Waste water heat recovery device and energy-saving dish washing machine

Abstract

The utility model provides a waste water heat recovery device and an energy-saving dish-washing machine, which comprises a waste water tank, a heat exchange tube and a plurality of fins arranged at intervals along the length direction of the waste water tank, the plurality of fins are used for dividing the waste water tank into a plurality of chambers, and the chambers are communicated with one another; the heat exchange pipe is of a coil pipe structure, and each fin is provided with a connecting hole for the heat exchange pipe to penetrate through; a waste water inlet communicated with an inner cavity of the waste water tank and a clear water inlet connected with one end of the heat exchange pipe are formed in one side wall of the waste water tank in the length direction, and a waste water outlet communicated with the inner cavity of the waste water tank and a clear water outlet connected with the other end of the heat exchange pipe are formed in the other side wall of the waste water tank. According to the waste water heat recovery device and the energy-saving dish washing machine, waste heat of waste hot water is recovered for heat exchange with clean water, so that the clean water is preheated before entering the heating bag, the heating time of the heating bag is shortened, and energy consumption is reduced.

Description

Technical Field

[0001] This utility model relates to the field of commercial dishwasher technology, and more specifically, to a wastewater heat recovery device and an energy-saving dishwasher. Background Technology

[0002] Commercial dishwashers are a new type of kitchen dishwashing equipment, mainly used in kitchens of schools, hotels, businesses, military units, and dishwashing disinfection companies where the volume of dishwashing is high. Compared to manual washing, commercial dishwashers have advantages such as high washing efficiency, reduced labor costs, and solving the problem of insufficient dishwashing supply.

[0003] Commercial dishwashers are mainly divided into: undermount dishwashers, top-loading dishwashers, aisle dishwashers, and long-line dishwashers. Among them, the workflow of a top-loading dishwasher mainly includes a main wash and a rinse process. Main wash: The main wash pump draws water from the main wash tank and sprays it directly onto the surface of the dishes through the washing arms, rinsing away food residue and grease. The water then returns to the main wash tank for reuse. Rinse: Tap water enters the dishwasher's heating element and is heated by a high-powered heating element to quickly reach a temperature above 80℃. The hot water from the heating element is then forced through the inlet and sprayed onto the surface of the dishes through the rinse spray arms, finally falling back into the main wash tank.

[0004] Existing top-loading dishwashers typically use external water for rinsing, which is directly heated by a heating element and then sprayed onto the dishes via a spray arm. This method requires a long time to heat the water from room temperature to above 80°C, resulting in high energy consumption. Furthermore, the overflow of hot water from the main wash tank is directly discharged into the drain, failing to fully utilize the residual heat and causing resource waste. Utility Model Content

[0005] To overcome at least one of the defects in the prior art, this utility model provides a wastewater heat recovery device and an energy-saving dishwasher. By recovering the residual heat of wastewater and exchanging it with clean water, the clean water is preheated before entering the heating pack, reducing the heating time of the heating pack and saving energy.

[0006] The technical solution adopted by this utility model is as follows: a wastewater heat recovery device is provided, including a wastewater tank, a heat exchange tube, and a plurality of fins arranged at intervals along the length of the wastewater tank. The plurality of fins are used to divide the wastewater tank into a plurality of chambers, and the chambers are interconnected. The heat exchange tube is a coil structure, and each of the fins is provided with a connection hole for the heat exchange tube to pass through. A wastewater inlet communicating with its inner cavity and a clean water inlet connected to one end of the heat exchange tube are provided on one side wall along the length of the wastewater tank. A wastewater outlet communicating with its inner cavity and a clean water outlet connected to the other end of the heat exchange tube are provided on the other side wall of the wastewater tank.

[0007] Furthermore, the wastewater tank includes a box body with an opening at the top. Multiple symmetrical and vertically extending insertion slots are provided on the inner walls of the two side plates of the box body in the width direction. Multiple fins are respectively inserted and fitted into the corresponding insertion slots. The top of the box body is connected to a top plate, and the upper and lower ends of each fin abut against the top plate and the bottom of the box body, respectively.

[0008] As an improvement, water passage holes with staggered vertical alignment are sequentially opened on each pair of adjacent fins, and multiple grooves and / or protrusions are provided on the surface of each fin.

[0009] In a further improvement, the heat exchange tube is one of a spiral coil, a serpentine coil, or a loop coil, and the heat exchange tube is formed by bending a metal corrugated tube.

[0010] Another technical solution adopted by this utility model is: providing an energy-saving dishwasher, including a frame, a mounting bracket at the rear end of the top of the frame, a cover that can move up and down connected to the front side of the mounting bracket, the cover, the mounting bracket and the upper end of the frame forming a cleaning chamber; a main washing tank is provided at the upper end of the frame, a lower spray arm is provided inside the main washing tank, an upper spray arm is provided on the mounting bracket, and a main water inlet pipe with a solenoid valve, a heating component, a water pump and a wastewater heat recovery device as described above are also provided at the lower end of the frame; one end of the main water inlet pipe passes through a heat exchange pipe, a heating component and a water pump in sequence and is connected to the upper spray arm and the lower spray arm; an overflow port connected to the wastewater inlet is provided on the side wall of the main washing tank, and the wastewater outlet is connected to an external drain pipe.

[0011] Furthermore, the heating assembly includes a cylinder and a PTC heating tube. The cylinder is divided into an inlet chamber, a mixing chamber, and an outlet chamber along its length. An inlet pipe communicating with the inlet chamber and an outlet pipe communicating with the outlet chamber are provided on the side wall of the cylinder. Water passages exist between adjacent chambers in the inlet, mixing, and outlet chambers. The PTC heating tube is detachably connected to the cylinder and extends axially into the inlet, mixing, and outlet chambers. A first detection element and a second detection element are also connected to the side wall of the cylinder for detecting the water temperature in the inlet and outlet chambers, respectively. When the water temperature in the inlet chamber is lower than a first set value, the PTC heating tube starts heating; when the water temperature in the outlet chamber is higher than a second set value, the PTC heating tube stops heating. In the above-mentioned improved design, a PTC heating element is used, which has a heat conversion efficiency of up to 99%, compared to the approximately 75% heating efficiency of the old-fashioned resistance wire heating element, thus increasing the heating efficiency by about 25%. Furthermore, the PTC heating element has anti-dry-burning characteristics and is not easily damaged. After the cylinder is filled with water, heating begins until the required temperature is reached, at which point hot water is released from the outlet pipe for use. The entire device is divided into three zones by a perforated partition: a low-temperature zone, a mixing zone, and a high-temperature zone. When the temperature probe in the low-temperature zone reads a temperature below a certain value, the PTC heating element starts heating; when the temperature in the high-temperature zone exceeds a certain value, the PTC heating element stops heating. This structure ensures that the temperature of the water outlet pipe remains constant within a certain range.

[0012] In a further improvement, two partitions are connected to the inner wall of the cylinder, which are spaced apart along the length of the cylinder, to divide the inner cavity of the cylinder into an inlet chamber, a mixing chamber and an outlet chamber. The middle of each of the two partitions is provided with a first mounting hole for the PTC heating tube to pass through, and each partition is also provided with multiple connecting holes to form the water passage.

[0013] In a further improvement, the cylinder includes a hollow circular tube, with end caps connected to both ends of the circular tube. Each end cap has a second mounting hole for the PTC heating tube to pass through, and one end of the PTC heating tube is connected to a connecting flange. The connecting flange is detachably connected to the end cap with the second mounting hole.

[0014] In a further improvement, both the first and second detection elements are temperature probes, and the detection ends of the two temperature probes extend through the side wall of the cylinder to the water inlet chamber and the water outlet chamber, respectively.

[0015] Compared with the prior art, the wastewater heat recovery device and energy-saving dishwasher of this utility model have the following advantages:

[0016] 1. Multiple finned structures were added inside the wastewater tank, dividing the tank's interior into several interconnected chambers. This effectively extends the residence time of hot wastewater within the tank, allowing for better heat exchange between the clean water and the hot wastewater in the heat exchange tubes. This improves preheating efficiency, reduces heating time in the subsequent main heating stage, and lowers energy consumption. Furthermore, the fins themselves can quickly absorb heat from the wastewater and conduct it to the heat exchange tubes, thereby heating the clean water.

[0017] 2. The heat exchange tubes are made of metal corrugated tubes, which increases the heat exchange area and improves efficiency compared to straight-wall coil structures. In addition, the corrugated structure inside the tubes makes the water flow in a "turbulent" state inside the tubes, with no dead corners and less prone to scaling.

[0018] 3. In addition to the wastewater heat recovery device, the dishwasher mechanism has also been improved by adopting a PTC heating element, which boasts a heat conversion efficiency of up to 99%, approximately 25% higher than the 75% efficiency of older resistance wire heating elements. Furthermore, the PTC heating element is designed to prevent dry burning and is less prone to damage. Heating begins once the drum is filled with water and continues until the desired temperature is reached, at which point hot water is released from the outlet. The entire system is divided into three zones by perforated partitions: a low-temperature zone, a mixing zone, and a high-temperature zone. When the temperature probe in the low-temperature zone reads a value below a certain threshold, the PTC heating element activates; conversely, when the temperature in the high-temperature zone exceeds a certain threshold, the PTC heating element stops heating. This design ensures that the outlet water temperature remains constant within a certain range, while also achieving energy savings.

[0019] Other improvements and advantages of this invention will be set forth in the detailed description that follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the structures particularly pointed out in the description and drawings. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural view of the energy-saving dishwasher of this utility model;

[0021] Figure 2 This is a structural diagram of the wastewater heat recovery device of this utility model; (without cover plate).

[0022] Figure 3 This is a structural diagram of the wastewater heat recovery device in this utility model without the outer casing.

[0023] Figure 4 for Figure 3 Another perspective view of the structure;

[0024] Figure 5This is a structural diagram of the heating component in this utility model;

[0025] Figure 6 This is a cross-sectional view of the heating component in this utility model.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Wastewater tank; 2. Heat exchange tube; 3. Fins; 4. Wastewater inlet; 5. Clean water inlet; 6. Wastewater outlet; 7. Clean water outlet; 8. Water passage hole; 9. Frame; 10. Mounting bracket; 11. Main washing tank; 12. Lower spray arm; 13. Upper spray arm; 14. Water pump; 15. PTC heating tube; 16. Water inlet chamber; 17. Mixing chamber; 18. Water outlet chamber; 19. Water inlet pipe; 20. Water outlet pipe; 21. Connecting hole; 22. First detection element; 23. Second detection element; 24. Baffle plate; 25. Round tube; 26. End cover plate; 27. Connecting flange; 28. Drain bolt; 29. ​​Mounting base; 30. Fixing clip. Detailed Implementation

[0028] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0029] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "fixed" and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0030] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] See Figures 2-4As shown in the embodiment of this application, a wastewater heat recovery device is disclosed, including a rectangular wastewater tank 1, a heat exchange tube 2, and a plurality of fins 3 arranged at intervals along the length of the wastewater tank 1. The plurality of fins 3 are used to divide the inner cavity of the wastewater tank 1 into a plurality of independent chambers, and the chambers are interconnected. The heat exchange tube 2 is a coil structure, and each fin 3 is provided with a connection hole for the heat exchange tube 2 to pass through. A wastewater inlet 4 communicating with its inner cavity and a clean water inlet 5 connected to one end of the heat exchange tube 2 are provided on one side wall along the length of the wastewater tank 1. A wastewater outlet 6 communicating with its inner cavity and a clean water outlet 7 connected to the other end of the heat exchange tube 2 are provided on the other side wall of the wastewater tank 1. In this structure, hot wastewater enters the wastewater tank 1 from the wastewater inlet 4, passes through multiple chambers in sequence, and is discharged from the wastewater outlet 6. Clean water enters the heat exchange tube 2 from the water inlet and flows out from the clean water outlet 7. Inside the wastewater tank 1, the hot wastewater transfers heat to the heat exchange tube 2, thereby preheating the clean water inside the heat exchange tube 2. The multiple chambers can slow down the circulation speed of the hot wastewater and improve the heat exchange efficiency. In addition, multiple fins 3 can also quickly absorb the heat in the hot wastewater and then conduct it to the heat exchange tube 2 to preheat the clean water.

[0032] Specifically, in this embodiment, the wastewater tank 1 includes a box body with an opening at the top. Multiple symmetrical and vertically extending insertion slots (not shown in the figure) are provided on the inner walls of both side plates in the width direction of the box body. Multiple fins 3 are inserted and fitted into the corresponding insertion slots from top to bottom. The top of the box body is connected to a top plate, and the upper and lower ends of each fin 3 abut against the top plate and the bottom of the box body, respectively, so that the inner cavity of the wastewater tank 1 is divided into multiple independent chambers. Moreover, the size of the chambers can be customized and the spacing of the fins 3 can be adjusted according to actual needs. Furthermore, the insertion form of the fins 3 simplifies the installation process. During assembly, it is convenient to connect the heat exchange tube 2 to each fin 3 first and then install the whole into the inner cavity of the wastewater tank 1, thereby improving production efficiency.

[0033] Of course, in some other embodiments, each fin 3 can also be directly fixed to the inner wall of the wastewater tank 1 by welding or screwing.

[0034] Additionally, in the above structure of this embodiment, see Appendix Figure 3 and 4 Each pair of adjacent fins 3 has staggered water passage holes 8. This arrangement can further extend the residence time of hot wastewater in the wastewater tank 1, so that heat can be better transferred to the clean water in the heat exchange tube 2, thereby improving the preheating effect. Preferably, multiple grooves and / or ridges are provided on the surface of each fin 3, which can improve the heat absorption efficiency of the fin 3 and improve the preheating efficiency of clean water from another perspective.

[0035] Furthermore, in the above structure, the heat exchange tube 2 is one of a spiral coil, a serpentine coil, or a loop coil, and the heat exchange tube 2 is formed by bending a metal corrugated tube. Preferably, a stainless steel corrugated tube is used to make the heat exchange tube 2. The inner wall of the corrugated tube has a corrugated structure, which increases the heat exchange area and improves efficiency compared to a straight-walled coil structure. In addition, the corrugated structure inside the corrugated tube makes the water flow in a "turbulent" state inside the tube, with no dead corners and less prone to scaling.

[0036] To reduce heat loss, an additional layer of insulation cotton was added to the outside of the wastewater tank 1 in this embodiment.

[0037] See appendix Figure 1 This application also discloses an energy-saving dishwasher, including a frame 9, a mounting bracket 10 at the rear end of the top of the frame 9, a cover that can move up and down connected to the front side of the mounting bracket 10, and the cover, the mounting bracket 10 and the upper end of the frame 9 forming a cleaning chamber; a main washing tank 11 is provided at the upper end of the frame 9, a lower spray arm 12 is provided inside the main washing tank 11, an upper spray arm 13 is provided on the mounting bracket 10, and a main water inlet pipe with a solenoid valve, a heating component, a water pump 14 and a front... The wastewater heat recovery device is described above; specifically, a mounting base 29 is connected to the lower end of the frame 9, and the wastewater heat recovery device is connected to the mounting base through two gate-shaped fixing strips 30; in addition, one end of the main water inlet pipe passes through the heat exchange pipe 2, the heating component, and the water pump 14 in sequence and then connects to the upper spray arm 13 and the lower spray arm 12; the side wall of the main washing tank 11 is provided with an overflow port connected to the wastewater inlet 4, and the wastewater outlet 6 is connected to the external drain pipe or directly discharged into the kitchen sewer.

[0038] In the entire dishwasher water circulation system, external clean water first passes through the heat exchange tube 2 in the wastewater heat recovery device to exchange heat with hot wastewater for preheating, and then enters the main heating element for heating. Because the clean water has been preheated by the wastewater heat recovery element, it takes less time to heat to the preset temperature in the heating element and consumes less energy. According to experimental statistics, this preheating before heating can save 40%-50% of energy consumption.

[0039] For others, see Appendix Figure 5 and 6The heating assembly includes a cylindrical body, which is sequentially divided along its length into an inlet chamber 16, a mixing chamber 17, and an outlet chamber 18. An inlet pipe 19 communicating with the inlet chamber 16 and an outlet pipe 20 communicating with the outlet chamber 18 are provided on the side wall of the cylindrical body. Water passages exist between adjacent chambers in the inlet chamber 16, mixing chamber 17, and outlet chamber 18. Additionally, a PTC heating pipe 15 is detachably connected to the cylindrical body, extending axially to the inlet chamber 16, mixing chamber 17, and outlet chamber 18. A first detection element 22 and a second detection element are also connected to the side wall of the cylindrical body for respectively detecting the water temperature in the inlet chamber 16 and outlet chamber 18. 23. Specifically, a corresponding controller is also set in the entire heating assembly, and the first detection element 22, the second detection element 23 and the PTC heating tube 15 are all electrically connected to the controller. That is, when the first detection element 22 detects that the water temperature in the inlet chamber 16 is lower than the first set value, it will transmit the signal to the controller, and the controller will control the PTC heating tube 15 to start heating. When the second detection element 23 detects that the water temperature in the outlet chamber 18 is higher than the second set value, the second detection element 23 will feed the signal back to the controller, and the controller will control the PTC heating tube 15 to stop heating, thereby ensuring that the temperature of the outlet pipe 20 is always kept constant within a certain range.

[0040] Furthermore, in the above structure, the chamber inside the cylinder is divided into three areas: a low-temperature zone, a mixing zone, and a high-temperature zone. The high-temperature zone is equipped with a water outlet pipe 20 connected to the upper and lower spray arms on the side wall of the cylinder, which ensures that the spray water temperature is constant within a certain range. At the same time as water is discharged from the water outlet pipe 20, cold water is added by the water inlet pipe 19. The added cold water does not directly mix into the high-temperature zone, but flows slowly into the mixing zone first. Therefore, the addition of external cold water will not cause excessive fluctuations in the temperature of the high-temperature zone. Moreover, when the temperature of the low-temperature zone drops below the first set value as cold water is added by the water inlet pipe 19, the PTC heating tube 15 will start working. Under the action of the second detection element 23, the PTC heating tube 15 will not heat continuously, but will stop heating when the temperature of the high-temperature zone reaches the second set value. This can better ensure the constant temperature of the water outlet pipe 20 with a very small fluctuation range.

[0041] In this embodiment, please refer again to the appendix. Figure 6Two partition plates 24, spaced apart along their length, are connected to the inner wall of the cylinder. These two partition plates 24 are welded and fixed to the inner wall of the cylinder. The two partition plates 24 divide the inner cavity of the cylinder into an independent inlet chamber 16, a mixing chamber 17, and an outlet chamber 18. Each partition plate 24 has a first mounting hole in its center for the PTC heating element 15 to pass through. Each partition plate 24 also has multiple connecting holes 21 to form a water passage. Preferably, the connecting holes 21 are through holes with a diameter controlled between 0.5 and 1 cm. The area of ​​the water passage should not be too large to slow down the time it takes for cold water in the inlet chamber 16 to enter the mixing chamber 17 and the outlet chamber 18, thus preventing large fluctuations in the stability of the outlet chamber 18.

[0042] In this embodiment, preferably, the cylinder includes a hollow circular tube 25, with end caps 26 connected to both ends of the tube 25. Specifically, both end caps 26 are welded and fixed to both ends of the circular tube 25, and a second mounting hole for the PTC heating tube 15 to pass through is provided on either end cap 26. One end of the PTC heating tube 15 is connected to a connecting flange 27, which is detachably connected to the end cap 26 with the second mounting hole. This allows for a detachable connection between the PTC heating tube 15 and the cylinder, facilitating the removal of the PTC heating tube 15 for cleaning its outer wall and ensuring heating efficiency. More specifically, corresponding mounting holes are provided at the center of the two end caps 26 and the two partitions 24 to ensure that the PTC heating tube 15 is located at the center of the cylinder after installation, enabling it to heat the water in each chamber more evenly.

[0043] In addition, in the above structure, the first detection element 22 and the second detection element 23 are both cylindrical temperature probes, and the two temperature probes are connected along the direction of the outer wall of the vertical circular tube 25. The detection ends of the two temperature probes extend through the side wall of the cylinder to the center of the water inlet chamber 16 and the water outlet chamber 18, respectively, so as to obtain the real-time water temperature of the water inlet chamber 16 and the water outlet chamber 18 more accurately.

[0044] In this embodiment, when the heating component is working, the cylinder is horizontally arranged along its length and is connected and fixed to the dishwasher frame 9 by a corresponding fixed base on its exterior. The side wall at the bottom of the cylinder is also provided with a drain bolt 28 that communicates with any of the chambers. When the heating component is not used for a long time, the water in the cylinder can be drained in time through the drain bolt 28, thereby improving the service life of the device.

[0045] In the description of this application, the references to terms such as "this embodiment," "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0046] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wastewater heat recovery device, characterized in that: The system includes a wastewater tank (1), a heat exchange tube (2), and multiple fins (3) spaced apart along the length of the wastewater tank (1). The multiple fins (3) are used to divide the wastewater tank (1) into multiple chambers, and the chambers are interconnected. The heat exchange tube (2) is a coil structure, and each fin (3) has a connection hole for the heat exchange tube (2) to pass through. A wastewater inlet (4) communicating with its inner cavity and a clean water inlet (5) connected to one end of the heat exchange tube (2) are provided on one side wall along the length of the wastewater tank (1). A wastewater outlet (6) communicating with its inner cavity and a clean water outlet (7) connected to the other end of the heat exchange tube (2) are provided on the other side wall of the wastewater tank (1).

2. The wastewater heat recovery device according to claim 1, characterized in that: The wastewater tank (1) includes a box body with an opening at the top. Multiple symmetrical and vertically extending insertion slots are provided on the inner walls of the two side plates in the width direction of the box body. Multiple fins (3) are respectively inserted and fitted into the corresponding insertion slots. The top of the box body is connected to a top plate, and the upper and lower ends of each fin (3) abut against the top plate and the bottom of the box body, respectively.

3. The wastewater heat recovery device according to claim 1 or 2, characterized in that: Each pair of adjacent fins (3) has water passage holes (8) that are staggered vertically, and each fin (3) has multiple grooves and / or protrusions on its surface.

4. The wastewater heat recovery device according to claim 1 or 2, characterized in that: The heat exchange tube (2) is one of a spiral coil, a serpentine coil, or a loop coil, and the heat exchange tube (2) is formed by bending a metal corrugated tube.

5. An energy-saving dishwasher, characterized in that: Includes a frame (9), with a mounting bracket (10) at the rear end of the top of the frame (9). A cover that can move up and down is connected to the front of the mounting bracket (10). The cover, the mounting bracket (10), and the upper end of the frame (9) form a cleaning chamber. A main washing tank (11) is located at the upper end of the frame (9). A lower spray arm (12) is located inside the main washing tank (11), and an upper spray arm (13) is located on the mounting bracket (10). The lower end is also provided with a main water inlet pipe with a solenoid valve, a heating component, a water pump (14) and a wastewater heat recovery device as described in any one of claims 1 to 4; one end of the main water inlet pipe passes through the heat exchange pipe (2), the heating component, and the water pump (14) in sequence and is connected to the upper spray arm (13) and the lower spray arm (12); the side wall of the main washing tank (11) is provided with an overflow port connected to the wastewater inlet (4), and the wastewater outlet (6) is connected to the external drain pipe.

6. The energy-saving dishwasher according to claim 5, characterized in that: The heating assembly includes a cylinder and a PTC heating tube (15). The cylinder is divided along its length into an inlet chamber (16), a mixing chamber (17), and an outlet chamber (18). The side wall of the cylinder is provided with an inlet pipe (19) communicating with the inlet chamber (16) and an outlet pipe (20) communicating with the outlet chamber (18). Adjacent chambers in the inlet chamber (16), mixing chamber (17), and outlet chamber (18) have water passages. The PTC heating tube (15) and the… The cylinder is detachably connected and extends axially to the inlet chamber (16), the mixing chamber (17), and the outlet chamber (18); the side wall of the cylinder is also connected to a first detection element (22) and a second detection element (23) for detecting the water temperature of the inlet chamber (16) and the outlet chamber (18) respectively; when the water temperature in the inlet chamber (16) is lower than the first set value, the PTC heating tube (15) starts heating, and when the water temperature in the outlet chamber (18) is higher than the second set value, the PTC heating tube (15) stops heating.

7. The energy-saving dishwasher according to claim 6, characterized in that: The inner wall of the cylinder is connected to two partitions (24) spaced apart along its length to divide the inner cavity of the cylinder into a water inlet chamber (16), a mixing chamber (17) and a water outlet chamber (18). The middle of each of the two partitions (24) is provided with a first mounting hole for the PTC heating tube (15) to pass through, and each partition (24) is also provided with a plurality of connecting holes (21) to form the water passage.

8. The energy-saving dishwasher according to claim 6, characterized in that: The cylinder includes a hollow circular tube (25), and end caps (26) are connected to both ends of the circular tube (25). A second mounting hole is provided on any one of the end caps (26) for the PTC heating tube (15) to pass through. A connecting flange (27) is connected to one end of the PTC heating tube (15). The connecting flange (27) is detachably connected to the end cap (26) with the second mounting hole.

9. The energy-saving dishwasher according to claim 6, characterized in that: The first detection element (22) and the second detection element (23) are both temperature probes, and the detection ends of the two temperature probes extend through the side wall of the cylinder to the water inlet chamber (16) and the water outlet chamber (18), respectively.

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