EP2055826A1 - Exhaust air dryer with heat recovery and condensation bath and method for its operation - Google Patents

Abstract

The dryer (1) has an air supply duct (2) for supplying air, and heat pumps (12, 18) for heating supply air and the heated supply air, where the air are supplied over articles to be dried using a blower (19). An air exhaust duct (16) and an engine (21) drive a drying chamber (3), a heat exchanger (14) of the exhaust duct and a condensate tub (20) that is arranged underneath the exchanger. An opening (22), a blower (23) and an inlet (25) dissipate warm air from a housing inner area (27) to the tub, where the opening enables influence of air present over the tub based on suction effect. An independent claim is also included for a method for operating an exhaust air dryer with a drying chamber for drying articles.

Description

The invention relates to an exhaust air dryer with heat recovery and condensate tray and a preferred method for its operation.

In general, tumble dryers are operated as exhaust air or condensation dryers. Condensation dryers, whose operation is based on the condensation of moisture evaporated from the laundry by means of warm process air, do not require an exhaust hose and allow energy recovery from the heated process air, for example by using a heat pump. However, condensation dryers generally require that the accumulated condensate be collected and either pumped off or disposed of by manually emptying catch containers.

In the case of exhaust air dryers, on the other hand, generally the air laden with moisture after passage through a laundry drum is passed out of the dryer, wherein heat recovery does not take place. However, exhaust air dryers with heat recovery are known.

The DE 30 00 865 A1 discloses a clothes dryer with heat recovery. The tumble dryer consists of a container receiving and moving the laundry, into which a supply air flow heated by a heating element opens, while the moist hot air is conducted as exhaust air via an outlet. In the supply air flow, a heat exchanger is arranged in front of the heating element, which is flowed through by the moist hot exhaust air from the container.

In the DE 40 23 000 C2 a tumble dryer is described with a heat pump circuit, in which a supply air opening is arranged in the process air channel between the condenser and the evaporator, which is closable with a controllable closure device.

In the case of exhaust air dryers with heat recovery, ambient air (of, for example, 20 ° C. and 60% relative humidity, so-called supply air) generally flows into the heat exchanger surfaces of an air-to-air heat exchanger and is cooled therefrom, leaving the drying chamber heated up warm process air. Depending on the cooling capacity or the heat exchange, condensate is produced which is collected or pumped away in a container (condensate tray). In the first case an emptying is necessary and in the second case a connection to the sewage network. The amount of accumulating condensate is a measure of the heat energy emitted in the heat exchanger and thus a measure of the improvement of energy efficiency.

Object of the present invention was to provide a vented dryer with high energy efficiency, in which it is unnecessary to pump out condensate or to empty a condensate pan.

The solution of this object is achieved according to this invention by an exhaust air dryer with the features of claim 1 and the method of claim 12.

Preferred embodiments of the exhaust air dryer according to the invention are listed in the subclaims 2 to 11. A preferred embodiment of the method according to the invention is listed in claim 13.

The invention thus relates to an exhaust air dryer with a drying chamber for objects to be dried, a supply air duct for process air in which there is a heater for heating supply air and the heated supply air (process air) can be performed by means of a first blower on the objects to be dried, an exhaust duct, a motor for driving the drying chamber, a first heat exchanger in the exhaust duct and arranged below the first heat exchanger condensate pan, wherein the exhaust air dryer has first means for discharging warm air from a motor housing comprehensive housing interior to the condensate pan and across.

The heating for heating the exhaust air (process air) may be, for example, an electrical resistance heater and / or a second heat exchanger. Preferably, both an electrical resistance heater and a second heat exchanger are used. The second heat exchanger can be an air-to-air heat exchanger, in which the warm air from the drying chamber is used for heating the process air, or the condenser of a heat pump. In general, the supply air duct and the warm air from the air intersect Drying chamber having exhaust duct or the heated refrigerant having condenser of the heat pump.

In a preferred embodiment of the invention, the exhaust air duct between the first heat exchanger and an exhaust outlet on an opening, which due to a suction effect caused by passing through the opening exhaust air (venturi effect), the entrainment (also called "entrainment") of allows air above the condensate tray. The opening is preferably located above the condensate tray.

In a further preferred embodiment, the aforesaid first means comprise a second fan (also termed an "evaporative fan") which directs the warm air from a housing interior comprising the engine to and from the condensate tray. In this case, it is again preferred that the first fan and the second fan are driven by the same motor. It is particularly preferred here that the first fan and the second fan are arranged on opposite sides of the engine. Most preferably, this motor is the motor that is also used to drive the drying chamber.

Both of the above-mentioned embodiments can be combined so that the discharge of the warm air to the condensate tray and across it is effected by cooperation of the suction produced at the opening in the exhaust air channel and the second fan.

The above-mentioned first means are, for example, an embodiment of the interior of the housing and of the air passages in the region of the engine and the supply line from the housing interior to the condensate pan, which enables effective removal of the waste heat, and finally the means for discharging the warm air, such as, for example second fan and / or a hole in the exhaust duct between the exhaust air outlet and the first heat exchanger. The aforesaid first means are preferably chosen so as to allow the discharge of warm air at a rate of 10 to 100 m ³ / hour.

The dryer according to the invention has at least one first heat exchanger, by means of which the heat contained in the exhaust air is recovered in the condensate tray with the formation of condensate.

This may be an air-to-air heat exchanger, in which the moist, hot process air from the drying chamber (drum) is used to heat supply air, which is then fed to the drying chamber.

Alternatively or as a supplement, an evaporator of a heat pump circuit can be used as the first heat exchanger. In a dryer equipped with a heat pump, the cooling of the warm, moisture-laden process air essentially takes place in the evaporator of the heat pump, where the heat transferred is used to evaporate a refrigerant used in the heat pump cycle. The refrigerant of the heat pump evaporated due to the heating is supplied via a compressor to the condenser of the heat pump, where due to the condensation of the gaseous refrigerant heat is released, which is used to heat the supply air before entering the drying chamber (drum).

In preferred embodiments of the dryer according to the invention with a heat pump, the condenser of the heat pump is in the supply air duct between the first fan and the heater or between the first fan and the supply air access.

It can also be used several heat exchangers, where each can form condensate. In such a case more than one condensate tray can be used.

The condensate tray is preferably designed so that it can hold a sufficient amount of condensate, generally at least 0.5 l. The accumulated amount of condensate and thus the predetermined capacity of the condensate tray for condensate will usually depend on the efficiency of the first heat exchanger. However, in general, with a capacity of the exhaust air dryer of 5 kg of laundry with 60% relative humidity, a capacity of at least 0.5 l will be required.

According to the invention, it is preferred that the condensate tray has second means for detecting and / or discharging a quantity of condensate exceeding a predetermined limit quantity. For example, a second container may be provided, which can catch any overflowing condensate. Alternatively or in addition to this, when the limit quantity is reached, an audible and / or visual warning indication can take place.

In a preferred embodiment of the present invention, a body having a high surface area is present in the condensate tray. This body is preferably a fleece.

The evaporation of the condensate is generally particularly effective at the beginning and towards the end of a drying process, since in both cases, the loading of the process air with moisture is relatively low.

In the event that a residual amount of condensate (liquid water) should remain in the condensate tray after completion of a drying process, the dryer according to the invention is preferably designed so that this residual condensate evaporates during the cooling of the dryer. This can be done, for example, in the embodiment with an opening between the exhaust air outlet and the first heat exchanger by the fact that in the presence of an external exhaust pipe - especially in windy weather - a small air flow in the area of the condensate tray.

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

Since, as the degree of drying of the objects to be dried in the exhaust air dryer decreases, the energy required for drying decreases, the heating is appropriately regulated, that is to say in accordance with the invention. As the degree of drying progresses, its heat output is reduced.

The invention also relates to a method for operating an exhaust air dryer with a drying chamber for objects to be dried, a supply air duct for process air, in which there is a heater for heating the supply air and the heated supply air (process air) by means of a first blower on the objects to be dried can be performed, an exhaust duct, a motor for driving the drying chamber, a first heat exchanger in the exhaust duct, arranged below the first heat exchanger condensate pan and first means for discharging warm air from the motor housing comprehensive housing interior to the condensate pan and across, wherein during operation of the exhaust air dryer in the condensate pan condensate by means of warm air, which consists of the motor housing comprehensive interior is led to the condensate pan and over this away, is evaporated and the resulting warm, moist air is led out of the exhaust air dryer.

In a preferred embodiment of the method, a second fan directs the warm air from the housing interior, which surrounds the engine, to the drain pan and over it.

The warm and humid air guided over the condensate pan can be conveyed either directly into the installation room of the dryer or mixed into the exhaust air of the dryer.

The exhaust air dryer according to the invention and the method according to the invention for its operation have the advantage that the exhaust air dryer falls into a better energy efficiency class and accumulating condensate can be transported to the outside only by removal by means of exhaust air without the need for a condensate pan or a pump to be emptied. In addition, the invention has the advantage that, according to the invention, the waste heat of the engine is dissipated. Due to the active cooling of the motor this can be made smaller in terms of laminated core and winding.

Further details of the invention will become apparent with reference to the FIGS. 1 to 3 from the following description of non-limiting embodiments of the exhaust air dryer according to the invention and the method for operating this exhaust air dryer.

FIG. 1 shows a vertically cut exhaust air dryer (hereinafter abbreviated to "dryer") according to an embodiment of the invention, in which both an opening in the exhaust duct between exhaust outlet and first heat exchanger as well as a second fan for the transport of warm air from a housing interior to the condensate pan is used.

FIG. 2 shows a section of an embodiment of an exhaust air dryer according to the invention.

Fig. 3 shows a section of a further embodiment of an exhaust air dryer according to the invention.

In the FIGS. 2 and 3 The large arrows indicate the flow direction of the exhaust air, while the small arrows indicate the flow direction of the coming from the housing interior and via the condensate tray warm air.

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. Supply air is conducted by means of a first blower 19 from the supply air inlet 11 through a supply air duct 2 via a condenser 12 of a heat pump 12,13,14,15 as a second heat exchanger and a heater 18 through the drum 3. After exiting the drum 3, the laden with moisture process air as exhaust air is further passed through an exhaust duct 16 via an evaporator 14 of a heat pump 12,13,14,15 and an exhaust outlet 17 the installation room of the dryer 1. In this case, after passing through the drum 3, the moist, warm process air is cooled and, after condensation of the moisture contained in the process air, is conducted as exhaust air into the installation space of the dryer. In this case, heated air from the heater 18, ie from the side of the drum 3 opposite a 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 closing the filling opening door 5. Subsequently, the air flow in the door 5 is deflected downward and directed from the exhaust duct 16 to the evaporator 14 of the heat pump 12,13,14,15. As a result of cooling, the moisture absorbed by the process air from the items of laundry condenses there and is collected in a condensate tray 20. The cooled and dehumidified process air leaves the exhaust air duct 16 at the exhaust air outlet 17 as exhaust air.

In this embodiment, a warm air stream, which originates from the surroundings of a motor 21 for driving the drum 3 and the first blower 19, is conducted via the feed line 25 via the condensate located in the condensate tray 20. As a result, the condensate evaporates and is continued by the warm, now humid air flow. The continuation of the warm humid air flow takes place at the in FIG. 1 shown embodiment through an opening 22 in the exhaust duct 16, which is located in the region of the condensate pan, preferably above the condensate pan. The opening 22 connects the gaseous phase on the condensate tray with the exhaust air in the exhaust duct 16 of the exhaust air dryer. The exhaust air guided through the opening 22 creates a suction (Venturi effect), which leads to entrainment of the warm, moist air above the condensate. In the embodiment of FIG. 1 is the warm air flow from the environment of the Motor 21 with the aid of a second blower 23 ("evaporation fan") through the supply line 25 via the condensate contained in the condensate tray 20 condensate. However, it is also possible to dispense with the second fan 23 or the opening 22. If the opening 22 is dispensed with, the warm, moist air resulting from the evaporation of the condensate can be separated via a separate, in FIG. 1 dashed lines, channel 24 are directed into the installation room of the dryer. It is also conceivable to combine the warm, condensate-laden air with the exhaust air in the exhaust duct 16 at a location closer to the exhaust air outlet 17. Here, "nearer point" means that the combination takes place in the exhaust duct downstream of the point at which an opening could possibly be provided for the emergence of a suction.

The moist, warm process air is led to the evaporator 14 of a heat pump 12, 13, 14, 15, where it is cooled. The refrigerant of the heat pump evaporated in the evaporator 14 is conducted to the condenser 12 via a compressor 13. In the condenser 12, the refrigerant liquefies with release of heat to the entering through the Zulufteingang 11 supply air in the supply air channel 2. The now in liquid form refrigerant is again passed through a throttle valve 15 to the evaporator 14, whereby the refrigerant circuit is closed.

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 exhaust air dryer via a control device 10, which can be controlled by the user via an operating unit 9.

At the in FIG. 1 In the embodiment shown, the first blower 19, the second blower 23 and the drum 3 are driven by the same motor 21, with the first blower 19 and the second blower 23 on opposite sides of the engine 21.

At the in Fig. 1 In the embodiment shown, a body 26 with a large surface, preferably a fleece, is located in the condensate tray 20. The body 26 has the task to assist by distribution of the condensate over a large area of its evaporation.

FIG. 2 shows a section of a further embodiment of an exhaust air dryer according to the invention. In this embodiment, warm air from the housing interior, in particular the environment of the motor 21, not shown here by means of a second fan 23 ("evaporation fan") in a feed line 25 to the condensate pan 20, in which the condensate collected at the first heat exchanger 14 is collected , The condensate can easily evaporate due to the warm air flow. The evaporated condensate is carried by the warm air flow and can - in FIG. 2 not shown in detail - either discharged directly into the installation room for the exhaust air dryer or its exhaust air are mixed in the exhaust duct 16.

Fig. 3 shows a section of a further embodiment of an exhaust air dryer according to the invention. In this embodiment, the warm air from the environment of the motor 21, not shown here, is conducted in a supply line 25 due to the suction effect occurring at an opening 22 in the exhaust duct 16 via the condensate located in a condensate tray 20 without the aid of a second blower. The evaporated condensate containing air is transported together with the exhaust air in the installation room of the exhaust air dryer. In Fig. 3 14 means a first heat exchanger.

The embodiments of the FIGS. 2 and 3 can also be combined, as for example in FIG. 1 is shown.

Claims (13)

Exhaust air dryer (1) with a drying chamber (3) for objects to be dried, a supply air duct (2) for supply air, in which a heater (12, 18) for heating the supply air and the heated supply air (process air) by means of a first blower ( 19) can be guided over the objects to be dried, an exhaust air duct (16), a motor (21) for driving the drying chamber (3), a first heat exchanger (14) in the exhaust air duct (16) and one below the first heat exchanger (14 ) arranged condensate tray (20),
characterized in that the exhaust air dryer (1) has first means (22, 23, 25) for discharging warm air from a housing interior (27) surrounding the motor (21) to the condensate tray (20) and over the latter. Exhaust air dryer (1) according to claim 1, characterized in that the exhaust air duct (16) between the heat exchanger (14) and an exhaust outlet (17) has an opening (22) due to a suction effect passing through the opening (22) Guided exhaust air is created, the entrainment of over the condensate pan (20) located air allows. Exhaust air dryer (1) according to claim 1 or 2, characterized in that the first means (22, 23, 25) comprise a second fan (23), the warm air from a motor (21) comprising the housing interior (27) towards the Conduct condensate tray (20) and over it. Exhaust air dryer (1) according to claim 3, characterized in that the first fan (19) and the second fan (23) are driven by the same motor (21). Exhaust air dryer (1) according to claim 4, characterized in that the first fan (19) and the second fan (23) are arranged on opposite sides of the motor (21). Exhaust air dryer (1) according to one of claims 1 to 5, characterized in that in the condensate tray (20) is a body (26) with a large surface is present. Exhaust air dryer (1) according to claim 6, characterized in that the body (26) is a nonwoven. Exhaust air dryer (1) according to one of claims 1 to 7, characterized in that the means allow the discharge of hot air at a rate of 10 to 100 m ³ / hour. Exhaust air dryer (1) according to one of claims 1 to 8, characterized in that the first heat exchanger (14) is an evaporator (14) of a heat pump circuit (12, 13, 14, 15). Exhaust air dryer (1) according to one of claims 1 to 8, characterized in that the first heat exchanger (14) is an air-to-air heat exchanger. Exhaust air dryer (1) according to one of claims 1 to 10, characterized in that the condensate tray (20) has second means for detecting and / or discharge of a predetermined limit amount exceeding amount of condensate. A method for operating an exhaust air dryer (1) with a drying chamber (3) for objects to be dried, a supply air duct (2) for process air in which a heater (12, 18) for heating the supply air and the heated supply air (process air) by means a first blower (19) can be guided over the objects to be dried, an exhaust duct (16), a motor (21) for driving the drying chamber (3), a first heat exchanger (14) in the exhaust duct (16), one below the first heat exchanger (14) arranged condensate tray (20) and first means (22, 23, 25) for the discharge of hot air from a motor (21) comprising the housing interior (27) towards the condensate pan (20) and across, thereby in that condensate arising in the condensate tray (20) during operation of the exhaust air dryer (1) is conveyed by means of warm air coming from the housing interior (27) surrounding the motor (21) to the condensate tray (20) and beyond is passed, is evaporated and the resulting warm, moist air from the exhaust air dryer (1) is guided. A method according to claim 12, characterized in that a second fan (23) directs the warm air from the motor housing (21) housing interior (27) towards the condensate pan (20) and across it.

Images