Multiple heat exchange heat pump system for commercial dishwasher

Abstract

This utility model relates to a multi-heat exchange heat pump system for commercial dishwashers, belonging to the field of dishwasher technology. It includes: a compressor, a four-way valve, a condenser, an evaporator, a throttling device, a return gas enthalpy exchanger, and a condenser-evaporator exchanger; a wastewater heat exchanger, which has a dishwasher wastewater heat inlet and outlet, and is connected to the dishwasher's waste heat channel via a pipe; a heat collection hood, located at the dishwasher's waste heat exhaust port, and connected to the evaporator's air inlet side via the dishwasher's waste heat channel; and a system overload protection bypass consisting of an unloading valve and a capillary tube, with its inlet end connected to the compressor exhaust end and its outlet end connected to the refrigerant inlet of the return gas enthalpy exchanger. This utility model integrates the wastewater heat exchanger and the counter-current heat exchange channel into the same housing, forming a two-stage heating structure. Cold water is first preheated by the corrugated plate wastewater heat exchanger, and then further heated by the counter-current heat exchange channel, maximizing the recovery of wastewater heat energy and improving heating efficiency.

Description

Technical Field

[0001] This utility model relates to the field of dishwasher technology, and in particular to a multi-heat exchange heat pump system for commercial dishwashers. Background Technology

[0002] Commercial dishwashers generate significant amounts of waste heat (including waste hot water and waste gas) during operation. Traditional systems typically discharge this waste heat directly, resulting in energy waste and potentially raising ambient temperatures. While existing heat pump systems can recover some waste heat, they generally suffer from the following problems:

[0003] Traditional heat pump systems recover waste heat through a single path, failing to fully integrate the dual heat sources of waste water and waste gas from dishwashers, resulting in insufficient heat recovery efficiency. The compressor is prone to overload under high pressure or fluctuating load conditions, lacking an effective pressure protection mechanism, which may lead to equipment damage or operational interruption. The evaporator is prone to frosting in low-temperature, high-humidity environments, affecting heat exchange efficiency, and the defrosting process is energy-intensive and inefficient. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a multi-heat exchange heat pump system for commercial dishwashers, aiming to solve the problems in the background art.

[0005] To achieve the aforementioned objectives, the first aspect of this utility model proposes a multi-stage heat pump system for commercial dishwashers, comprising:

[0006] Compressor, four-way valve, condenser, evaporator, expansion valve, return gas enthalpy exchanger, and condenser-evaporator exchanger;

[0007] The waste water exchanger is equipped with a waste water inlet and a waste water outlet for the dishwasher, and is connected to the waste heat channel of the dishwasher through a pipe.

[0008] A heat collection hood is installed at the waste heat exhaust port of the dishwasher and connected to the air inlet side of the evaporator through the waste heat passage of the dishwasher;

[0009] The system overload protection bypass, consisting of an unloading valve and a capillary tube, has its inlet end connected to the compressor discharge end and its outlet end connected to the refrigerant inlet of the return gas enthalpy exchanger.

[0010] The refrigerant circulation piping includes:

[0011] Hot water production main circuit: Compressor → Four-way valve → Condenser → First pipe port → First check valve → Return gas enthalpy exchanger → Condensation-evaporation exchanger main circuit → Throttling device → Second check valve → Second pipe port → Evaporator → Four-way valve → Return gas enthalpy exchanger → Compressor;

[0012] Defrosting main circuit: Compressor → Four-way valve → Evaporator → Second pipe port → Third check valve → Return gas enthalpy exchanger → Condensation-evaporation exchanger main circuit → Throttling device → Fourth check valve → First pipe port → Condenser → Four-way valve → Return gas enthalpy exchanger → Compressor;

[0013] The water system includes:

[0014] Hot water flow path: Cold water inlet → Waste water heat exchanger → Countercurrent heat exchange channel → Hot water outlet;

[0015] Waste heat recovery flow path: Dishwasher → Dishwasher waste hot water inlet → Waste hot water exchanger → Dishwasher waste hot water outlet.

[0016] Optionally, the condenser-evaporator exchanger is provided with parallel bidirectional branches, the first branch is connected to the evaporator via a throttle valve, and the second branch forms a bypass circuit via an unloading valve and a capillary tube.

[0017] The capillary has a length of 800-1500 mm and an inner diameter of 2-3 mm.

[0018] Optionally, a gas-liquid separation structure is provided between the refrigerant outlet of the return gas enthalpy exchanger and the compressor suction port.

[0019] Optionally, the wastewater heat exchanger and the countercurrent heat exchange channel are integrated into the same housing to form a two-stage heating structure;

[0020] The waste hot water exchanger adopts a corrugated plate heat exchanger with a plate gap of 3-5mm.

[0021] Optionally, in the system overload protection bypass, the unloading valve is a pressure-driven normally closed valve, and its opening pressure is set to 110%-120% of the system safety threshold.

[0022] Optionally, the refrigerant flow channel and the water flow channel of the counter-current heat exchange channel are arranged in an alternating counter-current manner, and the heat exchange surface is provided with a turbulence enhancement structure.

[0023] Optionally, the evaporator has a fin spacing of 2.0-3.0 mm and a surface coated with a hydrophobic and anti-corrosion coating.

[0024] The beneficial effects of this utility model are:

[0025] 1. This utility model discloses a multi-stage heat pump system for commercial dishwashers, which integrates a wastewater hot water exchanger and a counter-current heat exchange channel within the same housing to form a two-stage heating structure. Cold water is first preheated by a corrugated plate wastewater hot water exchanger, and then further heated by the counter-current heat exchange channel, maximizing the recovery of wastewater heat energy and improving heating efficiency. Furthermore, a heat collection hood collects the waste heat emitted by the dishwasher, and after controlling the flow rate through an adjustable damper, it is sent to the evaporator's air inlet side as an auxiliary heat source for the evaporator, reducing the refrigerant circulation load and lowering energy consumption.

[0026] 2. This utility model discloses a multi-heat exchange heat pump system for commercial dishwashers. The condenser-evaporator exchanger has parallel bidirectional branches. Under normal operating conditions, the refrigerant enters the evaporator through a throttling device to absorb heat. When the system is overloaded, the unloading valve automatically opens, and the refrigerant bypasses through a capillary tube, allowing for flexible adjustment of the refrigerant flow, preventing compressor overload, and improving system stability. Simultaneously, a four-way valve switches the refrigerant flow direction. In defrost mode, high-temperature, high-pressure refrigerant directly enters the evaporator for defrosting. This reverse circulation design shortens defrost time and reduces energy loss. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a multi-heat exchange heat pump system for a commercial dishwasher, provided as an exemplary embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Compressor; 2. Four-way valve; 3. Condenser; 4. First pipe port; 5. First check valve; 6. Return gas enthalpy exchanger; 7. Condensation-evaporation exchanger; 8. Throttling device; 9. Second check valve; 10. Second pipe port; 11. Evaporator; 12. Unloading valve; 13. Capillary tube; 14. Third check valve; 15. Fourth check valve; 16. Dishwasher; 17. Waste water exchanger; 18. Dishwasher waste water inlet; 19. Dishwasher waste water outlet; 20. Countercurrent heat exchange channel; 21. Hot water outlet; 22. Dishwasher waste heat channel; 23. Heat collection hood.

[0030] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] Reference Figure 1 This utility model provides an embodiment of a multi-stage heat pump system for commercial dishwashers, comprising:

[0034] Compressor 1, four-way valve 2, condenser 3, evaporator 11, expansion valve 8, return gas enthalpy exchanger 6, and condenser-evaporator exchanger 7;

[0035] Waste hot water exchanger 17 is provided with dishwasher waste hot water inlet 18 and dishwasher waste hot water outlet 19, and is connected to the waste heat channel 22 of dishwasher 16 through a pipe.

[0036] The heat collection hood 23 is installed at the waste heat exhaust port of the dishwasher 16 and is connected to the air inlet side of the evaporator 11 through the waste heat channel 22 of the dishwasher.

[0037] The system overload protection bypass, consisting of unloading valve 12 and capillary tube 13, has its inlet end connected to the exhaust end of compressor 1 and its outlet end connected to the refrigerant inlet of return gas enthalpy exchanger 6.

[0038] The refrigerant circulation piping includes:

[0039] Hot water production main circuit: Compressor 1 → Four-way valve 2 → Condenser 3 → First pipe port 4 → First check valve 5 → Return gas enthalpy exchanger 6 → Condenser-evaporator exchanger 7 main circuit → Throttling device 8 → Second check valve 9 → Second pipe port 10 → Evaporator 11 → Four-way valve 2 → Return gas enthalpy exchanger 6 → Compressor 1.

[0040] Defrosting main circuit: Compressor 1 → Four-way valve 2 → Evaporator 11 → Second pipe port 10 → Third check valve 14 → Return gas enthalpy exchanger 6 → Condensation-evaporation exchanger 7 main circuit → Throttling device 8 → Fourth check valve 15 → First pipe port 4 → Condenser 3 → Four-way valve 2 → Return gas enthalpy exchanger 6 → Compressor 1.

[0041] The water system includes:

[0042] Hot water flow path: Cold water inlet → Waste hot water exchanger 17 → Countercurrent heat exchange channel 20 → Hot water outlet 21;

[0043] Waste heat recovery flow path: Dishwasher 16 → Dishwasher waste hot water inlet 18 → Waste hot water exchanger 17 → Dishwasher waste hot water outlet 19.

[0044] It should be noted that this utility model provides a multi-stage heat pump system for commercial dishwashers, the core components of which include a compressor 1, a four-way valve 2, a condenser 3, an evaporator 11, a throttle 8, a return gas enthalpy exchanger 6, a condenser-evaporator exchanger 7, a waste hot water exchanger 17, a heat collection hood 23, and a system overload protection bypass.

[0045] The refrigerant circulation path includes the following:

[0046] Main hot water production circuit: Compressor 1 compresses the low-temperature, low-pressure refrigerant into a high-temperature, high-pressure gas, which then enters the condenser 3 through the four-way valve 2 to release heat and condense into a high-temperature, high-pressure liquid. Subsequently, it enters the return gas enthalpy exchanger 6 through the first one-way valve 5, where it exchanges heat with the low-temperature refrigerant before entering the condenser-evaporator exchanger 7. After being depressurized by the expansion valve 8, the refrigerant enters the evaporator 11 at a low temperature and low pressure to absorb heat and evaporate, completing the heating cycle.

[0047] Main defrosting circuit: When the evaporator 11 is frosted, the four-way valve 2 switches the direction, and the high-temperature and high-pressure refrigerant discharged by the compressor 1 directly enters the evaporator 11 for defrosting. At the same time, it forms a reverse circulation through the third one-way valve 14 and the fourth one-way valve 15 to ensure the efficient operation of the system.

[0048] The water system includes the following:

[0049] Hot water flow path: After being preheated by the waste hot water exchanger 17, the cold water enters the countercurrent heat exchange channel 20 for further heating, and is finally delivered to the dishwasher 16 through the hot water outlet 21.

[0050] Waste heat recovery flow path: The waste hot water discharged from the dishwasher 16 enters the waste hot water exchanger 17 through the dishwasher waste hot water inlet 18, exchanges heat with cold water, and is discharged through the dishwasher waste hot water outlet 19, realizing the efficient recovery and utilization of waste heat.

[0051] Waste heat recovery: The heat collection hood 23 collects the waste heat emitted by the dishwasher 16 and sends it to the air inlet side of the evaporator 11 through the dishwasher waste heat channel 22, serving as an auxiliary heat source for the evaporator 11 and further improving the system energy efficiency.

[0052] In some embodiments, the condenser-evaporator 7 is provided with parallel bidirectional branches, the first branch is connected to the evaporator 11 via a throttle valve 8, and the second branch forms a bypass circuit via an unloading valve 12 and a capillary tube 13.

[0053] The capillary tube 13 has a length of 800-1500 mm and an inner diameter of 2-3 mm.

[0054] It should be noted that the condenser-evaporator exchanger 7 is equipped with parallel bidirectional branches, including:

[0055] First branch: The refrigerant enters the evaporator 11 after being depressurized by the throttle 8, realizing the conventional heating cycle.

[0056] The second branch: The refrigerant forms a bypass circuit through the unloading valve 12 and the capillary tube 13 to regulate the system flow.

[0057] Capillary tube 13 parameter optimization: The length of capillary tube 13 is 800-1500mm, and the inner diameter is 2-3mm. By precisely controlling the throttling and pressure reduction effect, it ensures that the refrigerant is fully evaporated in the evaporator 11, preventing liquid refrigerant from entering the compressor 1 and improving system safety. By switching between the first and second branches, the system can dynamically adjust the refrigerant flow rate according to actual operating conditions such as load changes and ambient temperature fluctuations, optimizing the energy efficiency ratio and reducing energy consumption.

[0058] In one example, a gas-liquid separation structure is provided between the refrigerant outlet of the return gas enthalpy exchanger 6 and the suction port of the compressor 1.

[0059] It should be noted that a gas-liquid separation structure is provided between the refrigerant outlet of the return gas enthalpy exchanger 6 and the suction port of the compressor 1.

[0060] The gas-liquid separation structure effectively separates the liquid components in the refrigerant, preventing liquid refrigerant from entering the compressor 1 and causing liquid slugging, thus extending the service life of the compressor 1. The separated gaseous refrigerant is more easily drawn into the compressor 1, reducing suction resistance and improving system operating efficiency.

[0061] In some embodiments, the waste hot water exchanger 17 and the countercurrent heat exchange channel 20 are integrated in the same housing to form a two-stage heating structure;

[0062] The waste hot water exchanger 17 adopts a corrugated plate heat exchanger with a plate gap of 3-5mm.

[0063] It should be noted that the waste water heat exchanger 17 and the counter-current heat exchange channel 20 are integrated into the same housing, forming a two-stage heating structure. The waste water heat exchanger 17 adopts a corrugated plate heat exchanger with a plate gap of 3-5mm. Cold water first exchanges heat with waste water through the waste water heat exchanger 17, and then enters the counter-current heat exchange channel 20 for further heating, achieving staged heating and maximizing waste heat recovery. The plate gap design of 3-5mm, combined with the corrugated structure, increases the heat exchange area and enhances the turbulence effect, significantly improving heat exchange efficiency.

[0064] In some embodiments, in the system overload protection bypass, the unloading valve 12 is a pressure-driven normally closed valve, and its opening pressure is set to 110%-120% of the system safety threshold.

[0065] It should be noted that the system overload protection bypass consists of unloading valve 12 and capillary tube 13. Unloading valve 12 is a pressure-driven normally closed valve, with its opening pressure set at 110%-120% of the system safety threshold. When the system pressure exceeds the safety threshold, unloading valve 12 automatically opens, allowing refrigerant to bypass and return through capillary tube 13, preventing compressor 1 from overloading and ensuring stable system operation. Setting the pressure to 110%-120% of the safety threshold ensures the reliability of overload protection while preventing malfunctions, thus improving system safety.

[0066] In some embodiments, the refrigerant flow channel and the water flow channel of the counter-current heat exchange channel 20 are arranged in an alternating counter-current manner, and the heat exchange surface is provided with a turbulence enhancement structure.

[0067] The refrigerant flow channel and the water flow channel of the counter-current heat exchange channel 20 are arranged in an alternating counter-current manner, and the heat exchange surface is provided with a turbulence enhancement structure.

[0068] The refrigerant flows in the opposite direction to the water flow, maximizing the temperature gradient and improving heat transfer efficiency. Surface protrusions or grooves disrupt the boundary layer, enhancing turbulence, reducing thermal resistance, and significantly improving heat transfer performance.

[0069] In some embodiments, the evaporator 11 has a fin spacing of 2.0-3.0 mm and is coated with a hydrophobic and anti-corrosion coating. The fin spacing of 2.0-3.0 mm balances the heat exchange area and airflow resistance, ensuring efficient heat absorption by the evaporator 11 while reducing airflow loss. The hydrophobic and anti-corrosion coating effectively prevents scaling or corrosion on the fin surface, extending the service life of the evaporator 11 and reducing maintenance costs.

[0070] Furthermore, temperature sensors and pressure sensors are respectively installed on the pipes of the condenser 3 and the evaporator 11, and the sensor signals are connected to the dishwasher's main control system. An adjustable damper is provided between the heat collection hood 23 and the dishwasher's waste heat channel 22 to control the waste heat gas flow rate.

[0071] It should be noted that temperature and pressure sensors are respectively installed on the pipes of condenser 3 and evaporator 11 to monitor the system's operating status in real time and feed the signals back to the dishwasher's main control system for intelligent regulation. The sensor data is linked with the main control system to dynamically adjust the refrigerant circulation path, defrosting mode, etc., improving system adaptability and energy efficiency. An adjustable damper is installed between the heat collection hood 23 and the dishwasher's waste heat channel 22. The opening degree is adjusted to control the waste heat gas flow rate, adapting to different dishwasher operating conditions and optimizing the heat recovery efficiency of evaporator 11. The adjustable damper can adjust its opening degree according to the waste heat gas flow rate requirements, preventing excessive heat from affecting the performance of evaporator 11 while ensuring maximum waste heat recovery.

[0072] In practical applications, the waste hot water and waste heat generated during the operation of the dishwasher 16 are used as the initial heat source. The waste hot water discharged from the dishwasher enters the waste hot water exchanger 17 through the dishwasher waste hot water inlet 18, where it exchanges heat with cold water in a corrugated plate heat exchanger. The preheated cold water then enters the counter-current heat exchange channel 20, where the refrigerant flow channel and the water flow channel are arranged in a staggered counter-current manner. The heat exchange surface is equipped with a turbulence enhancement structure. After being heated by the heat pump system, it is output to the hot water outlet 21, achieving the goal of high efficiency and energy saving through dual-stage heating. At the same time, the waste heat discharged from the dishwasher is collected by the heat collection hood 23, and after the flow rate is regulated by the adjustable damper, it is sent to the air inlet side of the evaporator 11 as an auxiliary heat source for the evaporator 11, improving the heat absorption efficiency of the evaporator 11. When the system starts, the compressor 1 compresses the low-temperature, low-pressure refrigerant into a high-temperature, high-pressure gas, which is switched to the condenser 3 through the four-way valve 2 to release heat. After condensing into a liquid, it enters the return gas enthalpy exchanger 6 through the first one-way valve 5 to exchange heat with the low-temperature refrigerant, and then enters the condenser-evaporator exchanger 7. The condenser-evaporator exchanger 7 has a parallel bidirectional branch: under normal operating conditions, the refrigerant enters the evaporator 11 for heat absorption and evaporation after being depressurized by the throttle valve 8; when the system pressure exceeds the safety threshold, the pressure-driven unloading valve 12 automatically opens, and the refrigerant forms a bypass circuit through the capillary tube 13 to prevent the compressor 1 from being overloaded. When the evaporator 11 is frosted, the four-way valve 2 switches to defrost mode, and the high-temperature and high-pressure refrigerant discharged from the compressor 1 directly enters the evaporator 11 for defrosting, while simultaneously circulating in reverse through the third one-way valve 14 and the fourth one-way valve 15 to ensure efficient system operation. A gas-liquid separation structure is provided between the refrigerant outlet of the return gas enthalpy exchanger 6 and the suction port of the compressor 1 to prevent liquid refrigerant from entering the compressor 1 and causing liquid slugging. Temperature and pressure sensors of the condenser 3 and the evaporator 11 monitor the system status in real time and feed the data back to the dishwasher main control system to achieve dynamic adjustment.

[0073] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the content of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A multi-stage heat pump system for commercial dishwashers, characterized in that, include: Compressor (1), four-way valve (2), condenser (3), evaporator (11), throttle (8), return gas enthalpy exchanger (6) and condenser-evaporator exchanger (7); Waste hot water exchanger (17) is provided with a dishwasher waste hot water inlet (18) and a dishwasher waste hot water outlet (19), and is connected to the waste heat channel (22) of the dishwasher (16) through a pipe; The heat collection hood (23) is installed at the waste heat exhaust port of the dishwasher (16) and connected to the air inlet side of the evaporator (11) through the waste heat channel (22) of the dishwasher; The system overload protection bypass, consisting of unloading valve (12) and capillary tube (13), has its inlet end connected to the exhaust end of compressor (1) and its outlet end connected to the refrigerant inlet of return gas enthalpy exchanger (6). The refrigerant circulation piping includes: Hot water production main circuit: compressor (1) → four-way valve (2) → condenser (3) → first pipe port (4) → first check valve (5) → return gas enthalpy exchanger (6) → condenser-evaporator exchanger (7) main circuit → throttle (8) → second check valve (9) → second pipe port (10) → evaporator (11) → four-way valve (2) → return gas enthalpy exchanger (6) → compressor (1); Defrosting main circuit: Compressor (1) → Four-way valve (2) → Evaporator (11) → Second pipe port (10) → Third check valve (14) → Return gas enthalpy exchanger (6) → Condensation evaporation exchanger (7) main circuit → Throttling device (8) → Fourth check valve (15) → First pipe port (4) → Condenser (3) → Four-way valve (2) → Return gas enthalpy exchanger (6) → Compressor (1); The water system includes: Hot water flow path: cold water inlet → waste hot water exchanger (17) → countercurrent heat exchange channel (20) → hot water outlet (21); Waste heat recovery flow path: dishwasher (16) → dishwasher waste hot water inlet (18) → waste hot water exchanger (17) → dishwasher waste hot water outlet (19).

2. The multi-stage heat pump system for commercial dishwashers according to claim 1, characterized in that, The condenser-evaporator exchanger (7) is provided with parallel bidirectional branches. The first branch is connected to the evaporator (11) via a throttle valve (8), and the second branch forms a bypass circuit via an unloading valve (12) and a capillary tube (13). The length of the capillary (13) is 800-1500 mm and the inner diameter is 2-3 mm.

3. The multi-stage heat pump system for commercial dishwashers according to claim 1, characterized in that, The refrigerant outlet of the return gas enthalpy exchanger (6) and the suction port of the compressor (1) are provided with a gas-liquid separation structure.

4. The multi-stage heat pump system for commercial dishwashers according to claim 1, characterized in that, The waste hot water exchanger (17) and the counter-current heat exchange channel (20) are integrated in the same shell to form a two-stage heating structure; The waste hot water exchanger (17) adopts a corrugated plate heat exchanger with a plate gap of 3-5mm.

5. The multi-stage heat pump system for commercial dishwashers according to claim 1, characterized in that, In the system overload protection bypass, the unloading valve (12) is a pressure-driven normally closed valve, and its opening pressure is set to 110%-120% of the system safety threshold.

6. The multi-stage heat pump system for commercial dishwashers according to claim 1, characterized in that, The refrigerant flow channel and the water flow channel of the counter-current heat exchange channel (20) are arranged in an alternating counter-current manner, and the heat exchange surface is provided with a turbulence enhancement structure.

7. The multi-stage heat pump system for commercial dishwashers according to claim 1, characterized in that, The evaporator (11) has a fin spacing of 2.0-3.0 mm and is coated with a hydrophobic and anti-corrosion coating.

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