WO2014186182A2

WO2014186182A2 - Batch dishwasher and method for operating a batch dishwasher

Info

Publication number: WO2014186182A2
Application number: PCT/US2014/037059
Authority: WO
Inventors: Harald Disch; Dietrich Berner
Original assignee: Premark Feg L.L.C.
Priority date: 2013-05-17
Filing date: 2014-05-07
Publication date: 2014-11-20
Also published as: CN105246390A; US20160113478A1; WO2014186182A3; EP2996535A2

Abstract

The invention relates to a commercial dishwasher (1) which is in the form of a batch dishwasher and has a treatment chamber (2) for accommodating washware which is to be cleaned and also has a drying device for drying washware which is accommodated in the treatment chamber (2) as required. The treatment chamber (2) is divided into a first region (2a) and a second region (2b) which is or can be physically separated from said first region. The drying device has a first sorption unit (3) containing a reversibly dehydratable dry material and has a first fan (5), which is associated with the first sorption unit (3), for forming a first air circuit in the first region (2a) as required in such a way that air is conducted out of the first region (2a) through the first sorption unit (3) and then returned to the first region (2a). The drying device has a second sorption unit (4) containing a reversibly dehydratable dry material and has a second fan (6), which is associated with the second sorption unit (4), for forming a second air circuit in the second region (2b) as required in such a way that air is conducted out of the second region (2b) through the second sorption unit (4) and then returned to the second region (2b).

Description

BATCH DISHWASHER AND METHOD FOR

OPERATING A BATCH DISHWASHER

Description

The invention relates to a commercial dishwasher as claimed in the preamble of patent claim 1.

Accordingly, the invention relates, in particular, to a commercial dishwasher which is in the form of a batch dishwasher and has a treatment chamber for accommodating washware which is to be cleaned and also has a drying device for drying washware which is accommodated in the treatment chamber as required.

Batch dishwashers are dishwashers which can be manually loaded and unloaded. Batch dishwashers (also called "box-type warewashers") may be hood-type dishwashers ("hood- type warewashers") or front-loader dishwashers ("front-loader warewashers"). Front-loader dishwashers may be under-counter machines, top-counter machines or free-standing front- loader dishwashers.

A dishwasher which is in the form of a batch dishwasher usually has a single treatment chamber for cleaning washware. The treatment chamber generally has arranged beneath it a wash tank in which liquid from the treatment chamber can flow back due to the force of gravity. The wash tank contains wash liquid which is usually water to which detergent may be added if required.

A dishwasher which is in the form of a batch dishwasher usually also has a wash system with a wash pump, a line system which is connected to the wash pump, and with a large number of spray nozzles which are formed in at least one wash arm. The wash liquid contained in the wash tank can be conveyed from the wash pump to the wash nozzles via the line system and be sprayed onto the washware to be cleaned through the wash nozzles in the treatment chamber. The sprayed wash liquid then flows back into the wash tank. A dishwasher of this kind which is in the form of a batch dishwasher is known, for example, from document DE 10 2005 023 429 Al .

The term "washware" used in the present document is understood to mean, in particular, crockery, glasses, cutlery, cooking utensils, baking utensils and serving trays.

A commercial dishwasher which is in the form of a batch dishwasher differs from a domestic dishwasher in particular in that a commercial dishwasher has to be designed in such a way that - depending on the cleaning program selected - program run times of between one and five minutes can be realized, whereas domestic dishwashers generally have run times of up to 2.5 hours or more. On account of the short program duration required in commercial dishwashers, techniques employed in domestic dishwashers generally cannot be readily transferred to commercial dishwashers.

Commercial dishwashers which are in the form of batch dishwashers normally operate in two main process steps: a first step which includes washing with a wash liquid, and a second step which includes final rinsing with heated fresh water with the metered addition of a final rinse aid.

In order to be able to carry out these process steps, a commercial dishwasher, which is in the form of a batch dishwasher, is generally equipped with two independent liquid systems which are completely separate from one another. One of the liquid systems is a wash water circuit which is responsible for washing the washware, with washing being carried out using recirculated water from the wash tank of the dishwasher. The other liquid system is a fresh water system which is responsible for final rinsing. Final rinsing is carried out using fresh water, preferably using fresh water from a water heater (boiler). The fresh water is likewise collected by the wash tank of the dishwasher after being sprayed.

The main objective of final rinsing is to remove wash liquor from the washware. In addition, the final rinse water which flows into the wash tank during the final rinse step serves to regenerate the wash water which is present in the wash tank. Before fresh water is sprayed and thus conducted into the wash tank of the dishwasher as final rinse liquid as a result of final rinsing, a quantity of wash liquid which is equal to the quantity of fresh water is pumped out of the wash tank.

Commercial dishwashers which are in the form of batch dishwashers are usually equipped with several programs. These programs differ mainly due to program run times of the wash process of different lengths. The operator has the option of selecting a short wash program for washware which is lightly soiled, or of selecting a correspondingly longer wash program for washware which is heavily soiled.

Commercial dishwashers, which are in the form of batch dishwashers and are designed for loading washware into and unloading washware from the treatment chamber in batches, are, in particular, front- loader machines or hood-type machines. In the case of front- loader machines, the washware is placed in a rack and the rack which is loaded with washware is placed in the treatment chamber of the dishwasher through a front door and, after cleaning, is removed again through the front door. In the case of hood-type machines, the dish racks which are loaded with washware are pushed manually into the treatment chamber from an entry side and manually removed from the treatment chamber from an exit side when a wash program is complete. Front-loader machines and hood-type machines contain only a single treatment chamber for treating the washware. The front-loader machines may be under-counter machines or top-counter machines.

Mainly two drying methods are used in commercial dishwashers which are in the form of batch dishwashers. In the first method, the washware which is still hot following the final rinse process is removed from the machine, where it then dries in the ambient air within four to ten minutes. In order for the washware to dry, in the method described above, it is usually left in the racks in which it was arranged in order to be cleaned in the dishwasher.

According to the second method, air drying takes place within the treatment chamber of the dishwasher. Fresh-air drying systems are used in this case. Fresh-air drying systems of this kind for commercial front-loader or under-counter dishwashers always operate with a high volumetric flow rate of air in the range of from 25 to 100 m³ per hour, in order for it to be possible to dry the washware remaining in the treatment chamber over a very short time. The high volumetric flow rates of air are necessitated by the brevity of the drying process in the commercial sector. In comparison to conventional drying in a domestic dishwasher, the active drying time of a commercial dishwasher is many times shorter. Whereas the drying program run time in a domestic dishwasher is approximately 30 minutes to 2.5 hours, the drying program run time in commercial use is between 1.5 and 5 minutes.

In the case of air drying in a commercial dishwasher which is in the form of a batch dishwasher, fresh air is drawn in from the outside and conducted through the treatment chamber of the dishwasher in order to absorb moisture from the washware which is to be dried. The drying air which is laden with moisture is then generally blown out as waste air into the room in which the dishwasher is installed.

Particularly in the case of sculleries in which several dishwashers which are in the form of batch dishwashers are sometimes operated at the same time, blowing the drying air out into the room in which the dishwashers are installed leads to a negative influence on the climate of the room since the moisture content of the air in the room in which the dishwashers are installed (ambient air) is necessarily increased as a result of the drying air which is laden with moisture and is hot compared to the air in the room in which the dishwashers are installed being blown out. There is a particular risk in this case of the moisture content of the air in the room in which the dishwashers are installed being increased to such an extent that undesired condensation of steam occurs, in particular on cool boundary surfaces in the room in which the dishwashers are installed.

In order to counteract this problem, it is known in the technical field of commercial dishwashing to conduct the waste air which is to be discharged from the treatment chamber of the dishwasher during the drying phase first through a drying channel in which at least some of the moisture contained in the waste air is separated off from the waste air by condensation, before the waste air, which is then cooled and of which the moisture content is correspondingly reduced, is then output to the outside, that is to say into the atmosphere of the room in which the dishwasher is installed, via a blow-out opening in the dishwasher. Specifically, at least some of the moisture which is discharged from the treatment chamber with the waste air condenses in the drying channel. The much shorter drying process which is required in commercial dishwashers in comparison to domestic dishwashers results in the significant risk of - in particular on account of the high volumetric flow of air which is conducted through the treatment chamber of the dishwasher during the drying phase - the condensate which accumulates in the drying channel also being blown out through the blow-out opening in the dishwasher. Furthermore, there is a risk of relatively small quantities of wash and final rinse liquid entering the drying channel since the drying channel is generally connected to the interior of the dishwasher. In standby phases and when the machine is first started up or heated up each day, it is likewise possible for droplets of condensate to form in the drying channel.

If the drying process is then started, the high air speeds cause the droplets of water which are located, or suspended, in the drying channel to be carried along and conveyed or blown out of the blow-out opening in the dishwasher. Furthermore, as a result of the air flow, a film of water which forms on the base of the drying channel is also discharged, in part, through the blow-out opening. This leads firstly to individual droplets being slung out of the dishwasher into the surrounding area and secondly to dripping water running out of the channel outlet on, for example, the front face of the machine. The total quantity of water which is discharged in this way, said quantity varying depending on the mode of operation or cycle sequence, may be up to approximately 10 ml during a single drying phase.

Furthermore, in the case of commercial dishwashers which are in the form of batch dishwashers, the drying channel is generally not large enough to reduce the moisture content of the waste air which is to be discharged from the treatment chamber of the dishwasher to such an extent that said moisture content corresponds to the moisture content of the air (ambient air) in the room in which the dishwasher is installed. In conventional dishwashers, blowing the waste air out into the room in which the dishwasher is installed inevitably leads to an increase in the atmospheric moisture in the ambient air, that is to say the air in the room in which the dishwasher is installed.

One problem with the commercial dishwashers which are known from the prior art and are in the form of batch dishwashers can accordingly be seen in that, despite the provision of a drying channel, water is still undesirably discharged from the dishwasher in the drying process (drying phase) while the dishwasher program is running. The object of the invention is to provide a way of being able to further reduce the discharge of water from a commercial dishwasher, it being necessary to ensure, in particular, that the dishwasher can be operated in a manner which is as simple as possible to realize, even without a complicated drying channel system in the room in which the dishwasher is installed. A corresponding method for operating a commercial dishwasher of this kind which is in the form of a batch dishwasher is also intended to be specified.

According to the invention, this object is achieved by the subject matter of independent patent claim 1 in respect of the dishwasher, and by the subject matter of independent patent claim 15 in respect of the method for operating a commercial dishwasher of this kind which is in the form of a batch dishwasher. Advantageous developments of the dishwasher according to the invention are specified in dependent patent claims 2 to 14. Advantageous developments of the method according to the invention are specified in dependent patent claims 16 and 17.

Accordingly, the invention proposes a commercial dishwasher which is in the form of a batch dishwasher and has a treatment chamber for accommodating washware which is to be cleaned. The commercial dishwasher which is in the form of a batch dishwasher further has a drying device in order to dry washware which is accommodated in the treatment chamber as required. According to the invention, the treatment chamber is divided into a first region and into a second region which is or can be physically separated from said first region. Furthermore, provision is made for the drying device to have a first sorption unit containing a reversibly dehydratable dry material and a first fan, which is associated with the first sorption unit, in order to form a first air circuit in the first region of the treatment chamber as required in such a way that air is conducted out of the first region of the treatment chamber through the first sorption unit and then returned to the first region of the treatment chamber. The drying device according to the present invention further has a second sorption unit containing a reversibly dehydratable dry material and a second fan, which is associated with the second sorption unit, in order to form a second air circuit in the second region of the treatment chamber as required in such a way that air is conducted out of the second region of the treatment chamber through the second sorption unit and then returned to the second region of the treatment chamber. The advantages which can be achieved by the solution according to the invention are obvious: owing to the provision of a drying device which has a first sorption unit and also an additional second sorption unit, air drying in the corresponding regions of the treatment chamber using drying air is possible, without the drying air then having to be blown to the outside into the atmosphere of the room in which the dishwasher is installed, since - on account of the provision of the two sorption units - the drying air can be continuously recirculated into the two regions of the treatment chamber. According to the invention, the moisture which is drawn from the drying air during the drying process is adsorbed by at least one of the two sorption units by air being conducted out of the corresponding region of the treatment chamber by the sorption unit which contains the reversibly dehydratable dry material in such a way that the dry material absorbs moisture from the air stream. The dried air is then again supplied to the corresponding region of the treatment chamber.

While one of the two sorption units is in its adsorption phase, the other of the two sorption units is operated in a desorption phase during which the dry material of this sorption unit is heated and air is conducted out of the region of the treatment chamber which is associated with the sorption unit through the sorption unit, which contains the heated dry material, in such a way that moisture is desorbed from the dry material and at least a portion of the thermal energy which was previously introduced into the dry material and at least a portion of the moisture which is desorbed from the dry material is discharged from the sorption unit with the aid of the air stream which is conducted through the sorption unit.

Accordingly, moisture can be drawn in a continuous manner from the drying air which is circulating in the corresponding region of the treatment chamber, and therefore - in comparison to conventional dishwashers with fresh-air drying systems - no fresh air or - in comparison to solutions known from the prior art - far less fresh air has to be supplied for the purpose of drying the washware in the dishwasher. In particular, the drying air is only recirculated into the corresponding regions of the treatment chamber in the solution according to the invention.

According to an advantageous development, the dishwasher according to the invention further has a first heating unit which is associated with the first sorption unit. This first heating unit, which is associated with the first sorption unit, serves to heat the dry material of the first sorption unit as required, this taking place when the first sorption unit is in the desorption phase and the dry material of the sorption unit is regenerated. In addition to this, a second heating unit, which is associated with the second sorption unit, is preferably provided in order to heat the dry material of the second sorption unit as required. This is the case when the dry material of the second sorption phase is regenerated, that is to say when the second sorption unit is in its desorption phase.

In a particularly preferred realization of the dishwasher according to the invention, said dishwasher further has a control device which is designed (e.g., programmed or otherwise configured) to operate the first sorption unit and the second sorption unit in antiphase to one another during operation of the dishwasher so that, in principle, there is always enough regenerated dry material and moisture can be drawn from the drying air, which is recirculated in one of the two regions of the treatment chamber. Specifically, the control device is designed to actuate the fan which is associated with the first sorption unit, the heating unit which is associated with the first sorption unit, the fan which is associated with the second sorption unit, and the heating unit which is associated with the second sorption unit during a drying phase in the first region of the treatment chamber in such a way that air is conducted out of the first region of the treatment chamber through the first sorption unit in such a way that the dry material of the first sorption unit absorbs moisture from the air stream while, at the same time or with a time delay, the dry material of the second sorption unit is heated and air is conducted out of the second region of the treatment chamber through the second sorption unit, which contains the heated dry material, specifically in such a way that moisture is desorbed from the dry material and at least a portion of the thermal energy which was previously introduced into the dry material and at least a portion of the moisture which is desorbed from the dry material is discharged from the second sorption unit with the aid of the air stream which is conducted through the second sorption unit.

A sensor device is particularly preferably provided in the last-mentioned embodiment of the dishwasher according to the invention, said sensor device serving to ascertain the moisture-absorption capacity of the dry material of the first and/or second sorption unit. In this case, it is advantageous when the control device is designed to terminate the adsorption phase of the corresponding sorption unit and to initiate the desorption phase of the sorption unit as a function of the ascertained moisture-absorption capacity, preferably automatically, and more preferably selectively automatically.

In order to be able to operate the dishwasher in as energy-efficient a manner as possible, provision is made in a preferred development for the drying device to have a first heat exchanger unit which is associated with the first sorption unit in such a way that, when the first air circuit is formed, at least a portion of the drying air which is routed through the first sorption unit then passes the first heat exchanger unit. Furthermore, the drying device should have a second heat exchanger unit which is associated with the second sorption unit in such a way that, when the second air circuit is formed, at least a portion of the drying air which is routed through the second sorption unit then passes the second heat exchanger unit.

However, as an alternative to this, it is also feasible for the drying device to have a heat exchanger unit which is jointly associated with the first and second sorption units in such a way that, when the first and/or second air circuits or circuit are/is formed, at least a portion of the drying air which is routed through the first and/or second sorption unit then passes the common heat exchanger unit.

The first and second heat exchanger units or the common heat exchanger unit in each case have or has a heat exchanger which is cooled with water, in particular fresh water, and also have or has an inlet which is connected or can be connected to a fresh water supply line, and have or has an outlet which is connected or can be connected to the wash nozzle system of the dishwasher and/or to the final rinse nozzle system of the dishwasher. In this way, the heat which is dissipated from the sorption unit can be used during the desorption phase to heat up the fresh water which is then used as wash liquid or final rinse liquid.

In this case, it is particularly feasible for the outlet of the heat exchanger unit to not be connected directly to the wash nozzle system or final rinse nozzle system of the dishwasher but rather to issue into an intermediate tank from which the wash nozzle system or the final rinse nozzle system is supplied with fresh water. An exemplary embodiment of the solution according to the invention will be described in greater detail below with reference to the appended drawing, in which: fig. 1 : schematically shows a commercial dishwasher according to an exemplary embodiment of the invention.

The invention relates to commercial dishwashers, in particular utensil washers, in the form of a batch dishwasher. They contain a program control device 101 for controlling at least one cleaning program and a treatment chamber 2, which can be closed by at least one door (not shown) or at least one hood (not shown), in a machine housing 10 for accommodating washware (not shown) which is to be cleaned, such as, for example, crockery, cutlery, pots, pans and trays.

At least one wash tank 12a, 12b for accommodating sprayed liquid from the corresponding regions 2a, 2b of the treatment chamber 2 is located beneath the treatment chamber 2. At least one wash pump 13 a, 13b is provided for conveying wash liquid from the at least one wash tank 12a, 12b through a wash liquid line system 16a, 16b to wash nozzles 11a, l ib which are directed into the two regions 2a, 2b of the treatment chamber 2 in the direction of the washware which is to be cleaned and spray the wash liquid onto the washware which is to be cleaned. The sprayed wash liquid falls back into the at least one wash tank 12a, 12b due to the force of gravity. As a result, the at least one wash tank 12a, 12b, the at least one wash pump 13a, 13b, the wash liquid line system 16a, 16b, the wash nozzles 11a, l ib, together with the corresponding regions 2a, 2b of the treatment chamber 2, form a wash liquid circuit.

In the embodiments of the solution according to the invention which are illustrated by way of example in the drawings, a respectively separate wash tank 12a, 12b and a respectively separate wash pump 13a, 13b are associated with each region 2a, 2b of the treatment chamber 2. In this case, a wash liquid line system 16a, 16b, which is likewise associated with the corresponding region 2a, 2b of the treatment chamber 2, connects the delivery end of the corresponding wash pump 13a, 13b to the corresponding wash nozzles 11a, l ib which are arranged in the respective region 2a, 2b of the treatment chamber 2. The intake end of the corresponding wash pump 13 a, 13b forms or can form a flow connection with the wash tank 12a, 12b which is associated with the corresponding region 2a, 2b of the treatment chamber 2. However, it goes without saying that it would also be feasible for a single (common) wash pump 13 to be associated with the two regions 2a, 2b of the treatment chamber 2, it being possible for the intake end of said wash pump to be selectively connected to the wash liquid line system 16a which is associated with the first region 2a of the treatment chamber 2 or to the wash liquid line system 16b which is associated with the second region 2b of the treatment chamber 2. As an alternative or in addition to this, it would further be feasible to provide only one single (common) wash tank instead of two separate wash tanks 12a, 12b.

A final rinse system for conveying final rinse liquid to final rinse nozzles 15 a, 15b through a final rinse line system 16a, 16b by means of at least one final rinse pump 14a, 14b is further provided in the exemplary embodiments which are illustrated in the drawings, said final rinse nozzles being directed into the two regions 2a, 2b of the treatment chamber 2 in the direction of the washware which is to be cleaned. The sprayed final rinse liquid falls into the corresponding wash tank 12a, 12b, which is associated with the region 2a, 2b of the treatment chamber 2, or into the common wash tank from the corresponding region 2a, 2b of the treatment chamber 2 due to the force of gravity. The final rinse liquid line system 16a, 16b connects the delivery end of the corresponding final rinse pump 14a, 14b to the corresponding final rinse nozzles 15a, 15b which are arranged in the respective regions 2a, 2b of the treatment chamber 2.

Although a total of two final rinse pumps 14a, 14b are used in the exemplary embodiments which are illustrated in the drawings, it goes without saying that it is feasible for a single (common) final rinse pump to be used for the two regions 2a, 2b of the treatment chamber 2, it being possible for the delivery end of this common final rinse pump to be selectively connected to the final rinse liquid line system 16a of the first region 2a of the treatment chamber 2 and/or to the final rinse liquid line system 16b of the second region 2b of the treatment chamber 2.

In each region 2a, 2b of the treatment chamber 2, a large number of wash nozzles 11a, 1 lb is in each case preferably provided on at least one upper wash arm 18a, 18b, a large number of wash nozzles 11a, l ib is preferably provided on at least one lower wash arm 19a, 19b, a large number of final rinse nozzles 15a, 15b is preferably provided on at least one upper final rinse arm 20a, 20b, and a large number of final rinse nozzles 15a, 15b is preferably provided on at least one lower final rinse arm 21a, 21b.

Before final rinse liquid is sprayed in a region 2a, 2b of the treatment chamber 2 during the final rinse phase, a quantity of wash liquid which corresponds to the final rinse liquid is in each case pumped out of the wash tank 12a, 12b which is associated with the corresponding region 2a, 2b or out of the common wash tank by means of a discharge pump (not shown), the intake end of said discharge pump being connected to a sump of the wash tank 12a, 12b (likewise not shown).

If the wash tanks 12a, 12b or the common wash tank are/is empty before the dishwasher 1, which is in the form of a batch dishwasher, is started for the first time, said wash tanks or wash tank first have/has to be filled with fresh water by means of a fresh water line (not shown) or with fresh water or another final rinse liquid or wash liquid by means of the final rinse system and the at least one final rinse pump 14a, 14b thereof.

The final rinse liquid may be fresh water or fresh water which is mixed with final rinse aid.

The wash liquid contains detergent which is preferably automatically added in a metered manner to the liquid which is contained in the wash tank 12a, 12b by a detergent metering apparatus (not shown).

The program control device 101 controls the at least one wash pump 13a, 13b, the at least one final rinse pump 14a, 14b, the outflow pump(s) (not shown) and the detergent solution pump(s) (likewise not shown) as a function of the cleaning program which is selected by an operator on the program control device 101 in each case. At least one cleaning program is provided; a plurality of cleaning programs which can be selectively chosen are preferably provided.

The embodiments of the dishwasher 1 according to the invention which are illustrated in the drawings are each provided with a drying system in order to recirculate the air in at least one region 2a, 2b of the treatment chamber 2 after the drying process is started in the corresponding region 2a, 2b of the treatment chamber 2, that is to say during the drying phase in this region 2a, 2b of the treatment chamber 2, with moisture being drawn from the air which is circulating in the corresponding region 2a, 2b of the treatment chamber 2 (drying air) at the same time. To this end, the dishwasher 1 has a drying device with a first and a second sorption unit 3, 4. In the exemplary embodiments of the dishwasher 1 according to the invention which are illustrated in the drawings, the first sorption unit 3 is associated with the first region 2a of the treatment chamber 2, and the second sorption unit 4 is associated with the second region 2b of the treatment chamber 2.

Both sorption units 3, 4 in each case have a container containing a reversibly dehydratable dry material. This dry material is preferably a sorption means which contains zeolite. Zeolite is a crystalline mineral which contains silicon and aluminum oxides in a framework structure. This regular framework structure contains cavities in which water molecules can be adsorbed with the release of heat. The water molecules are subject to strong field forces within the framework structure, the strength of said field forces depending on the quantity of water already contained in the lattice structure and on the temperature of the zeolite material.

A suitable dry material is, in particular, Y-type zeolite since this material is also particularly stable under extreme hydrothermal conditions.

Moisture is drawn from the drying air circulating in the corresponding region 2a, 2b of the treatment chamber 2 during the drying phase by at least some of this air being routed through the sorption units 3, 4 which are associated with the region 2a, 2b of the treatment chamber 2. In the process, the dry material (zeolite) of this sorption unit 3, 4 adsorbs moisture from the drying air, this moisture being incorporated in the structure of the dry material. The heat of adsorption is also released during the adsorption phase in which moisture is adsorbed from the drying air by the dry material, as a result of which the proportion of drying air which passes one of the two sorption units 3, 4, is correspondingly heated.

Therefore, the corresponding sorption unit 3, 4 which is operated in its adsorption phase is provided with a double function: firstly, when drying air is routed through the corresponding sorption unit 3, 4, at least a portion of the steam which is present in the drying air is bound by the dry material of this sorption unit 3, 4, so that the drying air which passes the sorption unit 3, 4 is correspondingly dried. Secondly, the drying air which is routed through the sorption unit 3, 4 is heated when the sorption unit 3, 4 is in its adsorption phase since heat is released when moisture is adsorbed by the dry material of the sorption unit. Therefore, the air which is routed through the sorption unit 3, 4 which is in its adsorption phase is not only dried but the temperature of the air is also increased at the same time.

The hot air which is dried after passing the sorption unit 3, 4 is returned to the corresponding region 2a, 2b of the treatment chamber 2 of the dishwasher 1 and used to dry the washware in this region 2a, 2b of the treatment chamber 2. A significant improvement in the drying quality, especially for washware which is composed of plastic material and also for glasses and cutlery, is possible on account of the relatively high air temperature. In particular, the drying time can therefore also be considerably reduced under certain circumstances. This is an important factor particularly in the case of commercial dishwashing.

In the dishwasher 1 according to the invention, the two regions 2a, 2b of the treatment chamber 2 which are or can be physically separated from one another can be used independently of one another for treating washware. To this end, the two regions 2a, 2b of the treatment chamber 2 are preferably in each case equipped with a wash system, it being possible for these wash systems to be actuated independently of one another, and with a final rinse system, it being possible for these final rinse systems to be actuated independently of one another. It is further preferred for two sorption units 3, 4 which can be actuated independently of one another to be used, so that a treatment program can be carried out, for example, in the first region 2a of the treatment chamber 2, while the second region 2b of the treatment chamber 2 can be loaded or unloaded at the same time.

During this "inoperative phase" in which no treatment program is carried out in the region 2a, 2b of the treatment chamber 2, the sorption unit 3, 4 which is associated with this region 2a, 2b is preferably operated in its desorption phase. This ensures that moisture can be continuously drawn from the drying air which is circulating in the region 2a, 2b of the treatment chamber 2 during a subsequent drying phase, without the drying capability of the drying device being influenced.

The term "adsorption phase" used in this document is to be understood to mean a state of the corresponding sorption unit 3, 4 in which air is routed out of the correspondingly associated region 2a, 2b of the treatment chamber 2 through the reversibly dehydratable dry material of this sorption unit 3, 4 in such a way that the dry material absorbs moisture from the air stream, with the dried and heated air then being returned to the region 2a, 2b of the treatment chamber 2.

On the other hand, in this document, the term "desorption phase" is intended to be understood to mean a state which the sorption unit 3, 4 is in when the dry material heats this sorption unit 3, 4 and air is conducted out of the correspondingly associated region 2a, 2b of the treatment chamber 2 through the sorption unit 3, 4, which contains the heated dry material, in such a way that moisture is desorbed from the dry material and at least a portion of the thermal energy which was previously introduced into the dry material and at least a portion of the moisture which is desorbed from the dry material is discharged from the sorption unit 3, 4 with the aid of the air stream which is conducted through the sorption unit 3, 4.

On account of the fact that the drying air only has to be recirculated within the corresponding regions 2a, 2b of the treatment chamber 2 during the drying phase in the case of the dishwasher 1 , it is no longer necessary for fresh air to be conducted through the treatment chamber 2. As a result, the quantity of waste air which has to be discharged from the treatment chamber 2 is reduced to a significant extent, and ideally to zero, in comparison to conventional dishwashers.

In order to supply air from the corresponding region 2a, 2b of the treatment chamber 2 to the first and/or second sorption unit 3, 4 during the adsorption phase and desorption phase, a corresponding fan 5, 6 which can be actuated by a control device 100 is associated with each of the two sorption units 3, 4. This control device 100 can be part of the program control device 101 which has already been mentioned. Furthermore, the two sorption units 3, 4 are each provided with a heating unit 7, 8 which serves to heat the dry material of this sorption unit 3, 4 during the desorption phase of the corresponding sorption unit 3, 4. The subprocess of desorption is carried out following the adsorption phase, specifically by heat, for example in the form of electrical energy, steam, gas or hot water, being supplied to the corresponding sorption unit 3, 4. At the same time or with a time delay, air is blown out of the correspondingly associated region 2a, 2b of the treatment chamber 2 by the corresponding sorption unit 3, 4, which is in the desorption phase, with the aid of the associated fan 5, 6, said air absorbing the water which is desorbed from the dry material as steam. In the process, it is particularly advantageous for air to be conducted through the corresponding sorption unit 3, 4 during the desorption phase in order to reduce the risk of (local) overheating of the dry material.

In the embodiments of the dishwasher 1 according to the invention which are illustrated in the drawings, a heat exchanger system is associated with the two sorption units 3, 4. In this case, it is feasible for the heat exchanger system to have two separate heat exchanger units 17, 18, with in each case one of the two heat exchanger units 17, 18 being associated with one of the two sorption units 3, 4 (cf. fig. 1). However, as an alternative to this, the heat exchanger system can also have a common heat exchanger unit. Irrespective of whether a heat exchanger unit 17, 18 is used for each sorption unit 3, 4 or a common heat exchanger unit is used for both sorption units 3, 4, said heat exchanger unit or units serves/serve to transmit thermal energy from at least a portion of the dry air which is treated in the drying device, in particular during the desorption phase of one of the two sorption units 3, 4, to the cooling medium of the heat exchanger unit 17, 18.

Specifically, the dry material of this sorption unit 3 is heated with the aid of the first heating unit 7 during the desorption phase of, for example, the first sorption unit 3, and air is conducted out of the first region 2a of the treatment chamber 2 with the aid of the first fan 5 through the first sorption unit 3, which contains the heated dry material, in such a way that moisture is desorbed from the dry material and at least a portion of the thermal energy which was previously introduced into the dry material and also at least a portion of the moisture which was desorbed from the dry material is discharged from the first sorption unit 3 with the aid of the air stream which is conducted through the first sorption unit 3. At least a portion of the thermal energy which is discharged from the first sorption unit 3 with the air stream is then transmitted to the cooling water of the heat exchanger 17 in the heat exchanger unit 17 which is cooled with water, in particular fresh water.

Specifically, in the desorption phase of, for example, the first sorption unit 3, the air stream which is conducted through the sorption unit 3 which contains the heated dry material is then cooled in the heat exchanger unit 17 in such a way that at least a portion of the moisture which was previously desorbed from the dry material and discharged from the first sorption unit 3 with the air stream condenses in the heat exchanger 17, with the result that the condensation enthalpy which is released in the event of condensation can be used to heat the cooling water of the heat exchanger unit.

The cooling water preferably flows in countercurrent in the heat exchanger unit 17, 18 in each case, and therefore the cooling water can be heated to up to 75°C. This fresh water which is heated up in the heat exchanger unit 17, 18 can be used either to fill the at least one wash tank 12a, 12b or to supply fresh water to the dishwasher 1. It is feasible in this case for the heated fresh water to be temporarily stored in an intermediate tank 22a, 22b, with the intake-end connection of the at least one final rinse pump 14a, 14b being connected to the corresponding intermediate tank 22a, 22b in order to supply the heated fresh water, which is temporarily stored in the intermediate tank 22a, 22b, to the corresponding final rinse nozzles 15a, 15b, for example during final rinsing in a region 2a, 2b of the treatment chamber 2.

It goes without saying that it is also feasible to provide just one single (common) intermediate tank instead of two separate intermediate tanks 22a, 22b.

In the embodiments of the dishwasher 1 according to the invention which are schematically illustrated in the drawings, each of the two sorption units 3, 4 has a respectively associated sensor device 9 which serves to ascertain either the moisture-absorption capacity of the dry material of the corresponding sorption unit 3, 4 and/or the temperature. In this case, it is feasible for the moisture-absorption capacity of the dry material to be ascertained by means of the weight of the dry material, by means of the duration of the adsorption phase and/or by means of the moisture content of the air at the outlet of the corresponding sorption unit 3, 4. The adsorption phase of the corresponding sorption unit 3, 4 is preferably automatically terminated and the desorption phase initiated as a function of the ascertained moisture-absorption capacity.

According to one aspect of the present invention, the control device 100, which has already been mentioned and which can, for example, be part of the program control device 101, is designed to suitably actuate the fan 5 which is associated with the first sorption unit 3, the heating unit 7 which is associated with the first sorption unit 3, the fan 6 which is associated with the second sorption unit 4, and the heating unit 8 which is associated with the second sorption unit 4, when a drying phase is carried out in one of the two regions 2a, 2b of the treatment chamber 2, with the result that the sorption units 3, 4 are operated in antiphase. Specifically, according to embodiments of the invention, the control device 100 is designed to actuate the fan 5, which is associated with the first sorption unit 3, in such a way that air is conducted out of the first region 2a of the treatment chamber 2 through the first sorption unit 3, so that the dry material of the first sorption unit 3 can absorb moisture from the air stream. At the same time, the control device 100 actuates the heating unit 8 which is associated with the second sorption unit 4 in such a way that the dry material of the second sorption unit 4 is heated. Furthermore, the control device 100 actuates the fan 6, which is associated with the second sorption unit 4, such that air is conducted out of the second region 2b of the treatment chamber 2 through the second sorption unit 4 which contains the heated dry material, so that moisture is desorbed from the dry material of the second sorption unit 4 and at least a portion of the thermal energy which was previously introduced into the dry material and at least a portion of the moisture which was desorbed from the dry material is discharged from the second sorption unit 4 with the aid of the air stream which is conducted through the second sorption unit 4.

Finally, it is also advantageous for a sensor to be provided in the treatment chamber 2 itself in order to ascertain the moisture content and/or the temperature of the air in this region 2a, 2b of the treatment chamber 2 during drying in one of the two regions 2a, 2b of the treatment chamber 2. The fan 5, 6 which is associated with the corresponding region 2a, 2b of the treatment chamber 2 is then actuated as a function of the ascertained moisture content and/or the temperature in such a way that the quantity of air by volume which is conducted through the sorption unit 3, 4, which is in its adsorption phase, per unit time is set in such a way that the ascertained moisture content and/or the temperature of the air does not exceed a predefined or predefmable setpoint value.

The invention is not restricted to the embodiment which is illustrated in the drawing but rather results from looking at all of the features disclosed in this document together.

In particular, it is feasible in this connection for air to also be conducted from the first region 2a of the treatment chamber through the (second) sorption unit 4 which is associated with the second region 2b and/or for air to be conducted from the second region 2b of the treatment chamber through the (first) sorption unit 3 which is associated with the first region 2a as required in order either to dry the air or to regenerate the sorption material of the corresponding sorption unit 3, 4. In this way, the dishwasher can continue to operate even in the event of failure of or a fault in a sorption unit.

Claims

Patent claims

1. A commercial dishwasher (1) which is in the form of a batch dishwasher and has a treatment chamber (2) for accommodating washware which is to be cleaned and also has a drying device for drying washware which is accommodated in the treatment chamber (2) as required,

characterized

in that the treatment chamber (2) is divided into a first region (2a) and a second region (2b) which is or can be physically separated from said first region, and

in that the drying device has a first sorption unit (3) containing a reversibly dehydratable dry material and has a first fan (5), which is associated with the first sorption unit (3), for forming a first air circuit in the first region (2a) as required in such a way that air is conducted out of the first region (2a) through the first sorption unit (3) and then returned to the first region (2a), and wherein the drying device has a second sorption unit (4) containing a reversibly dehydratable dry material and has a second fan (6), which is associated with the second sorption unit (4), for forming a second air circuit in the second region (2b) as required in such a way that air is conducted out of the second region (2b) through the second sorption unit (4) and then returned to the second region (2b).

2. The dishwasher (1) as claimed in claim 1,

wherein the treatment chamber (2) is formed in such a way that washware can be introduced into the first region (2a) of the treatment chamber (2) or removed from the first region (2a) of the treatment chamber (2) while, independently of this, washware can be introduced into the second region (2b) of the treatment chamber (2) or removed from the second region (2b) of the treatment chamber (2).

3. The dishwasher (1) as claimed in claim 1 or 2,

wherein the treatment chamber (2) has a door or hood which is associated with the first region (2a) and has a further door or hood which is associated with the second region (2b).

4. The dishwasher (1) as claimed in one of claims 1 to 3,

wherein the drying device has a first heating unit (7), which is associated with the first sorption unit (3), for heating the dry material of the first sorption unit (3) as required, and has a second heating unit (8), which is associated with the second sorption unit (4), for heating the dry material of the second sorption unit (4) as required.

5. The dishwasher (1) as claimed in claim 4,

wherein the heating unit (7) which is associated with the first sorption unit (3) and/or the heating unit (8) which is associated with the second sorption unit (4) are/is formed in such a way that, as a result of electrical energy and/or heat being supplied, the corresponding heating unit (7, 8) heats the dry material in the associated sorption unit (3, 4) in such a way that at least some of the moisture which was previously absorbed by the dry material is released by the dry material again.

6. The dishwasher (1) as claimed in claim 4 or 5,

wherein a control device (100) is also provided, said control device being designed to actuate the fan (5) which is associated with the first sorption unit (3), the heating unit (7) which is associated with the first sorption unit (3), the fan (6) which is associated with the second sorption unit (4), and the heating unit (8) which is associated with the second sorption unit (4) during a drying phase in the first region (2a) of the treatment chamber (2) in such a way that air is conducted out of the first region (2a) through the first sorption unit

(3) in such a way that the dry material of the first sorption unit (3) absorbs moisture from the air stream while, at the same time as or with a time delay with respect to or during a wash and/or final rinse phase in the second region (2b) of the dishwasher, the dry material of the second sorption unit (4) is heated and air is conducted out of the treatment chamber (2) through the second sorption unit (4), which contains the heated dry material, in such a way that moisture is desorbed from the dry material and at least a portion of the thermal energy which was previously introduced into the dry material and at least a portion of the moisture which is desorbed from the dry material is discharged from the second sorption unit (4) with the aid of the air stream which is conducted through the second sorption unit

(4) ·

7. The dishwasher (1) as claimed in claim 6,

wherein the control device (100) is also designed to actuate the heating unit (8) which is associated with the second sorption unit (4), preferably during the drying phase in the second region (2b) of the treatment chamber (2), in such a way that the dry material of the second sorption unit (4) is heated by thermal energy being supplied, and wherein the control device (100) is also designed to actuate the fan (6) which is associated with the second sorption unit (4) with a time delay with respect to or at the same time as the actuation of the heating unit (8) which is associated with the second sorption unit (4) in such a way that air is conducted out of the second region (2b) of the treatment chamber (2) through the second sorption unit (4).

8. The dishwasher (1) as claimed in claim 6 or 7,

wherein a sensor device (9) which is connected or can be connected to the control device (100) is also provided for the purpose of ascertaining the moisture-absorption capacity and/or the temperature of the dry material of the first and/or second sorption unit (3, 4), and wherein the control device (100) is designed to initiate or to terminate the adsorption phase and/or the desorption phase of the corresponding sorption unit (3, 4) as a function of the ascertained moisture-absorption capacity and/or temperature of the dry material of the first and/or second sorption unit (3, 4), preferably automatically, and more preferably selectively automatically.

9. The dishwasher (1) as claimed in one of claims 1 to 8, which also has a first wash system which is associated with the first region (2a) and has a second wash system which is associated with the second region (2b), wherein the first and second wash system are each in the form of a recirculation circuit and have a nozzle system with at least one wash nozzle (11a, l ib) for spraying wash liquid onto the washware which is accommodated in the corresponding region (2a, 2b) of the treatment chamber (2), a wash tank (12a, 12b), which is arranged beneath the corresponding region (2a, 2b) of the treatment chamber (2), for capturing at least a portion of the wash liquid which is sprayed in the corresponding region (2a, 2b) of the treatment chamber (2), and at least one wash pump (13a, 13b) for supplying wash liquid which has collected in the wash tank (12a, 12b) to the at least one wash nozzle (11), wherein a first final rinse system, which is associated with the first region (2a), and a second final rinse system, which is associated with the second region (2b), each with at least one final rinse pump (14a, 14b) and a final rinse nozzle system (15a, 15b), which is arranged in the corresponding region (2a, 2b) of the treatment chamber (2), are provided in order to spray final rinse liquid, in particular fresh water, in the region (2a, 2b) of the treatment chamber (2) during a final rinse phase in the first or second region (2a, 2b) of the treatment chamber (2).

10. The dishwasher (1) as claimed in one of claims 1 to 9,

wherein the drying device has a first heat exchanger unit (17) which is associated with the first sorption unit (3) in such a way that, when the first air circuit is formed, at least a portion of the drying air which is routed through the first sorption unit (3) then passes the first heat exchanger unit (17), and wherein the drying device has a second heat exchanger unit (18) which is associated with the second sorption unit (4) in such a way that, when the second air circuit is formed, at least a portion of the drying air which is routed through the second sorption unit (4) then passes the second heat exchanger unit (18).

11. The dishwasher (1) as claimed in one of claims 1 to 9,

wherein the drying device has a heat exchanger unit which is jointly associated with the first and second sorption units (3, 4) in such a way that, when the first and/or second air circuits or circuit are/is formed, at least a portion of the drying air which is routed through the first and/or second sorption unit (3, 4) then passes the common heat exchanger unit.

12. The dishwasher (1) as claimed in claims 9 and 10 or 9 and 11,

wherein the first and second heat exchanger units (17, 18) or the common heat exchanger unit each have a heat exchanger which is cooled with water, in particular fresh water, and also have an inlet which is connected or can be connected to a fresh water supply line, and have an outlet which is connected or can be connected to the first and/or second wash nozzle system (13a, 13b) and/or to the first and/or second final rinse nozzle system (15a, 15b).

13. The dishwasher (1) as claimed in one of claims 1 to 10,

wherein the dry material preferably contains zeolite, in particular type-Y zeolite.

14. The dishwasher (1) as claimed in one of claims 1 to 13,

wherein a sensor device (9) for the purpose of ascertaining the moisture-absorption capacity and/or the temperature of the dry material of the first and/or the second sorption unit (3, 4) and a control device (100) are also provided, wherein the control device (100) is designed to induce the output of a corresponding visual and/or audible indication or regeneration of the dry material when the ascertained moisture-absorption capacity and/or the temperature of the dry material falls below/exceeds a predefined or predefmable value.

15. A method for operating a commercial dishwasher (1) which is in the form of a batch dishwasher, in particular a dishwasher (1) as claimed in one of claims 1 to 14, wherein the dishwasher (1) has a treatment chamber (2) for accommodating washware which is to be cleaned, wherein the treatment chamber (2) is divided into a first region (2a) and a second region (2b) which is or can be physically separated from said first region, and wherein the method comprises the following method steps:

i) during an adsorption phase in the first or second region (2a, 2b) of the treatment chamber (2), air is conducted out of the corresponding region (2a, 2b) of the treatment chamber (2) through a sorption unit (3, 4), which contains a reversibly dehydratable dry material, in such a way that the dry material absorbs moisture from the air stream, wherein the air is then returned to the region (2a, 2b) of the treatment chamber (2); and

ii) during a desorption phase in the first or second region (2a, 2b) of the treatment chamber (2), the dry material of the sorption unit (3, 4) is heated and air is conducted out of the corresponding region (2a, 2b) of the treatment chamber (2) through the sorption unit (3, 4), which has the heated dry material, in such a way that moisture is desorbed from the dry material and at least a portion of the thermal energy which was previously introduced into the dry material and at least a portion of the moisture which was desorbed from the dry material are discharged from the sorption unit (3, 4) with the aid of the air stream which is conducted through the sorption unit (3, 4), wherein at least a portion of the thermal energy which is discharged from the sorption unit (3, 4) with the air stream being transferred in a heat exchanger unit (17, 18, 19) which is cooled by water, in particular fresh water, to the cooling water of the heat exchanger unit (17, 18, 19), and wherein the cooling water which is heated in the heat exchanger unit (17, 18, 19) is then sprayed in the treatment chamber (2) of the dishwasher (1) as final rinse liquid during a final rinse phase and/or as wash liquid during a wash phase.

16. The method as claimed in claim 15,

wherein, in method step ii), the air stream which is conducted through the sorption unit (3, 4) which contains the heated dry material is then cooled in the heat exchanger unit (17, 18) in such a way that at least a portion of the moisture which was previously desorbed from the dry material and discharged from the sorption unit (3, 4) with the air stream is condensed, and wherein the air is returned to the corresponding region of the treatment chamber (2) again after passing the heat exchanger unit (17, 18).

17. The method as claimed in claim 15 or 16,

wherein the dishwasher (1) has a first sorption unit (3) and at least one second sorption unit (4), these sorption units being operated in antiphase to one another in such a way that, in the first sorption unit (3), the method step ii) is carried out and the dry material of the first sorption unit (3) is regenerated, while, in the second sorption unit (4), the method step i) is carried out and the dry material of the second sorption unit (4) absorbs moisture from the air which is circulating in the second region (2b) of the treatment chamber (2) of the dishwasher (1).