e.g. proportional to the temperature difference. In particular, the flow cross section may be increased with increasing temperature difference and reduced with decreasing temperature difference. In addition, the flow cross-section may assume a smallest (but finite) value if the temperature difference when the auxiliary heater 7 is switched off reaches or falls below a lower threshold value. Also, the flow cross-section may assume a maximum value, if the temperature difference reaches or exceeds an upper threshold value when the auxiliary heater 7 is operated at maximum power. By adjusting the flow cross section, the heat pump 8 to 1 1 with high accuracy to the operation of the exhaust air dryer 1 with and without additional heater 7 adapted, even if a power of the auxiliary heater 7 is variable.

2 shows a sketch of an exhaust air drying device 21 according to a second embodiment. The exhaust air dryer 21 is similar to the exhaust air dryer 1, except that now the flow cross-section of the expansion valve 1 1 in response to a current heating power of the auxiliary heater 7 is adjustable. The current heating power can be sensed by means of a current sensor 22 or otherwise, for example indirectly, detected or calculated. In particular, can the flow cross-section of the expansion valve 1 1 increases with increasing heating power and be reduced with decreasing heating power.

3 shows a sketch of an exhaust air drying device 31 according to a third embodiment. The exhaust air dryer 21 is similar to the exhaust air dryer 1 formed, but now the flow diameter of the expansion valve 1 1 is reduced or narrowed at a deactivated auxiliary heater 7 to a smallest flow area (first operating position) and at a connected auxiliary heater 7 to a largest Flow cross section is increased or expanded (second operating position). The exhaust air drying device 31 does not need any sensors for this, but likes the on state ("on" or "off") of the auxiliary heater 7, e.g. by means of the controller 14, e.g. by occupying certain flags or signal levels. This adaptation of the heat pump 8 to 1 1 is particularly advantageous applicable if the auxiliary heater 7 only on and off, but their heating power is not variably adjustable.

In another variant of an exhaust air drying apparatus covered by FIG. 3, the flow diameter of the expansion valve 11 (in particular stepwise) may be set as a function of a setpoint value of the heating output of the additional heating 7 (in particular, can be changed stepwise). Here, too, can be dispensed with a sensor, since the desired value (in the present example, as an absolute value or as a relative value (eg as a heating level)) is already known and can be stored for example in the control device 14. 4 shows a sketch of an exhaust air drying device 41 according to a fourth embodiment. The exhaust air drying device 41 is similar to the exhaust air dryer 1 constructed, but now has a group of four fluidly connected in parallel capillaries 42a-d as a relaxation device, of which three capillary 42b-e by means of the control device 14 are either obvious and closed. The capillary 42a, however, has a fixed flow cross-section. As a result, a flow cross-section of the expansion device 42a-d is adjustable in four stages here. The exhaust air drying device 41 is also able to monitor the temperature difference at the evaporator 8 and at least one previously closed capillary 42b-d to open with increasing temperature difference and to close at sinking temperature difference at least one previously opened capillary 42b-d. In particular, to open or close one of the capillaries 42b-d, an associated threshold value of the temperature difference may have been reached or exceeded or fallen short of.

Of course, the present invention is not limited to the embodiments shown.

Thus, the exhaust air dryer 41 may adjust the capillary 42a-d also dependent on a stably adjustable setpoint heating power, wherein the number of possible setpoints of the heating power (including zero for a disabled additional heater 7) preferably corresponds to the number of capillary 42a-d. Each setpoint can then be assigned a specific number of open capillaries.

Even otherwise, features of different embodiments and variants can be combined or alternatively used.

LIST OF REFERENCE NUMBERS

1 exhaust air dryer

2 laundry drum

3 air intake duct

4 fans

5 air outlet duct

7 additional heating

8 evaporator

9 liquefier

10 compressors

1 1 expansion valve

12 temperature sensors

13 temperature sensors

14 control device

21 Extract air dryer

22 current sensor

31 Extract air dryer

41 Exhaust air dryer

42a-d capillary

A outdoor space

L air

W laundry

Claims

claims

Exhaust air-drying machine (1; 21; 31; 41), comprising

an air inlet duct (3) leading from outside (A) to a heatable laundry treatment room (2),

an air outlet duct (5) leading from the laundry treatment room (2) to the outside (A),

a heat recovery unit (8-1 1, 8-10, 42a-d) for transferring heat from the air outlet passage (5) to the air inlet passage (3) and an auxiliary heater (7) disposed at the air inlet passage (3);

in which

the heat recovery unit (8-1 1, 8-10, 42a-d) is a heat pump having an evaporator (8), a condenser (9), a compressor (10) and a depressurizer (1 1, 42a-d) the condenser (9) is thermally coupled to the air inlet duct (3) and the evaporator (8) is thermally coupled to the air outlet duct (5), as well as

a relaxation characteristic of the expansion device (1 1; 42a-d) is adjustable as a function of at least one parameter related to an activity of the additional heater (7).

Exhaust air-drying device (21) according to claim 1, wherein the relaxation characteristic of the expansion device (1 1) in dependence on at least one operating parameter of the auxiliary heater (7) is adjustable.

Exhaust air-drying machine (21) according to claim 2, wherein the relaxation property of the expansion device (1 1) in dependence on a current heating power of the auxiliary heater (7) is adjustable.

Exhaust air-drying machine (31) according to claim 2, wherein the relaxation property of the expansion device (1 1) in response to a switch-on state of the auxiliary heater (7) is adjustable.

5. exhaust air dryer (1; 21; 31) according to one of the preceding claims, wherein the expansion device is an expansion valve (1 1) and a flow cross-section of the expansion valve (1 1) in response to the at least one parameter is adjustable.

6. exhaust air dryer (41) one of the preceding claims, wherein the expansion device (42a-d) comprises a group of fluidly connected in parallel capillary (42a-d), of which at least one capillary (42b-d) in dependence on the at least one Parameter is either obvious and lockable.

7. exhaust air drying device (31) according to any one of the preceding claims, wherein the expansion device (1 1) is switchable between a first operating position and a second operating position.

8. exhaust air dryer (1; 21; 31; 41) according to one of the preceding claims, wherein the expansion device (1 1; 42a-d) is multi-stage or continuously adjustable.

9. exhaust air drying device (1; 41) according to one of the preceding claims, wherein the relaxation property of the expansion device (1 1; 42a-d) in response to a temperature difference and / or a pressure difference, in particular at the evaporator (8) is adjustable ,

10. A method for operating an exhaust air dryer (1; 21; 31; 41) with a compression heat pump (8-1 1) with a relaxation device (1 1) and with an auxiliary heater (7), the method comprising at least the following steps :

(A) monitoring at least one associated with an activity of the additional heating (7) parameter, in particular operating parameters, and

(B) changing a relaxation characteristic of the expansion device (1 1;

42a-d) as a function of the at least one parameter.

The method of claim 10, wherein the expansion device (11) is an expansion valve and the method comprises at least the following steps:

(a) monitoring an on state of a booster heater (7) and

(B) extending a flow diameter of the expansion valve (1 1) with a connected auxiliary heater (7) and narrowing the flow diameter of the expansion valve (1 1) with an off additional heater (7).

(a) monitoring a temperature difference and / or a pressure difference, in particular at the evaporator (8);

(B) expanding a flow diameter of the expansion valve (1 1) with increasing temperature difference and / or pressure difference and

(c) reducing the flow diameter of the expansion valve (1 1) with decreasing temperature difference and / or pressure difference.

The method of claim 10, wherein the expansion means comprises a set of fluidically coupled capillaries (42a-d), at least one capillary (42b-d) being selectively open and closed depending on the at least one parameter, and the method at least the following Steps:

(a) monitor a heating power of the auxiliary heater (7) and

(B) opening at least one previously closed capillary (42b-d) with increasing heating power and

(C) closing at least one previously opened capillary (42b-d) with decreasing heating power.

14. The method of claim 10, wherein the expansion device comprises a group of fluidly connected parallel capillary (42a-d), of which at least one capillary (42b-d) depending on the at least one parameter is optionally visible and closable, and the method at least the following steps:

(a) monitoring a temperature difference and / or a pressure difference, in particular at the evaporator (8), and

(B) opening at least one previously closed capillary (42b-d) with increasing temperature difference and / or pressure difference and

(c) closing at least one previously opened capillary (42b-d) with decreasing temperature difference and / or pressure difference.