A cascade heat pump system

Abstract

The utility model provides a kind of cascade heat pump system, including by the first circulating device and the second circulating device connected by cascade heat exchanger, the first circulating device includes evaporator and first compressor connected in turn, and cascade heat exchanger is located the export end of first compressor;Second circulating device includes second compressor and condenser connected in turn, and cascade heat exchanger is located the import end of second compressor;Cooler is arranged between first compressor and cascade heat exchanger, and the cooling inlet end of cooler has water inlet pipe, and the cooling outlet end of cooler is connected with the condensation inlet end of condenser, and the condensation outlet end of condenser has water outlet pipe;The technical problem solved in the scheme is in specific scene such as beverage factory container cleaning, high-temperature water is needed and directly discharged after use, and the existing cascade heat pump needs to heat low-temperature water into high-temperature water once, so that when low-temperature water exchanges heat in low-temperature area, effective energy loss is large, leading to the energy efficiency COP of existing cascade heat pump is still difficult to improve, and energy-saving effect is poor.

Description

Technical Field

[0001] This utility model relates to the technical field of heat pumps, and more specifically, to a cascade heat pump system. Background Technology

[0002] With the increasing demand for industrial decarbonization, traditional boilers with high energy consumption and high carbon emissions are gradually being replaced. Heat pumps, due to their high energy efficiency and low carbon emissions, are expanding their market share in industrial heating engineering and have become an important technological path for decarbonization. Industrial heat pumps are commonly divided into two categories: waste heat recovery type, which relies on industrial wastewater and can recover waste heat, but its application is limited by the waste heat scenario and supply volume; and air heat source type, which does not require specific waste heat, can be flexibly deployed, has a wide range of applications, and is more widely used in industrial heating. However, air-source heat pumps face bottlenecks in low-temperature winter environments: low ambient temperatures cause a sharp drop in evaporator evaporation temperature, resulting in insufficient heating capacity to meet stable production heating needs, decreased energy efficiency, and increased energy costs, thus hindering their widespread adoption in cold-region industrial settings. To address this, engineers proposed a cascade circulation system. Through multi-stage circulating heat transfer, the system can mitigate the impact of low temperatures to some extent, suppressing heating capacity attenuation and energy efficiency decline, and improving low-temperature operating performance. However, the relevant technologies have at least one of the following problems: In specific scenarios such as container cleaning in beverage factories, high-temperature water is required and it is discharged directly after use. Existing cascade heat pumps need to heat the low-temperature inlet water into high-temperature water in one go. As a result, when the inlet water exchanges heat in the low-temperature region, there is a large effective energy loss, which makes it difficult to improve the energy efficiency COP of existing cascade heat pumps and results in poor energy-saving effect. Utility Model Content

[0003] The technical problem solved by this utility model is that in specific scenarios such as container cleaning in beverage factories, high-temperature water is required and it is directly discharged after use. Existing cascade heat pumps need to heat the low-temperature inlet water to high-temperature water in one go. As a result, when the inlet water exchanges heat in the low-temperature region, there is a large loss of effective energy, which makes it difficult to improve the energy efficiency COP of existing cascade heat pumps and results in poor energy-saving effect.

[0004] To solve the above-mentioned technical problems, this utility model provides a cascade heat pump system, which includes a first circulation device for supplying a first refrigerant and a second circulation device for supplying a second refrigerant, and the first circulation device and the second circulation device are connected by a cascade heat exchanger. The first circulation device includes an evaporator and a first compressor connected in sequence by a first refrigerant pipeline for the flow of a first refrigerant. A cascade heat exchanger is located at the outlet end of the first compressor, and the first outlet of the cascade heat exchanger is connected to the evaporation inlet of the evaporator. The second circulation device includes a second compressor and a condenser connected in sequence by a second refrigerant pipeline for the flow of the second refrigerant. The cascade heat exchanger is located at the inlet end of the second compressor, and the first inlet of the cascade heat exchanger is connected to the refrigerant outlet of the condenser. A cooler is provided between the first compressor and the cascade heat exchanger; The cooler has a cooling water inlet connected to a water inlet pipe, a cooling water outlet connected to a condenser condenser inlet, and a condenser condenser outlet connected to a water outlet pipe.

[0005] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: The cascade heat pump system in this solution solves the problems of large effective energy loss and difficulty in improving energy efficiency COP in existing cascade heat pumps. Specifically, this solution utilizes a cascade heat exchanger to transfer heat between the first and second circulation units. In the first circulation unit, the heat absorbed by the evaporator is compressed by the first compressor, then pre-cooled by a cooler before entering the cascade heat exchanger to exchange heat with the refrigerant in the second circulation unit. In the second circulation unit, the high-temperature refrigerant compressed by the second compressor is preheated in the cascade heat exchanger before entering the condenser. This avoids the direct, one-time heat exchange between low-temperature inlet water and high-temperature refrigerant in existing technologies, reducing the effective energy loss of the inlet water in the low-temperature region. Simultaneously, the cooling water outlet of the cooler is connected to the condensing water inlet of the condenser, allowing the waste heat from the cooler to be used to preheat the inlet water of the condenser, achieving cascaded heat utilization to further reduce energy waste. Furthermore, the cascade heat exchangers are located at the outlet of the first compressor and the inlet of the second compressor, forming a highly efficient "compression-heat exchange-recompression" cycle, improving the refrigerant's heat exchange efficiency and temperature rise stability, avoiding energy efficiency fluctuations caused by sudden temperature increases in single-stage cycles, thereby improving the COP of the cascade heat pump system.

[0006] In one embodiment of this utility model, a control valve is provided at the cooling water outlet, which is used to control the amount of warm water entering the condenser.

[0007] Compared with existing technologies, the technical effects achieved by this solution are as follows: A control valve is added to the cooling water outlet to regulate the amount of warm water entering the condenser. On the one hand, this achieves precise control of heat utilization in stages to improve energy efficiency. The control valve adjusts the amount of warm water in real time based on the condenser inlet water temperature, target outlet water temperature, and cooler outlet water temperature, ensuring that waste heat precisely matches the preheating requirements of the inlet water. This avoids heat waste caused by insufficient warm water and prevents excessive preheating of the inlet water from affecting subsequent heat exchange in the condenser, further reducing effective energy loss and thus improving the Co-operational Performance Index (COP). On the other hand, the control valve can dynamically balance the condenser heat exchange load by adjusting the amount of warm water, in conjunction with the synergistic effect of the cascade heat exchanger and cooler. When the load increases, the amount of warm water is increased to improve the preheating effect and reduce heating pressure; when the load decreases, the amount of warm water is reduced to avoid excess heat, thereby maintaining stable evaporator evaporation temperature and condenser condensation temperature. This ensures that the system can stably output high-temperature water at the target temperature under different production loads, thereby improving the heat exchange efficiency of the cascade heat pump system in variable load high-temperature heating scenarios.

[0008] In one embodiment of this utility model, a first temperature sensor is installed on the water inlet pipe, which is used to monitor the temperature of the water inlet pipe.

[0009] Compared with existing technologies, the technical effects achieved by this solution are as follows: By adding a first temperature sensor to the water inlet pipe at the cooling water inlet end to monitor the condensate temperature, this solution can accurately detect the initial temperature fluctuations of the condensate entering the cooler in real time (such as deviations from the normal temperature), avoiding the imbalance of waste heat utilization caused by unknown condensate temperature. This allows for dynamic adjustment of the heat exchange matching strategy based on the actual condensate temperature, ensuring that the heat transfer between the cooler and condenser is more adapted to the preheating requirements of the inlet water, further reducing the effective energy loss of heat exchange in low-temperature areas, improving the energy efficiency COP, and enhancing the adaptability of the cascade heat pump system to condensate temperature fluctuations, ensuring that the cascade heat pump system can still operate stably when the condensate temperature is unstable.

[0010] In one embodiment of this utility model, the control valve includes a first inlet, a second inlet, and a first outlet; The first water inlet is connected to the cooling water outlet, the second water inlet is connected to the water inlet pipe, and the first water outlet is connected to the condensate inlet.

[0011] Compared with existing technologies, the technical effects achieved by this solution are as follows: The control valve provided by this solution can achieve flexible mixing and precise delivery of waste heat water at the cooling outlet and condensate in the inlet pipe. When the temperature or flow rate of the waste heat water at the cooling outlet fluctuates, or the initial temperature of the condensate in the inlet pipe deviates from the expected value, the mixing ratio of the water sources at the cooling outlet and the inlet pipe is adjusted by the control valve. This ensures that the water temperature entering the condensate inlet can stably meet the preheating requirements, and can also dynamically balance the inlet water temperature and flow rate according to the actual heat exchange conditions of the condenser. This further improves the efficiency of heat cascade utilization, reduces the effective energy loss of heat exchange in low-temperature areas, and improves the energy efficiency COP.

[0012] In one embodiment of this utility model, a first expansion valve is provided between the first outlet and the evaporation inlet.

[0013] Compared with existing technologies, the technical effects achieved by this solution are as follows: Adding a first expansion valve between the first outlet and the evaporation inlet prevents the high-pressure subcoolant flowing from the cascade heat exchanger from directly entering the evaporator in a liquid state. This avoids the refrigerant failing to fully evaporate and absorb heat within the evaporator, resulting in wasted heat exchange area and reduced heat absorption efficiency, thus improving the heating efficiency of the first circulation device. Furthermore, the first expansion valve throttles and expands the high-pressure subcoolant into a low-pressure two-phase flow (containing liquid and gaseous refrigerant), allowing the refrigerant to be evenly distributed and efficiently absorb heat from the external environment after entering the evaporator, maximizing the evaporator's heat absorption capacity, providing a sufficient heat source for the second circulation device, reducing energy loss at the first circulation device level, and improving the COP of the cascade heat pump system.

[0014] In one embodiment of this utility model, a second expansion valve is provided between the first inlet and the refrigerant outlet.

[0015] Compared with existing technologies, the technical effects achieved by this solution are as follows: This solution installs a second expansion valve between the first inlet and the refrigerant outlet, preventing the high-pressure subcoolant flowing from the condenser from directly entering the cascade heat exchanger in a high-pressure liquid state. This avoids the refrigerant from failing to fully absorb heat and vaporize within the cascade heat exchanger, thus wasting the heat exchange area of ​​the cascade heat exchanger and affecting the heating capacity of the second circulation device, thereby improving the energy efficiency of the cascade heat pump system. Furthermore, the second expansion valve throttles and expands the high-pressure subcoolant into a low-pressure two-phase flow, allowing the refrigerant to be evenly distributed and efficiently absorb heat from the first refrigerant after entering the cascade heat exchanger, fully vaporizing to form low-pressure superheated gas. This provides a stable intake state for the second circulation device, improving its heat exchange efficiency.

[0016] In one embodiment of this invention, a pressure sensor is provided at the outlet end of the first compressor to monitor the pressure of the fluid entering the cooler.

[0017] Compared with existing technologies, the technical advantages achieved by this solution are as follows: A pressure sensor is installed at the outlet of the first compressor to monitor the fluid pressure entering the cooler. This allows for real-time pressure data detection, and when the fluid pressure exceeds a safe threshold, the control components (such as the first compressor) are activated to rapidly reduce the pressure, preventing equipment damage and safety accidents. Furthermore, the fluid pressure within the cooler is directly related to its saturation temperature. The fluid saturation temperature can be indirectly calculated using pressure sensor data, thereby accurately matching the cooler's heat exchange requirements and preventing fluid temperature deviations from the heat exchange range due to abnormal pressure, thus further reducing effective energy loss.

[0018] In one embodiment of this utility model, a second temperature sensor is installed on the water outlet pipe, which is used to monitor the temperature of the water outlet pipe.

[0019] Compared with existing technologies, the technical effects achieved by adopting this technical solution are as follows: By installing a second temperature sensor on the outlet pipe of the condenser, the actual temperature of the condensate can be monitored in real time to avoid deviation of the actual outlet temperature from the target value. The second temperature sensor can detect the outlet temperature deviation in real time, and control the frequency of the first compressor and the second compressor, control the valve opening, and dynamically adjust the heat exchange load to ensure that the condensate reaches the target temperature stably.

[0020] In one embodiment of this utility model, the cascade heat pump system further includes an outlet water temperature control unit, which is communicatively connected to the first compressor, the second compressor, and the second temperature sensor.

[0021] Compared with existing technologies, the technical effects achieved by this solution are as follows: In the cascade heat pump system, an outlet water temperature control unit is added, communicating with the first compressor, the second compressor, and the second temperature sensor. This allows for precise linkage and dynamic adjustment of core components, ensuring a stable target outlet water temperature. This avoids the outlet water temperature fluctuations caused by fixed compressor frequencies or lagging control in existing technologies, ensuring that the high-temperature water temperature always matches process requirements. This solves the problem of insufficient precision in traditional manual adjustment or single-component control. Furthermore, it can synergistically optimize the energy efficiency of the cascade heat pump system, reducing ineffective energy consumption and further minimizing effective energy loss.

[0022] In one embodiment of this utility model, the cascade heat pump system further includes a cooling control unit, which is communicatively connected to a first temperature sensor, a control valve, and a pressure sensor.

[0023] Compared with existing technologies, the technical effects achieved by this solution are as follows: In the cascade heat pump system, a cooling control unit is added, communicating with the first temperature sensor, control valve, and pressure sensor. On the one hand, this integrates multi-dimensional data to precisely optimize heat exchange matching, further reducing effective energy loss and avoiding heat exchange imbalance caused by single-parameter control in existing technologies. This ensures that the waste heat from the cooler precisely matches the preheating requirements of the condenser inlet water. On the other hand, when the pressure sensor detects that the fluid pressure exceeds the threshold, or the first temperature sensor detects a sudden change in condensate temperature, the cooling control unit can quickly activate the control valve to adjust the flow rate, preventing equipment damage due to overpressure and extending the service life of the cascade heat pump system.

[0024] By adopting the technical solution of this utility model, the following technical effects can be achieved: This invention utilizes a cascade heat exchanger to transfer heat between the first and second circulation devices. In the first circulation device, the heat absorbed by the evaporator is compressed by the first compressor, then pre-cooled by the cooler before entering the cascade heat exchanger to exchange heat with the refrigerant in the second circulation device. In the second circulation device, the high-temperature refrigerant compressed by the second compressor is preheated in the cascade heat exchanger before entering the condenser. This avoids the direct, one-time heat exchange between low-temperature inlet water and high-temperature refrigerant in existing technologies, reducing the effective energy loss of the inlet water in the low-temperature region. Simultaneously, the cooling water outlet of the cooler is connected to the condensing water inlet of the condenser, allowing the waste heat of the cooler to be used to preheat the inlet water of the condenser, achieving cascaded utilization of heat to further reduce energy waste. Furthermore, the cascade heat exchangers are located at the outlet of the first compressor and the inlet of the second compressor, forming a highly efficient "compression-heat exchange-recompression" cycle, improving the heat exchange efficiency and temperature rise stability of the refrigerant, avoiding energy efficiency fluctuations caused by sudden temperature rises in single-stage cycles, thereby improving the COP of the cascade heat pump system. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of a cascade heat pump system provided in an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures: 100. Cascade heat exchanger; 110. First expansion valve; 120. Second expansion valve; 200. Evaporator; 300. First compressor; 310. Pressure sensor; 400. Second compressor; 500. Condenser; 510. Water outlet pipe; 520. Second temperature sensor; 600. Cooler; 610. Water inlet pipe; 620. First temperature sensor; 700. Control valve; 800. Water outlet temperature controller; 900. Cooling controller. Detailed Implementation

[0027] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0028] See Figure 1 This utility model provides a cascade heat pump system, which includes a first circulation device for supplying a first refrigerant and a second circulation device for supplying a second refrigerant, and the first and second circulation devices are connected by a cascade heat exchanger 100; the first circulation device includes an evaporator 200 and a first compressor 300 sequentially connected by a first refrigerant pipeline for supplying the first refrigerant, the cascade heat exchanger 100 being located at the outlet end of the first compressor 300, and the first outlet of the cascade heat exchanger 100 being connected to the evaporation inlet of the evaporator 200; the second circulation device includes a second refrigerant pipeline for supplying the second refrigerant. A second compressor 400 and a condenser 500 are connected in sequence. A cascade heat exchanger 100 is located at the inlet end of the second compressor 400, and the first inlet of the cascade heat exchanger 100 is connected to the refrigerant outlet of the condenser 500. The outlet end of the second compressor 400 is connected to the refrigerant inlet of the condenser 500. A cooler 600 is provided between the first compressor 300 and the cascade heat exchanger 100. The cooling water inlet end of the cooler 600 is connected to a water inlet pipe 610, the cooling water outlet end of the cooler 600 is connected to the condenser water inlet end of the condenser 500, and the condenser water outlet end of the condenser 500 is connected to a water outlet pipe 510.

[0029] In use, the condensate enters the cooler 600 through the inlet pipe 610 for the first heat exchange, and then enters the condenser 500 through the outlet pipe. After the second heat exchange in the condenser 500, it flows out through the outlet pipe 510.

[0030] Specifically, this solution addresses the issues of high effective energy loss and difficulty in improving COP (Coefficient of Performance) in existing cascade heat pump systems. Specifically, this solution uses a cascade heat exchanger 100 to achieve heat transfer between the first and second circulation units. In the first circulation unit, the heat absorbed by the evaporator 200 is compressed by the first compressor 300, then pre-cooled by the cooler 600 before entering the cascade heat exchanger 100 to exchange heat with the refrigerant in the second circulation unit. In the second circulation unit, the high-temperature refrigerant compressed by the second compressor 400 is preheated in the cascade heat exchanger 100 before entering the condenser 500. This avoids the direct, one-time heat exchange between low-temperature inlet water and high-temperature refrigerant in existing technologies, reducing the effective energy loss of the inlet water in the low-temperature region. Energy loss is minimized. Meanwhile, the cooling water outlet of the cooler 600 is connected to the condensing water inlet of the condenser 500, allowing the waste heat of the cooler 600 to be used to preheat the inlet water of the condenser 500, thus achieving cascade utilization of heat to further reduce energy waste. Furthermore, the cascade heat exchangers 100 are located at the outlet of the first compressor 300 and the inlet of the second compressor 400, respectively, forming a highly efficient cycle of "compression-heat exchange-recompression". This improves the heat exchange efficiency and temperature rise stability of the refrigerant, avoids energy efficiency fluctuations caused by sudden temperature rises in a single-stage cycle, and thus improves the COP of the cascade heat pump system.

[0031] like Figure 1 As shown, in one embodiment of this utility model, a control valve 700 is provided at the cooling water outlet, which is used to control the amount of warm water entering the condenser 500.

[0032] Specifically, a control valve 700 is added to the cooling water outlet of this solution to regulate the amount of warm water entering the condenser 500. On the one hand, this achieves precise control of heat utilization in stages to improve energy efficiency. The control valve 700 adjusts the amount of warm water in real time according to the inlet water temperature of the condenser 500, the target outlet water temperature, and the outlet water temperature of the cooler 600, ensuring that the waste heat is just right to match the preheating requirements of the inlet water. This avoids heat waste caused by insufficient warm water and prevents excessive warm water from overheating the inlet water and affecting the subsequent heat exchange of the condenser 500, further reducing effective energy loss and thus improving energy efficiency. Energy efficiency COP; on the other hand, the control valve 700 can dynamically balance the heat exchange load of the condenser 500 by adjusting the amount of warm water, in conjunction with the synergistic effect of the cascade heat exchanger 100 and the cooler 600. When the load increases, the amount of warm water is increased to improve the preheating effect and reduce the heating pressure. When the load decreases, the amount of warm water is reduced to avoid excess heat, thereby maintaining the evaporation temperature of the evaporator 200 and the condensation temperature of the condenser 500 stable. This ensures that the system can stably output high-temperature water at the target temperature under different production loads, thereby improving the heat exchange efficiency of the cascade heat pump system in variable load high-temperature heating scenarios.

[0033] like Figure 1As shown, in one embodiment of the present invention, a first temperature sensor 620 is installed on the water inlet pipe 610, and the first temperature sensor 620 is used to monitor the temperature of the water inlet pipe 610.

[0034] Specifically, this solution adds a first temperature sensor 620 to the water inlet pipe 610 at the cooling water inlet end to monitor the condensate temperature. This allows for real-time and accurate detection of initial temperature fluctuations in the condensate entering the cooler 600 (such as deviations from the normal temperature), avoiding imbalances in waste heat utilization caused by unknown condensate temperature. The solution then dynamically adjusts the heat exchange matching strategy based on the actual condensate temperature, ensuring that the heat transfer between the cooler 600 and the condenser 500 is better suited to the preheating requirements of the incoming water. This further reduces effective energy loss in low-temperature heat exchange areas, improves energy efficiency COP, and enhances the adaptability of the cascade heat pump system to condensate temperature fluctuations, ensuring stable operation of the cascade heat pump system even when the condensate temperature is unstable.

[0035] like Figure 1 As shown, in one embodiment of the present invention, the control valve 700 includes a first inlet, a second inlet, and a first outlet. The first water inlet is connected to the cooling water outlet, the second water inlet is connected to the water inlet pipe 610, and the first water outlet is connected to the condensate inlet.

[0036] Specifically, the control valve 700 provided in this solution can achieve flexible mixing and precise delivery of waste heat water at the cooling water outlet and condensate in the inlet pipe 610. When the temperature or flow rate of the waste heat water at the cooling water outlet fluctuates, or the initial temperature of the condensate in the inlet pipe 610 deviates from the expected value, the control valve 700 adjusts the mixing ratio of the water sources at the cooling water outlet and the two ends of the inlet pipe 610. This ensures that the water temperature entering the condensate inlet can stably meet the preheating requirements, and can also dynamically balance the inlet water temperature and water volume according to the actual heat exchange conditions of the condenser 500, further improving the efficiency of heat cascade utilization, reducing the effective energy loss of heat exchange in the low-temperature area, and improving the energy efficiency COP.

[0037] like Figure 1 As shown, in one embodiment of this utility model, a first expansion valve 110 is provided between the first outlet and the evaporation inlet.

[0038] Specifically, a first expansion valve 110 is added between the first outlet and the evaporation inlet to prevent the high-pressure subcoolant flowing out of the cascade heat exchanger 100 from directly entering the evaporator 200 in liquid form. This would prevent the refrigerant from fully evaporating and absorbing heat in the evaporator 200, resulting in wasted heat exchange area and reduced heat absorption efficiency, thereby improving the heating efficiency of the first circulation device. Furthermore, the first expansion valve 110 throttles and expands the high-pressure subcoolant into a low-pressure two-phase flow (containing liquid and gaseous refrigerant), allowing the refrigerant to be evenly distributed and efficiently absorb heat from the external environment after entering the evaporator 200, maximizing the heat absorption capacity of the evaporator 200, providing a sufficient heat source for the second circulation device, reducing energy loss at the level of the first circulation device, and improving the COP of the cascade heat pump system.

[0039] like Figure 1 As shown, in one embodiment of this utility model, a second expansion valve 120 is provided between the first inlet and the refrigerant outlet.

[0040] Specifically, this solution sets a second expansion valve 120 between the first inlet and the refrigerant outlet. This prevents the high-pressure subcoolant flowing from the condenser 500 from directly entering the cascade heat exchanger 100 in a high-pressure liquid state. This would prevent the refrigerant from fully absorbing heat and vaporizing within the cascade heat exchanger 100, thus wasting the heat exchange area of ​​the cascade heat exchanger 100 and affecting the heating capacity of the second circulation device. This improves the energy efficiency of the cascade heat pump system. Furthermore, the second expansion valve 120 throttles and expands the high-pressure subcoolant into a low-pressure two-phase flow, allowing the refrigerant to be evenly distributed and efficiently absorb heat from the first refrigerant after entering the cascade heat exchanger 100, fully vaporizing to form low-pressure superheated gas. This provides a stable intake state for the second circulation device and improves the heat exchange efficiency of the second circulation device.

[0041] like Figure 1 As shown, in one embodiment of the present invention, a pressure sensor 310 is provided at the outlet end of the first compressor 300 to monitor the pressure of the fluid entering the cooler 600.

[0042] Specifically, a pressure sensor 310 is installed at the outlet of the first compressor 300 to monitor the fluid pressure entering the cooler 600. This allows for real-time pressure monitoring, and when the fluid pressure exceeds a safety threshold, the control components (such as the first compressor 300) are activated to rapidly reduce the pressure, preventing equipment damage and safety accidents. Furthermore, the fluid pressure within the cooler 600 is directly related to its saturation temperature. Data from the pressure sensor 310 can be used to indirectly calculate the fluid saturation temperature, thereby accurately matching the heat exchange requirements of the cooler 600 and preventing the fluid temperature from deviating from the heat exchange range due to abnormal pressure, thus further reducing effective energy loss.

[0043] like Figure 1As shown, in one embodiment of this utility model, a second temperature sensor 520 is installed on the water outlet pipe 510, which is used to monitor the temperature of the water outlet pipe 510.

[0044] Specifically, a second temperature sensor 520 is installed on the outlet pipe 510 at the condensate outlet of the condenser 500. On the one hand, it monitors the actual temperature of the condensate in real time to avoid the actual outlet temperature deviating from the target value; on the other hand, the second temperature sensor 520 can detect the outlet temperature deviation in real time, and control the frequency of the first compressor 300 and the second compressor 400 and the opening of the control valve 700 in conjunction with the control to dynamically adjust the heat exchange load and ensure that the condensate outlet temperature stably reaches the target temperature.

[0045] like Figure 1 As shown, in one embodiment of the present invention, the cascade heat pump system further includes an outlet water temperature control unit, which is communicatively connected to the first compressor 300, the second compressor 400, and the second temperature sensor 520.

[0046] Specifically, an outlet water temperature control unit is added to the cascade heat pump system, communicating with the first compressor 300, the second compressor 400, and the second temperature sensor 520. This allows for precise linkage and dynamic adjustment of the core components, ensuring a stable target outlet water temperature. This avoids the outlet water temperature fluctuations caused by fixed compressor frequencies or lagging control in existing technologies, ensuring that the high-temperature water temperature always matches process requirements. This solves the problem of insufficient precision in traditional manual adjustment or single-component control. Furthermore, it can synergistically optimize the energy efficiency of the cascade heat pump system, reducing ineffective energy consumption and further minimizing effective energy loss.

[0047] like Figure 1 As shown, in one embodiment of the present invention, the cascade heat pump system further includes a cooling control unit, which is communicatively connected to the first temperature sensor 620, the control valve 700, and the pressure sensor 310.

[0048] Specifically, a cooling control unit is added to the cascade heat pump system, which is communicatively connected to the first temperature sensor 620, control valve 700, and pressure sensor 310. On the one hand, it can integrate multi-dimensional data to accurately optimize heat exchange matching, further reduce effective energy loss, and avoid heat exchange imbalance caused by single parameter control in existing technologies, ensuring that the waste heat of the cooler 600 is precisely matched with the preheating requirements of the condenser 500's inlet water. On the other hand, when the pressure sensor 310 detects that the fluid pressure exceeds the threshold, or when the first temperature sensor 620 detects a sudden change in condensate temperature, the cooling control unit can quickly link with the control valve 700 to adjust the flow rate, preventing equipment damage due to overpressure and extending the service life of the cascade heat pump system.

[0049] In a specific embodiment of this utility model, the calculation conditions are: first refrigerant R410A, second refrigerant R134a, outer ring temperature 7DB / 6WB℃, inlet water temperature T1=15℃, and outlet water temperature T2=75℃. The outlet water temperature control unit adjusts the frequency of the first compressor 300 and the second compressor 400 to 50Hz respectively to maintain the measured value of the second temperature sensor 520 at the target value of 75℃. In the existing technology, cascade heat pumps handle a temperature difference of 15.0℃→75.0℃, or 60℃, through a condenser 500; The cooling control unit compares the saturation temperature of the cooler 600 calculated from the measured value of the pressure sensor 310 with the measured value of the first temperature sensor 620, and adjusts the opening of the control valve 700 so that the saturation temperature of the cooler 600 is sufficiently higher than the inlet water temperature, thereby controlling the amount of warm water passing through the cooler 600. The states of the first refrigerant in the first circulation device and the second refrigerant in the second circulation device at this time are shown in Table 1: Table 1. Status of the first refrigerant and the second refrigerant. in, Figure 1 The numbers 1, 2, 3, 6, 7, 9, 10, 13, and 14 in Table 1 correspond to Low-pressure superheated gas 1, High-pressure superheated gas 2, High-pressure superheated gas 3, High-pressure supercoolant 6, Low-pressure two-phase flow 7, Low-pressure superheated gas 9, High-pressure superheated gas 10, High-pressure supercoolant 13, and Low-pressure two-phase flow 14.

[0050] The enthalpy difference of the condenser is set to 500 kJ / kg as h. CND The enthalpy difference of the cascade heat exchanger is 100 kJ / kg. CAS The enthalpy difference of the cooler at 600°C [kJ / kg] is h. GC The second refrigerant flow rate [kg / s] is m³ / s. H The first refrigerant flow rate [kg / s] is m³ / s. L The second compressor has a power rating of 400 kJ / kg. H The first compressor has a power rating of 300 kJ / kg. L The COP[-] of the first circulation device is COP. L The COP[-] of the second circulation device is COP. H We can obtain the following formula: Condenser: ; Cascade heat exchanger: ; Cooler: ; Overall COP in summary: ; In this implementation example: ; ; ; ; Therefore, we can conclude that: ; The inlet water in cooler 600 is heated by 10°C from 15°C to 25.0°C, and the temperature in condenser 500 is increased by 50°C to the target value of 75°C, handling the load of the 50°C temperature difference; that is, the inlet water temperature of condenser 500 is increased by 10°C compared with the existing warm water inlet temperature, the effective energy loss generated by heating in the low temperature region is reduced, and at the same time the heating load is transferred to cooler 600, thereby reducing the heat exchange load of condenser 500.

[0051] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A cascade heat pump system, characterized in that, The cascade heat pump system includes a first circulation device for the circulation of a first refrigerant and a second circulation device for the circulation of a second refrigerant, and the first circulation device and the second circulation device are connected by a cascade heat exchanger (100). The first circulation device includes an evaporator (200) and a first compressor (300) connected in sequence by a first refrigerant pipeline for the first refrigerant to flow through. The cascade heat exchanger (100) is located at the outlet end of the first compressor (300), and the first outlet of the cascade heat exchanger (100) is connected to the evaporation inlet of the evaporator (200). The second circulation device includes a second compressor (400) and a condenser (500) connected in sequence by a second refrigerant pipeline for the flow of the second refrigerant. The cascade heat exchanger (100) is located at the inlet end of the second compressor (400), and the first inlet of the cascade heat exchanger (100) is connected to the refrigerant outlet of the condenser (500). A cooler (600) is provided between the first compressor (300) and the cascade heat exchanger (100). The cooler (600) has a cooling water inlet connected to a water inlet pipe (610), the cooler (600) has a cooling water outlet connected to the condenser (500) has a condenser water inlet connected to the condenser water outlet connected to a water outlet pipe (510).

2. The cascade heat pump system according to claim 1, characterized in that, The cooling water outlet is equipped with a control valve (700), which is used to control the amount of warm water entering the condenser (500).

3. The cascade heat pump system according to claim 2, characterized in that, The water inlet pipe (610) is equipped with a first temperature sensor (620), which is used to monitor the temperature of the water inlet pipe (610).

4. The cascade heat pump system according to claim 3, characterized in that, The control valve (700) includes a first inlet, a second inlet, and a first outlet; The first water inlet is connected to the cooling water outlet, the second water inlet is connected to the water inlet pipe (610), and the first water outlet is connected to the condensate inlet.

5. The cascade heat pump system according to claim 1, characterized in that, A first expansion valve (110) is provided between the first outlet and the evaporation inlet.

6. The cascade heat pump system according to claim 1, characterized in that, A second expansion valve (120) is provided between the first inlet and the refrigerant outlet.

7. The cascade heat pump system according to claim 3, characterized in that, A pressure sensor (310) is provided at the outlet end of the first compressor (300) to monitor the pressure of the fluid entering the cooler (600).

8. The cascade heat pump system according to any one of claims 1-7, characterized in that, The water outlet pipe (510) is equipped with a second temperature sensor (520), which is used to monitor the temperature of the water outlet pipe (510).

9. The cascade heat pump system according to claim 8, characterized in that, The cascade heat pump system further includes an outlet water temperature control unit, which is communicatively connected to the first compressor (300), the second compressor (400), and the second temperature sensor (520).

10. The cascade heat pump system according to claim 7, characterized in that, The cascade heat pump system further includes a cooling control unit, which is communicatively connected to the first temperature sensor (620), the control valve (700), and the pressure sensor (310).

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