WO2014094855A1

WO2014094855A1 - Household appliance and method of operating a household appliance

Info

Publication number: WO2014094855A1
Application number: PCT/EP2012/076336
Authority: WO
Inventors: Stefan Jonsson; Marie MINDE; Giuseppe Dreossi; Bernd Krische
Original assignee: Electrolux Home Products Corporation N. V.
Priority date: 2012-12-20
Filing date: 2012-12-20
Publication date: 2014-06-26

Abstract

The invention in particular is directed to a household appliance (1), such as a dishwasher. The household appliance (1), comprises a dehumidifying unit (3) adapted to dehumidify a process gas (5). The dehumidifying unit (3) comprises a cyclonic moisture condenser (4) thermally coupled to a cold reservoir (7).

Description

Title: Household appliance and method of operating a household appliance

The present invention is directed to a household appliance and a method of operating a household appliance.

In particular, the invention is directed to household appliances in which a flow of dry process gas, in particular process air, is used to dry objects contained in a chamber of the household appliance. An example for such an appliance is a dishwasher, where dry air is used to dry tableware at the end of the washing process.

In the field of dishwashers it is in particular known to use condensation surfaces to dehumidify air used for drying the tableware inside the

dishwasher tub. Exemplary reference is made to document DE 35 15 592 Al.

The problem with known household appliances is that they often show poor condensation efficiency for drying air used in drying cycles. Therefore, there is still room for improving condensation efficiency for drying air used in drying cycles in household appliances, in particular dishwashers.

It is an object of the invention to avoid the shortcomings of prior art technology set out above. In particular, a household appliance shall be provided having improved condensation efficiency for producing drying air used in object drying cycles. Further, a corresponding method of operating a household appliance shall be provided.

This object is solved by the independent claims. Embodiments result from respective dependent claims. According to claim 1, a household appliance is provided which comprises a dehumidifying unit adapted to dehumidify a process gas, in particular drying gas, in particular drying air. The dehumidified process gas, in particular drying air, is intended for drying wetted objects present in a tub or chamber of the household appliance, for example. Respective objects may for example be tableware in a tub of a dishwasher, or laundry in a drum of a laundry dryer.

The dehumidifying unit comprises a cyclonic moisture condenser which is thermally coupled to a cold reservoir. Using a cyclonic type condenser in combination with a cold reservoir has been shown to result in improved and advanced condensation efficiency, in particular as compared to state of the art technology. A cold reservoir shall in particular be understood a source or material that can be cooled down by draining heat. In other words, a cold reservoir may also be a heat sink. As an example, a heat pump may drain heat from the cold reservoir, which may be a water tank. The temperature in the water tank then decreases and the water tank therefore implements a cold reservoir for the heat pump.

The cyclonic moisture condenser in particular may be adapted to generate a cyclone effect in the process gas, in particular in a circuit of the process gas, to thereby guide or direct the process gas along or to a condenser surface. This means that the process gas is brought in an efficient way in heat exchanging contact with the condenser surface. In other words, the cyclonic moisture condenser in particular may make use of a cyclone effect for condensing, at a condenser surface, moisture contained in the process gas. Via the cyclone effect the process gas can be brought in close and intensive contact with the condenser surface resulting in advantageous condensation efficiency. The cyclone effect generated by the cyclonic moisture condenser in particular has the advantage that the combined effect of acceleration and cyclonic movement of the process gas may lead to optimal, in particular comparatively thin, boundary layers between condenser surface and process gas. This in particular supports efficient heat exchange between the process gas and condenser surface, which in turn may result in efficient moisture

condensation. In particular, comparatively high heat exchange factors can be obtained. Due to density differences between dry and humid air, the cyclonic centrifugal force in particular is advantageous for pushing the humid air towards the cold walls, i.e. condenser surfaces. At the cold walls, the humid air is cooled down below the humid dew point such that humidity can be removed by condensation.

In particular, the air temperature decreases in passing over/through the condenser unit. Therefore, it may be advantageous to reheat the air again before entering the tub again. In particular in this way, evaporation between the items, such as dish load, may be improved and thereby a better drying result may be achieved.

The fact that the cyclonic moisture condenser, in particular a condenser surface thereof, is thermally coupled to a cold reservoir in particular has the advantage that the cyclonic moisture condenser, in particular condenser surface, can be optimally supplied with cooling energy which in turn leads to improved condensation. Thermal coupling between the cold reservoir and cyclonic moisture condenser may be implemented in that a condenser surface is in direct contact with the cold reservoir, in particular a cold storage material, medium or substance of the cold reservoir.

In an embodiment, the cyclonic moisture condenser comprises at least one cyclone tube, or cyclone chamber. At least one in particular shall mean that the moisture condenser may comprise two or more, in particular multiple cyclone tunes. Multiple cyclones in particular may be connected to each other in series to enhance condensation efficiency.

Further, an outer surface of a heat conductive cyclone wall of the cyclone tube is thermally coupled to, in particular is in direct contact with, the cold reservoir, in particular with a cold medium or substance thereof/therein.

In this embodiment, the cyclone wall of the cyclone tube as such functions as a condenser surface. Preferably, the cyclone wall may be made from a metal or metal alloy material, in general having high, at least sufficient and satisfactory heat conductivity.

Note that walls of cyclone tubes in general may have a tapered overall structure, such that the cyclone effect may lead to a helical accelerated movement within the cyclone tub. However, also tube and/or skirt shaped cyclones or cyclone tubes may be used.

The cyclone effect generated within the cyclone tube as soon as the process gas is injected into the cyclone tube in general causes the incoming process gas to pass in a helical movement along the inner wall of the cyclone tube. As already mentioned, comparatively high rotational speed, as well as centrifugal forces, may lead to optimal, in particular thin, boundary layers, which is beneficial for optimal heat transfer or heat exchange between the cold reservoir and the process gas.

Heat transfer from the cold reservoir to the process gas has the effect that the process gas is cooled down, which in turn causes moisture contained in the process gas to condense, in particular at the condenser surface. In this way, the process gas can be dehumidified.

Condensed moisture can be drained from the cyclone tube via a drain outlet defined at one axial end of the cyclone tube, provided at a bottom site averted from the inlet. In particular in tapered cyclones, the drain outlet may therefore be at the narrow end of the cyclone tube, whereas in shirt cyclones, the drain outlet may be at the wide end of the cyclone tube. From the drain outlet the condensed moisture can be guided to a collection tank or similar.

Note that an inlet for incoming process air and an outlet for dried process air leaving the cyclone tube may both be provided at one axial end of the cyclone tube, in particular at an axial end averted from the drain outlet, of the cyclone tube.

If the cyclonic moisture condenser comprises at least one cyclone tube, the cold reservoir in one further embodiment may surround or envelope the at least one cyclone tube. This in particular shall mean, that the cold reservoir, in particular phase change material (PCM) or an other cold storage material, is or can be placed immediately adjacent, preferably contact or direct contact, to the outer side of the cyclone tube wall. In particular, the cyclone tube wall itself may establish a wall section of the cold reservoir. Placing the cold reservoir and/or cold storage material in close or direct proximity to the heat exchange surface of the cyclonic moisture condenser, in particular a wall or sidewall of the cyclone tube, is optimal for obtaining efficient energy transfer. For a PCM material, water or an aqueous solution may be used.

In a further embodiment, the cold reservoir comprises a storage tank adapted to accommodate therein, or adapted to receive or accommodate therein in ordinary operation, a phase change material. With phase change materials, in particular water or aqueous substances, the amount of latent heat per unit mass, available for cooling respective condenser surfaces, can be increased. Hence, the condensing capacity of the cyclonic moisture condenser can be improved.

In general, a phase change material shall in particular be understood any type of material in or with which latent heat of a phase transition between two phases, in particular solid phase, e.g. ice, and liquid phase, can be exploited.

In a further embodiment, the household appliance further comprises heat transfer elements which are thermally coupled to the cyclonic moisture condenser and which extend into the cold reservoir. The heat transfer elements are effective in improving heat transfer from the cold reservoir, in particular a cold storage material, in particular a phase change material, to a condenser wall, in particular condenser surface, of the cyclonic moisture condenser. Therefore, heat transfer to the process gas can be greatly improved.

The heat transfer elements may be formed integrally with a cyclone tube of the cyclonic moisture condenser. The heat transfer elements may be implemented at the outer side of the cyclone tube wall, as already mentioned preferably in an integrated, i.e. one-piece, manner. The heat transfer elements may be implemented, arranged and designed such that they extend, in particular normally and/or radially, from and/or into the cold reservoir, preferably into the cold storage material. The heat transfer elements may for example project from an outer side of the cyclone tube. Apart from an integral design, it is also possible, to attach or fix the heat transfer elements to the cyclone tube by a form-fit and/or bonded connection.

In an embodiment, the heat transfer elements may comprise at least one of heat conducting fins, fingers and plates. The fins, fingers and plates may project and extend, in particular in normal or radial direction, from an outer surface of the cyclone tube. Respective heat transfer elements are suitable for obtaining comparatively large heat exchanging surfaces, which is

favourable for heat transfer from the cold reservoir, in particular phase change material. In a yet further embodiment, the household appliance comprises a heat pump which is thermally coupled to the cold reservoir. The heat pump in particular is adapted and operable to cool the cold reservoir, i.e. to extract heat or drain out heat from the cold reservoir. In cooling the cold reservoir, the heat pump may and is able to transfer heat to the process gas.

Using a heat pump for cooling, in particular freezing the cold storage material, in particular phase change material, is an energy efficient way to cool the cold reservoir, in particular cold storage material. This in particular applies if cooling down the cold reservoir or cold storage, in particular cold storage material, may be done or conducted during an operational phase preceding a drying cycle with dehumidified process gas.

Here it shall be mentioned, that in one embodiment, the heat pump may be adapted to transfer in a cleaning or washing cycle heat from the cold reservoir to an operational fluid of the household appliance. The operational fluid may for example be a cleaning or washing fluid.

Operation of the heat pump may become clearer by the following example. In an operational stage prior to condensation cooling of the process gas, the operational fluid, e.g. cleaning or washing fluid, may be heated up during and/or prior to a cleaning cycle, by operating the heat pump to transfer heat from the cold reservoir, in particular cold storage material, to the operational fluid. During this operational cycle, the cold storage material can be cooled down, in particular such that it undergoes a phase change from liquid to solid, in particular to ice.

Note that the cold storage material may be selected such that a point of phase transition of the cold storage material is sufficient below room

temperature, in particular in the range between -5,0°C and 10°C, which preferably applies for water as a PCM. If other PCM are used, in particular such as eutecticum, temperatures in the range from -50°C to -10°C may apply.

In a subsequent operational stage or cycle after having finished the cleaning cycle mentioned above, a drying cycle may be conducted. During the drying cycle, the process gas may be dehumidified via condensation in the cyclonic moisture condenser using the cold storage material as a cold reservoir.

As can be seen, such a comprehensive utilization and interaction of the cyclonic moisture condenser and heat pump may lead to an energy efficient operation of the household appliance.

In a further embodiment, an inner condenser surface of the cyclonic moisture condenser comprises a coating for at least one of catalysing moisture condensation and providing an antimicrobial effect. Here, the overall energy efficiency of the household appliance may be improved. It shall be noted, that bacterial or microbial layers on condenser surfaces may disrupt energy transfer from the condenser surface to the process gas and may therefore degrade condensing efficiency. A respective coating material advantageously may provide both a catalytic and antimicrobial effect. Such coatings in particular may comprise copper, silver, chitosan, other polymers containing quaternary ammonium groups, zinc oxide, titanium oxide, micro structured surfaces, non-stick surfaces, possibly enhanced by electromagnetic

irradiation, such as UV and/or visible light, or nano scale particle sizes.

As already indicated above, the household appliance in particular may be a tumble dryer, dishwasher or washing machine. Such appliances have in common that an operational fluid, i.e. a liquid or gas, in general has to be heated, and that a process gas used in drying cycles has to be dehumidified. In case of a tumble dryer, the operational fluid may correspond to the process gas. As can be seen, the proposed household appliances provide enhanced condensation efficiencies and, in particular, can be operated in an energy efficient way.

According to claim 12, a method of operating a household appliance is provided. When carrying out the method, a process gas for drying objects accommodated within a tub of the household appliance is dehumidified in that wet or humid process gas is passed through at least one cyclonic moisture condenser which is thermally coupled to a cold reservoir. The term at least one in particular shall mean that one or more, in particular multiple, cyclonic moisture condensers may be provided.

By passing the process gas through the cyclonic moisture condenser, the process gas is cooled down, in particular to the dew point, and therefore condenses. Cooling down in particular results from the fact that the cyclonic moisture condenser, in particular a condenser surface thereof, is coupled to the cold reservoir and is thereby cooled by cold/heat transfer from the cold reservoir. Cooling of the process gas on or at the condenser surface to the dew point will lead to condensation of moisture contained in the process gas. In other words, impinging humid process gas to the condenser surface will lead to condensation of moisture contained in the process gas on or at the condenser surface.

At a temperature of the dew point, specified by the relative humidity, humid air becomes saturated and condensation occurs. The lower relative humidity, the lower the dew point temperature is. Hence, in order to condensate the humid air the condensing surface temperature preferably has to be at or lower than the air dew point. As the air becomes dehumidified the dew point gets lower and the span between the cold condensing surface and the dew point decreases. This also decreases the driving force that drives the humidity towards the condensing surface. Since humid air has higher density than dry air, a cyclonic condenser, due to the centrifugal force, may help to keep up the driving force towards the condensing surface.

Only for clarification it shall be noted that a condensation process on or at the condenser surface in general requires cooling down the process gas. Therefore, in general it is required that the temperature of the condenser surface, i.e. operating temperature of the cyclonic moisture condenser, be lower, in particular significantly lower, than the temperature of the process gas. The temperature of the cyclonic moisture condenser, in particular condenser surface may for example be at or below room temparture, preferentially close to the phase transition temperature of the phase change material, while the initial temperature of the process gas to be impinged on or to the cyclonic moisture condenser, in particular condenser surface, for drying may be in the range from 20° to 80° .

Passing the process gas through the cyclonic moisture condenser therefore leads to dehumidified, and cooled, process gas especially suitable for subsequent drying processes, in particular processes for drying objects within the tub. Since the air temperature decreases passing over/through the condenser unit it can be advantageous to re-heat the air again before it enters the tub. In this way, the evaporation between the items, such as dish load, becomes better and thereby a better drying result may be obtained.

As to advantages and advantageous effects of the proposed method, reference is made to the description above, related to the proposed

household appliance and embodiments thereof.

In an embodiment of the method, the cold reservoir comprises a phase change material, wherein latent heat of the phase change material is used for cooling, in particular is transferred to, a condenser surface of the cyclonic moisture condenser. As already mentioned, a phase change material may be advantageous as latent heat of the phase transition can be exploited and a comparatively large amount of latent heat per unit mass can be obtained or stored.

The condenser surface in particular may be a sidewall of a cyclone tube of the cyclonic moisture condenser. This in particular leads to compact designs. Further, process air circulated and accelerated within the cyclone tube is guided along the condenser surface with advantageous, i.e. comparatively thin, boundary layers, which is beneficial for optimal heat transfer.

In a further embodiment of the method, the household appliance comprises a heat pump, wherein the heat pump is operated to cool, in particular remove heat from, the cold reservoir. In connection with utilizing heat pumps, in particular with respect to advantages, further reference is made to the description above which applies mutatis mutandis.

In an embodiment of the method using a heat pump, the heat pump may be operated to heat or heat up an operational fluid of the household appliance by transferring heat from the cold reservoir to the operational fluid which is used for cleaning objects contained in a tub of the household appliance.

Transferring heat from the cold reservoir in particular means that the cold reservoir, in particular a cold storage material, e.g. a phase change material, is cooled down. At the same time, the operational fluid is heated up. As described above, the operational fluid may be a cleaning or washing liquid.

Taking into account the above description and explanations, it becomes clear that the method is effective in improving condensation efficiency for producing dried air, in particular draining out water from humid air, in particular dehumidifying air, used in object drying cycles in household appliances such as for example tumble dryers, dishwashers and laundry dryers. Embodiments of the invention will now be described in connection with the annexed figures. Note that the exemplary embodiments according to the figures will be described to the extent required for understanding the invention. In the figures,

FIG. 1 shows a schematic representation of selected components of a household appliance according to the invention;

FIG. 2 shows a perspective view of a cyclonic moisture condenser of the household appliance of FIG. 1;

FIG. 3 shows a broken-up view of the cyclonic moisture condenser;

FIG. 4 shows a perspective cross sectional view of the cyclonic moisture condenser; and

FIG. 5 shows a perspective cross sectional view of a cyclone tube of the cyclonic moisture condenser.

FIG. 1 shows a schematic representation of selected components of a household appliance 1 according to the invention. Without restricting the scope of the invention, the household appliance 1 will be described as a dishwasher. However, other types of household appliances with similar modes of operation shall also be covered by the present invention.

The household appliance 1, i.e. dishwasher 1, comprises a tub 2 adapted to receive dishes, i.e. objects, to be cleaned in a cleaning cycle. The dishwasher 1 further comprises a dehumidifying unit 3 adapted to dehumidify process gas, in particular used in the dishwasher to dry dishes within the tub 2 after the cleaning cycle. The dehumidifying unit 3 comprises a cyclonic moisture condenser 4. The cyclonic moisture condenser 4 in particular is adapted to extract moisture from the process gas 5, which may be ordinary air, by condensation at or on cold or cooled condensation surfaces. Note that the process gas 5 in FIG. 1 is schematically represented by open arrows indicating a circulating movement.

The cyclonic moisture condenser 4, in more detail a cyclone tube 6 thereof, is thermally coupled to a cold reservoir 7. The cold reservoir 7 in FIG. 1 is schematically indicated by a broken lined box.

The dishwasher 1 of the present embodiment further comprises a heat pump 8, adapted to transfer heat from the cold reservoir 7 to a cleaning liquid (not shown) within the tub 2. In transferring heat form the cold reservoir 7 to the cleaning liquid, which transfer is indicated by a dashed arrow, the cleaning liquid is heated up and the cold reservoir is cooled down. Heated-up cleaning liquid is normally required in cleaning cycles of the dishwasher.

In order to obtain the mentioned cooling and heating effects, an evaporator 9 of the heat pump 8 is thermally coupled to the cold reservoir 7, and a condenser 10 of the heat pump 8 is thermally coupled to the inner of the tub 2 so that a heat exchange with the cleaning liquid is possible.

An operational mode of the dishwasher 1 can be as follows. During or prior to cleaning objects contained in the tub 2 the cleaning liquid is heated up, inter alia by operation of the heat pump 8. The heat pump 8 transfers heat from the cold reservoir to the cleaning liquid. Here it is of relevance, that the cold reservoir is cooled down. Note that the cold reservoir may comprise a phase change medium, able to store comparatively large amounts of heat in latent heat of the phase transition.

After having finished the cleaning procedure, the objects contained in the tub 2 in general are dried. In the exemplary embodiment in FIG. 1, the drying process is conducted by circulating process gas 5 through the tub 2, wherein the process gas 5 is constantly dehumidified. For dehumidification, the process gas is guided through the cyclonic moisture condenser 4, in which moisture contained in the process gas 5 is condensed at a condenser surface 11. The condenser surface 11 is an inner surface of cyclone tube wall of the cyclone tube 6 which may be cooled by the cold storage which itself is cooled down in connection with the cleaning process.

The process gas 5 enters the cyclone tube 6 at an upper entrance opening 12 which can be seen in more detail in FIG. 2 showing a perspective view of the cyclonic moisture condenser 4. Within the cyclone tube 6, the process gas 5 is guided along the condenser surface 11 where moisture contained in the process gas 5 is condensed, and the process gas is cooled down to a certain extent.

After passing the condenser surface 11, dry process gas leaves the cyclone tube 6 at an upper outlet opening (seen FIG. 2). From there, the dried process gas can be cycled into the tub 2 for further drying the objects contained therein. Prior to entering the tub, the dried process gas 5 may be heated up in order to enhance drying efficiency.

Moisture, i.e. condensed water 14, condensed within the cyclone tub 2 in the present embodiment can be drained at a lower outlet opening 15. The lower outlet opening 15 in the present embodiment is implemented at an axial end of the cyclone tube 6. The upper entrance opening 12 and upper outlet opening 13 are implemented at the other axial end of the cyclone tube 6.

Note, that the cyclone tube 6 in the present case has a tapered, in cross- sections circular shape, wherein the cross section of the cyclone tube 6 decreases top-down, i.e. towards the axial end of the outlet opening 13.

However, it shall be expressly emphasized, that the cyclone tube 6 in embodiments may comprise skirt and tube shaped condensers, in particular cyclone tubes. In these cases, the cross section of the cyclone tube increases or is constant or remains unchanged from top-down, i.e. towards the axial end of the outlet opening 13 or over the axial length of the cyclone tube. The shape of the outer jacket of the cold reservoir 6 may correspond to that of the shape of the cyclone tube 6, and may in particular have a tapered, skirt or tubular shape.

Explicit reference is now made to FIG. 2 showing a perspective view of the cyclonic moisture condenser 4. As can be seen from FIG. 2, the cold reservoir 7 surrounds the cyclone tube 6, in more detail the tapered section of the cyclone tube 6. A thermally insulating material may be provided at the outer side of the cold reservoir 6.

Coming now to FIG. 3 and FIG. 4, respectively showing a broken-up view and a perspective cross sectional view of the cyclonic moisture condenser4.

From FIG. 3 it can be seen, that the cyclone tube 6 comprises, at the outer faces of the cyclone tube walls, several heat transfer elements which in the present case are implemented as fins 16. The fins 16 are integrally formed with the cyclone tube 6 and extend and radially project from at an outer surface of the cyclone tube 6.

From FIG. 4 it can be seen that the cold reservoir 7 comprises a storage tank 17. The storage tank 17 is adapted to accommodate therein a phase change material 18. As to the term phase change material 18, reference is made to the description further above.

From FIG. 4 it becomes obvious, that the storage tank 17 is directly coupled to the cyclone tube 6. In more detail, the cyclone tube 6 as such constitutes a wall of the storage tank 17. This means that an outer surface 19 of the cyclone tube 6 is in direct contact with the phase change material 18. In more general terms, the outer surface of the cyclone tube wall is thermally, in particular directly, coupled to the cold reservoir 7. It shall in particular be noted, that the cyclone tube 6 may be made from a material having

sufficiently high heat conductivity. Respective materials in particular may comprise metals and metal alloys.

From a combination of FIG. 3 and FIG. 4 it can be seen, that the fins 16, which in particular are thermally coupled to the outer side of the cyclone tube wall, project from the outer surface 19 of the cyclone tube 6 into the storage tank 17. By this, heat transfer from the storage tank 7, in particular from the phase change material 18 contained therein, to the cyclone tube wall, in particular to the condenser surface 11, can be greatly improved.

For the sake of completeness it shall be mentioned, that the condenser surface 11 may comprise a coating at least for one of catalyzing condensation of moisture and inhibiting microbial growth. Here, almost constant condensation efficiency, in particular in the long term, may be obtained.

Reference is now made to FIG. 5 showing a perspective cross sectional view of the cyclone tube 6 of the cyclonic moisture condenser 4. In FIG. 5, a flow 20 of process gas in and into the cyclone tube 6 is schematically indicated by solid arrows. Process gas 5 entering the cyclone tube 6 from the upper entrance opening 12 is guided such that it passes along the condenser surface 11 in a helical downward movement.

At the bottom of the cyclone tube 6, the flow of process gas 5 is directed upwards again, such that the process gas can leave the cyclone tube 6 at the upper outlet opening 13 and be recirculated into the tub 2 for further drying.

In entering the cyclone tub 2 and while being guided in a circular flow-path within the cyclone tube 6, the process gas 5 passes tightly along the condenser surface 11 and is cooled down. As a consequence of cooling down the process gas 5, moisture contained in the process gas 5 is condensed. The cyclone effect established within the cyclone tube 6 causes the process gas 5 to be accelerated. In this way, the boundary gas-layer between the condenser surface 11 and the process gas 5 can be greatly reduced. As a consequence, heat transfer from the condenser surface 11 to the process gas 5 can be greatly enhanced. As a consequence, condensation and dehumidification can be optimized, in particular with respect to energy efficiency.

Reference signs

1 household appliance

2 tub

3 dehumidifying unit

cyclonic moisture condenser

5 process gas

cyclone tube

cold reservoir

heat pump

evaporator

0 condenser

1 condenser surface

2 upper entrance opening 3 upper outlet opening

4 condensed water

5 lower outlet opening

6 fin

7 storage tank

8 phase change material 9 outer surface

0 airflow

Claims

1. Household appliance (1) comprising a dehumidifying unit (3) adapted to dehumidify a process gas (5), wherein the dehumidifying unit (3) comprises a cyclonic moisture condenser (4) thermally coupled to a cold reservoir (7).

2. Household appliance (1) according to claim 1, wherein the cyclonic

moisture condenser (4) comprises at least one cyclone tube (6), and wherein an outer surface of a heat conductive cyclone wall of the at least one cyclone tube (6) is thermally coupled to the cold reservoir (7).

3. Household appliance (1) according to claim 2, wherein the cold reservoir (7) surrounds or envelopes at least one cyclone tube (6).

4. Household appliance (1) according to at least one of claims 1 to 3,

wherein the cold reservoir (7) comprises a storage tank (17) to

accommodate therein a phase change material (18).

5. Household appliance (1) according to at least one of claims 1 to 4,

further comprising heat transfer elements (16) thermally coupled to the cyclonic moisture condenser (4) and extending into the cold reservoir (7).

6. Household appliance (1) according to claim 5, wherein the heat transfer elements comprise at least one of heat conducting fins (16), fingers and plates.

7. Household appliance (1) according to claim 5 or 6, wherein the heat

transfer elements (16) are implemented at the outer side (19) of the cyclone tube wall, preferably in an integrated manner, and extend, preferably radially, into the cold reservoir (7).

8. Household appliance (1) according to at least one of claims 1 to 7,

further comprising a heat pump (8) thermally coupled to the cold reservoir (7) and operable to cool the cold reservoir (7).

9. Household appliance (1) according to claim 8, wherein the heat pump (8) is adapted to transfer heat from the cold reservoir (7) to an operational fluid of the household appliance (1).

10. Household appliance (1) according to at least one of claims 1 to 9,

wherein an inner condenser surface (11) of the cyclonic moisture condenser (4) comprises a coating for at least one of catalysing moisture condensation and providing an antimicrobial effect.

11. Household appliance (1) according to at least one of claims 1 to 10,

selected from the group tumble dryer, dishwasher (1) and washing machine.

12. Method of operating a household appliance (1), wherein a process gas (5) for drying objects accommodated within a tub (2) of the household appliance (1) is dehumidified in that humid process gas (5) is passed through at least one cyclonic moisture condenser (2) which is thermally coupled to a cold reservoir (7).

13. Method according to claim 12, wherein the cold reservoir (7) comprises a phase change material (18), and wherein latent heat of the change material is used for cooling a condenser surface (11) of the cyclonic moisture condenser (4), in particular implemented at a sidewall of a cyclone tube (6).

14. Method according to claim 12 or 13, wherein the household appliance (1) comprises a heat pump (8) and wherein the heat pump (8) is operated to cool the cold reservoir (7).

15. Method according to claim 14, wherein the heat pump (8) is operated to heat an operational fluid of the household appliance (1) by transferring heat from the cold reservoir (7) to the operational fluid which is used for cleaning objects contained in a tub (2) of the household appliance (1).