Vented laundry drying having an additional heater and heat exchanger unit

Abstract

A vented laundry dryer has an air inlet duct, an air outlet duct, a heat recovery system for transferring heat from the air outlet duct to the air inlet duct, and an additional heater. The heat recovery system has an evaporator, a liquefier, a condenser, and a relaxation unit, wherein the liquefier is thermally coupled to the air inlet duct, and the evaporator is thermally coupled to the air outlet duct. A relaxation property of the relaxation unit can be adjusted depending on at least one parameter that is connected to an activity of the additional heater. A method for operating a vented dryer having an additional heater and a heat pump having a relaxation unit, monitoring at least one parameter connected to an activity of the additional heater and changing a relaxation property of the relaxation unit depending on the at least one parameter.

Claims

1. A vented laundry dryer, the vented laundry dryer comprising: an air inlet duct, which passes from the outside to a heatable laundry treatment compartment, an air outlet duct, which passes from the laundry treatment compartment to the outside, a heat recovery system for transferring heat from the air outlet duct to the air inlet duct and an additional heater disposed on the air inlet duct, wherein the heat recovery system is a heat pump with an evaporator, a condenser, a compressor and a relaxation unit, the condenser being thermally coupled to the air inlet duct and the evaporator being thermally coupled to the air outlet duct, and a relaxation property of the relaxation unit is set as a function of at least one parameter associated with an activity of the additional heater.

2. The vented laundry dryer as claimed in claim 1, wherein the relaxation property of the relaxation unit is set as a function of at least one operating parameter of the additional heater.

3. The vented laundry dryer as claimed in claim 2, wherein the relaxation property of the relaxation unit is set as a function of a current heating power of the additional heater.

4. The vented laundry dryer as claimed in claim 2, wherein the relaxation property of the relaxation unit is set as a function of an activation state of the additional heater.

5. The vented laundry dryer as claimed in claim 1, wherein the relaxation unit is an expansion valve and a flow cross section of the expansion valve is set as a function of the at least one parameter.

6. The vented laundry dryer as claimed in claim 1, wherein the relaxation unit has a group of capillaries connected fluidically in a parallel manner, of which at least one capillary is opened and closed as a function of the at least one parameter of the additional heater.

7. The vented laundry dryer as claimed in claim 1, wherein the relaxation unit is switched between a first operating position and a second operating position of the additional heater.

8. The vented laundry dryer as claimed in claim 1, wherein the relaxation unit is set in multiple stages or continuously.

9. The vented laundry dryer as claimed in claim 1, wherein the relaxation property of the relaxation unit is set as a function of a temperature difference and/or a pressure difference.

10. The vented laundry dryer as claimed in claim 9, wherein the relaxation property of the relaxation unit is set as a function of a temperature difference and/or a pressure at the evaporator.

11. A method for operating the vented laundry dryer as claimed in claim 1, the method comprising: (a) monitoring at least one parameter associated with an activity of the additional heater, and (b) changing a relaxation property of the relaxation unit as a function of the at least one parameter.

12. The method as claimed in claim 11, wherein the relaxation unit is an expansion valve, the method further comprising: (a) monitoring an activation state of the additional heater, and (b) widening a flow diameter of the expansion valve with the additional heater connected and narrowing the flow diameter of the expansion valve with the additional heater deactivated.

13. The method as claimed in claim 11, wherein the relaxation unit is an expansion valve, the method further comprising: (a) monitoring a temperature difference and/or a pressure difference, (b) widening a flow diameter of the expansion valve as the temperature difference and/or pressure difference rises, and (c) reducing the flow diameter of the expansion valve as the temperature difference and/or pressure difference drops.

14. The method as claimed in claim 13, wherein the temperature difference and/or a pressure difference is monitored at the evaporator.

15. The method as claimed in claim 11, wherein the relaxation unit has a group of capillaries connected fluidically in a parallel manner, of which at least one capillary is opened and closed optionally as a function of the at least one parameter, the method further comprising: (a) monitoring a heating power of the additional heater, (b) opening at least one previously closed capillary as the heating power rises, and (c) closing at least one previously opened capillary as the heating power drops.

16. The method as claimed in claim 11, wherein the relaxation unit has a group of capillaries connected fluidically in a parallel manner, of which at least one capillary is opened and closed optionally as a function of the at least one parameter, the method further comprising: (a) monitoring a temperature difference and/or a pressure difference, (b) opening at least one previously closed capillary as the temperature difference and/or pressure difference rises, and (c) closing at least one previously opened capillary as the temperature difference and/or pressure difference drops.

17. The method as claimed in claim 16, wherein the temperature difference and/or a pressure difference is monitored at the evaporator.

18. The method as claimed in claim 11, wherein the at least one parameter is an operating parameter.

Description

(1) The invention is described schematically in more detail based on exemplary embodiments in the figures below. Identical elements or those with the same effect can be shown with identical reference characters for greater clarity.

(2) FIG. 1 shows a sketch of a vented laundry dryer according to a first embodiment;

(3) FIG. 2 shows a sketch of a vented laundry dryer according to a second embodiment;

(4) FIG. 3 shows a sketch of a vented laundry dryer according to a third embodiment; and

(5) FIG. 4 shows a sketch of a vented laundry dryer according to a fourth embodiment.

(6) FIG. 1 shows a sketch of a vented laundry dryer 1 according to a first embodiment. The vented laundry dryer 1 is a front loader with a rotatable laundry drum 2 as its laundry treatment compartment. An air inlet duct 3 passes from an outer compartment A to the laundry drum 2. On the air inlet duct 3 is a fan 4 for conveying air L (still in the form of fresh air at this point) from the outer compartment A into the laundry drum 2 and on (as exhaust air) from the laundry drum 2 by way of an air outlet duct 5 back into the outer compartment A. As it flows through the laundry drum 2 the air L absorbs moisture from laundry W contained therein, in order to dry the laundry W.

(7) To heat the air L in the air inlet duct 3 in an energy-saving manner the vented laundry dryer 1 has a compression heat pump 8 to 11 with an evaporator 8, a condenser 9, a compressor 10 and a relaxation unit in the form of an expansion valve 11. 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. This causes heat to be extracted from the air outlet duct 5 or the hot moist air (exhaust air) L present in the air outlet duct 5 and transferred to the evaporator 8. Conversely, because 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. The temperatures or temperature differences at the evaporator 8 and condenser 9 allow the heat pump 8 to 11 to operate. A mode of operation of the heat pump 8 to 11 is well known in principle and does not have to be set out further here.

(8) An additional heater 7 is also disposed on the air inlet duct 3 to heat the laundry W further and accelerate its drying. The fan 4 can alternatively be disposed on the air outlet duct 5.

(9) The efficiency of the heat pump 8 to 11 is a function of these temperatures or temperature differences and can be optimized by design, for example by dimensioning the elements of the heat pump 8 to 11 for predetermined basic conditions. In order to be able to maintain a high level of efficiency even with changing basic conditions, in particular when operating the vented laundry dryer 1 optionally with and without the additional heater 7, a relaxation property of the expansion valve 11 can be set as a function of at least one parameter associated with an activity of the additional heater 7. To this end the expansion valve is configured as a (settable) expansion valve 11, the flow cross section of which can be set as a function of the at least one parameter.

(10) Provided in the heat pump or cooling circuit of the heat pump 8 to 11 upstream and downstream of the evaporator 8 to set the expansion valve 11 are temperature sensors 12 and 13, which detect an entry temperature or exit temperature of the coolant at the evaporator 8. The temperature sensors 12 and 13 are coupled to a control facility 14 that also serves as an evaluation apparatus, as shown by the associated broken lines. The control facility 14 can also control for example the operation of other components (such as the laundry drum 2 and additional heater 7). The sensor signals or temperature values detected by the temperature sensors 12 and 13 are linked to a temperature difference in the control facility 14.

(11) The control facility 14 therefore monitors the temperature difference and can set the flow cross section of the expansion valve 11 continuously as a function of the temperature difference, e.g. in proportion to the temperature difference. In particular the flow cross section may be enlarged as the temperature difference rises and reduced as the temperature difference drops. The flow cross section may also assume a smallest (although finite) value, if the temperature difference reaches or drops below a lower threshold value when the additional heater 7 is deactivated. Also the flow cross section may assume a greatest value, if the temperature difference reaches or exceeds an upper threshold value when the additional heater 7 is operated at maximum power. Setting the flow cross section adjusts the heat pump 8 to 11 to the operation of the vented laundry dryer 1 in a very accurate manner with and without the additional heater 7, even if the power of the additional heater 7 is variable.

(12) FIG. 2 shows a sketch of a vented laundry dryer 21 according to a second embodiment. The vented laundry dryer 21 is configured in a similar manner to the vented laundry dryer 1 but now the flow cross section of the expansion valve 11 can be set as a function of a current heating power of the additional heater 7. The current heating power can be detected by means of a current sensor 22 or can be captured or calculated in another manner, for example indirectly. In particular the flow cross section of the expansion valve 11 can be enlarged as the heating power increases and reduced as the heating power drops.

(13) FIG. 3 shows a sketch of a vented laundry dryer 31 according to a third embodiment. The vented laundry dryer 21 is configured in a similar manner to the vented laundry dryer 1 but now the flow diameter of the expansion valve 11 is reduced or narrowed to a smallest flow cross section when an additional heater 7 is deactivated (first operating position) and is enlarged or widened to a greatest flow cross section when an additional heater 7 is connected (second operating position). The vented laundry dryer 31 does not require a sensor system for this but may identify the activation state (on or off) of the additional heater 7 for example by means of the control facility 14, e.g. by the use of certain flags or signal levels. This adjustment of the heat pump 8 to 11 can be applied particularly advantageously, if the additional heater 7 can only be switched on and off but its heating power cannot be set in a variable manner.

(14) In another variant of a vented laundry dryer covered by FIG. 3 the flow diameter of the expansion valve 11 may be set (in particular in stages) as a function of a setpoint value (that can be changed in particular in stages) of the heating power of the additional heater 7. There is no need for a sensor system here either, as the setpoint value (in the present instance for example in the form of an absolute value or a relative value (e.g. as a heating stage) is already known and can be stored for example in the control facility 14.

(15) FIG. 4 shows a sketch of a vented laundry dryer 41 according to a fourth embodiment. The vented laundry dryer 41 is similar in structure to the vented laundry dryer 1 but now has a relaxation unit in the form of a group of four capillaries 42a-d connected fluidically in a parallel manner, of which three capillaries 42b-e can be opened and closed optionally by means of the control facility 14. The capillary 42a in contrast has a fixed flow cross section. This allows the flow cross section of the relaxation unit 42a-d to be set in four stages here.

(16) The vented laundry dryer 41 is also able to monitor the temperature difference at the evaporator 8 and to open at least one previously closed capillary 42b-d if the temperature difference rises and to close at least one previously opened capillary 42b-d if the temperature difference drops. In particular the temperature difference may reach or rise above or drop below an associated threshold value to open or close one of the capillaries 42b-d.

(17) Of course the present invention is not limited to the illustrated exemplary embodiments.

(18) The vented laundry dryer 41 may therefore also set the capillaries 42a-d as a function of a heating power setpoint value that can be set in stages, the number of possible setpoint values for the heating power (including zero for a deactivated additional heater 7) preferably corresponding to the number of capillaries 42a-d. A certain number of open capillaries can then be assigned to each setpoint value.

(19) Features of different exemplary embodiments and variants can also be combined with one another or used as alternatives.

LIST OF REFERENCE CHARACTERS

(20) 1 Vented laundry dryer

(21) 2 Laundry drum

(22) 3 Air inlet duct

(23) 4 Fan

(24) 5 Air outlet duct

(25) 7 Additional heater

(26) 8 Evaporator

(27) 9 Condenser

(28) 10 Compressor

(29) 11 Expansion valve

(30) 12 Temperature sensor

(31) 13 Temperature sensor

(32) 14 Control facility

(33) 21 Vented laundry dryer

(34) 22 Current sensor

(35) 31 Vented laundry dryer

(36) 41 Vented laundry dryer

(37) 42a-d Capillaries

(38) A Outer compartment

(39) L Air

(40) W Laundry