DISHWASHER WITH HEAT RECOVERY APPARATUS

Abstract

A dishwasher includes a heat recovery apparatus to recover at least a portion of the thermal energy of discharged exhaust air as utility heat and transfer it to a treatment liquid to be sprayed in the dishwasher. The heat recovery apparatus includes a primary circulation system having a heating pump assembly and a first secondary circulation system with a first heat exchanger unit configured such that at least a portion of the recovered energy is transferred to a carrier medium circulating in the first secondary circulation system. The first secondary circulation system includes a second heat exchanger unit configured such that at least a portion of the energy transferred to the carrier medium is transferred as utility heat for warming the treatment fluid to a refrigerant of the heating pump assembly of the primary circulation system, the drying air circulating in the primary circulation system.

Claims

1. A dishwasher, wherein the dishwasher comprises a heat recovery apparatus, which is configured so as to recover at least a portion of the thermal energy of the exhaust air discharged, or to be discharged, from the dishwasher as utility heat during operation of the dishwasher and to transfer said thermal energy to at least one treatment liquid, to be sprayed in the dishwasher (1) and/or to a drying air used for drying in the dishwasher, characterized in that wherein the heat recovery apparatus comprises a primary circulation system having a heating pump assembly and a first secondary circulation system, wherein the first secondary circulation system comprises a first heat exchanger unit, which is configured such that at least a portion of the energy to be recovered from the exhaust air is transferred or transferable to a fluid carrier medium circulating in the first secondary circulation system, wherein the first secondary circulation system comprises a second heat exchanger unit, which is configured such that at least a portion of the energy transferred via the first heat exchanger unit of the first secondary circulation system to the carrier medium circulating in the first secondary circulation system is transferred or transferable as utility heat for warming the at least one treatment fluid to be sprayed in the dishwasher and/or for warming the drying air to a refrigerant of the heating pump assembly of the primary circulation system, said drying air circulating in the primary circulation system.

2. The dishwasher according to claim 1, wherein the heating pump assembly of the primary circulation system is configured so as to transfer, via at least one heat exchanger unit of the heating pump assembly, at least a portion of the thermal energy transferred via the second heat exchanger unit of the first secondary circulation system to the refrigerant of the heating pump assembly of the primary circulation system circulating in the primary circulation system directly as utility heat to the at least one treatment liquid to be sprayed in the dishwasher and/or to the drying air.

3. The dishwasher according to claim 1, wherein the heat recovery apparatus further comprises at least one secondary circulation system, which comprises a first heat exchanger unit, which is configured such that at least a portion of the thermal energy transferred to the refrigerant of the heating pump assembly of the primary circulation system circulating in the primary circulation system is transferred or transferable to a fluid carrier medium circulating in the second secondary circulation system, wherein the second secondary circulation system comprises at least one second heat exchanger unit, which is configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the second secondary circulation system to the carrier medium circulating in the second secondary circulation system is transferred or transferable as utility heat to the at least one treatment liquid to be sprayed in the dishwasher and/or to the drying air.

4. The dishwasher according to claim 1, wherein the heating pump assembly of the primary circulation system is configured separately from an exhaust system of the dishwasher, via which the exhaust air is discharged or dischargeable from the dishwasher during operation of the dishwasher, such that no duct system of the heating pump assembly of the primary circulation system, in which the refrigerant of the heating pump assembly of the primary circulation system is present or is circulating, is present in the exhaust system.

5. The dishwasher according to claim 1, wherein the refrigerant circulating in the primary circulation system is a natural refrigerant, on the basis of hydrocarbons, and wherein the mass of the refrigerant circulating in the primary circulation system is at most 1000 g.

6. The dishwasher according to claim 1, wherein the at least one secondary circulation system is configured as a closed-loop circulation system.

7. The dishwasher according to claim 6, wherein the carrier medium circulating in the at least one secondary circulation system is a water-based carrier medium or is water.

8. The dishwasher according to claim 3, wherein the secondary circulation system is configured as an open-loop circulation system, and wherein the carrier medium circulating in the secondary circulation system is a treatment liquid rinsing liquid, to be sprayed in the dishwasher.

9. The dishwasher according to claim 1, wherein the at least one secondary circulation system comprises a pump, which is controlled by a control device of the dishwasher, with which the carrier medium can be conveyed through the at least one secondary circulation system as needed.

10. The dishwasher according to claim 3, wherein the at least one second heat exchanger unit of the second secondary circulation system is arranged in a washing tank of the dishwasher, in a fresh water tank of the dishwasher, and/or in a region for heating drying air.

11. The dishwasher according to claim 2, wherein the heating pump assembly of the primary circulation system is subdivided into a high pressure region and a low pressure region, and wherein the heating pump assembly of the primary circulation system comprises the following: a vaporizer unit, which is associated with the low-pressure region of the heating pump assembly and configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the first secondary circulation system to the carrier medium circulating in the first secondary circulation system is transferable to the refrigerant circulating in the primary circulation system, namely with simultaneous at least partial vaporizing of the refrigerant; a condenser unit, which is in fluid communication with the vaporizer unit and is configured so as to condense the refrigerant that has at least partially evaporated in the vaporizer unit to a higher pressure level; a liquefying unit associated with the high-pressure region of the heating pump assembly and being in fluid communication with the condenser unit and configured so as to liquefy at a high temperature the refrigerant condensed in the condenser unit, wherein at least a portion of the kinetic energy corresponding to the liquefaction temperature is transferred via the heat exchanger unit of the heating pump assembly directly as utility 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, which is in fluid communication with the liquefying unit and the vaporizer unit and is configured so as to decompress the refrigerant liquefied in the liquefying unit back to the vaporizing pressure.

12. The dishwasher according to claim 3, wherein the heating pump assembly of the primary circulation system is subdivided into a high pressure region and a low pressure region, and wherein the heating pump assembly of the primary circulation system comprises the following: a vaporizer unit, which is associated with the low-pressure region of the heating pump assembly and configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the first secondary circulation system to the carrier medium circulating in the first secondary circulation system is transferable to the refrigerant circulating in the primary circulation system, namely with simultaneous at least partial vaporizing of the refrigerant; a condenser unit, which is in fluid communication with the vaporizer unit and is configured so as to condense the refrigerant that has at least partially evaporated in the vaporizer unit to a higher pressure level; a liquefying unit associated with the high-pressure region of the heating pump assembly and being in fluid communication with the condenser unit and configured so as to liquefy at a high temperature the refrigerant condensed in the condenser unit, wherein at least a portion of the kinetic energy corresponding to the liquefaction temperature is transferred via the first heat exchanger unit of the second secondary circulation system to the carrier medium circulating in the second secondary circulation system; and an expansion valve unit, which is in fluid communication with the liquefying unit and the vaporizer unit and is configured so as to decompress the refrigerant liquefied in the liquefying unit back to the vaporizing pressure.

13. The dishwasher according to claim 1, wherein the dishwasher is configured as a conveyor dishwasher having a conveying apparatus for conveying the dishes through the individual treatment zones of the conveyor dishwasher, wherein the conveyor dishwasher comprises at least one washing zone, in which washing liquid from a washing tank associated with at least one washing zone is sprayed onto the dishes, wherein the conveyor dishwasher further comprises at least one rinsing zone arranged downstream from the at least one washing zone when viewed in the conveying direction of the dishes, in which rinsing liquid is sprayed onto the dishes, and wherein the conveyor dishwasher further comprises an exhaust system for discharging exhaust air from the conveyor dishwasher.

14. A heat recovery apparatus for a dishwasher, wherein the heat recovery apparatus is configured so as to recover at least a portion of the thermal energy of the exhaust air discharged, or to be discharged, from the dishwasher as utility heat during operation of the dishwasher and to transfer said thermal energy to at least one treatment liquid to be sprayed in the dishwasher and/or to a drying air used for drying in the dishwasher, wherein the heat recovery apparatus comprises a primary circulation system having a heating pump assembly and a first secondary circulation system, wherein the first secondary circulation system comprises a first heat exchanger unit, which is configured such that at least a portion of the energy to be recovered from the exhaust air is transferred or transferable to a fluid carrier medium circulating in the first secondary circulation system, wherein the first secondary circulation system comprises a second heat exchanger unit, which is configured such that at least a portion of the energy transferred via the first heat exchanger unit of the first secondary circulation system to the carrier medium circulating in the first secondary circulation system is transferred or transferable as utility heat for warming the at least one treatment fluid to be sprayed in the dishwasher and/or for warming the drying air to a refrigerant of the heating pump assembly of the primary circulation system, said drying air circulating in the primary circulation system.

15. The heat recovery apparatus according to claim 14, wherein the heat recovery apparatus further comprises at least one secondary circulation system, which comprises a first heat exchanger unit, which is configured such that at least a portion of the thermal energy transferred to the refrigerant of the heating pump assembly of the primary circulation system circulating in the primary circulation system is transferred or transferable to a fluid carrier medium circulating in the second secondary circulation system, wherein the second secondary circulation system comprises at least one second heat exchanger unit, which is configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit of the second secondary circulation system to the carrier medium circulating in the second secondary circulation system is transferred or transferable as utility heat to the at least one treatment liquid to be sprayed in the dishwasher and/or to the drying air.

16. The dishwasher of claim 1, wherein the heating pump assembly of the primary circulation system is configured as an exchangeable or replaceable module of the dishwasher.

17. The dishwasher of claim 4, wherein: the heating pump assembly is hermetically encapsulated with respect to the exhaust system of the dishwasher; and/or the heating pump assembly is 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 external atmosphere, wherein the at least one air exchange opening of the housing of the heating pump assembly is associated with at least one ventilator for forced ventilation of the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] The invention is described in further detail below on the basis of an exemplary embodiment, with reference to the accompanying drawing, in which:

[0091] The sole FIGURE shows, schematically, an exemplary embodiment of the dishwasher according to the present invention, configured in this exemplary embodiment as a conveyor dishwasher.

DETAILED DESCRIPTION

[0092] 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.

[0093] The exemplary embodiment of the conveyor dishwasher 1 shown in FIG. 1 comprises a pre-washing zone 11 as well as a main washing zone 12 located downstream of the pre-washing zone 11 when viewed in the conveying direction T of the washware. When viewed in the conveying direction T, in the conveyor dishwasher 1 shown in FIG. 1, downstream of the main washing zone 12, a post-washing or pre-rinsing zone 13 and a rinsing zone 14 are arranged.

[0094] When viewed in the conveying direction T, the washware received either directly on the conveyor belt or held by racks runs through an inlet tunnel 10, the subsequent pre-washing zone 11, the main washing zone 12, the post-washing or pre-rinsing zone 13, the rinsing zone 14, and through a drying zone 15, and into an outlet path 17.

[0095] Spraying nozzles are respectively associated with the aforementioned treatment zones 11, 12, 13, and 14 of the conveyor dishwasher 1, via which nozzles liquid is sprayed onto the washware conveyed by the conveyor belt through the respective treatment zones 11, 12, 13, and 14.

[0096] Although not shown in FIG. 1, it is preferred for the spraying nozzles, for example of the washing system associated with pre-washing zone 11 and main washing zone 12, to each be formed in an upper and lower washing tube such that corresponding washing arms are used in these treatment zones 11, 12. It is contemplated that the washing systems used comprise a plurality of washing tubes that form a washing arm battery, wherein the plurality of washing tubes are connected to a corresponding washing pump via a preferably common conduit system.

[0097] As indicated in FIG. 1, each washing zone (pre-washing zone 11, main washing zone 12, post-washing zone 13) is associated with a tank (washing tank 31, 32, 33) in which sprayed liquid is received and/or in which liquid is readied for the spraying nozzles of the relevant zones 11, 12, 13.

[0098] As used herein, the term washing zone generally refers to a treatment zone associated with a circulation tank (washing tank) and in which the liquid collected in the circulation tank of the treatment zone is circulated using a washing pump associated with the treatment zone. The term washing zone thus refers to the washing zone 11 and the main washing zone 12, but also a post-washing zone 13, which may be arranged downstream of the main washing zone 12 when viewed in the conveying direction T of the washware. The post-washing zone 13 is also sometimes referred to in the field of commercial washing as a pump rinsing zone or a pre-washing zone. This is a circulation rinsing arranged upstream of the fresh water rinsing.

[0099] By contrast, the term rinsing zone as used herein is understood to mean a zone in which a fresh water rinsing takes place, in which the washware is sprayed with fresh water, which is optionally mixed with a rinse aid, in order to completely rid the washware of dirt particles and cleaning solution.

[0100] Thus, in the exemplary embodiment shown in FIG. 1, the final rinse takes place in the rinsing zone 14 before drying in the drying zone 15. The drying zone 15 is associated with a corresponding fan 21 in order to surround the cleaned washware with warm air and thereby dry it.

[0101] Furthermore, a control device 100 shown merely schematically in FIG. 1 is provided, which, in the embodiment of the invention shown (among other things), serves to control the respective washing pumps of the washing zones 11, 12, 13 appropriately during a washing process in order to supply washing liquid to the respective spraying nozzles at least temporarily via the associated conduit system.

[0102] In the conveyor dishwasher 1 shown in FIG. 1, rinsing liquid is sprayed onto the washware, not shown in FIG. 1, in the form of fresh water, which can be mixed with further chemical additives such as rinsing agents, via the spraying nozzles 2 of the rinsing zone 14 arranged above and below a conveyor belt. Although also not shown, laterally arranged spraying nozzles can also be provided in the rinsing zone 14.

[0103] A portion of the rinsing liquid sprayed in the rinsing zone 14 is conveyed from zone to zone in a cascading system counter to the conveying direction T of the washware. The remaining portion is guided directly into the pre-washing tank 31 of the pre-washing zone 11 via a valve and a bypass conduit (not shown).

[0104] The rinsing liquid sprayed in the rinsing zone 14 is collected in the tank (post-washing or pre-rinsing tank 33) of the post-washing or pre-rinsing zone 13, from which it is conveyed to the spraying nozzles 3 (post-washing or pre-rinsing nozzles) of the post-washing or pre-rinsing zone 13 via the washing pump belonging to the washing system of the post-washing or pre-rinsing zone 13. In the post-washing or pre-rinsing zone 13, washing liquid is rinsed off of the washware.

[0105] The liquid accumulating here flows into the washing tank 32 of the main washing zone 12, and a cleaning agent is typically added, and then the liquid is sprayed onto the washware via the spraying nozzles (washing nozzles) of the washing system belonging to the main washing zone 12 using a washing pump belonging to the washing system of the main washing zone 12.

[0106] From the washing tank 32 of the main washing zone 12, the washing liquid then flows into the pre-washing tank 31 of the pre-washing zone 11. In the pre-washing zone 11, with the aid of a washing pump belonging to the washing system of the pre-washing zone 11, the washing liquid collected in the pre-washing tank 31 is sprayed on the washware via the spraying nozzles (pre-washing nozzles) of the washing system belonging to the pre-washing zone in order to remove coarse soiling from the washware.

[0107] It is contemplated here that a portion of the washing liquid sprayed in the main washing zone 12 enters the washing tank (pre-washing tank 31) of the pre-washing zone 11 via an overflow system. Like the main washing zone 12, the pre-washing zone 11 can be equipped with a tank cover screen configured as a flat screen. This tank cover screen is preferably arranged above the washing tank (pre-washing tank 31) of the pre-washing zone 11 in order to separate dirt particles from the washing liquid sprayed in the pre-washing zone 11 and flowing back into the pre-washing tank 31 due to gravity. The mesh size of the tank cover screen is preferably in a range between approximately 1 mm and 4 mm.

[0108] The heated washing and rinsing liquid creates steam plumes (vapor) when sprayed within the washing and rinsing zones 11, 12, 13, 14 of the conveyor dishwasher 1. In order to prevent the escape of these steam plumes from the conveyor dishwasher 1, it is advantageous if, in the embodiment shown schematically in FIG. 1, the individual treatment zones, in particular the washing and rinsing zones 11, 12, 13, 14, are separated with curtains.

[0109] To extract the steam plumes (vapor) created during operation of the conveyor dishwasher 1 as well as the wet, warm air from the interior of the conveyor dishwasher 1, the conveyor dishwasher 1 is equipped with a machine-side exhaust system 20, which is designed so as to discharge at least a majority of the warm and moist air created during operation of the conveyor dishwasher 1 in the treatment zones 11, 12, 13, 14 as exhaust air from the respective treatment zones 11, 12, 13, 14 of the machine.

[0110] In the embodiment of the conveyor dishwasher 1 according to the invention shown in FIG. 1, the central exhaust system 20 is arranged in the region of post-washing or pre-rinsing zone 13 and rinsing zone 14. In the illustrated embodiment, the exhaust system 20 comprises a single exhaust fan 4, which is controllable via the control device 100 in order to be able to adjust the flow rate of the exhaust fan 4.

[0111] The exhaust system 20 is further associated with an exhaust air heat recovery system, which can preferably also be controlled via the control device 100 and serves to continuously, or as needed, draw thermal energy from the exhaust air to be discharged from the conveyor dishwasher 1 with the exhaust system 20 and thus cool the exhaust air to be discharged from the conveyor dishwasher 1.

[0112] The heat recovery system used in the exemplary embodiment of the conveyor dishwasher 1 shown schematically in FIG. 1 will be described in further detail below.

[0113] Specifically, in the embodiment shown in FIG. 1, the heat recovery system and/or the heat recovery apparatus are configured as an exhaust air heat recovery apparatus. However, it is also contemplated to use the heat recovery apparatus as a wastewater heat recovery apparatus.

[0114] The heat recovery apparatus (heat recovery system) used for the exhaust air heat recovery in FIG. 1 serves for energy recovery (and thus for conserving resources in the operation of the conveyor dishwasher 1) and in particular eliminate the need for on-site exhaust air output installations.

[0115] For this purpose, the embodiment of the conveyor dishwasher 1 according to the invention as shown schematically in FIG. 1 comprises the heat recovery apparatus (heat recovery system) already mentioned and configured as an exhaust air heat recovery system, which operates according to the principle of heat pumping technology.

[0116] The heat recovery apparatus (heat recovery system) is divided into a primary circulation system 5 with a heating pump assembly on one hand and a first as well as a second secondary circulation system 6, 7 on the other. The first secondary circulation system 6 comprises a first heat exchanger unit 22, which is arranged in the exhaust system 20 of the conveyor dishwasher 1 and is configured such that at least a portion of the energy to be recovered from the exhaust air is or can be transferred into a fluid, in particular a liquid, carrier medium circulating in the first secondary circulation system 6.

[0117] The first secondary circulation system 6 comprises a further, second heat exchanger unit 23, which is configured such that at least a portion of the thermal energy transferred to the carrier medium circulating in the first secondary circulation system 6 via the first heat exchanger unit 22 of the first secondary circulation system 6 is or can be transferred into a refrigerant circulating in the primary circulation system 5 of the heating pump assembly of the primary circulation system 5.

[0118] The second secondary circulation system 7 of the heat recovery apparatus comprises a first heat exchanger unit 24, which is configured such that at least a portion of the thermal energy transferred to the refrigerant circulating in the primary circulation system 5 of the heating pump assembly of the primary circulation system 5 is or can be transferred into a fluid, in particular a liquid, carrier medium circulating in the second secondary circulation system 7.

[0119] The second secondary circulation system 7 further comprises at least one second heat exchanger unit 25, which is configured such that at least a portion of the thermal energy transferred into the second secondary circulation system 7 via the first heat exchanger unit 24 of the second secondary circulation system 7 is or can be transferred as a utility heat into the washing liquid to be sprayed in the dishwasher 1.

[0120] It is provided here that the heating pump assembly of the primary circulation system 5 is configured separately from the exhaust system 20 of the dishwasher 1 such that no duct system of the heating pump assembly of the primary circulation system 5, in which the refrigerant of the heating pump assembly of the primary circulation system 5 is present or circulates, is present in the exhaust system 20.

In particular, the heating pump assembly is designed so as to be encapsulated with respect to the exhaust system 20 of the dishwasher 1 and in particular hermetically encapsulated.

[0121] Although not shown in FIG. 1, it is preferred that the heating pump assembly is at least partially or regionally, and preferably completely, accommodated in a housing. At least one air exchange opening can be configured in the housing, via which the interior of the housing is in fluid communication with the external atmosphere, and in particular with a room atmosphere of the set-up room of the conveyor dishwasher 1. In this context, it is contemplated that the at least one air exchange opening of the housing of the heating pump assembly is associated with at least one ventilator for forced ventilation of the housing, in particular as needed.

[0122] The refrigerant circulating in the primary circulation system 5 is in particular a natural refrigerant, preferably based on hydrocarbons. This is preferably a refrigerant that either is propane or isobutane or contains propane or isobutane. In particular, a refrigerant belonging to the group R290A or R600A is expedient.

[0123] The mass of the refrigerant circulating in the primary circulation system 5 is preferably a maximum of 150 g.

[0124] In the embodiment of the conveyor dishwasher 1 according to the invention shown in FIG. 1, both the first and second secondary circulation systems 6, 7 are respectively configured as a closed-loop circulation system.

[0125] However, it is also contemplated in this context that the second secondary circulation system 7 is configured as an open-loop secondary circulation system, wherein the carrier medium circulating in the second secondary circulation system 7 is a treatment liquid to be sprayed in the conveyor dishwasher 1, in particular washing liquid or rinsing liquid.

[0126] In principle, the carrier medium circulating in the first and second secondary circulation systems 6, 7 is a water-based carrier medium or water.

[0127] It can further be seen in the illustration in FIG. 1 that both the first secondary circulation system 6 and the second secondary circulation system 7 are each associated with a pump 27, which can be controlled via the control device 100 of the conveyor dishwasher 1 and with which the carrier medium (water) can be conveyed by the first and second secondary circulation system 6, 7, respectively.

[0128] Although it is shown in FIG. 1 that the second heat exchanger unit 25 of the second secondary circulation system 7 is arranged in the washing tank 32 of the conveyor dishwasher 1, it is contemplated that the second heat exchanger unit 25 of the second secondary circulation system 7 is also arranged in the fresh water tank 33 of the conveyor dishwasher 1 and/or in a region for the heating of drying air.

[0129] In particular, the second secondary circulation system 7 can comprise a plurality of second heat exchanger units 25, which are supplied with the heated carrier medium (water) of the second secondary circulation system 7 via corresponding valves, as needed.

[0130] The heating pump assembly of the primary circulation system 5 is subdivided into a high-pressure region and a low-pressure region.

[0131] A vaporizer unit, which is associated with the low-pressure region of the heating pump assembly and configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit 22 of the first secondary circulation system 6 to the carrier medium (water) circulating in the first secondary circulation system 6 is transferable to the refrigerant circulating in the primary circulation system 5, namely with simultaneous at least partial vaporizing of the refrigerant.

[0132] A condenser unit 9 is in fluid communication with the vaporizer unit and is configured so as to condense the refrigerant that has at least partially evaporated in the vaporizer unit to a higher pressure level.

[0133] A liquefying unit is associated with the high-pressure region of the heating pump assembly and is in fluid communication with the condenser unit 9 and configured so as to liquefy at a high temperature the refrigerant condensed in the condenser unit 9, wherein at least a portion of the kinetic energy corresponding to the liquefaction temperature is transferred via the first heat exchanger unit 24 of the second secondary circulation system 7 to the carrier medium circulating in the second secondary circulation system 7.

[0134] An expansion valve unit 10 is in fluid communication with the liquefying unit and the vaporizer unit and is configured so as to decompress the refrigerant liquefied in the liquefying unit back to the vaporizing pressure.

[0135] The invention is not limited to the conveyor dishwasher 1 shown in FIG. 1, but rather results from a summary of all features disclosed herein.

[0136] In particular, the heat recovery system described above according to the invention or the heat recovery apparatus described above according to the invention can also be used with corresponding box-type dishwashers.

[0137] The invention further relates to a heat recovery apparatus as such, wherein the heat recovery apparatus is configured so as to recover at least a portion of the thermal energy of the exhaust air discharged or to be discharged from the dishwasher 1 as utility heat during operation of the dishwasher 1 and to transfer said thermal energy to at least one treatment liquid to be sprayed in the dishwasher 1, in particular washing liquid and/or rinsing liquid, and/or to a drying air used for drying in the dishwasher 1.

[0138] Alternatively, the heat recovery apparatus is configured so as to recover at least a portion of the thermal energy of the wastewater discharged or to be discharged from the dishwasher 1 as utility heat during operation of a dishwasher 1 and to transfer said thermal energy to at least one treatment liquid to be sprayed in the dishwasher 1, in particular washing liquid and/or rinsing liquid, and/or to a drying air used for drying in the dishwasher 1.

[0139] The heat recovery apparatus comprises a primary circulation system 5 having a heating pump assembly and a first secondary circulation system 6, wherein the first secondary circulation system 6 comprises a first heat exchanger unit 22, which is configured such that at least a portion of the energy to be recovered from the exhaust air is transferred or transferable to a fluid, in particular liquid, carrier medium circulating in the first secondary circulation system 6, wherein the first secondary circulation system 6 comprises a second heat exchanger unit 23, which is configured such that at least a portion of the energy transferred via the first heat exchanger unit 22 of the first secondary circulation system 6 to the carrier medium circulating in the first secondary circulation system 6 is transferred or transferable as utility heat for warming the at least one treatment fluid to be sprayed in the dishwasher 1 and/or for warming the drying air to a refrigerant of the heating pump assembly of the primary circulation system 5, said drying air circulating in the primary circulation system 5.

[0140] The heat recovery apparatus can further comprise at least one secondary circulation system 7, which comprises a first heat exchanger unit 24, which is configured such that at least a portion of the thermal energy transferred to the refrigerant of the heating pump assembly of the primary circulation system 5 circulating in the primary circulation system 5 is transferred or transferable to a fluid, in particular liquid, carrier medium circulating in the second secondary circulation system 7, wherein the second secondary circulation system 7 comprises at least one second heat exchanger unit 25, which is configured such that at least a portion of the thermal energy transferred via the first heat exchanger unit 24 of the second secondary circulation system 7 to the carrier medium circulating in the second secondary circulation system 7 is transferred or transferable as utility heat to the at least one treatment liquid to be sprayed in the dishwasher 1 and/or to the drying air.

LIST OF REFERENCE NUMERALS

[0141] 1 Dishwasher/conveyor dishwasher [0142] 2 Spray nozzles [0143] 3 Spray nozzles [0144] 4 Exhaust fan [0145] 5 Primary circulation system [0146] 6 First secondary circulation system [0147] 7 Second secondary circulation system [0148] 9 Condenser unit of the heating pump assembly [0149] 10 Expansion valve unit of the heating pump assembly [0150] 11 Pre-washing zone [0151] 12 Main washing zone [0152] 13 Post-washing or pre-rinsing zone [0153] 14 Rinsing zone [0154] 15 Drying zone [0155] 17 Outlet path [0156] 20 Exhaust system [0157] 21 Fan [0158] 22 First heat exchanger unit of the first secondary circulation system [0159] 23 Second heat exchanger unit of the first secondary circulation system [0160] 24 First heat exchanger unit of the second secondary circulation system [0161] 25 Second heat exchanger unit of the second secondary circulation system [0162] 27 Pump of the secondary circulation system [0163] 31 Pre-washing tank [0164] 32 Washing tank [0165] 33 Post-washing tank [0166] 100 Control device [0167] T Conveying direction