Multi-stage cascade heat recovery system for dishwasher
The multi-stage waste heat recovery system solves the problem of heat waste in traditional dishwashers, achieving efficient waste heat recovery and energy utilization, improving energy efficiency and reducing heating energy consumption.
Patent Information
- Application Number
- CN202521878585.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-02
- Publication Date
- 2026-08-04
- Estimated Expiration
- 2035-09-02
AI Technical Summary
Traditional dishwashers consume a lot of electricity in the main wash, rinsing and drying stages. The direct discharge of high-temperature wastewater leads to the waste of heat energy. The single-stage waste heat recovery design has low efficiency and cannot make full use of waste heat at different temperature ranges.
A multi-stage waste heat recovery system is adopted, including first- to fourth-stage waste heat recovery devices, which respectively recover waste heat from the main washing, rinsing and drying stages. Heat utilization is optimized through condensers and variable frequency heaters to achieve tiered temperature recovery.
It improves energy utilization efficiency, with waste heat recovery rate exceeding 70%, reduces heating energy consumption by more than 20%, and achieves cascade utilization of thermodynamic grade.
Smart Images
Figure CN224584728U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to dishwashers, and in particular to a multi-stage waste heat recovery system for dishwashers, used to recover waste heat during the main wash, rinsing and drying stages of the dishwasher, thereby improving energy efficiency. Background Technology
[0002] A dishwasher is a device that automatically cleans tableware such as bowls, chopsticks, plates, dishes, knives, and forks. Fully automatic dishwashers on the market can be divided into two categories: household and commercial. Household fully automatic dishwashers are only suitable for home use and mainly include cabinet-style, countertop-style, sink-integrated, and combined models. Commercial dishwashers can be classified into five main categories according to their structure: cabinet-style, hood-style, basket-type, belt-type, and ultrasonic. They reduce the labor intensity of kitchen staff in restaurants, hotels, and government canteens, improve work efficiency, and enhance hygiene.
[0003] Traditional dishwashers consume a large amount of electricity to heat cold water in the main wash, rinse and dry stages (usually accounting for more than 80% of the total energy consumption); high-temperature wastewater (main wash water ≈70℃, rinse water ≈60℃, dry exhaust gas ≈80℃) is discharged directly, resulting in heat energy waste; single-stage waste heat recovery design has low efficiency (usually <30%), and cannot make full use of waste heat at different temperature ranges. Utility Model Content
[0004] The purpose of this invention is to provide a multi-stage waste heat recovery system for dishwashers, which is used to recover waste heat during the main wash, rinsing and drying stages of the dishwasher, thereby improving energy utilization efficiency.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A multi-stage waste heat recovery system for dishwashers is used to recover waste heat generated by the dishwasher. The dishwasher has a water tank, a main wash compartment, a rinse compartment, and a drying compartment. The main wash compartment and the rinse compartment are both connected to the water tank. The drying compartment is located downstream of the rinse compartment, and the rinse compartment is located downstream of the main wash compartment. The system is characterized by: a primary waste heat recovery device in the water tank, which is connected to the dishwasher's high-temperature drain pipe; a secondary waste heat recovery device in the main wash compartment, which is connected to the water tank; a tertiary waste heat recovery device in the rinse compartment, which is connected to the water tank; and a quaternary waste heat recovery device in the drying compartment, which is connected to the water tank.
[0006] In the aforementioned multi-stage waste heat recovery system for dishwashers, the primary waste heat recovery device is a waste heat recovery coil located inside the water tank and used to heat the water supplied to the tank.
[0007] In the aforementioned multi-stage waste heat recovery system for dishwashers, the secondary waste heat recovery device is the first condenser. The water tank is connected to the water supply side of the first condenser, and the first condenser is used to absorb the heat of the high-temperature air in the main washing chamber to heat the water supplied by the water tank.
[0008] In the aforementioned multi-stage waste heat recovery system for dishwashers, the third-stage waste heat recovery device is a second condenser. The water tank is connected to the water supply side of the second condenser, which is used to absorb the heat of the high-temperature air in the rinsing chamber to heat the water supplied by the water tank.
[0009] In the aforementioned multi-stage waste heat recovery system for dishwashers, the fourth-stage waste heat recovery device is the third condenser. The water tank is connected to the water supply side of the third condenser, and the third condenser is used to absorb the heat of the high-temperature air in the drying chamber to heat the water supplied by the water tank.
[0010] In the aforementioned multi-stage waste heat recovery system for dishwashers, the water tank, the third-stage waste heat recovery device, the second-stage waste heat recovery device, and the fourth-stage waste heat recovery device are connected in sequence. The drain outlet of the fourth-stage waste heat recovery device is connected to the spray pipe of the rinsing chamber via a frequency converter heater. A temperature sensor is installed inside the fourth-stage waste heat recovery device, and the temperature sensor is electrically connected to the frequency converter heater.
[0011] A multi-stage waste heat recovery energy-saving control method for dishwashers, employing the aforementioned multi-stage waste heat recovery system, is characterized by comprising the following steps: S100: The high-temperature wastewater discharged from the main washing compartment and the rinsing compartment of the dishwasher is discharged after passing through the first-stage waste heat recovery device. The first-stage waste heat recovery device transfers the heat of the high-temperature wastewater to the water in the water tank, heating the water in the water tank. The heated water is then supplied to the rinsing compartment. S200: The temperature inside the rinsing compartment is higher than the high-temperature drainage temperature of the main washing compartment and the rinsing compartment of the dishwasher. The water in the water tank goes to the three-stage waste heat recovery device. The high-temperature air in the rinsing compartment heats the water inside through the three-stage waste heat recovery device. The heated water flows to the two-stage waste heat recovery device. S300: The temperature inside the main washing chamber is higher than that inside the rinsing chamber. The high-temperature air inside the main washing chamber heats the water inside through a secondary waste heat recovery device. The heated water then flows to a quaternary waste heat recovery device. S400: The temperature inside the drying chamber is higher than that inside the main washing chamber. The high-temperature air inside the drying chamber heats the water inside through a four-stage waste heat recovery device. The heated water then flows to the frequency converter heater. S500: The temperature sensor detects the water temperature flowing out of the four-stage waste heat recovery device and sends the detection signal to the variable frequency heater. The variable frequency heater increases or decreases its power according to the water temperature flowing out of the four-stage waste heat recovery device so that the water temperature flowing out of the variable frequency heater is the specified temperature. S600: The drain water from the variable frequency heater is supplied to the spray pipes of the rinsing chamber for rinsing tableware.
[0012] Compared with existing technologies, this invention recovers waste heat from the main wash, rinse, and dry stages of a dishwasher, improving energy efficiency. The recovery stages are arranged in descending order of waste heat temperature (water tank → main wash → rinse → dry), with cold water flowing sequentially through higher-temperature waste heat sources, achieving tiered utilization of thermodynamic grades. Actual measurements show that the four-stage recovery system improves energy efficiency by ≥45% compared to single-stage recovery. The waste heat recovery rate is >70%, reducing heating energy consumption by over 20%; it can be directly integrated into existing dishwasher drainage / exhaust systems. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the structure of one embodiment of the present utility model; Figure 2 This is a schematic diagram of the internal structure of a dishwasher.
[0014] Attached reference numerals: 1-Water tank, 2-Primary waste heat recovery device, 3-Main washing chamber, 4-Secondary waste heat recovery device, 5-Rinsing chamber, 6-Tertiary waste heat recovery device, 7-Drying chamber, 8-Fourth-stage waste heat recovery device.
[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation
[0016] Embodiment 1 of this utility model: A multi-stage waste heat recovery system for a dishwasher, used to recover waste heat generated by the dishwasher. The dishwasher has a water tank 1, a main washing compartment 3, a rinsing compartment 5, and a drying compartment 7. The main washing compartment 3 and the rinsing compartment 5 are both connected to the water tank 1. The drying compartment 7 is located downstream of the rinsing compartment 5, which is located downstream of the main washing compartment 3. The water tank 1 has a primary waste heat recovery device 2, which is connected to the high-temperature drain pipe of the dishwasher. The main washing compartment 3 has a secondary waste heat recovery device 4, which is connected to the water tank 1. The rinsing compartment 5 has a tertiary waste heat recovery device 6, which is connected to the water tank 1. The drying compartment 7 has a quaternary waste heat recovery device 8, which is connected to the water tank 1.
[0017] Example 2: A multi-stage waste heat recovery system for a dishwasher, used to recover waste heat generated by the dishwasher. The dishwasher has a water tank 1, a main wash compartment 3, a rinse compartment 5, and a drying compartment 7. The main wash compartment 3 and the rinse compartment 5 are both connected to the water tank 1. The drying compartment 7 is located downstream of the rinse compartment 5, which is located downstream of the main wash compartment 3. The water tank 1 has a primary waste heat recovery device 2, which is connected to the high-temperature drain pipe of the dishwasher. The main wash compartment 3 has a secondary waste heat recovery device 4, which is connected to the water tank 1. The rinse compartment 5 has a tertiary waste heat recovery device 6, which is connected to the water tank 1. The drying compartment 7 has a quaternary waste heat recovery device 8, which is connected to the water tank 1.
[0018] The primary waste heat recovery device 2 is a waste heat recovery coil located inside the water tank 1, used to heat the water supplied to the water tank 1. The secondary waste heat recovery device 4 is a first condenser, connected to the water supply side of the first condenser. The first condenser absorbs heat from the high-temperature air inside the main washing chamber 3 to heat the water supplied from the water tank 1.
[0019] Example 3: A multi-stage waste heat recovery system for a dishwasher, used to recover waste heat generated by the dishwasher. The dishwasher has a water tank 1, a main wash compartment 3, a rinse compartment 5, and a drying compartment 7. The main wash compartment 3 and the rinse compartment 5 are both connected to the water tank 1. The drying compartment 7 is located downstream of the rinse compartment 5, which is located downstream of the main wash compartment 3. The water tank 1 has a primary waste heat recovery device 2, which is connected to the high-temperature drain pipe of the dishwasher. The main wash compartment 3 has a secondary waste heat recovery device 4, which is connected to the water tank 1. The rinse compartment 5 has a tertiary waste heat recovery device 6, which is connected to the water tank 1. The drying compartment 7 has a quaternary waste heat recovery device 8, which is connected to the water tank 1.
[0020] The primary waste heat recovery device 2 is a waste heat recovery coil located inside the water tank 1, used to heat the water supplied to the water tank 1. The secondary waste heat recovery device 4 is a first condenser, connected to the water supply side of the first condenser. The first condenser absorbs heat from the high-temperature air inside the main washing chamber 3 to heat the water supplied from the water tank 1.
[0021] The third-stage waste heat recovery device 6 is the second condenser. The water tank 1 is connected to the water supply side of the second condenser, which absorbs the heat from the high-temperature air in the rinsing chamber 5 to heat the water supplied from the water tank 1. The fourth-stage waste heat recovery device 8 is the third condenser. The water tank 1 is connected to the water supply side of the third condenser, which absorbs the heat from the high-temperature air in the drying chamber 7 to heat the water supplied from the water tank 1. The water tank 1, the third-stage waste heat recovery device 6, the second-stage waste heat recovery device 4, and the fourth-stage waste heat recovery device 8 are connected in sequence. The drain outlet of the fourth-stage waste heat recovery device 8 is connected to the spray pipe of the rinsing chamber 5 via a frequency converter heater. A temperature sensor is installed inside the fourth-stage waste heat recovery device 8, and the temperature sensor is electrically connected to the frequency converter heater.
[0022] The energy-saving control method for multi-stage waste heat recovery in dishwashers, employing the multi-stage waste heat recovery system described in the above embodiments, includes the following steps: S100: The primary waste heat recovery device 2 transfers the heat from the high-temperature drainage to the water in the water tank 1, heating the water in the water tank 1, and the heated water is supplied to the rinsing chamber 5. S200: The temperature inside the rinsing chamber 5 is higher than the temperature of the high-temperature drainage discharged from the main washing chamber 3 and the rinsing chamber 5 of the dishwasher. The water in the water tank 1 goes to the three-stage waste heat recovery device 6. The high-temperature air in the rinsing chamber 5 heats the water inside through the three-stage waste heat recovery device 6. The heated water flows to the two-stage waste heat recovery device 4. S300: The temperature inside the main washing chamber 3 is higher than that inside the rinsing chamber 5. The high-temperature air inside the main washing chamber 3 heats the water inside through the secondary waste heat recovery device 4. The heated water flows to the quaternary waste heat recovery device 8. S400: The temperature inside the drying chamber 7 is higher than that inside the main washing chamber 3. The high-temperature air inside the drying chamber 7 heats the water inside through the four-stage waste heat recovery device 8. The heated water flows to the frequency converter heater. S500: The temperature sensor detects the water temperature flowing out of the four-stage waste heat recovery device 8 and sends the detection signal to the variable frequency heater. The variable frequency heater increases or decreases its power according to the water temperature flowing out of the four-stage waste heat recovery device 8 so that the water temperature flowing out of the variable frequency heater is the specified temperature. S600: The drain water from the variable frequency heater is supplied to the spray pipe of the rinsing chamber 5 for rinsing the tableware.
[0023] The main wash chamber 3 and rinse chamber 5 have exhaust water temperatures of approximately 50°C, main wash water approximately 70°C, rinse water approximately 60°C, and drying exhaust gas approximately 80°C. This application recovers heat sequentially according to the increasing temperature to heat the water supply, reaching the highest possible temperature. It also features a variable frequency heater that monitors the preheated water temperature in real time and adjusts the heating power using a variable frequency algorithm. This reduces redundant heating energy consumption and avoids overheating losses. Testing shows a waste heat recovery rate >70%, reducing heating energy consumption by more than 20%; and it can be directly integrated into existing dishwasher drainage / exhaust systems.
Claims
1. A multi-stage waste heat recovery system for a dishwasher, used to recover waste heat generated by the dishwasher, the dishwasher having a water tank (1), a main washing chamber (3), a rinsing chamber (5) and a drying chamber (7), the main washing chamber (3) and the rinsing chamber (5) being connected to the water tank (1), the drying chamber (7) being located downstream of the rinsing chamber (5), and the rinsing chamber (5) being located downstream of the main washing chamber (3), characterized in that: The water tank (1) has a primary waste heat recovery device (2), which is connected to the high-temperature drain pipe of the dishwasher; The main washing chamber (3) is equipped with a secondary waste heat recovery device (4), which is connected to the water tank (1); The rinsing chamber (5) is equipped with a three-stage waste heat recovery device (6), which is connected to the water tank (1); The drying chamber (7) is equipped with a four-stage waste heat recovery device (8), which is connected to the water tank (1).
2. The multi-stage waste heat recovery system for dishwashers according to claim 1, characterized in that, The primary waste heat recovery device (2) is a waste heat recovery coil located inside the water tank (1) and used to heat the water supply inside the water tank (1).
3. The multi-stage waste heat recovery system for dishwashers according to claim 1, characterized in that, The secondary waste heat recovery device (4) is the first condenser. The water tank (1) is connected to the water supply side of the first condenser. The first condenser is used to absorb the heat of the high-temperature air in the main washing chamber (3) to heat the water supplied by the water tank (1).
4. The multi-stage waste heat recovery system for dishwashers according to claim 1, characterized in that, The three-stage waste heat recovery device (6) is the second condenser. The water tank (1) is connected to the water supply side of the second condenser. The second condenser is used to absorb the heat of the high-temperature air in the rinsing chamber (5) to heat the water supplied by the water tank (1).
5. The multi-stage waste heat recovery system for dishwashers according to claim 1, characterized in that, The fourth-stage waste heat recovery device (8) is the third condenser. The water tank (1) is connected to the water supply side of the third condenser. The third condenser is used to absorb the heat of the high-temperature air in the drying chamber (7) to heat the water supplied by the water tank (1).
6. The multi-stage waste heat recovery system for dishwashers according to claim 1, characterized in that, Water tank (1), three-stage waste heat recovery device (6), two-stage waste heat recovery device (4) and four-stage waste heat recovery device (8) are connected in sequence. The drain outlet of the four-stage waste heat recovery device (8) is connected to the spray pipe of the rinsing chamber (5) via the frequency converter heater. A temperature sensor is installed inside the four-stage waste heat recovery device (8), and the temperature sensor is electrically connected to the frequency converter heater.