EP2140062B1 - Method for operating a condenser tumble-dryer comprising a thermal pump and a condenser tumble dryer that is suitable for said method - Google Patents

Abstract

The invention relates to a method for operating a condenser tumble dryer (1) with a drying chamber (3) for the objects to be dried, a process air circuit (2), in which a heating element (18) for heating the process air is situated and heated process air is conducted over the items to be dried using a fan (19), a heat pump circuit (13, 14, 15) comprising an evaporator (13), a compressor (14) and a condenser (15), and sensors (22, 23) for determining the humidity in the objects to be dried. In said method, the humidity is determined and the process air is heated by the condenser (15) until a predetermined value (F) for the humidity ranges between 0 % and 12 %. If the humidity drops below the predetermined value (F), the heating element (18) is activated and operated in such a way that over a period of at least 5 minutes the air temperature in the drying chamber reaches at least 70°C. The invention also relates to a condenser tumble dryer (1) that is particularly suitable for said method.

Description

The invention relates to a method for operating a condensation dryer with a drying chamber for the objects to be dried, a process air circuit in which there is a heater for heating the process air and the heated process air is guided by means of a blower over the objects to be dried, a heat pump cycle with a Evaporator, a compressor and a condenser, and sensors for determining the humidity of the objects to be dried, as well as a suitable condensation dryer (see, for example, the document DE-A-3 113 471 ). The method is suitable for disinfecting the articles, which are in particular laundry items.

Clothes dryers, whose operation is based on the condensation of the evaporated by means of warm process air moisture of the laundry from the process air discharged from the laundry - so-called condensation dryer - need no exhaust hose and are very popular because it uses in an internal bathroom or a laundry room of a larger residential complex can be. This applies both to specially designed for drying laundry clothes dryer as well as for so-called washer-dryer, so devices that both wash clothes and can dry. Any subsequent reference to a "tumble dryer" or "condenser dryer" therefore applies to both a drying and a washing and drying device.

In a condensation dryer air (so-called process air) is passed through a fan via a heater in a wet laundry containing drum as a drying chamber. The hot air absorbs moisture from the laundry to be dried. After passing through the drum, the now moist process air is directed into a heat exchanger, which is usually preceded by a lint filter.

In the heat exchanger, the moist process air is cooled, for example, by a separately guided cooling air flow, so that the moisture contained in the moist process air condenses. The water thus accumulated is then generally collected in a suitable container, and the cooled and dried air is returned to the heater and then to the drum.

This drying process is very energy-intensive, since the heat extracted during the cooling of the process air in the heat exchanger is lost to the process, at least when this heat is dissipated in a cooling air flow. By using a heat pump, this energy loss can be significantly reduced. As a heat pump is the well-known "compressor heat pump", in which circulates a cyclically to be evaporated and liquefied working or refrigerant and which is widely used for cooling or air conditioning, are used. In a condensation dryer equipped with such a heat pump, the cooling of the warm, moisture-laden process air essentially takes place in a first heat exchanger of the heat pump, in particular an evaporator, where the heat transferred is used to evaporate a refrigerant used in the heat pump. Such vaporized due to the heating refrigerant is fed via a compressor to a second heat exchanger, in the given case and hereinafter also called "condenser", the heat pump, where due to the condensation of the gaseous refrigerant heat is released, which in turn for heating the process air before entering the Drum is used. The liquefied refrigerant passes through a throttle, which reduces its pressure, back to the evaporator to evaporate there, with renewed absorption of heat from the process air.

In a condensation dryer with a compressor heat pump occurs due to the process in the drying chamber a temperature of only 50 ° C to 60 ° C, which is generally insufficient for a disinfection of laundry. The disinfecting in the condenser dryer, in particular the disinfection of laundry, but would in principle be easily possible if the drying chamber and thus the laundry contained in it would be kept for a sufficiently long period of time at a temperature of about 70 ° C.

The object of the invention is therefore to provide a method for operating a condensation dryer of the type specified above, in particular a condensation dryer with a heat pump, with which a disinfection at elevated temperature can be performed. Also, a particularly suitable for this process condensation dryer should be specified.

The solution of this object is achieved according to this invention by a method for operating a condensation dryer with the features of the independent Patent claim 1 and a particularly suitable for this purpose condensation dryer with the features of independent claim 8.

Preferred embodiments of the method according to the invention and preferred embodiments of the condensation dryer are listed in the dependent claims. Here, preferred embodiments of the condensation dryer correspond mutatis mutandis preferred embodiments of the method and vice versa, even if this is not particularly noted.

An object of the invention is thus a method for operating a condensation dryer with a drying chamber for the objects to be dried, a process air circuit in which there is a heater for heating the process air and heated process air is guided by means of a blower over the objects to be dried, and a Heat pump circuit comprising an evaporator, a compressor and a condenser, and a sensor arrangement for determining a moisture in the objects to be dried, wherein the humidity is determined and up to a predetermined value (F) of the humidity in the range of 0% to 12%, preferably 3% to 5%, the process air through the condenser (15), preferably exclusively by this, is heated and after falling below the predetermined value (F) the heater (18) is operated in such a way that over a period of at least 5 minutes , preferably at most 40 minutes, more preferably over a period dream of 10 to 15 minutes, in the drying chamber an air temperature of at least 70 ° C is.

In a preferred embodiment of the method according to the invention, the heat pump circuit is switched off before reaching an air temperature of 65 ° C. Particularly preferably, the heat pump cycle is switched off when switching on the heater.

It is also preferred if, when the heat pump cycle is switched off, an air-air heat exchanger optionally present in the condensation dryer is switched on. This also allows for a switched-off heat pump cycle (ie deactivated evaporator) a condensation of still in the objects to be dried, especially laundry, existing moisture.

Preferably, the heater is operated so that in the drying chamber, an air temperature in the range of 70 to 80 ° C consists.

The invention also relates to a condensation dryer for carrying out the method according to the invention with a drying chamber for the objects to be dried, a process air circuit in which there is a heater for heating the process air and heated process air by means of a blower over the objects to be dried, a heat pump cycle with an evaporator, a compressor and a condenser, and a sensor arrangement for determining the moisture in the objects to be dried, the condensation dryer having a control unit for switching on the heating when a predetermined value (F) of the humidity in the range of 0 to 12% is reached. , Preferably 3 to 5%, and is equipped to shut down a heat pump cycle.

The condensation dryer according to the invention is equipped with a sensor arrangement comprising at least one sensor for determining the moisture in the objects to be dried. The sensor assembly is generally located in the drying chamber.

As sensors, for example, two electrodes can be introduced into the drying chamber, usually a laundry drum, in such a way that they contact the wet items of laundry. An electrical voltage is applied to the electrodes and the current intensity or the electrical conductance between the electrodes is measured. If the measured current value or the measured electrical conductance falls below a predetermined threshold value, which corresponds to a predetermined humidity (F), this can be concluded by reaching the end of a normal drying phase, to which the generally to a disinfection of the dry material (laundry) leading inventive method connects. In general, then via a control unit, the switching on of the heater and switching off the heat pump cycle is effected. The disinfection of the dry material can be carried out via a separate program or as an integrated module at the end of a drying program.

In a preferred embodiment, the condensation dryer according to the invention has an air-to-air heat exchanger, and a control unit, upon reaching a predetermined value (F) of the humidity in the range of 0 to 12% causes the switching of the air-to-air heat exchanger.

In a preferred embodiment of the condensation dryer, the air-air heat exchanger can be removed. This is particularly advantageous because a removable heat exchanger can be easily cleaned of lint.

The refrigerant used in the heat pump cycle is preferably selected from the group consisting of a butane / isopropane mixture, carbon dioxide and fluorocarbon compounds. As such, these agents are known as refrigerants.

The heat pump in the condensation dryer according to the invention has, in addition to evaporator, condenser and compressor in the flow direction of the refrigerant between the condenser and the evaporator, an expansion valve (also referred to as throttle valve or throttle) on.

The refrigerant used in the heat pump preferably circulates in the heat pump circuit with a turbulent flow. A turbulent flow may be adjusted by a suitable structural design of a flow channel and / or by suitable drive means (e.g., compressor).

The temperature of the refrigerant of the heat pump, in particular in the condenser, according to the invention is generally kept within the permissible range via the control of heat pump, heating and air-air heat exchanger.

According to the invention, it is preferred if process air and cooling air or process air and refrigerant in the heat pump are each passed through the corresponding heat exchangers in a crossflow or countercurrent process.

The heater used in the condensation dryer according to the invention is preferably a two-stage heater. The heating power of the heater is preferably in the range of 1000 to 2500 watts. especially between 1300 and 2000 watts.

As the degree of drying of the objects to be dried in the condenser dryer decreases the energy required for drying, it is appropriate to regulate the heating accordingly, that is. As the degree of dryness progresses, their heating power is reduced to maintain a balance between the supplied and necessary drying energy.

To control the temperature of the refrigerant or heat pump and the temperature of the process air generally known to those skilled in temperature sensors in the heat pump circuit and / or in the process air circuit are used.

The invention has the advantage that an energetically favorable drying process is connected with the disinfection of the objects to be dried or dried. Moreover, the disinfection can be achieved in a particularly gentle way. In addition, the heat pump is spared.

Further details of the invention will become apparent from the following description of a non-limiting embodiment of a condensation dryer and a process using this condensation dryer. It is referred to FIG. 1 ,

FIG. 1 shows a vertically cut condensation dryer (hereinafter abbreviated to "dryer") according to an embodiment of the invention with a heat pump circuit, a heater and an air-to-air heat exchanger.

The in FIG. 1 shown dryer 1 has a drum rotatable about a horizontal axis as a drying chamber 3, are mounted within which driver 4 for moving laundry during a drum rotation. Process air is conducted by means of a blower 19 via a heater 18, by a drum 3, an air-air heat exchanger 11, 12 and a heat pump 13, 14, 15 in an air channel 2 in a closed circuit (process air circuit 2). After passage through the drum 3, the moist, warm process air is cooled and reheated after condensation of moisture contained in the process air. In this case, heated air from the heater 18, ie from the side of the drum 3 opposite a dryer door 5, is passed through the perforated bottom into the drum 3, where it comes into contact with the laundry to be dried and flows through the filling opening of the drum 3 to a lint filter 6 within a drying door closing the filling opening 5. Subsequently, the air flow is deflected in the dryer door 5 down and passed from the air duct 2 to the air-air heat exchanger 11, 12. As a result of cooling, the moisture absorbed by the process air from the items of laundry condenses there and is absorbed in a FIG. 1 dashed drawn condensate tank 21 collected from which they can be disposed of. Subsequently, the somewhat cooled process air to the evaporator 13 of a heat pump 13, 14, 15 out, where it is further cooled. The refrigerant of the heat pump evaporated in the evaporator 13 is conducted to the condenser 15 via a compressor 14. In condenser 15, the refrigerant liquefies with heat being released to the process air. The now in liquid form refrigerant is then via a throttle valve 17 again led to the evaporator 13, whereby the refrigerant circuit is closed. The cooling air is taken from the room air and, after passing through the air-to-air heat exchanger 11, 12 again supplied to the room air. 20 means a fan in the cooling air passage 12 of the air-to-air heat exchanger.

Sensors 22 and 23 are used to determine the moisture in the objects to be dried, in particular laundry. The signals of the sensors are supplied to a control device 16, which in turn is connected via lines 10 to the heater 18, the heat pump circuit 13, 14, 15 and the air-air cooler 11, 12. The control device 16 causes in response to a predetermined humidity (F) and the humidity measured by the sensors 22 and 23, a connection of the heater 18, a shutdown of the heat pump circuit 13, 14, 15 and a connection of the air-air cooler 11,12 ,

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 condensation dryer can be controlled by the user via an operating unit 9.

A drying process with disinfection is commonly carried out on appropriate selection of the control unit 9. In this case, the presence of the conventional heater 18 in addition to the heat pump 13, 14, 15 is utilized. First, the laundry items loaded in the drum 3 for drying are conventionally dried using the heat pump 13, 14, 15 in an energy-saving manner. For the disinfection, the heat pump 13, 14, 15 can not be used because they can not work at the high temperatures of the process air, which are required for disinfecting, or only poorly. Consequently, it is turned off, and only the conventional heater 18 is used. Since the laundry items are already largely dried, their heat absorption capacity is relatively low, and the thermal performance of the heater 18 is sufficient to achieve the necessary high temperatures. Optionally, in addition to the deactivated heat pump 13, 14, 15, the air-air cooler 11, 12 are deactivated to keep losses of heat low. Then the disinfection takes place by appropriate heating of the laundry items. For a subsequent rapid cooling of the laundry items may optionally be the air-to-air cooler 11, 12 are used.

Overall, the invention provides a new, useful and useful application option for a dryer of the hybrid genus.

Claims (10)

1. Method of operating a condensation dryer (1) with a drying chamber (3) for the articles to be dried, a process air circuit (2) in which a heating means (18) for heating the process air is located and heated process air is conducted by means of a fan (19) over the articles to be dried and a heat pump circuit (13, 14, 15) with an evaporator (13), a compressor (14) and a condenser (15), and a sensor arrangement (22, 23) for determining moisture in the articles to be dried, characterised in that the moisture is determined and up to a predetermined value (F) of the moisture in the range of 0% to 12% the process air is heated by the condenser (15) and after the predetermined value (F) is fallen below the heating means (18) is switched off and operated in such a way that an air temperature of at least 70° C is present over a time period of at least 5 minutes.
2. Method according to claim 1, characterised in that the heat pump circuit (13, 14, 15) is switched off before reaching an air temperature of 65° C.
3. Method according to claim 1 or 2, characterised in that the heat pump circuit (13, 14, 15) is switched off when the heating means (18) is switched on.
4. Method according to any one of claims 1 to 3, characterised in that when the heat pump circuit (13, 14, 15) is switched off an air/air heat exchanger (11, 12) is switched on.
5. Method according to any one of claims 1 to 4, characterised in that the predetermined value (F) of the moisture lies in the region of 3 to 5%.
6. Method according to any one of claims 1 to 5, characterised in that the time period is 10 to 15 minutes.
7. Method according to any one of claims 1 to 6, characterised in that an air temperature in the region of 70 to 80° C is present.
8. Condensation dryer (1) for performance of the method according to any one of claims 1 to 7, with a drying chamber (3) for the articles to be dried, a process air circuit (2) in which a heating means (18) for heating the process air, which enables heating of the dryer to a temperature of at least 70° C, is disposed and heated process air can be conducted by means of a fan (19) over the articles to be dried, a heat pump circuit (13, 14, 15) with an evaporator (13), a compressor (14) and a condenser (15), and a sensor arrangement (22, 23) for determining moisture in the articles to be dried, characterised in that the condensation dryer (1) is equipped with a control unit (16) for switching on the heating means (18) on attainment of a predetermined value (F) of the moisture in the range of 0 to 12% and for switching off a heat pump circuit (13, 14, 15).
9. Condensation dryer according to claim 8, characterised in that it comprises an air/air heat exchanger (11, 12) and the control unit (16) on attainment of a predetermined value (F) of the moisture in the range of 0 to 12% causes switching-on of the air/air heat exchanger (11, 12).
10. Condensation dryer according to claim 9, characterised in that the air/air heat exchanger (11, 12) is removable.

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