DE102009046547A1 - Dryer with a drying chamber for objects to be dried and a latent heat storage - Google Patents

Abstract

The invention relates to a dryer with a drying chamber 2 for objects to be dried and a process air duct 3, which is designed for supplying air into the drying chamber 2 and for removing air from the drying chamber 2, and a latent heat store 7, which has a storage medium 9 and is thermally coupled to the process air duct 3, the latent heat accumulator 7 having a thermally conductive filling material 10.

Description

The invention relates to a dryer with a drying chamber for objects to be dried, and a process air guide, which is designed for supplying air into the drying chamber and for removing air from the drying chamber. The dryer further comprises a latent heat storage, which has a storage medium and which is thermodynamically coupled to the process air duct.

Dryers, which are designed for drying laundry items, are known in various designs. With regard to the principle of operation, in particular so-called condensation dryers, exhaust air dryers and also heat pump dryers are known. A heat pump dryer can be designed as an exhaust or condensation dryer and has as a characteristic component of a heat pump, with which the required in each dryer process of heating process air is at least partially accomplished.

A tumble dryer, whose operation is based on the condensation of the moisture vaporized by means of warm process air from the laundry - a so-called condensation dryer - unlike a so-called exhaust air dryer, the heated air once passes through the wet laundry items and then expels, no exhaust hose for leading out the exhaust air The building in which it is installed and is very popular because it can be used in an internal bathroom or a laundry room of a larger residential complex.

Exhaust air dryers and condensation dryers are collectively referred to herein as dryers unless the context requires otherwise. 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 a heat exchanger (eg air-air heat exchanger), the moist process air is cooled so that the water contained in the moist process air condenses. The condensed water is then usually collected in a suitable container and the cooled and dried process air supplied to the heater again and then the drum (circulating air dryer) or in the installation room of the dryer (exhaust air dryer).

The DE 37 10 710 A1 describes a condensation dryer with a closed recirculation circuit in which a circulating air fan, an electric air heater, a laundry container, a heat exchanger and a latent heat storage are arranged with a storage medium, wherein the latent heat storage is located in the recirculation loop between the heat exchanger and the electric air heater. The latent heat storage stores at least partially the heat energy dissipated by the moist, warm process air from the drying chamber. If the entire content of the latent heat storage medium has melted on storage medium and the coolant supply to the heat exchanger must be turned on, the electric air heater can be throttled or turned off, because the latent heat storage can be used to heat the process air.

The DE 102 24 940 A1 discloses a condensation dryer with a drying chamber, a closed process air circuit, a process air blower, a heater and a removably arranged in the process air circuit latent heat storage. This replaces the common, air-working heat exchanger. The removably arranged latent heat storage device can be discharged separately, independently of the dryer, wherein discharging means discharging stored heat from the latent heat storage device.

In addition, the applicant also knows a condensation dryer with a latent heat storage, said latent heat storage is arranged in a cooling air duct.

The used in the known household appliances for the care of laundry latent heat storage are limited in terms of energy efficiency and thus in terms of their efficiency.

It is an object of the present invention to provide a dryer with a latent heat storage, in which an improvement in the efficiency of the latent heat storage is achieved.

This object is achieved by a dryer having the features of the independent claim.

A dryer according to the invention, which may be designed, for example, as a tumble dryer or as a washer-dryer, accordingly has a drying chamber for articles to be dried. This is in particular a drum rotating about a horizontal axis. The dryer further comprises a process air duct, which is used to supply air into the drying chamber and to remove air from the drying chamber is trained. In addition, the dryer comprises at least one latent heat storage, which has a storage medium. The latent heat accumulator is thermally coupled to the process air duct. In addition to the storage medium, the latent heat storage on a thermally conductive filler. By this configuration, the energy efficiency and thus the efficiency of the latent heat storage can be significantly increased.

The heat recovery by such a configuration can thus be significantly improved.

It is particularly advantageously provided that the filling material is a foam, in particular a metal foam. By means of such foam materials, a particularly large surface area of the filling material can be achieved, as a result of which, with regard to the thermal conductivity, a particular advantage is achieved.

Metal foams have a low density due to pores and voids, but have a high specific rigidity and strength. Preferably aluminum or aluminum alloys are foamed, since the starting materials already have a very low density. Using suitable blowing agents it is also possible to produce foams of copper, zinc, lead or steel / iron.

In particular, it is provided that the storage medium is introduced into the foam. By such a preferably filling and quasi introduction of the storage medium into the pores of the foam material, a very large heat-conductive surface can still be provided in a particularly compact and space-minimized embodiment, and be contacted with storage medium. The energy efficiency in terms of heat recovery is thereby particularly advantageous and is guaranteed in a particularly compact design.

In addition, it is particularly advantageously provided that the filling material is sheathed with a sheath, which is formed in particular from metal or plastic. Even so, the above advantages can be further improved.

In particular, the latent heat accumulator is designed such that its loading and unloading temperature is matched to the process air temperature in the process air duct. By such a configuration, a particularly matched operating behavior can be made possible and improved in terms of energy efficiency.

Preferably, it is provided that the dryer has a heat exchanger, wherein in a first operating phase of the dryer, in which the latent heat storage is a temperature sink, the cooling capacity of the heat exchanger compared to a second operating phase of the dryer, in which the latent heat storage is no temperature sink, at least reduced is. In particular, it is provided in this regard that in a one-engine concept of the dryer by means of controllable valves in the cooling air or by a controllable separate cooling air blower, such a cooling power setting takes place. Also, the energy efficiency of the dryer can be improved because just the required energy for the cooling of the heat exchanger can at least be reduced.

It is preferably provided that the dryer has a heater for heating the process air, and in an operating phase of the dryer, in which the latent heat storage is charged, the heating is at least reduced in their heating power.

Thus, it can be provided in this regard that when the latent heat storage is charged during a drying process, which can be monitored in particular by a temperature measurement, especially in a vented dryer or a condensation dryer, this heater is reduced in power or switched off completely.

It is particularly advantageously provided that the heat exchanger in an operating phase of the dryer, in which the heater is operated with at least reduced heating power, and thus the latent heat storage is fully charged, this heat exchanger is operated with the cooling power according to the second operating phase. This means that when the heat exchanger was subjected to reduced cooling power or was switched off, then when the heater is reduced or turned off in the heating power and the latent heat storage is charged, a connection of the heat exchanger takes place.

Preferably, the storage medium of the latent heat storage is a PCM (Phase Change Material) material. In particular, this is based on salts or paraffins.

In a preferred embodiment of the condensation dryer, the latent heat storage medium contains a storage medium with a phase transition from the liquid to the solid state in the temperature range of 30 to 65 ° C, more preferably in the temperature range of 35 to 60 ° C and most preferably in the temperature range of 45 to 55 ° C.

It is also preferred that the latent heat storage contains a storage medium containing an inorganic salt hydrate and / or an organic compound. In a particularly preferred embodiment of the invention, the storage medium used contains a salt hydrate, wherein the salt hydrate preferably contains at least one salt selected from the group consisting of sodium acetate, sodium thiosulfate, magnesium nitrate and magnesium chloride. As additions to other salts, potassium nitrate, ammonium nitrate and lithium nitrate may also be used. In such salts is exploited that they melt at an appropriate temperature while absorbing significant amounts of heat, this melting in many cases the transition from a crystalline hydrate, ie a crystal, in addition to the actual ionized components of the salt certain amounts of water molecules (water of crystallization) in a regular lattice, to an aqueous solution of the salt, the salt being in a state which is a solution of the salt in its own water of crystallization.

• – eine Mischung von 58,7 Gew.-% Mg(NO₃)₂·6 H₂O und 41,3 Gew.-% MgCl₂·6 H₂O mit einem Schmelzpunkt von 59°C;
• – eine Mischung von 61,5 Gew.-% Mg(NO₃)₂·6 H₂O und 38,5 Gew.-% NH₄NO₃ mit einem Schmelzpunkt von 52°C;
• – CH₃COONa (Natriumacetat)·3 H₂O mit einem Schmelzpunkt von 54°C; und
• – Na₂S₂O₃ (Natriumthiosulfat)·5 H₂O mit einem Schmelzpunkt von 48°C.

Examples of suitable salt hydrates are, for example:

• - a mixture of 58.7 wt .-% Mg (NO _{3) 2} · 6H ₂ O and 41.3 wt .-% MgCl ₂ · 6 H ₂ O having a melting point of 59 ° C;
• A mixture of 61.5% by weight of Mg (NO ₃ ) ₂ .6H ₂ O and 38.5% by weight of NH ₄ NO ₃ with a melting point of 52 ° C .;
• - CH ₃ COONa (sodium acetate) · 3 H ₂ O with a melting point of 54 ° C; and
• Na ₂ S ₂ O ₃ (sodium thiosulfate) 5H ₂ O with a melting point of 48 ° C.

• – Paraffine (Wärmeparaffine) mit unterschiedlichen Schmelzpunkten;
• – Myristinsäure mit einem Schmelzpunkt von 58°C;
• – eine Mischung von 89 Gew.-% Palmitinsäure und 11 Gew.-% Acetamid mit einem Schmelzpunkt von 57,2°C;
• – eine Mischung von 74,9 Gew.-% Palmitinsäure und 25,1 Gew.-% Propionamid mit einem Schmelzpunkt von 50°C.

In a further particularly preferred embodiment of the invention, the storage medium contains an organic compound. Examples of suitable organic compounds or mixtures of organic compounds are:

• Paraffins (heat paraffins) with different melting points;
• Myristic acid with a melting point of 58 ° C;
• A mixture of 89% by weight of palmitic acid and 11% by weight of acetamide having a melting point of 57.2 ° C .;
• - A mixture of 74.9 wt .-% palmitic acid and 25.1 wt .-% propionamide having a melting point of 50 ° C.

Moreover, as a storage medium in the latent heat storage and a mixture of organic and inorganic compounds can be used. An example of this is a mixture of 80 wt .-% acetamide and 20 wt .-% NaNO ₃ with a melting point of 59 ° C.

The melting point of the storage medium corresponds to the discharge temperature of the latent heat storage. The volume flow and the power of the air-to-air heat exchanger are generally tuned to the discharge temperature, so that the difference between the discharge temperature and the temperature of the cooling air at the exit from the heat exchanger is sufficiently large to allow efficient charging of the latent heat accumulator. This temperature difference is generally 3 to 25 ° C, preferably 5 to 20 ° and most preferably 8 to 15 ° C. Under these conditions, the heat exchange is particularly favorable.

The usable storage media show a more or less pronounced tendency to hypothermia, which in so-called emergency packs, as z. B. can be used as a pocket warmer, find application. In these, heat energy is deliberately released by triggering a crystallization process in the supercooled solution at temperatures below the melting point (discharge temperature).

Although a storage medium in the form of a supercooled solution can be used. Preferably, however, supercooling is avoided. For this purpose, a nucleating agent is added to the storage medium. A nucleating agent is, for example, a solid substance dispersed in the storage medium and chemically inert with respect to the storage medium, which melts at no temperature which can be expected in the latent heat storage and thus represents seeds from which the storage medium passing into the solid phase can form crystals. Examples include quartz (silica) and talc (magnesium silicate). The person skilled in the art is aware of suitable nucleating agents for various storage media.

Preferably, the latent heat storage is an air-bearing components of the dryer and a component of the process air.

It can also be provided that the latent heat storage is arranged non-destructively detachable in the dryer.

In an alternative embodiment, the dryer is preferably designed as a vented dryer, in which case in particular the latent heat accumulator is arranged in front of or in a recirculating air duct. In an exhaust air dryer, the process air duct with the associated air ducts is open, which means that the sucked from outside the dryer air is passed through the drying chamber, thereby absorbs moisture from the laundry to be dried and after leaving the drying chamber sometime along the process air is led out of the dryer again.

Preferably, in such an embodiment of the exhaust air dryer is provided, the at least one flap is formed, by means of which the proportion of the air flowing in the recirculation air process air, which flows to the latent heat storage device, is adjustable.

In the case of an exhaust air dryer operated with circulating air, the latent heat accumulator releases its heat energy to the process air as soon as the process air temperature drops below that of the latent heat accumulator. The drying can thus continue at a low temperature. When the latent heat storage tank is discharged, a heating phase begins again until the next discharge facility.

In a further alternative embodiment it can be provided that the dryer is a condensation dryer, wherein in a condensation dryer, the process air duct is designed as a closed circuit. In a condensation dryer, it is preferably provided that the latent heat accumulator is arranged in an air guide region between the outlet from the drying chamber and a heater arranged in the process air guide. In this regard, an arrangement of the latent heat storage in all air passage areas from the drum outlet, including the condenser, can be used until the heat recovery of the air heat.

A further embodiment of a dryer can be realized in that it comprises a heat pump comprising an evaporator and a condenser. In such a design of a dryer, the heat pump is thermally coupled to the process air duct, wherein the latent heat storage is arranged immediately before or after the evaporator of the heat pump in the process air duct.

Preferably, it can be provided that this mode of operation by means of the latent heat storage device is a special program that can be individually selected by the user of the dryer, which can also be referred to as energy-saving mode, for example.

The specific design of the latent heat accumulator with a storage medium and in addition a thermally conductive filler allows not only the significantly improved thermal conductivity faster loading and unloading cycles. The then higher transmission powers improve the energy efficiency of the dryer through heat recovery. Especially with heat pump dryer thereby the heating phase is supported, since a start with a warm machine is possible.

Further features of the invention will become apparent from the claims and the figures and the description of the figures. The features and combinations of features mentioned above in the description, in particular also the features and combinations of features shown alone in the figures and the description of the figures, can be used not only in the respectively specified combination but also in other combinations or in isolation without the scope of the invention leave.

An embodiment of the invention will be explained in more detail with reference to a schematic drawing.

The single FIGURE shows a vertically cut condensation dryer, hereinafter referred to as dryer.

The in 1 illustrated dryer 1 has a drum rotatable about a horizontal axis 2 as a drying chamber 2 on, within which carriers 15 are attached to the movement of laundry during a drum rotation. Process air is achieved by means of a blower 6 in the process air duct 3 via an electric heater 4 through the drum 2 guided. After leaving the drum 2 the process air laden with moisture is in the process air duct 3 through an air-to-air heat exchanger 5 directed where a heat exchange with cooling air coming from a cooling air inlet 16 comes, takes place. The process air cools down by condensation of the moisture contained in it and in turn via the blower 6 and the electric heater 4 in the drying chamber 2 guided, whereby the process air circuit of the trained process air guide is closed. The condensed moisture is in an in 1 collected condensate tank, not shown. The in the air-air heat exchanger 5 heated cooling air is through a latent heat storage 7 where they pass by transferring heat energy from the heated cooling air to a storage medium 9 is cooled. The storage medium shown 9 Here is a salt hydrate, which can store heat energy by a phase transition from solid to liquid. The cooled cooling air is then via a cooling air outlet 17 in the installation room of the dryer 1 directed.

For drying laundry items not shown here in detail in the drum 2 is from the electric heater 4 heated air from behind, ie from a door 18 opposite side of the drum 2 through whose perforated bottom into the drum 2 passed, comes there with the laundry to be dried in contact and flows through the filling opening of the drum 2 to a lint filter 19 within a door closing the filling opening 18 , Subsequently, the air flow in the door 18 deflected down and to the air-to-air heat exchanger 5 directed.

After completion of the phase transition in the storage medium is the latent heat storage 7 charged. This condition is about a decrease of two in front of and behind the latent heat storage 7 arranged temperature sensors 13 and 14 measured temperature difference detected. The temperature difference is a control device 22 which they provide with regard to the charging of the latent heat storage 7 evaluates and a shutdown of the electric heater 4 causes. The temperature of the drum 2 entering process air decreases and the drying is due to the heat transfer from the latent heat storage 7 on the drum 2 continued at a lower temperature level. For efficient heat transfer in the embodiment of the invention shown here is the distance between the drum 2 and the latent heat storage 7 from 5 to 10 mm.

At a detected discharge of the latent heat storage 7 (Termination of the phase transition in the storage medium from liquid to solid), which also by evaluating the temperature measurements by means of temperature sensors 13 and 14 can be determined, the electric heater 4 be turned on again. Thereafter, the temperature of the process air and thus the cooling air rises after passing through the air-to-air heat exchanger 5 , so that the latent heat storage 7 is recharged.

The drum 2 will be in the in 1 shown embodiment on the rear floor by means of a pivot bearing and front by means of a bearing plate 20 stored, with the drum 2 with a brim on a sliding strip 21 on the bearing plate 20 rests and is held at the front end. The control of the dryer via the control device 22 by the user via a control unit 23 can be regulated.

The trained as a condensation dryer dryer in the embodiment 1 also includes a cooling air duct 8th with the in the heat exchanger 5 heated cooling air to latent heat storage 7 is directed.

The latent heat storage 7 includes in addition to the already mentioned storage medium 9 a thermally conductive filler 10 which in the exemplary embodiment a metal foam 10 is. This metal foam 10 is with the storage medium 9 filled, leaving the storage medium 9 is introduced in the pores of the foam. In addition, the latent heat storage 7 with a shell 11 at least partially surrounded, in this regard, in particular the metal foam 10 is sheathed accordingly. The case 11 can be made of plastic or metal.

In the exemplary embodiment it is provided that the latent heat storage 7 at a distance between 5 mm and 10 mm on the outer surface 12 the drum 2 is arranged.

In addition to the position shown in the cut figure according to the embodiment of a condensation dryer, the latent heat storage in other areas between the drum outlet to the heater 4 be used for heat recovery and positioned accordingly.

In addition to the condensation dryer explicitly explained in the exemplary embodiment, the dryer can also be designed as an exhaust air dryer. There is the latent heat storage 7 then preferably positioned so that it receives a proportion of recirculated air. The exhaust air dryer is the latent heat storage 7 preferably arranged in front of or in the recirculating air channel. By means of flaps, a process-dependent disconnection and connection or regulation of the recirculated-air proportion can be achieved.

In a further embodiment it can be provided that the dryer is designed as a heat pump dryer and a heat pump with a heat sink 5 , in particular an evaporator 5 in the case of the heat pump of the compressor type, in place of the heat exchanger 5 and a heat source 4 , in particular a liquefier 4 in the case of the heat pump of the compressor type, in place of the heater 4 having. In the heat pump there is next to the heat source 4 and the heat sink 5 a presently not shown for clarity pump device, which heat in the heat sink 5 was taken to the heat source 4 pumps to release them there at a different temperature. Preferably, in a heat pump dryer, the latent heat storage 7 in areas immediately before or after the heat sink 5 arranged.

Generally spoken is in phases, in which the latent heat storage 7 to the temperature sink, a heat exchanger 5 reduced or switched off in its cooling capacity. In a single-engine concept, this is made possible by controllable flaps in the cooling air and by a controllable separate cooling air blower. Is the latent heat storage 7 During a drying process, monitored by a temperature measurement, charged, the heater can be reduced or shut down in an exhaust or condenser dryer. Was the heat exchanger 5 reduced or switched off, it is then switched back on.

LIST OF REFERENCE NUMBERS

1

dryer

2

Drying chamber, drum

3

Process air duct

4

Heating, heat source

5

Heat exchanger, heat sink

6

fan

7

Latent heat storage

8th

Cooling air duct

9

storage medium

10

metal foam

11

shell

12

outer surface

15

takeaway

16

Cooling air inlet

17

Cooling air outlet

18

door

19

lint

20

end shield

21

lubricating strip

22

control device

23

operating unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3710710 A1 [0005]
• DE 10224940 A1 [0006]

Claims (15)

Dryer ( 1 ) with a drying chamber ( 2 ) for objects to be dried, and a process air guide ( 3 ), which for supplying air into the drying chamber ( 2 ) and for removing air from the drying chamber ( 2 ) is formed, and a latent heat storage ( 7 ), which is a storage medium ( 9 ) and with the process air guide ( 3 ) is thermally coupled, characterized in that the latent heat storage ( 7 ) a heat-conductive filler material ( 10 ) having. Dryer ( 1 ) according to claim 1, characterized in that the filling material is a foam, in particular a metal foam ( 10 ) is. Dryer ( 1 ) according to claim 2, characterized in that the storage medium ( 9 ) in the foam ( 10 ) is introduced. Dryer ( 1 ) according to one of the preceding claims, characterized in that the filling material ( 10 ) with a shell ( 11 ) is encased in metal or plastic. Dryer ( 1 ) according to one of the preceding claims, characterized in that the loading and unloading temperature of the latent heat accumulator ( 7 ) is tuned to the process air temperature. Dryer ( 1 ) according to one of the preceding claims, characterized in that it comprises a heat exchanger ( 5 ), and in a first phase of operation of the dryer ( 1 ), in which the latent heat storage ( 7 ) is a temperature sink, the cooling capacity of the heat exchanger ( 5 ) compared to a second phase of operation of the dryer ( 1 ), in which the latent heat storage ( 7 ) is no temperature sink, at least reduced. Dryer ( 1 ) according to one of the preceding claims, characterized in that it has a heater ( 4 ) for heating the process air, and in an operating phase of the dryer ( 1 ), in which the latent heat storage ( 7 ), the heating ( 4 ) is at least reduced in their heating power. Dryer ( 1 ) according to claim 6 and claim 7, characterized in that the heat exchanger ( 5 ) in an operating phase of the dryer ( 1 ), in which the heating ( 4 ) is operated with at least reduced heating power, the heat exchanger ( 5 ) is acted upon by a cooling power according to the second operating phase. Dryer ( 1 ) according to one of the preceding claims, characterized in that the storage medium ( 9 ) is a PCM material, in particular based on salts, salt hydrates or paraffins. Dryer ( 1 ) according to one of the preceding claims, characterized in that the latent heat store ( 7 ) an air-conducting component of the dryer ( 1 ) or a component flown by the process air. Dryer ( 1 ) according to one of the preceding claims, characterized in that the latent heat store ( 7 ) detachable in the dryer ( 1 ) is arranged. Dryer ( 1 ) according to one of the preceding claims, characterized in that it is an exhaust air dryer and the latent heat storage ( 7 ) is arranged in front of or in a circulating air duct of the process air duct. Dryer ( 1 ) according to claim 12, characterized in that at least one flap is formed, by means of which the proportion of the process air flowing in the recirculating air channel, which to the latent heat storage ( 7 ) flows, adjustable. Dryer ( 1 ) according to one of claims 1 to 11, characterized in that it comprises a condensation dryer ( 1 ), and the latent heat storage ( 7 ) in an air guide region between the exit from the drying chamber ( 2 ) and a heater arranged in the process air duct ( 4 ) is arranged. Dryer ( 1 ) according to any one of claims 1 to 11, characterized in that it is a heat pump dryer and having a thermally coupled to the process air duct heat pump with an evaporator and a condenser, and the latent heat storage ( 7 ) is arranged immediately before or after the evaporator in the process air duct.

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