Dishwasher with heat recovery device

Abstract

The invention relates to a dishwasher (1), wherein the dishwasher (1) has a heat recovery device which is designed to recover at least part of the thermal energy of the exhaust air discharged from the dishwasher (1) during operation of the dishwasher (1) as useful heat and to transfer it to a treatment liquid to be sprayed in the dishwasher (1).According to the invention, it is particularly provided that the heat recovery device has a primary circuit system (5) with a heat pump assembly and a first secondary circuit system (6), wherein the first secondary circuit system (6) has a first heat exchanger unit (22) which is designed such that at least a portion of the energy to be recovered from the exhaust air is transferred to a carrier medium circulating in the first secondary circuit system (6), wherein the first secondary circuit system (6) has a second heat exchanger unit (23) which is designed such that at least a portion of the thermal energy transferred to the carrier medium via the first heat exchanger unit (22) is transferred as useful heat for heating the treatment liquid to be sprayed in the dishwasher (1) to a coolant of the heat pump assembly of the primary circuit system (5) circulating in the primary circuit system (5).

Description

[0001] The present invention relates generally to the field of commercial dishwashing in particular.

[0002] In particular, the present invention relates to a dishwasher, in particular a commercial dishwasher, which is designed as a program machine or as a conveyor dishwasher.

[0003] According to one aspect of the invention, this particularly relates to a conveyor dishwasher with a transport device for transporting washware through the individual treatment zones of the conveyor dishwasher, wherein the conveyor dishwasher has at least one wash zone in which wash liquid is sprayed onto the washware from a wash tank assigned to the wash zone. The conveyor dishwasher according to this aspect of the invention further has at least one final rinse zone arranged behind the at least one wash zone, as seen in the transport direction of the washware, in which final rinse liquid is sprayed onto the washware. Furthermore, the conveyor dishwasher has an exhaust air system for removing exhaust air generated during operation of the machine from the conveyor dishwasher.

[0004] A conveyor warewasher according to the present invention is in particular a belt conveyor warewasher (slight-type warewasher) or a rack conveyor warewasher (rack conveyer warewasher).

[0005] A conveyor dishwasher of the type mentioned above is, in principle, known from the state of the art and is typically used in commercial applications. Unlike so-called program-controlled dishwashers, in which the items to be cleaned remain stationary in the machine during cleaning, conveyor dishwashers transport the items through various treatment zones.

[0006] A conveyor dishwasher typically has at least one pre-wash zone and at least one main wash zone as treatment zones, which are located after the pre-wash zone(s) in the direction of transport of the washware. Viewed in the direction of transport, at least one final rinse zone is usually located after the main wash zone(s).

[0007] It is also known to provide at least one post-wash zone or pre-rinse zone between the main wash zone and the final rinse zone.

[0008] Viewed in the transport direction of the wash ware, the wash ware, which is either picked up directly on a conveyor belt or held by wash baskets, usually runs through an inlet tunnel, the adjoining pre-wash zone(s), main wash zone(s), any provided post-wash zone(s), final rinse zone(s), a drying zone into an outlet section.

[0009] Each of the aforementioned wash zones (pre-wash zone(s), main wash zone(s), and any post-wash zone(s)) of the conveyor dishwasher is assigned a wash system. This system includes a wash pump and a piping system connected to the wash pump, through which wash liquid is supplied to the corresponding spray nozzles in the wash zones. The wash liquid supplied to the spray nozzles is sprayed onto the washware in the respective wash zone, which is then transported through the respective wash zones by a conveyor device of the conveyor dishwasher.

[0010] Each washing zone is assigned a washing tank in which sprayed liquid is collected and / or in which liquid is provided for the spray nozzles of the respective zones.

[0011] In conventional conveyor dishwashers, rinse aid in the form of fresh water, which can be pure or mixed with other additives such as rinse aid, is sprayed onto the washware via the spray nozzles in the rinse zone. At least a portion of the sprayed rinse aid is transported from treatment zone to treatment zone via a cascade system, counter to the direction of travel of the washware.

[0012] The sprayed rinse aid liquid is collected in a tank (post-wash tank) in the post-wash zone, from which it is pumped to the spray nozzles (post-wash nozzles) of the post-wash zone via the wash pump of the wash system belonging to the post-wash zone. In the post-wash zone, wash liquid is rinsed off the dishes. The resulting liquid flows into the wash tank of at least one main wash zone, which is located upstream of the post-wash zone in the direction of transport of the dishes. Here, the liquid is usually treated with a cleaning agent and sprayed onto the dishes via the nozzles (wash nozzles) of the main wash zone by a pump system (wash pump system) belonging to the wash system of the main wash zone.

[0013] From the wash tank of the main wash zone, the liquid then flows into the pre-wash tank of the pre-wash zone—unless another main wash zone is provided. The liquid in the pre-wash tank is sprayed onto the washware via the pre-wash nozzles of the pre-wash zone by a pump system belonging to the pre-wash zone's wash system to remove coarse contaminants from the washware.

[0014] In the field of commercial dishwashing, there are various standards and guidelines that define the requirements regarding the hygiene performance of cleaning processes and their process testing. What all standards and guidelines have in common is that minimum temperatures are prescribed in the washing and rinsing zones of commercial dishwashers during the cleaning process. This is intended to ensure, among other things, at least partial thermal disinfection.

[0015] The requirements regarding the specified minimum temperatures in the relevant treatment zones of the conveyor dishwasher mean that a relatively large amount of energy is required during operation of the commercial dishwasher to heat the washing or rinsing liquids to the required minimum temperatures. On the other hand, in currently known conveyor dishwashers, up to 55% of the energy consumed during operation is lost as heat to the wastewater and exhaust air.

[0016] The problem discussed above with reference to a conveyor dishwasher, namely that a large part of the energy used during operation of the dishwasher is released as waste heat to waste water and exhaust air, also exists in dishwashers, in particular commercial dishwashers which are designed as programmable machines.

[0017] Programmable dishwashers are manually loaded and unloaded. These automated dishwashers (also known as box-type or batch dishwashers) can be pass-through dishwashers, also called hood-type warewashers, or front-loaders. Front-loaders can be undercounter machines, top-counter machines, or freestanding front-loaders.

[0018] A dishwasher designed as a programmable automatic machine typically has a treatment chamber for cleaning dishes. A wash tank is usually located below the treatment chamber, into which liquid from the treatment chamber can flow back by gravity. The wash tank contains wash liquid, which is usually water, to which detergent can be added if necessary.

[0019] A dishwasher designed as a programmable automatic machine typically also has a wash system with a wash pump, a pipe system connected to the wash pump, and a plurality of spray nozzles formed in at least one wash arm. The wash liquid in the wash tank can be pumped by the wash pump via the pipe system to the wash nozzles and sprayed onto the items to be cleaned by the wash nozzles in the treatment chamber. The sprayed wash liquid then flows back into the wash tank.

[0020] Such a dishwasher designed as a programmer is known, for example, from the document DE 10 2005 023 429 A1.

[0021] The term "washable items" as used herein includes, in particular, dishes, glasses, cutlery, cooking utensils, baking utensils and serving trays.

[0022] A commercial dishwasher designed as a programmable automatic dishwasher differs from a domestic dishwasher in that a commercial dishwasher must be designed to allow program runs of between one and five minutes, depending on the selected cleaning program, whereas domestic dishwashers typically have run times of up to 2.5 hours or more. Due to the short program durations required for commercial dishwashers, the technologies used in domestic dishwashers are generally not readily transferable to commercial dishwashers.

[0023] Commercial dishwashers designed as programmable automatic machines usually operate in two main process steps: a first step, which involves washing with a washing liquid, and a second step, which involves rinsing with heated fresh water and dosed rinse aid.

[0024] To perform these process steps, a commercial dishwasher designed as a programmable automatic machine is typically equipped with two independent, completely separate fluid systems. One fluid system is a wash water circuit, which is responsible for washing the dishes, with the washing being carried out using recirculated water from the dishwasher's wash tank. The other fluid system is a fresh water system, which is responsible for the final rinse. The final rinse is carried out with fresh water, preferably fresh water from a water heater. The fresh water, after spraying, is also collected by the dishwasher's wash tank.

[0025] The primary function of the final rinse is to remove any caustic soda from the washware. In addition, the rinse water flowing into the wash tank during the final rinse step serves to regenerate the wash water present in the wash tank.

[0026] Before fresh water is sprayed as rinse aid through the final rinse and thus fed into the wash tank of the dishwasher, an amount of wash liquid equal to the amount of fresh water is pumped out of the wash tank.

[0027] Commercial dishwashers designed as programmable automatic dishwashers are typically equipped with several programs. These programs differ primarily in the length of the wash cycle. The operator has the option of selecting a short wash program for lightly soiled items or a correspondingly longer wash program for heavily soiled items.

[0028] Commercial dishwashers designed as automatic programmers and for batch-wise loading and unloading of the treatment chamber with wash ware are primarily front-loading machines or pass-through rack machines. With front-loading machines, the wash ware is placed in a rack, and the loaded rack is placed through a front door into the treatment chamber of the dishwasher and removed again through the front door after cleaning. With pass-through rack machines, the loaded dish baskets are manually pushed into the treatment chamber from an inlet side and manually removed from the treatment chamber from an outlet side after the end of a wash program. Front-loading machines and pass-through rack machines contain only a single treatment chamber for treating the wash ware. Front-loading machines can be undercounter or overcounter machines.

[0029] In commercial dishwashers designed as programmable automatic dishwashers, two drying processes are primarily used. In the first process, the hot dishes are removed from the machine after the final rinse process, where they are then allowed to dry in the ambient air for four to ten minutes. In the process described above, the dishes are usually left in the racks in which they were placed for cleaning in the dishwasher.

[0030] According to the second method, air drying takes place within the treatment chamber of the dishwasher. This involves the use of fresh air drying systems. Such fresh air drying systems for commercial front-loading or undercounter dishwashers always operate with a high air volume flow in the range of 25 to 100 m³ per hour in order to dry the dishes remaining in the treatment chamber in a very short time. The high air volume flows are due to the short drying process in commercial applications. Compared to conventional drying in a household dishwasher, the active drying time of a commercial dishwasher is many times shorter. While the program runtime for drying in a household dishwasher is approximately 30 minutes to 2.5 hours, the program runtime for drying in commercial applications is between 1.5 and 5 minutes.

[0031] During air drying in a programmable commercial dishwasher, fresh air is drawn in from outside and passed through the dishwasher's treatment chamber to absorb moisture from the items being dried. Typically, the moisture-laden drying air is then exhausted into the dishwasher's installation space.

[0032] Particularly in dishwashing areas where several programmable dishwashers are operated, sometimes simultaneously, the discharge of drying air into the room where the dishes are stored has a negative impact on the indoor climate. This is because the discharge of moisture-laden drying air, which is warm compared to the air in the room where the dishes are stored, inevitably increases the humidity of the air in the room (ambient air). In particular, there is a risk that the humidity of the air in the room will be increased to such an extent that undesirable condensation of water vapor occurs, particularly at cool interfaces in the room.

[0033] Apart from this, the shortened drying time required for programmed machines is inevitably accompanied by increased energy consumption in order to heat the drying air accordingly.

[0034] In order to save resources, in particular energy, during the operation of a dishwasher - whether a machine designed as a programmable automatic dishwasher or as a conveyor dishwasher - it is already known from the state of the art to use waste water and exhaust air heat recovery systems with which at least part of the kinetic energy of the waste water and / or the exhaust air of the machine can be recovered as useful heat.

[0035] In this regard, reference is made, for example, to document DE 10 2014 208 813 A1, which relates to a conveyor dishwasher with a heat recovery device.

[0036] A heat pump device is used as the exhaust air heat recovery system in the conveyor dishwasher known from this prior art. With the help of this heat pump device, a portion of the kinetic energy of the conveyor dishwasher's exhaust air is transferred to a refrigerant circulating in the heat pump device. The recovered kinetic energy is absorbed by evaporating the refrigerant at low pressure in an evaporator device. The gaseous refrigerant is subsequently compressed by a compressor unit to a higher pressure level and then liquefied at a high temperature in a condenser unit. The refrigerant is then expanded back to the evaporation pressure with the help of an expansion valve device. The condensation temperature of the refrigerant in the condenser device is used to heat the final rinse or wash liquid of the conveyor dishwasher.For this purpose, a corresponding heat exchanger is provided in the rinse aid tank or washing liquid tank.

[0037] Heat pump technology therefore offers an effective method for recovering the energy stored in the warm, humid exhaust air of a dishwasher. The warm, humid air flow of the dishwasher's exhaust air can be passed through an evaporator device of a refrigeration system, which cools the machine's exhaust air to ambient temperature. The energy transfer causes the heat pump's refrigerant to evaporate. After complete evaporation and superheating, it is compressed in a gaseous state by the heat pump compressor and brought to a higher pressure and temperature level. On the high-pressure side, the energy is transferred as heat to the washing, rinsing, and / or drying zones of the conveyor dishwasher. In the process, the refrigerant condenses, liquefies, and subcools before being released via an expansion valve, thereby reaching a lower pressure level.

[0038] Heat pump technology makes it possible to fully recover the energy contained in the exhaust air, thus supplying the exhaust air to the installation room (scullery) in an energy-neutral manner. Therefore, no on-site exhaust system is required, as the machine's exhaust air can be fed directly into the room.

[0039] The exhaust air heat pumps currently in use are operated with the refrigerants R513a in Europe and R450a in North America. Compared to the previously used refrigerant R134a, these two refrigerants already have significantly better GWP values of 631 and 605, respectively, compared to 1,430 for R134a.

[0040] "GWP" is the abbreviation for "Global Warming Potential," meaning the global warming or greenhouse potential of a substance. The GWP value of a refrigerant defines its relative greenhouse potential in relation to CO2 (also known as CO2 equivalent).

[0041] The refrigerants mainly used in heat pumps to date, in particular R513a and R450a, are also not harmless for various environmental and climate protection reasons, as they still have a significant greenhouse effect.

[0042] Accordingly, there is an effort to specify a waste water and / or exhaust air heat recovery system for a dishwasher, in particular a commercial one, wherein the waste water and / or exhaust air heat recovery system has the lowest possible potential negative environmental impacts.

[0043] Natural refrigerants, such as propane (R290a) or isobutane (R600a), have the advantage of having a significantly lower GWP value of 3 compared to, for example, the refrigerant R513a or the refrigerant R450a. However, unlike R513a and R450a, these refrigerants are highly flammable, which, with regard to the operational safety of the system, entails some serious changes to the familiar heat pump concept for commercial dishwashers.

[0044] It should be noted that heat pump systems using natural refrigerants, especially hydrocarbons (such as propane R290a or isobutane R600a), may only be used to a limited extent, if at all, in enclosed spaces.

[0045] Hydrocarbons are flammable and are classified in safety group A3 according to DIN EN 378-1:2016+A1:2020. According to the current product safety standard DIN EN 60335-2-40:2014-01, flammable refrigerants can only be used indoors at lower capacities and with a very low refrigerant charge (regardless of the size of the room). For larger charge quantities, special measures, such as forced ventilation, are required.

[0046] Therefore, hydrocarbons are currently only used in low-capacity heat pumps for heating and primarily in outdoor heat pumps. For outdoor use, fill volumes of up to 5 kg are permitted.

[0047] The natural refrigerant R744 (CO2) is characterized by its thermodynamic properties and high coefficients of performance when used in domestic hot water heat pumps. However, its application in heat pumps for dishwashers is limited by its supercritical heat dissipation. For CO2 heat pumps, the energy efficiency is lower at narrower temperature ranges, such as for exhaust air heat recovery. Both R744 (CO2) and R717 (ammonia) are primarily used in higher performance ranges and currently have little relevance for heat pumps for dishwashers.

[0048] Due to this problem, the present invention is based on the object of specifying a dishwasher, in particular a commercial dishwasher, with an exhaust air and / or waste heat recovery system, wherein the exhaust air / waste water heat recovery system does not have the problems with regard to environmental and climate protection described in connection with the previously commonly used refrigerants R513a or R450a, and wherein at the same time the heat recovery system can be used in the interior or in a dishwashing area without additional structural measures.

[0049] This object is achieved according to the invention by the subject matter of independent patent claim 1, wherein advantageous further developments thereof are specified in the dependent claims.

[0050] Accordingly, the invention relates in particular to a dishwasher, in particular a commercial dishwasher, which is designed as a programmable automatic dishwasher and preferably as a conveyor dishwasher. The dishwasher has a heat recovery device which is designed to recover at least a portion of the thermal energy of the exhaust air discharged or to be discharged from the dishwasher during operation of the dishwasher as useful heat and to transfer it to at least one treatment liquid to be sprayed in the dishwasher and / or to a drying air used for drying in the dishwasher. The at least one treatment liquid to be sprayed in the dishwasher is in particular wash liquid and / or rinse aid liquid.

[0051] The solution according to the invention is characterized in particular by the fact that the heat recovery device is divided into different circulation systems, whereby care is taken to ensure that a refrigerant circulating in one of the circulation systems can escape and accumulate in the dishwasher due to, for example, a defect, a leak or incorrect operation.

[0052] Specifically, the invention provides that the heat recovery device comprises a primary circuit system with a heat pump assembly and a first secondary circuit system. The first secondary circuit system comprises a first heat exchanger unit, which is designed such that at least a portion of the energy to be recovered from the dishwasher's exhaust air is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the first secondary circuit system.

[0053] The first secondary circuit system further comprises a further, second heat exchanger unit which is designed such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the first secondary circuit system to the (fluid and in particular liquid) carrier medium circulating in the first secondary circuit system is transferred or can be transferred as useful heat for heating the at least one treatment liquid to be sprayed in the dishwasher and / or for heating the drying air to a refrigerant of the heat pump assembly of the primary circuit system circulating in the primary circuit system.

[0054] The advantages achievable with the solution according to the invention are obvious: in particular, the division of the heat recovery device into a primary circuit system on the one hand and a first secondary circuit system on the other allows a natural hydrocarbon-based refrigerant, such as propane (R290A), isobutane (R600A), or propane-propene (R441A), to be used as the refrigerant circulating in the primary circuit system. Compared to, for example, the refrigerant R513A or the refrigerant R450A, these natural refrigerants have the advantage of having a significantly lower GWP value of 3.

[0055] Although natural and hydrocarbon-based refrigerants, in contrast to, for example, R513A and R450A, have the disadvantage of being highly flammable, which entails some serious changes to the known heat pump concept for commercial dishwashers with regard to the operational safety of the system / dishwasher, by dividing the heat recovery device into the primary circuit system and the first secondary circuit system, it can be achieved in an easy-to-implement but nevertheless effective manner that, on the one hand, the refrigerant charge, i.e. the amount of refrigerant circulating in the primary circuit system, can be limited to the smallest possible minimum.

[0056] On the other hand, the solution according to the invention provides that the first secondary circuit system (and only the first secondary circuit system) comes into contact with the dishwasher's exhaust air. The primary circuit system with the hydrocarbon-based refrigerant is encapsulated by the dishwasher's exhaust air system, so that in the event of a leak or refrigerant escaping from the primary circuit system, there is no risk of the hydrocarbon-based refrigerant accumulating, for example, in the dishwasher's sump, which could lead to a risk of explosion.

[0057] In addition, the solution according to the invention makes it possible to limit the refrigerant charge to the lowest possible minimum. The invention is based, among other things, on the finding that the smaller the amount of refrigerant in the primary circuit system that can escape in the event of a leak or similar event, the lower the risk of an ignitable mixture forming with the ambient air, which could pose a significant safety risk.

[0058] The inventive design, particularly of the heat recovery device, primarily aims to keep the overall structure of the actual heat pump as compact as possible. This involves, on the one hand, using components that are as small in volume as possible. On the other hand, the focus of this design is primarily on adapting the basic functional concept of the heat pump to make it as compact as possible and to avoid the previously common long refrigerant lines, especially to the liquid tank (e.g., washing tank) and / or the dryer.

[0059] The invention is based in particular on the finding that, in currently known heat pump concepts for commercial dishwashers for heating machine zones, such as the wash zone, final rinse zone, and drying zone, the respective machine zones are always directly supplied with the heat pump's hot refrigerant. This is achieved by directing the hot refrigerant via relatively long refrigerant lines from the evaporator unit, including the compressor, directly into a heat exchanger in the wash tank or, optionally, also into the drying tank. There, the hot refrigerant then transfers the energy to the wash water or, optionally, also to the drying air, and then flows back to the evaporator unit through further relatively long refrigerant lines.

[0060] In order to achieve efficient heat transfer in the washing tank, a heat exchanger (condenser) with a comparatively large heat exchange surface of approximately 1.5 to 2 m 2 is required, which, due to the current operating principle of direct refrigerant loading of the heat exchanger, entails a very high refrigerant filling quantity.

[0061] With the approach presented in independent patent claim 1, this problem is solved in a particularly easy to implement but nevertheless efficient manner.

[0062] According to the invention proposed in independent patent claim 1, the heating of the dishwasher's operating fluid (rinse aid or wash fluid) or the drying air is no longer carried out directly by means of a refrigerant directly applied to the respective treatment zone of the dishwasher, but rather by means of an additional secondary circuit. This makes it possible to implement the entire heat pump as a small, compact, and above all, self-contained unit, for example, on the roof of the conveyor dishwasher, without having to supply refrigerant directly to the consumers.

[0063] In the solution according to the invention, this is achieved by providing the (first) secondary circuit, using an additional carrier medium, such as water. The carrier medium is heated to approximately 80°C in the heat pump assembly using a compact plate heat exchanger and then fed into the heat exchanger, for example, in the wash tank, by means of an additional circulation pump. There, it then transfers the energy to the wash water before flowing back into the heat exchanger of the heat pump assembly, which is preferably designed as a plate heat exchanger, and the cycle begins again.

[0064] Preferably, the secondary circuit is a closed secondary circuit.

[0065] According to a conceivable realization of the dishwasher according to the invention, it is provided that the heat pump assembly of the primary circuit system is designed to transfer, via at least one heat exchanger unit of the heat pump assembly, at least part of the thermal energy transferred via the second heat exchanger unit of the first secondary circuit system to the coolant of the heat pump assembly of the primary circuit system circulating in the primary circuit system directly as useful heat to the at least one treatment liquid to be sprayed in the dishwasher and / or to the drying air.

[0066] It is conceivable that the heat exchanger unit of the heat pump assembly is located in a wash tank of the dishwasher and / or in a container for temporarily storing rinse aid. Alternatively or additionally, the heat exchanger unit of the heat pump assembly can be located in an area where the drying air of the dishwasher is heated.

[0067] As an alternative to a direct transfer of the recovered thermal energy as useful heat to the at least one treatment liquid to be sprayed in the dishwasher and / or to the drying air, it is conceivable for the heat recovery device to further comprise at least one second secondary circuit system which comprises a first heat exchanger unit which is designed such that at least a portion of the thermal energy transferred to the coolant of the heat pump assembly of the primary circuit system circulating in the primary circuit system is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the second secondary circuit system.The second secondary circuit system can have at least one second heat exchanger unit which is designed such that at least a part of the thermal energy transferred via the first heat exchanger unit of the second secondary circuit system to the carrier medium circulating in the second secondary circuit system is transferred or can be transferred as useful heat to the at least one treatment liquid to be sprayed in the dishwasher and / or to the drying air.

[0068] In principle, it is preferred that the heat pump assembly of the primary circuit system is designed to be separated from an exhaust air system, in particular an exhaust air duct system, of the dishwasher, via which the exhaust air from the dishwasher is or can be discharged during operation of the dishwasher, in such a way that no duct system of the heat pump assembly of the primary circuit system, in which the coolant of the heat pump assembly of the primary circuit system is present or circulates, is present in the exhaust air system, in particular exhaust air duct system.

[0069] In other words, the heat pump assembly of the primary circuit system is preferably encapsulated and, in particular, hermetically sealed with respect to the exhaust air system / exhaust air duct system of the dishwasher.

[0070] In a conceivable implementation, particularly of the last-mentioned embodiment of the dishwasher according to the invention, it is provided that the heat pump assembly of the primary circuit system is at least partially or regionally, and preferably completely, accommodated in a corresponding housing, wherein the housing is different from the machine housing of the dishwasher. Preferably, at least one air exchange opening is formed in the housing of the heat pump assembly, via which the interior of the housing is in fluid communication with the outside atmosphere and, in particular, with the atmosphere of the room in which the dishwasher is installed.

[0071] It is advisable that at least one fan is preferably assigned to the at least one air exchange opening of the housing of the heat pump assembly of the primary circuit system, in particular for forced ventilation of the housing as required.

[0072] In preferred embodiments of the dishwasher according to the invention, the refrigerant circulating in the primary circuit system is a natural refrigerant, in particular based on hydrocarbons, and preferably a refrigerant that is preferably propane or isobutane or contains propane or isobutane. In this context, it is conceivable that the refrigerant of the primary circuit system is, in particular, a refrigerant belonging to the R290A or R600A group.

[0073] In addition, the mass of the refrigerant circulating in the primary circuit system can be drastically reduced to a maximum of 400 g and, in particular, a maximum of 150 g.

[0074] The first and / or second secondary circulation system of the dishwasher according to the invention can be designed as a closed circulation system. In particular, in these embodiments, the carrier medium circulating in the first and second secondary circulation systems is a water-based carrier medium, in particular water.

[0075] As an alternative to the design of the first and second secondary circuit systems each as a closed circuit system, it is also conceivable that at least the second secondary circuit system is designed as an open circuit system, wherein the carrier medium circulating in the second secondary circuit system is a treatment liquid to be sprayed in the dishwasher, in particular washing liquid or rinse aid liquid.

[0076] In order for the corresponding carrier medium to be able to circulate in the first and second secondary circuit systems, each secondary circuit system should be assigned a pump which can be controlled in particular via a control device of the dishwasher and with which the carrier medium can be conveyed through the corresponding secondary circuit system as required.

[0077] In conceivable implementations of the dishwasher according to the invention, in which the primary circuit system serves to transfer at least a portion of the thermal energy transferred via the second heat exchanger unit of the first secondary circuit system to the refrigerant of the heat pump assembly of the primary circuit system circulating in the primary circuit system directly as useful heat to the at least one treatment liquid to be sprayed in the dishwasher and / or to the drying air via at least one heat exchanger unit of the heat pump assembly of the primary circuit system, it is provided that the heat pump assembly of the primary circuit system is divided into a high-pressure zone and a low-pressure zone. The heat pump assembly has the following: An evaporator unit assigned to the low-pressure region of the heat pump assembly, which is configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the first secondary circuit system to the carrier medium circulating in the first secondary circuit system can be transferred to the refrigerant circulating in the primary circuit system, while simultaneously at least partially evaporating the refrigerant; A compressor unit fluidly connected to the evaporator unit, which is configured to compress the refrigerant at least partially evaporated in the evaporator unit to a higher pressure level;a condenser unit assigned to the high-pressure region of the heat pump assembly, which is in fluid communication with the compressor unit and is designed to condense the refrigerant compressed in the compressor unit at a high temperature, wherein at least a portion of the kinetic energy corresponding to the condensation temperature is transferred via the heat exchanger unit of the heat pump assembly directly as useful heat to the at least one treatment liquid to be sprayed in the dishwasher and / or to the drying air; and an expansion valve unit in fluid communication with the condenser unit and the evaporator unit, which is designed to expand the refrigerant liquefied in the condenser unit back to the evaporation pressure.

[0078] In the alternative embodiment of the dishwasher according to the invention, in which at least one further, second secondary circuit system is used in addition to the first secondary circuit system, which second secondary circuit system has a second heat exchanger unit designed such that at least part of the thermal energy transferred via the first heat exchanger unit of the second secondary circuit system to the carrier medium circulating in the second secondary circuit system is transferred as useful heat to the at least one treatment liquid to be sprayed in the dishwasher and / or to the drying air, it is also provided that the heat pump assembly of the primary circuit system is divided into a high-pressure area and a low-pressure area, whereby the heat pump assembly has the following: An evaporator unit assigned to the low-pressure region of the heat pump assembly, which is configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the first secondary circuit system to the carrier medium circulating in the first secondary circuit system can be transferred to the refrigerant circulating in the primary circuit system, while simultaneously at least partially evaporating the refrigerant; A compressor unit fluidly connected to the evaporator unit, which is configured to compress the refrigerant at least partially evaporated in the evaporator unit to a higher pressure level;a condenser unit assigned to the high-pressure region of the heat pump assembly, which is in fluid communication with the compressor unit and is designed to condense the refrigerant compressed in the compressor unit at a high temperature, wherein at least a portion of the kinetic energy corresponding to the condensation temperature is transferred via the first heat exchanger unit of the second secondary circuit system to the carrier medium circulating in the second secondary circuit system; and an expansion valve unit in fluid communication with the condenser unit and the evaporator unit, which is designed to expand the refrigerant liquefied in the condenser unit back to the evaporation pressure.

[0079] According to preferred implementations of the dishwasher according to the invention, it is provided that the second secondary circuit system has a heat exchanger unit which is in fluid communication with the heat exchanger unit of the heat pump assembly via a first branch line system or, if required, can be brought into fluid communication with the heat exchanger unit of the heat pump assembly by means of a first valve arrangement, wherein the second secondary circuit system further has at least one second heat exchanger unit which is in fluid communication with the heat exchanger unit of the heat pump assembly via a second branch line system running in particular parallel to the first branch line system or, if required, can be brought into fluid communication with the heat exchanger unit of the heat pump assembly by means of a second valve arrangement.

[0080] The heat pump assembly is preferably designed as a replaceable or interchangeable module of the dishwasher.

[0081] Thus, the present invention also relates to a heat pump assembly as such, and not necessarily in combination with a dishwasher.

[0082] In this context, it is preferably provided in particular that the units of the heat pump assembly are accommodated in a separate housing, which is arranged or can be arranged on the dishwasher in such a way that the units of the heat pump assembly are accessible from the outside.

[0083] In particular, the heat pump assembly is designed as a replaceable or interchangeable module of the dishwasher. The module can preferably be placed on the roof of the dishwasher and is therefore easily replaceable in the event of a service call without the need for a refrigeration technician, as the refrigeration system no longer needs to be opened (as was previously the case).

[0084] The second secondary circuit allows several consumers or machine zones to be operated in parallel in a simple manner, particularly by means of additional valve devices, so that the heating output can be distributed to one or more consumers as required, without the need for complex circuits or controls in the refrigeration circuit.

[0085] The invention is described in more detail below using an exemplary embodiment with reference to the accompanying drawings.

[0086] It shows: FIG. 1 schematically shows an exemplary embodiment of the dishwasher according to the invention, which in this embodiment is designed as a conveyor dishwasher.

[0087] In FIG. 1 As an example of the solution according to the invention, a conveyor dishwasher 1 is shown in a schematic longitudinal sectional view.

[0088] The FIG. 1 The exemplary embodiment of the conveyor dishwasher 1 shown has a pre-wash zone 11 and a main wash zone 12 arranged after the pre-wash zone 11 as seen in the transport direction T of the washware. As seen in the transport direction T after the main wash zone 12, in the FIG. 1 In the conveyor dishwasher 1 shown, a post-wash or pre-wash zone 13 and a final rinse zone 14 are arranged.

[0089] Viewed in the transport direction T, the wash ware, which is either picked up directly on a conveyor belt or held by baskets, runs through an inlet tunnel 10, the adjoining pre-wash zone 11, the main wash zone 12, the post-wash or pre-rinse zone 13, the final rinse zone 14, and through a drying zone 15 into an outlet section 17.

[0090] The aforementioned treatment zones 11, 12, 13 and 14 of the conveyor dishwasher 1 are each assigned spray nozzles, via which liquid is sprayed onto the items to be washed, which are transported by the conveyor belt through the respective treatment zones 11, 12, 13, 14.

[0091] Although in FIG. 1 Not shown, it is preferred if the spray nozzles, for example, of the washing system assigned to the pre-wash zone 11 and the main wash zone 12 are each formed in an upper and lower wash pipe, so that corresponding wash arms are used in these treatment zones 11, 12. It is conceivable here that the washing systems used have a plurality of wash pipes which form a wash arm battery, wherein the plurality of wash pipes is connected to a corresponding wash pump via a preferably common line system.

[0092] As in FIG. 1 As indicated, each washing zone (pre-wash zone 11, main wash zone 12, post-wash zone 13) is assigned a tank (wash tank 31, 32, 33) in which sprayed liquid is collected and / or in which liquid is provided for the spray nozzles of the respective zones 11, 12, 13.

[0093] The term "wash zone" used herein generally refers to a treatment zone to which a circulation tank (wash tank) is assigned, and in which the liquid collected in the circulation tank of the treatment zone is circulated by means of a wash pump assigned to the treatment zone. The term "wash zone" thus includes wash zone 11, main wash zone 12, but also, if applicable, a post-wash zone 13 located downstream of the main wash zone 12 in the transport direction T of the washware. Post-wash zone 13 is occasionally referred to in the field of commercial dishwashing as a "pump rinse zone" or "pre-wash zone." This is a recirculating rinse zone that precedes the fresh water rinse.

[0094] On the other hand, the term "rinse zone" used herein refers to a zone in which a fresh water rinse takes place, in which the items to be washed are sprayed with fresh water, which may contain rinse aid, in order to completely remove dirt particles and cleaning solution from the items to be washed.

[0095] At the FIG. 1 In the exemplary embodiment shown, the final rinse cycle takes place in the final rinse zone 14 before drying in the drying zone 15. A corresponding fan 21 is assigned to the drying zone 15 in order to circulate warm air around the already cleaned items and thereby dry them.

[0096] Furthermore, a FIG. 1 A control device 100, only shown schematically, is provided which, in the embodiment of the invention shown, serves (among other things) to suitably control the respective washing pumps of the washing zones 11, 12, 13 during a washing process in order to supply washing liquid to the corresponding spray nozzles at least temporarily via the associated line system.

[0097] At the FIG. 1 In the conveyor dishwasher 1 shown, rinse aid liquid in the form of fresh water, which may be mixed with other chemical additives such as rinse aid, is sprayed onto the FIG. 1 not shown. Although also not shown, laterally arranged spray nozzles can also be provided in the final rinse zone 14.

[0098] A portion of the rinse liquid sprayed in the rinse zone 14 is transported from zone to zone via a cascade system, counter to the transport direction T of the washware. The remaining portion is directed via a valve and a bypass line directly into the pre-wash tank 31 of the pre-wash zone 11 (not shown).

[0099] The rinse liquid sprayed in the final rinse zone 14 is collected in the tank (post-wash or pre-wash tank 33) of the post-wash or pre-wash zone 13, from which it is pumped to the spray nozzles 3 (post-wash or pre-wash nozzles) of the post-wash or pre-wash zone 13 via the wash pump belonging to the wash system of the post-wash or pre-wash zone 13. In the post-wash or pre-wash zone 13, the wash liquid is rinsed off the washware.

[0100] The resulting liquid flows into the wash tank 32 of the main wash zone 12, is usually provided with a cleaner and is sprayed onto the washware by means of a wash pump belonging to the wash system of the main wash zone 12 via spray nozzles (wash nozzles) of the wash system belonging to the main wash zone 12.

[0101] From the wash tank 32 of the main wash zone 12, the washing liquid then flows into the pre-wash tank 31 of the pre-wash zone 11. The washing liquid collected in the pre-wash tank 31 is sprayed onto the washware in the pre-wash zone 11 with the aid of a wash pump belonging to the wash system of the pre-wash zone via spray nozzles (pre-wash nozzles) of the wash system belonging to the pre-wash zone 11 in order to remove coarse contaminants from the washware.

[0102] It is conceivable that a portion of the washing liquid sprayed in the main wash zone 12 flows into the wash tank (pre-wash tank 31) of the pre-wash zone 11 via an overflow system. Like the main wash zone 12, the pre-wash zone 11 can be equipped with a tank cover screen designed as a flat screen. This tank cover screen is preferably arranged above the wash tank (pre-wash tank 31) of the pre-wash zone 11 in order to separate dirt particles from the washing liquid sprayed in the pre-wash zone 11 and flowing back into the pre-wash tank 31 by gravity. The mesh size of the tank cover screen is preferably in a range between approximately 1 mm and 4 mm.

[0103] Due to the heated wash and rinse liquid, vapors are generated when sprayed within the wash and rinse zones 11, 12, 13, 14 of the conveyor dishwasher 1. To prevent these vapors from escaping from the conveyor dishwasher 1, it is advantageous if FIG. 1 In the schematically illustrated embodiment, the individual treatment zones and in particular the washing and rinsing zones 11, 12, 13, 14 are separated by curtains.

[0104] In order to remove the steam clouds (vapours) and moist, warm air from the interior of the conveyor dishwasher 1 during operation, the conveyor dishwasher 1 is equipped with a machine-side exhaust air system 20 which is designed to remove at least a large part of the warm and moist air generated in the treatment zones 11, 12, 13, 14 during operation of the conveyor dishwasher 1 as exhaust air from the respective treatment zones 11, 12, 13, 14 of the machine.

[0105] At the FIG. 1 In the illustrated embodiment of the conveyor dishwasher 1 according to the invention, the central exhaust air system 20 is arranged in the area near the post-wash or pre-wash zone 13 and the final rinse zone 14. In the illustrated embodiment, the exhaust air system 20 has a single exhaust air fan 4, which can be controlled via the control device 100 in order to be able to adjust the flow rate of the exhaust air fan 4.

[0106] The exhaust air system 20 is further assigned an exhaust air heat recovery system, which can preferably also be controlled via the control device 100 and which serves to extract thermal energy continuously or as needed from the exhaust air to be discharged from the conveyor dishwasher 1 via the exhaust air system 20 and thus to cool the exhaust air to be discharged from the conveyor dishwasher 1.

[0107] The following is the FIG. 1 The heat recovery system used in the schematically illustrated exemplary embodiment of the conveyor dishwasher 1 is described in more detail.

[0108] In detail, the FIG. 1 In the embodiment shown, the heat recovery system or heat recovery device is designed as an exhaust air heat recovery device. However, it is also conceivable to use the heat recovery device as a wastewater heat recovery device.

[0109] The exhaust air heat recovery in FIG. 1 The heat recovery device (heat recovery system) serves to recover energy (and thus to save resources during operation of the conveyor dishwasher 1) and, in particular, to eliminate the need for on-site exhaust air extraction installations.

[0110] For this purpose, the FIG. 1 The schematically illustrated embodiment of the conveyor dishwasher 1 according to the invention has the already mentioned heat recovery device (heat recovery system) designed as an exhaust air heat recovery system, which operates according to the principle of heat pump technology.

[0111] The heat recovery device (heat recovery system) is divided into a primary circuit system 5 with a heat pump assembly, on the one hand, and a first and second secondary circuit system 6, 7, on the other. The first secondary circuit system 6 has a first heat exchanger unit 22, which is arranged in the exhaust air system 20 of the conveyor dishwasher 1 and is designed such that at least a portion of the energy to be recovered from the exhaust air is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the first secondary circuit system 6.

[0112] The first secondary circuit system 6 has a further, second heat exchanger unit 23, which is designed such that at least a part of the thermal energy transferred via the first heat exchanger unit 22 of the first secondary circuit system 6 to the carrier medium circulating in the first secondary circuit system 6 is transferred or can be transferred to a refrigerant of the heat pump assembly of the primary circuit system 5 circulating in the primary circuit system 5.

[0113] The second secondary circuit system 7 of the heat recovery device has a first heat exchanger unit 24 which is designed such that at least a part of the thermal energy transferred to the refrigerant of the heat pump assembly of the primary circuit system 5 circulating in the primary circuit system 5 is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the second secondary circuit system 7.

[0114] The second secondary circuit system 7 further comprises at least one second heat exchanger unit 25, which is designed such that at least a portion of the thermal energy transferred via the first heat exchanger unit 24 of the second secondary circuit system 7 to the carrier medium circulating in the second secondary circuit system 7 is transferred or can be transferred as useful heat to the washing liquid to be sprayed in the dishwasher 1.

[0115] It is provided that the heat pump assembly of the primary circuit system 5 is designed to be separated from the exhaust air system 20 of the dishwasher 1 in such a way that no duct system of the heat pump assembly of the primary circuit system 5, in which the refrigerant of the heat pump assembly of the primary circuit system 5 is present or circulates, is present in the exhaust air system 20.

[0116] In particular, the heat pump assembly is encapsulated with respect to the exhaust air system 20 of the dishwasher 1 and, in particular, is hermetically encapsulated.

[0117] Although in FIG. 1 Not shown, it is preferred that the heat pump assembly be accommodated at least partially or in regions, and preferably completely, in a housing. At least one air exchange opening can be formed in the housing, via which the interior of the housing is in fluid communication with the outside atmosphere and, in particular, with the atmosphere of the room in which the conveyor dishwasher 1 is installed. In this context, it is conceivable that at least one fan, for forced ventilation of the housing, in particular as needed, is assigned to the at least one air exchange opening of the housing of the heat pump assembly.

[0118] The refrigerant circulating in the primary circuit system 5 is, in particular, a natural refrigerant, preferably based on hydrocarbons. This is preferably a refrigerant that is propane or isobutane, or that contains propane or isobutane. A refrigerant belonging to the R290A or R600A group is particularly suitable.

[0119] The mass of the refrigerant circulating in the primary circuit system 5 is preferably a maximum of 150 g.

[0120] At the FIG. 1 In the embodiment of the conveyor dishwasher 1 according to the invention shown, both the first and the second secondary circuit system 6, 7 are each designed as a closed circuit system.

[0121] However, it is also conceivable in this context that the second secondary circuit system 7 is designed as an open secondary circuit system, wherein the carrier medium circulating in the second secondary circuit system 7 is a treatment liquid to be sprayed in the conveyor dishwasher 1, in particular washing liquid or rinsing liquid.

[0122] Basically, the carrier medium circulating in the first and second secondary circulation systems 6, 7 is a water-based carrier medium or water.

[0123] The representation in FIG. 1 It can also be seen that both the first secondary circuit system 6 and the second secondary circuit system 7 are each assigned a pump 27 which can be controlled in particular via the control device 100 of the conveyor dishwasher 1 and with which the carrier medium (water) can be conveyed through the first or second secondary circuit system 6, 7 as required.

[0124] Although in FIG. 1 It is shown that the second heat exchanger unit 25 of the second secondary circuit system 7 is arranged in the wash tank 32 of the conveyor dishwasher 1, it is conceivable that the second heat exchanger unit 25 of the second secondary circuit system 7 is also arranged in the fresh water tank 33 of the conveyor dishwasher 1 and / or in an area for heating drying air.

[0125] In particular, the second secondary circuit system 7 can have a plurality of second heat exchanger units 25, which are supplied with the heated carrier medium (water) of the second secondary circuit system 7 via corresponding valves as required.

[0126] The heat pump assembly of the primary circuit system 5 is divided into a high pressure section and a low pressure section.

[0127] In the low-pressure region of the heat pump assembly, an evaporator unit is provided which is designed such that at least a portion of the thermal energy transferred via the first heat exchanger unit 22 of the first secondary circuit system 6 to the carrier medium (water) circulating in the first secondary circuit system 6 can be transferred to the refrigerant circulating in the primary circuit system 5, with simultaneous at least partial evaporation of the refrigerant.

[0128] A compressor unit 9 is in fluid communication with the evaporator unit and is designed to compress the refrigerant at least partially evaporated in the evaporator unit to a higher pressure level.

[0129] A condenser unit is assigned to the high-pressure region of the heat pump assembly, which is in fluid communication with the compressor unit 9 and is designed to condense the refrigerant compressed in the compressor unit 9 at a high temperature, wherein at least part of the kinetic energy corresponding to the condensation temperature is transferred via the first heat exchanger unit 24 of the second secondary circuit system 7 to the carrier medium circulating in the second secondary circuit system 7.

[0130] In fluid communication with the condenser unit and the evaporator unit is an expansion valve unit 10 which is designed to expand the refrigerant liquefied in the condenser unit back to the evaporation pressure.

[0131] The invention is not limited to the FIG. 1 shown conveyor dishwasher 1, but results from a synopsis of all features disclosed herein.

[0132] In particular, the heat recovery system according to the invention described above or the heat recovery device according to the invention described above can also be used in corresponding program machines.

[0133] The invention also relates to a heat recovery device as such, wherein the heat recovery device is designed to recover at least part of the thermal energy of the exhaust air discharged or to be discharged from the dishwasher 1 during operation of the dishwasher 1 as useful heat and to transfer it to at least one treatment liquid to be sprayed in the dishwasher 1, in particular washing liquid and / or rinse liquid, and / or to a drying air used for drying in the dishwasher 1.

[0134] Alternatively, the heat recovery device is designed to recover at least part of the thermal energy of the wastewater discharged or to be discharged from the dishwasher 1 during operation of the dishwasher 1 as useful heat and to transfer it to at least one treatment liquid to be sprayed in the dishwasher 1, in particular washing liquid and / or rinse liquid, and / or to a drying air used for drying in the dishwasher 1.

[0135] The heat recovery device comprises a primary circuit system 5 with a heat pump assembly and a first secondary circuit system 6, wherein the first secondary circuit system 6 has a first heat exchanger unit 22 which is designed such that at least part of the energy of the exhaust air to be recovered is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the first secondary circuit system 6, wherein the first secondary circuit system 6 has a second heat exchanger unit 23 which is designed such thatthat at least a portion of the thermal energy transferred via the first heat exchanger unit 22 of the first secondary circuit system 6 to the carrier medium circulating in the first secondary circuit system 6 is transferred or transferable as useful heat for heating the at least one treatment liquid to be sprayed in the dishwasher 1 and / or for heating the drying air to a refrigerant of the heat pump assembly of the primary circuit system 5 circulating in the primary circuit system 5.

[0136] The heat recovery device can further comprise at least one second secondary circuit system 7, which has a first heat exchanger unit 24, which is designed such that at least a part of the thermal energy transferred to the refrigerant of the heat pump assembly of the primary circuit system 5 circulating in the primary circuit system 5 is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the second secondary circuit system 7, wherein the second secondary circuit system 7 has at least one second heat exchanger unit 25, which is designed such thatthat at least a part of the thermal energy transferred via the first heat exchanger unit 24 of the second secondary circuit system 7 to the carrier medium circulating in the second secondary circuit system 7 is transferred or can be transferred as useful heat to the at least one treatment liquid to be sprayed in the dishwasher 1 and / or to the drying air. Bezugszeichenliste

[0137] 1 Dishwasher / Conveyor dishwasher 2 Spray nozzles 3 Spray nozzles 4 Exhaust fan 5 Primary circuit system 6 First secondary circuit system 7 Second secondary circuit system 9Compressor unit of the heat pump assembly 10Expansion valve unit of the heat pump assembly 11Pre-wash zone 12Main wash zone 13Post-wash / pre-rinse zone 14Rinse zone 15Drying zone 17Discharge section 20Exhaust air system 21Fan 22First heat exchanger unit of the first secondary circuit system 23Second heat exchanger unit of the first secondary circuit system 24First heat exchanger unit of the second secondary circuit system 25Second heat exchanger unit of the second secondary circuit system 27Secondary circuit system pump 31Pre-wash tank 32Wash tank 33Post-wash tank 100Control device Transport direction

Claims

1. Dishwasher (1), in particular commercial dishwasher (1), which is preferably designed as a conveyor dishwasher, wherein the dishwasher (1) has a heat recovery device which is designed to recover at least part of the thermal energy of the exhaust air discharged or to be discharged from the dishwasher (1) during operation of the dishwasher (1) as useful heat and to transfer it to at least one treatment liquid to be sprayed in the dishwasher (1), in particular washing liquid and / or rinse liquid, and / or to a drying air used for drying in the dishwasher (1), characterized in thatthe heat recovery device comprises a primary circuit system (5) with a heat pump assembly and a first secondary circuit system (6), wherein the first secondary circuit system (6) comprises a first heat exchanger unit (22) which is designed such that at least part of the energy of the exhaust air to be recovered is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the first secondary circuit system (6), wherein the first secondary circuit system (6) comprises a second heat exchanger unit (23) which is designed such thatthat at least a portion of the thermal energy transferred via the first heat exchanger unit (22) of the first secondary circuit system (6) to the carrier medium circulating in the first secondary circuit system (6) is transferred or transferable as useful heat for heating the at least one treatment liquid to be sprayed in the dishwasher (1) and / or for heating the drying air to a refrigerant circulating in the primary circuit system (5) of the heat pump assembly of the primary circuit system (5), wherein the heat pump assembly of the primary circuit system (5) is preferably designed as a replaceable or interchangeable module of the dishwasher (1).

2. Dishwasher (1) according to claim 1, wherein the heat pump assembly of the primary circuit system (5) is designed to transfer, via at least one heat exchanger unit of the heat pump assembly, at least a portion of the thermal energy transferred via the second heat exchanger unit (23) of the first secondary circuit system (6) to the coolant of the heat pump assembly of the primary circuit system (5) circulating in the primary circuit system (5) directly as useful heat to the at least one treatment liquid to be sprayed in the dishwasher (1) and / or to the drying air.

3. Dishwasher (1) according to claim 1, wherein the heat recovery device further comprises at least one second secondary circuit system (7) which has a first heat exchanger unit (24) which is designed such that at least a part of the thermal energy transferred to the coolant of the heat pump assembly of the primary circuit system (5) circulating in the primary circuit system (5) is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the second secondary circuit system (7), wherein the second secondary circuit system (7) has at least one second heat exchanger unit (25) which is designed such thatthat at least part of the thermal energy transferred via the first heat exchanger unit (24) of the second secondary circuit system (7) to the carrier medium circulating in the second secondary circuit system (7) is transferred or can be transferred as useful heat to the at least one treatment liquid to be sprayed in the dishwasher (1) and / or to the drying air.

4. Dishwasher (1) according to one of claims 1 to 3, wherein the heat pump assembly of the primary circuit system (5) is designed to be separated from an exhaust air system (20) of the dishwasher (1), via which the exhaust air from the dishwasher (1) is or can be discharged during operation of the dishwasher (1), in such a way that no duct system of the heat pump assembly of the primary circuit system (5), in which the coolant of the heat pump assembly of the primary circuit system (5) is present or circulates, is present in the exhaust air system (20), wherein the heat pump assembly is preferably encapsulated and in particular hermetically encapsulated with regard to the exhaust air system (20) of the dishwasher (1);and / or wherein the heat pump assembly is at least partially or regionally and preferably completely accommodated in a housing, wherein at least one air exchange opening is formed in the housing, via which the interior of the housing is in fluid communication with the outside atmosphere and in particular with a room atmosphere of the installation space of the dishwasher (1), wherein the at least one air exchange opening of the housing of the heat pump assembly is preferably assigned at least one fan for forced ventilation of the housing, in particular as required.; 5. Dishwasher (1) according to one of claims 1 to 4, wherein the refrigerant circulating in the primary circuit system (5) is a natural refrigerant, in particular based on hydrocarbons, and preferably a refrigerant which is preferably propane or isobutane or comprises propane or isobutane, in particular a refrigerant belonging to the group R290A or R600A, and wherein the mass of the refrigerant circulating in the primary circuit system (5) is preferably a maximum of 1000 g and more preferably a maximum of 700 g and more preferably a maximum of 400 g and in particular a maximum of 150 g.

6. Dishwasher (1) according to one of claims 1 to 5, wherein the at least one secondary circuit system (6, 7) is designed as a closed circuit system.

7. Dishwasher (1) according to one of claims 1 to 6 and in particular according to claim 6, wherein the carrier medium circulating in the at least one secondary circulation system (6, 7) is a water-based carrier medium or water.

8. Dishwasher (1) according to one of claims 1 to 5 and at least according to claim 3, wherein the second secondary circulation system (7) is designed as an open circulation system, and wherein the carrier medium circulating in the second secondary circulation system (7) is a treatment liquid to be sprayed in the dishwasher (1), in particular washing liquid or rinse aid liquid.

9. Dishwasher (1) according to one of claims 1 to 8, wherein the at least one secondary circuit system (6, 7) has a pump (27) which can be controlled in particular via a control device (100) of the dishwasher (1), with which pump the carrier medium can be conveyed through the at least one secondary circuit system (6, 7) as required.

10. Dishwasher (1) according to one of claims 1 to 9 and at least according to claim 3, wherein the at least one second heat exchanger unit (25) of the second secondary circuit system (7) is arranged in a wash tank (31, 32) of the dishwasher (1), in a fresh water tank (33) of the dishwasher (1) and / or in a region for heating drying air.

11. Dishwasher (1) according to one of claims 1 to 10 and at least according to claim 2, wherein the heat pump assembly of the primary circuit system (5) is divided into a high-pressure region and a low-pressure region, and wherein the heat pump assembly of the primary circuit system (5) comprises the following: - an evaporator unit assigned to the low-pressure region of the heat pump assembly, which evaporator unit is designed such that at least a portion of the thermal energy transferred via the first heat exchanger unit (22) of the first secondary circuit system (6) to the carrier medium circulating in the first secondary circuit system (6) can be transferred to the refrigerant circulating in the primary circuit system (5), with simultaneous at least partial evaporation of the refrigerant;- a compressor unit (9) which is in fluid communication with the evaporator unit and is designed to compress the refrigerant at least partially evaporated in the evaporator unit to a higher pressure level; - a condenser unit which is assigned to the high-pressure region of the heat pump assembly, which is in fluid communication with the compressor unit (9) and is designed to liquefy the refrigerant compressed in the compressor unit (9) at a high temperature, wherein at least part of the kinetic energy corresponding to the condensation temperature is transferred via the heat exchanger unit of the heat pump assembly directly as useful heat to the at least one treatment liquid to be sprayed in the dishwasher (1) and / or to the drying air;and - an expansion valve unit (10) in fluid communication with the condenser unit and the evaporator unit, which is designed to expand the refrigerant liquefied in the condenser unit back to the evaporation pressure; 12. Dishwasher (1) according to one of claims 1 to 10 and at least according to claim 3, wherein the heat pump assembly of the primary circuit system (5) is divided into a high-pressure region and a low-pressure region, and wherein the heat pump assembly of the primary circuit system (5) comprises the following: - an evaporator unit assigned to the low-pressure region of the heat pump assembly, which evaporator unit is designed such that at least a portion of the thermal energy transferred via the first heat exchanger unit (22) of the first secondary circuit system (6) to the carrier medium circulating in the first secondary circuit system (6) can be transferred to the refrigerant circulating in the primary circuit system (5), with simultaneous at least partial evaporation of the refrigerant;- a compressor unit (9) fluidly connected to the evaporator unit, which is designed to compress the refrigerant at least partially evaporated in the evaporator unit to a higher pressure level; - a condenser unit assigned to the high-pressure region of the heat pump assembly, which is fluidly connected to the compressor unit (9) and designed to liquefy the refrigerant compressed in the compressor unit (9) at a high temperature, wherein at least part of the kinetic energy corresponding to the condensation temperature is transferred via the first heat exchanger unit of the second secondary circuit system to the carrier medium circulating in the second secondary circuit system; and - an expansion valve unit (10) fluidly connected to the condenser unit and the evaporator unit, which is designed to expand the refrigerant liquefied in the condenser unit back to the evaporation pressure.

13. Dishwasher (1) according to one of claims 1 to 12, wherein the dishwasher (1) is designed as a conveyor dishwasher with a transport device for transporting wash ware through the individual treatment zones of the conveyor dishwasher, wherein the conveyor dishwasher has at least one wash zone (11, 12, 13) in which wash liquid from a wash tank (31, 32) assigned to the at least one wash zone (11, 12, 13) is sprayed onto the wash ware, wherein the conveyor dishwasher further has at least one final rinse zone (14) arranged behind the at least one wash zone (11, 12, 13) as seen in the transport direction (T) of the wash ware, in which final rinse liquid is sprayed onto the wash ware, and wherein the conveyor dishwasher further has an exhaust air system (20) for removing exhaust air from the conveyor dishwasher.

14. Heat recovery device for a dishwasher (1), in particular a commercial dishwasher (1), which is preferably designed as a conveyor dishwasher, and preferably for a dishwasher (1) according to one of claims 1 to 13, wherein the heat recovery device is designed to recover at least part of the thermal energy of the exhaust air discharged or to be discharged from the dishwasher (1) during operation of the dishwasher (1) as useful heat and to transfer it to at least one treatment liquid to be sprayed in the dishwasher (1), in particular washing liquid and / or rinse liquid, and / or to a drying air used for drying in the dishwasher (1), characterized in thatthe heat recovery device comprises a primary circuit system (5) with a heat pump assembly and a first secondary circuit system, wherein the first secondary circuit system (6) comprises a first heat exchanger unit which is designed such that at least part of the energy of the exhaust air to be recovered is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the first secondary circuit system (6), wherein the first secondary circuit system (6) comprises a second heat exchanger unit which is designed such thatthat at least a portion of the thermal energy transferred via the first heat exchanger unit of the first secondary circuit system (6) to the carrier medium circulating in the first secondary circuit system (6) is transferred or transferable as useful heat for heating the at least one treatment liquid to be sprayed in the dishwasher (1) and / or for heating the drying air to a refrigerant of the heat pump assembly of the primary circuit system (5) circulating in the primary circuit system (5).

15. Heat recovery device according to claim 14, wherein the heat recovery device further comprises at least one second secondary circuit system, which has a first heat exchanger unit, which is designed such that at least a part of the thermal energy transferred to the refrigerant of the heat pump assembly of the primary circuit system (5) circulating in the primary circuit system (5) is transferred or can be transferred to a fluid, in particular liquid, carrier medium circulating in the second secondary circuit system, wherein the second secondary circuit system has at least one second heat exchanger unit, which is designed such thatthat at least part of the thermal energy transferred via the first heat exchanger unit of the second secondary circuit system to the carrier medium circulating in the second secondary circuit system is transferred or can be transferred as useful heat to the at least one treatment liquid to be sprayed in the dishwasher (1) and / or to the drying air.

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