US-12622567-B2 - Dishwasher with heat recovery apparatus

US12622567B2US 12622567 B2US12622567 B2US 12622567B2US-12622567-B2

Abstract

A dishwasher includes a heat recovery apparatus to recover thermal energy of the wastewater and/or exhaust air and to transfer the thermal energy to at least one treatment liquid to be sprayed and/or to a drying air. A primary circulation system has a heat pump assembly and a secondary circulation system. A heat exchanger unit of the heat pump assembly enables at least a portion of the thermal energy transferred to refrigerant of the primary circulation system to be transferred to a carrier medium in the secondary circulation system. A heat exchanger unit of the secondary circulation system enables at least a portion of the thermal energy transferred to the carrier medium to be transferred as utility heat to the treatment liquid and/or to the drying air.

Inventors

Harald Disch
Martin Schrempp

Assignees

ILLINOIS TOOL WORKS INC.

Dates

Publication Date: 20260512
Application Date: 20240112
Priority Date: 20230116

Claims (16)

1 . A dishwasher, adapted as a program machine or as a transport washer, wherein the dishwasher comprises a heat recovery apparatus, adapted to recover at least a portion of a thermal energy of the wastewater discharged, or to be discharged, from the dishwasher during operation of the dishwasher and/or at least a portion of a 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 heat pump assembly and at least one secondary circulation system, wherein the heat pump assembly is adapted to transfer at least a portion of the reclaimed thermal energy of the wastewater and/or the exhaust air to a refrigerant circulating in the primary circulation system, and wherein the heat pump assembly comprises a heat exchanger unit associated with the secondary circulation system and the secondary circulation system comprises at least one heat exchanger unit in fluid communication with the heat exchanger unit of the heat pump assembly, wherein, with the aid of the heat exchanger unit of the heat pump assembly, at least a portion of the thermal energy transferred to the refrigerant circulating in the primary circulation system is transferred to a fluidic carrier medium circulating in the secondary circulation system, and wherein, with the aid of the at least one heat exchanger unit of the secondary circulation system, at least a portion of the thermal energy transferred to the carrier medium circulating in the secondary circulation system is transferred as utility heat to the at least one treatment liquid and/or to the drying air to be sprayed in the dishwasher; wherein the at least one heat exchanger unit of the secondary circulation system is arranged in a washing tank of the dishwasher, in a fresh water tank of the dishwasher or in an area for heating drying air.
2 . The dishwasher according to claim 1 , wherein the refrigerant circulating in the primary circulation system is a natural refrigerant, belonging to the group R290a or R600a.
3 . The dishwasher according to claim 1 , wherein the mass of the refrigerant circulating in the primary circulation system is at most 1,000 g.
4 . The dishwasher according to claim 1 , wherein the secondary circulation system is a closed-loop circulation system.
5 . The dishwasher according to claim 4 , wherein the carrier medium circulating in the secondary circulation system is a water-based carrier medium or water.
6 . The dishwasher according to claim 1 , wherein the secondary circulation system is adapted as an open-loop circulation system, and wherein the carrier medium circulating in the secondary circulation system is a treatment liquid to be sprayed in the dishwasher.
7 . The dishwasher according to claim 1 , wherein the secondary circulation system comprises a pump, controlled by a control device, by which the carrier medium can be conveyed by the secondary circulation system.
8 . The dishwasher according to claim 1 , wherein the heat exchanger unit of the heat pump assembly comprises a plate heat exchanger.
9 . The dishwasher according to claim 1 , wherein the secondary circulation system comprises a first heat exchanger unit that is in fluid communication with the heat exchanger unit of the heat pump assembly over a first branch line system, or can be in fluid communication with the heat exchanger unit of the heat pump assembly using a first valve assembly, and wherein the secondary circulation system further comprises at least a second heat exchanger unit that is in fluid communication with the heat exchanger unit of the heat pump assembly over a second branch line system that is parallel to the first branch line system, or can be in fluid communication with the heat exchanger unit of the heat pump assembly using a second valve arrangement.
10 . The dishwasher according to claim 1 , wherein the primary circulation system of the heat pump assembly of the heat recovery apparatus is divided into a high-pressure side and a low-pressure side, and wherein the heat pump assembly comprises: an evaporator unit associated with the low-pressure side of the heat pump assembly and adapted such that at least a portion of the thermal energy of the exhaust air and/or the wastewater of the dishwasher is transferable to the refrigerant circulating in the primary circulation system while at least partially evaporating the refrigerant at the same time; a compressor unit in fluid communication with the evaporator unit and adapted to compress the refrigerant having at least partially evaporated in the evaporator unit to a higher pressure level; a condenser unit associated with the high-pressure side of the heat pump assembly and being in fluid communication with the compressor unit and adapted to liquefy the refrigerant compressed in the compressor unit, wherein at least a portion of the thermal energy corresponding to the condensation temperature is transferred over the heat exchanger unit of the heat pump assembly to the carrier medium circulating in the secondary circulation system; and an expansion valve unit in fluid communication with the condenser unit and the evaporator unit, adapted to decompress the refrigerant liquefied in the condenser unit back to the evaporation pressure.
11 . The dishwasher according to claim 10 , wherein the units of the heat pump assembly are accommodated in a housing arranged on the dishwasher such that the units of the heat pump assembly are accessible from the outside.
12 . The dishwasher according to claim 1 , wherein the heat pump assembly is adapted as an exchangeable or replaceable module of the dishwasher.
13 . The dishwasher according to claim 1 , wherein the dishwasher is adapted as a transport dishwasher with a conveyor apparatus for conveying the items of washware through multiple individual treatment zones, wherein the transport 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 washware, wherein the transport dishwasher further comprises at least one rinsing zone arranged downstream from the at least one washing zone when viewed in the transport direction (T) of the washware, in which rinsing liquid is sprayed onto the washware, and wherein the transport dishwasher further comprises an exhaust system for discharging exhaust air from the transport dishwasher.
14 . The dishwasher according to claim 13 , wherein the heat recovery apparatus is adapted as an exhaust air heat recovery apparatus for transferring at least a portion of the thermal energy of the exhaust air discharged, or to be discharged, from the transport dishwasher as utility heat to the rinsing liquid to be sprayed in the at least one rinsing zone and/or to the washing liquid to be sprayed in the at least one washing zone.
15 . A dishwasher, adapted as a program machine or as a transport washer, wherein the dishwasher comprises a heat recovery apparatus, adapted to recover at least a portion of a thermal energy of the wastewater discharged, or to be discharged, from the dishwasher during operation of the dishwasher and/or at least a portion of a 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 heat pump assembly and at least one secondary circulation system, wherein the heat pump assembly is adapted to transfer at least a portion of the reclaimed thermal energy of the wastewater and/or the exhaust air to a refrigerant circulating in the primary circulation system, and wherein the heat pump assembly comprises a heat exchanger unit associated with the secondary circulation system and the secondary circulation system comprises at least one heat exchanger unit in fluid communication with the heat exchanger unit of the heat pump assembly, wherein, with the aid of the heat exchanger unit of the heat pump assembly, at least a portion of the thermal energy transferred to the refrigerant circulating in the primary circulation system is transferred to a fluidic carrier medium circulating in the secondary circulation system, and wherein, with the aid of the at least one heat exchanger unit of the secondary circulation system, at least a portion of the thermal energy transferred to the carrier medium circulating in the secondary circulation system is transferred as utility heat to the at least one treatment liquid and/or to the drying air to be sprayed in the dishwasher; wherein the primary circulation system is a closed-loop circulation system and the secondary circulation system is a closed-loop circulation system.
16 . The dishwasher according to claim 15 , wherein the at least one heat exchanger unit of the secondary circulation system is arranged in (i) a washing tank of the dishwasher, (ii) a fresh water tank of the dishwasher or (iii) an area for heating drying air.

Description

TECHNICAL FIELD The present invention relates generally to the field of commercial washing, in particular. Specifically, the present invention relates to a dishwasher, in particular commercial dishwasher, which is configured as a box-type dishwasher or as a conveyor dishwasher. According to one aspect of the invention, this relates in particular to a conveyor dishwasher having a conveyor apparatus for conveying washware 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 the washing zone is sprayed onto the washware. The conveyor dishwasher according to this aspect of the invention further comprises at least one rinsing zone arranged behind the at least one washing zone when viewed in the conveying direction of the washware, in which rinsing zone rinsing liquid is sprayed onto the washware. Furthermore, the conveyor dishwasher comprises an exhaust system for removing exhaust air from the conveyor dishwasher that is produced during operation of the machine A conveyor dishwasher according to the present invention is, in particular, a slight-type dishwasher or a rack conveyor dishwasher. A conveyor dishwasher of the aforementioned type is known in principle from the prior art and is typically used in the commercial realm. In contrast to so-called box-type dishwashers, in which the washware to be cleaned remain stationary in the machine during cleaning, in conveyor dishwashers the washware are conveyed through different treatment zones of the conveyor dishwasher. A conveyor dishwasher typically comprises as treatment zones at least one pre-washing zone and at least one main washing zone located downstream of the pre-washing zone(s) when viewed in the conveying direction of the washware. When viewed in the conveying direction, at least one rinsing zone is typically arranged downstream of the main washing zone(s). It is also known to provide at least one additional post-washing zone or pre-rinsing zone between the main washing zone and the rinsing zone. When viewed in the conveying direction of the washware, the washware which has either been received directly on the conveyor belt or is held by racks typically travels through an inlet tunnel, the subsequent pre-washing zone(s), main washing zone(s), post-washing zone(s) if provided, rinsing zone(s), a drying zone, and into an outlet path. The aforementioned washing zones of the conveyor dishwasher (pre-washing zone(s), main washing zone(s), and, if provided, post-washing zone(s)) are each associated with a washing system comprising a washing pump and a conduit system connected to the washing pump, via which washing liquid is fed to respective spraying nozzles of the washing zones. The washing liquid fed to the spraying nozzles is sprayed onto the washware in the respective washing zone, which is conveyed by a conveyor apparatus of the conveyor dishwasher through the respective washing zones. Each washing zone has an associated washing tank in which sprayed liquid is received and/or in which liquid for the spraying nozzles of the respective zones is provided. In conveyor dishwashers known from the prior art, rinsing liquid in the form of fresh water, which can be pure or can be mixed with further additives such as a rinsing agent, is sprayed via the spraying nozzles of the rinsing zone onto the washware. At least a portion of the sprayed rinsing liquid is conveyed from treatment zone to treatment zone in a cascading system counter to the conveying direction of the washware. The sprayed rinsing liquid is collected in a tank (post-washing tank) of the post-washing zone, from which it is conveyed via the washing pump system of the washing system belonging to the post-washing zone to the spraying nozzles (post-washing nozzles) of the post-washing zone. In the post-washing zone, washing liquid is rinsed off of the washware. The resulting liquid flows into the washing tank of the at least one main washing zone, which is upstream of the post-washing zone when viewed in the conveying direction of the washware. Here, a cleaning agent is typically added to the liquid, and then the liquid is sprayed onto the washware by a pumping system belonging to the washing system of the main washing zone (washing pump system) via the nozzles (washing nozzles) of the main washing zone. From the washing tank of the main washing zone, the liquid then flows into the pre-washing tank of the pre-washing zone, unless a further main washing zone is provided. The liquid in the pre-washing tank is sprayed onto the washware by a pumping system belonging to the washing system of the pre-washing zone via the pre-washing nozzles of the pre-washing zone, in order to remove coarse impurities from the washware. In the field of commercial dishwashing, there are different standards and guidelines that define the hygiene performance requirements of cleaning processe