Cascade active jet enthalpy-increasing heat pump system and control method thereof

Abstract

The present invention proposes a cascade active jet enthalpy heat pump system and a control method thereof. The first stage is a low-temperature conventional jet enthalpy heat pump, which increases the degree of supercooling through conventional jet enthalpy to absorb more air energy and provide a heat source for the evaporation side of the second-stage high-temperature heat pump; the low-temperature heat pump generates thermal storage hot water for heating, which serves as an external heat source for the active jet enthalpy of the second-stage high-temperature heat pump; the second stage is a high-temperature active jet enthalpy heat pump, and the thermal storage heat is converted into heating capacity in the form of jet enthalpy difference, which greatly improves the performance of the heat pump unit. In addition, when the system is defrosted, the high-temperature heat pump system does not participate in defrosting and maintains heating operation. The low-temperature heat pump uses the thermal storage heat for thermal storage defrosting, and jet enthalpy is increased during the defrosting process to increase the circulation volume of the refrigerant involved in the defrosting operation, increase the low pressure, speed up the defrosting speed, improve the defrosting effect, and increase the compressor exhaust superheat during the defrosting process to avoid compressor damage due to liquid return during the defrosting process.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to a cascade active jet enthalpy-increasing heat pump system and a control method thereof. Background Art

[0002] Air source heat pump is a heating device that converts electrical energy and air energy into heat through the work of the compressor. However, the heating capacity and energy efficiency are seriously attenuated in low temperature environments, and it cannot be used in extremely low temperature environments. The main solution at present is the jet enthalpy technology, which has been commercialized due to its simple structure and low additional cost. However, conventional jet enthalpy has great defects, which are manifested as follows: the injection heat of the injected refrigerant comes from the heat pump itself, which is a passive jet enthalpy. The injection enthalpy difference in the jet enthalpy process cannot be converted into heating capacity, and the performance improvement of the heat pump is limited, and it cannot be used in extremely low temperature environments below -20°C. The invention patent with the patent publication number CN111649504 heat pump and the name of "Refrigerant Active Jet Heat Pump Based on Solar Energy and Its Control Method" proposes an active jet enthalpy technology based on the heat of an external low-grade heat source. Its principle is: the refrigerant is injected into the economizer to absorb the heat of the external heat source, and the heat of the external heat source is converted into heating capacity in the form of injection enthalpy difference. However, the source of external low-grade heat sources has become a bottleneck in the application of this technology, and how to solve this problem is crucial. Summary of the invention

[0003] In view of the deficiencies in the prior art, an object of the present invention is to provide a cascade active jet enthalpy-increasing heat pump system and a control method thereof.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A cascade active jet enthalpy heat pump system and a control method thereof, comprising an outdoor unit module, a cascade active jet enthalpy heat pump module and a heat storage module, wherein the cascade active jet enthalpy heat pump module is connected to the outdoor unit module and the heat storage module through a pipeline;

[0006] The outdoor unit module includes a low-temperature heat pump compressor, an oil separator, a four-way valve, a gas-liquid separator, an outdoor heat exchanger, and a main electronic expansion valve. The exhaust pipe of the low-temperature heat pump compressor is connected to the d pipe of the four-way valve through the oil separator, the e pipe of the four-way valve is connected to the main air pipe, the c pipe of the four-way valve is connected to one end of the outdoor heat exchanger, the s pipe of the four-way valve is connected to the inlet pipe of the gas-liquid separator, the outlet pipe of the gas-liquid separator is connected to the return pipe of the low-temperature heat pump compressor, and the other end of the outdoor heat exchanger is connected to the main electronic expansion valve and the high-pressure liquid storage tank in sequence, and the other end of the high-pressure liquid storage tank is connected to the liquid pipe stop valve of the low-temperature heat pump;

[0007] The cascade active jet enthalpy-increasing heat pump module comprises a cascade heat exchanger, a cascade heat pump solenoid valve, a high-temperature heat pump compressor, a high-temperature heat pump plate heat exchanger, a high-temperature heat pump main electronic expansion valve, an active jet enthalpy-increasing subcooling electronic expansion valve, an active jet enthalpy-increasing subcooler and a high-temperature heat pump water pump;

[0008] The exhaust pipe of the high-temperature heat pump compressor is connected to the air inlet pipe of the high-temperature heat pump plate heat exchanger, the air outlet pipe of the high-temperature heat pump plate heat exchanger is connected to the main electronic expansion valve of the high-temperature heat pump and the inlet pipe of the cascade heat exchanger in sequence, the outlet pipe of the cascade heat exchanger is connected to the return pipe of the high-temperature heat pump compressor, the hot water inlet pipe and the hot water outlet pipe of the high-temperature plate heat exchanger are respectively connected to the load side, the hot water outlet pipe is installed with a high-temperature heat pump water pump, and the high-temperature heat pump water pump pumps hot water to circulate in the high-temperature heat pump plate heat exchanger and the load side;

[0009] One end of the active jet reheat-added enthalpy subcooling electronic expansion valve is connected to the liquid pipe section between the high-temperature heat pump plate heat exchanger and the high-temperature heat pump main electronic expansion valve, and the other end of the active jet reheat-added enthalpy subcooling electronic expansion valve is connected to the active jet reheat-added enthalpy inlet pipe of the active jet reheat-added enthalpy subcooler, the active jet reheat-added enthalpy injection pipe of the active jet reheat-added enthalpy subcooler is connected to the injection port of the high-temperature heat pump compressor, and the heating hot water inlet pipe and the heating hot water outlet pipe of the active jet reheat-added enthalpy subcooler are respectively connected to the heat storage module.

[0010] Furthermore, the outdoor unit module also includes a conventional jet reheat enthalpy subcooler and a conventional jet reheat enthalpy subcooling electronic expansion valve, the conventional jet reheat enthalpy subcooler is connected with a conventional jet reheat enthalpy injection inlet pipe, a conventional jet reheat enthalpy injection main pipe, a liquid storage tank outlet pipe, and a main liquid pipe, the conventional jet reheat enthalpy injection inlet pipe is connected to the liquid pipe section between the high-pressure liquid storage tank and the conventional jet reheat enthalpy subcooler, the conventional jet reheat enthalpy subcooling electronic expansion valve is connected to the conventional jet reheat enthalpy injection inlet pipe, the conventional jet reheat enthalpy injection main pipe is connected to the injection port of the low-temperature stage heat pump compressor, and the injection refrigerant is injected into the intermediate pressure chamber of the compressor, the main liquid pipe connects the conventional jet reheat enthalpy subcooler and the outdoor heat exchanger, and the main electronic expansion valve is connected to the main liquid pipe.

[0011] Furthermore, the heat storage module includes a heat storage module solenoid valve, a heat storage module plate heat exchanger, a heat storage water tank, a heat storage hot water water pump, an active jet reheat water pump and a water temperature sensor for the heat storage tank. The heat storage tank is connected with a heat storage hot water inlet pipe, a heat storage hot water outlet pipe, a heating hot water inlet pipe and a heating hot water outlet pipe. The heat storage hot water pump pumps hot water through the heat storage hot water inlet pipe and the heat storage hot water outlet pipe to circulate between the heat storage module plate heat exchanger and the heat storage water tank. The active jet reheat water pump pumps hot water through the heating hot water inlet pipe and the heating hot water outlet pipe to circulate between the heat storage water tank and the active jet reheat supercooler.

[0012] Furthermore, it also includes a temperature detection module, which includes a water temperature sensor for a hot water storage tank, a jet enthalpy water inlet temperature sensor, a jet enthalpy water outlet temperature sensor, a jet enthalpy refrigerant inlet temperature sensor, a jet enthalpy refrigerant outlet temperature sensor, a liquid pipe temperature sensor, a water inlet temperature sensor, and a return water temperature sensor. The water temperature sensor for the hot water storage tank is used to detect the actual hot water temperature Ttank,cur in the hot water storage tank, and the jet enthalpy water inlet temperature sensor is used to detect the active jet enthalpy hot water inlet temperature Tw,in j,in, the jet enthalpy water outlet temperature sensor is used to detect the active jet enthalpy hot water outlet temperature Tw,inj,out, the jet enthalpy refrigerant inlet temperature sensor is used to detect the active jet enthalpy refrigerant inlet temperature Tref,inj,in, the jet enthalpy refrigerant outlet temperature sensor is used to detect the active jet enthalpy refrigerant outlet temperature Tref,inj,out, the liquid pipe temperature sensor is used to detect the liquid pipe temperature Tliq, and the return water temperature sensor is used to detect the return water temperature Tw,in,cur.

[0013] A cascade active jet enthalpy-increasing heat pump control method, applied to the cascade active jet enthalpy-increasing heat pump system as described in any one of the above, comprising:

[0014] Step S1A: a preset start-up condition for producing thermal storage hot water is configured. When the start-up condition for producing thermal storage hot water is met, the control for producing thermal storage hot water is started;

[0015] Step S1B: a preset shutdown condition for producing thermal storage hot water is configured. When the shutdown condition for producing thermal storage hot water is met, the thermal storage hot water production operation control is shut down;

[0016] Step S2A: a preset cascade heat pump heating operation start condition is configured, and when the cascade heat pump heating operation start condition is met, the cascade heat pump heating operation control is started;

[0017] Step S2B: a preset cascade heat pump heating operation shut-down condition is configured, and when the cascade heat pump heating operation shut-down condition is met, the cascade heat pump heating operation control is shut down;

[0018] Step S3A: a preset cascade active jet enthalpy heat pump heating operation start-up condition is configured, and when the cascade active jet enthalpy heat pump heating operation start-up condition is met, the cascade active jet enthalpy heat pump heating operation is started;

[0019] Step S3B: The preset cascade active jet enthalpy heat pump heating operation shutdown conditions and heat pump heating shutdown conditions are configured. When the cascade active jet enthalpy heat pump heating operation shutdown conditions are met, the cascade active jet enthalpy heat pump heating operation is shut down, and the cascade heat pump heating operation control is performed. When the heat pump heating shutdown conditions are met, the cascade active jet enthalpy heat pump module is shut down.

[0020] Further, in step S1A, the thermal storage hot water production operation start condition is configured with a preset first ambient temperature threshold and a water temperature setting target value. When it is detected that the outdoor ambient temperature is lower than the preset first ambient temperature threshold and the duration reaches the preset duration, and when it is detected that the actual stored water temperature is lower than the difference between the water temperature setting target value and the preset first stored water temperature return difference temperature and the duration reaches the preset duration, it is deemed that the thermal storage hot water production operation start condition is met;

[0021] In step S1B, the thermal storage hot water production operation shut-down condition is configured with a preset second thermal storage water temperature hysteresis temperature. When it is detected that the actual thermal storage hot water temperature is higher than the sum of the water temperature setting target value and the second thermal storage water temperature hysteresis temperature, and the duration reaches a preset time, the thermal storage hot water production operation shut-down condition is deemed to be met.

[0022] Further, in step S2A, the cascade heat pump heating operation start-up condition is configured with a preset return water temperature target value and a preset first return water return temperature difference. When the detected return water temperature is less than the difference between the return water temperature target value and the first return water return temperature difference, and the duration reaches a preset time, the cascade heat pump heating operation start-up condition is deemed to be met;

[0023] In step S2B, the cascade heat pump heating operation shutdown condition is configured with a preset second return water return temperature difference. When the detected return water temperature is greater than the sum of the return water temperature target value and the preset second return water return temperature difference, and the duration reaches a preset time, the cascade heat pump heating operation shutdown condition is deemed to be met.

[0024] Further, the exhaust superheat is defined as the difference between the exhaust temperature detected by the high-temperature heat pump exhaust temperature sensor of the high-temperature heat pump compressor and the saturation temperature corresponding to the high-pressure pressure detected by the high-temperature heat pump high-pressure sensor;

[0025] In step S3A, the cascade active jet enthalpy heat pump heating operation start-up condition is configured with a preset second ambient temperature threshold, a first exhaust superheat target value, and a thermal storage hot water temperature hysteresis setting threshold. When it is detected that the outdoor ambient temperature is lower than the second ambient temperature threshold, and the cascade heat pump is turned on and runs for more than a preset running time, it is detected that the exhaust superheat is greater than the preset first exhaust superheat target value, and it is detected that the thermal storage hot water temperature is greater than the sum of the liquid pipe temperature and the thermal storage hot water temperature hysteresis setting threshold and the duration exceeds a preset time, it is deemed that the cascade active jet enthalpy heat pump heating operation start-up condition is met;

[0026] In step S3B, the cascade active jet enthalpy heat pump heating operation shutdown condition is configured with a third ambient temperature threshold, a second exhaust superheat target value and a hysteresis setting value. When it is detected that the outdoor ambient temperature is higher than the third ambient temperature threshold, or the exhaust superheat is less than the preset second exhaust superheat target value, or when the active jet enthalpy hot water inlet temperature is less than or equal to the sum of the active jet enthalpy refrigerant outlet temperature and the hysteresis setting value, or the active jet enthalpy hot water outlet temperature is less than or equal to the sum of the active jet enthalpy refrigerant inlet temperature and the hysteresis setting value, the cascade active jet enthalpy heat pump heating operation shutdown condition is deemed to be met;

[0027] In step S3B, the heat pump heating shutdown condition is configured with a return water temperature target value and a return water temperature hysteresis threshold. When the return water temperature is detected to be higher than the sum of the return water temperature target value and the return water temperature hysteresis threshold, the heat pump heating shutdown condition is deemed to be met.

[0028] Furthermore, the method further comprises step S4A: configuring a preset defrost operation start condition, and starting the defrost operation control when the defrost operation start condition is met;

[0029] Step S4B: a preset defrost operation closing condition is configured, and when the defrost operation closing condition is met, the defrost operation control is closed.

[0030] Beneficial effects of the present invention:

[0031] The first stage is a low-temperature conventional jet enthalpy heat pump, which increases the degree of supercooling through conventional jet enthalpy to absorb more air energy and provide a heat source for the evaporation side of the second-stage high-temperature heat pump; the heat pump generates thermal storage hot water as an external low-grade heat source for the second-stage high-temperature heat pump active jet enthalpy; the second stage is a high-temperature active jet enthalpy heat pump, and the thermal storage heat is converted into heating capacity in the form of jet enthalpy difference, which greatly improves the performance of the heat pump unit and solves the technical bottleneck that the heat pump cannot be used in extremely low temperature environments. In addition, when the system is defrosted, the high-temperature heat pump system does not participate in defrosting and maintains heating operation. The low-temperature heat pump uses the thermal storage heat for thermal storage defrosting, which speeds up the defrosting speed and improves the defrosting effect. It can also reduce the compressor exhaust superheat during the defrosting process to avoid compressor damage due to liquid return during the defrosting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the principle of the cascade active jet enthalpy-increasing heat pump system of the present invention;

[0033] Figure 2 It is a schematic diagram of the flow path of the cascade heat pump cycle in the present invention;

[0034] Figure 3 Schematic diagram of the flow path of the active jet enthalpy-increasing heat pump cycle in the present invention;

[0035] Figure 4 It is a schematic diagram of the flow path of the heat pump heat storage cycle in the present invention;

[0036] Figure 5 It is a schematic diagram of the flow path of the cascade heat pump cycle and the heat pump thermal storage cycle performed simultaneously in the present invention;

[0037] Figure 6 is a schematic diagram of the flow path of the defrost cycle in the present invention;

[0038] Figure 7 is a schematic diagram of an active jet enthalpy-increasing subcooler in the present invention;

[0039] Figure 8 It is a flow chart of the cascade active jet enthalpy-increasing heat pump control method of the present invention.

[0040] Reference numerals:

[0041] 1. Low temperature heat pump compressor; 2. Low temperature heat pump exhaust pipe; 3. Oil separator; 4. Main solenoid valve; 5. Four-way valve; 6. Main gas pipe; 7. Gas pipe stop valve of low temperature heat pump; 8. Liquid pipe stop valve of low temperature heat pump; 9. High pressure liquid storage tank; 10. Conventional jet enthalpy increase subcooler; 11. Main electronic expansion valve; 12. Outdoor heat exchanger; 13. Return air pipe; 14. Gas-liquid separator; 15. Conventional jet enthalpy increase subcooling electronic expansion valve; 16. Conventional Jet enthalpy injection main pipe; 17. Stop valve; 18. Low-temperature heat pump high-pressure pressure sensor; 19. Low-temperature heat pump low-pressure pressure sensor; 20. Low-temperature heat pump exhaust temperature sensor; 31. Heat storage module gas pipe stop valve; 32. Heat storage module solenoid valve; 33. Heat storage module plate heat exchanger; 35. Cascade heat pump solenoid valve; 36. Cascade heat exchanger; 37. Check valve; 38. Active jet enthalpy heat pump liquid pipe stop valve; 39. Active jet Enthalpy-increasing heat pump gas pipe stop valve; 41. High-temperature heat pump compressor; 42. High-temperature heat pump exhaust pipe; 43. High-temperature heat pump plate heat exchanger; 44. High-temperature heat pump main electronic expansion valve; 45. Active jet enthalpy-increasing subcooling electronic expansion valve; 46. Active jet enthalpy-increasing subcooler; 47. Active jet enthalpy-increasing injection pipe; 48. Load side; 49. High-temperature heat pump water pump; 50. Heat storage tank; 51. Heat storage hot water pump; 52. Active jet enthalpy-increasing water pump; 5 3. Water temperature sensor for hot water storage tank; 54. Inlet water temperature sensor for jet enthalpy increase; 55. Outlet water temperature sensor for jet enthalpy increase; 56. Inlet temperature sensor for jet enthalpy increase refrigerant; 57. Outlet temperature sensor for jet enthalpy increase refrigerant; 58. Liquid pipe temperature sensor; 59. Outlet water temperature sensor for hot water generated by heat pump; 60. Return water temperature sensor for hot water generated by heat pump; 61. High-temperature heat pump high-pressure sensor; 62. Exhaust temperature sensor for high-temperature heat pump. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0045] like Figure 1 As shown, a cascade active jet reheat enthalpy heat pump system of this embodiment includes an outdoor unit module, a cascade active jet reheat enthalpy heat pump module and a heat storage module. The cascade active jet reheat enthalpy heat pump module is connected to the outdoor unit module and the heat storage module through a connecting pipe.

[0046] The outdoor unit module includes a low-temperature heat pump compressor 1, an oil separator 3, a four-way valve 5, a gas-liquid separator 14, an outdoor heat exchanger 12, a main electronic expansion valve 11, a conventional jet enthalpy-increasing subcooler 10 and a conventional jet enthalpy-increasing subcooling electronic expansion valve 15. The low-temperature heat pump exhaust pipe 2 of the low-temperature heat pump is connected to the d pipe of the four-way valve 5 through the oil separator 3, the e pipe of the four-way valve 5 is connected to the main air pipe 6, the c pipe of the four-way valve 5 is connected to one end of the outdoor heat exchanger 12, the s pipe of the four-way valve 5 is connected to the inlet pipe of the gas-liquid separator 14, and the outlet pipe of the gas-liquid separator 14 is connected to the return air pipe 13 of the low-temperature heat pump compressor 1. The other end of the outdoor heat exchanger 12 is connected to the main electronic expansion valve 11, the conventional jet enthalpy-increasing subcooler 10, and the high-pressure liquid storage tank 9 in sequence, and the other end of the high-pressure liquid storage tank 9 is connected to the liquid pipe stop valve 8 of the low-temperature heat pump. When the unit is installed, the gas pipe stop valve 7 of the low temperature heat pump and the gas pipe stop valve 31 of the heat storage module are connected through a connecting pipe, and the liquid pipe stop valve 8 of the low temperature heat pump and the liquid pipe stop valve 38 of the active jet enthalpy heat pump are connected through a connecting pipe.

[0047] The conventional jet enthalpy-increasing supercooler 10 is connected with a conventional jet enthalpy-increasing injection inlet pipe, a conventional jet enthalpy-increasing injection main pipe 16, a liquid storage tank outlet pipe, and a main liquid pipe. The conventional jet enthalpy-increasing injection inlet pipe is connected to the liquid pipe section between the high-pressure liquid storage tank 9 and the conventional jet enthalpy-increasing supercooler 10, and the conventional jet enthalpy-increasing supercooler 10 is connected to the conventional jet enthalpy-increasing supercooler 10 through two pipelines, wherein the injection inlet pipe is connected between the inlet end of the conventional jet enthalpy-increasing supercooling electronic expansion valve 15 and the liquid pipe section between the high-pressure liquid storage tank 9 and the conventional jet enthalpy-increasing supercooler 10, and the injection outlet pipe is connected between the outlet end of the conventional jet enthalpy-increasing supercooling electronic expansion valve 15 and the conventional jet enthalpy-increasing supercooler 10. The conventional jet reheat injection main pipe 16 is connected to the injection port of the low-temperature heat pump compressor 1, and the injection refrigerant is injected into the intermediate pressure chamber of the low-temperature heat pump compressor 1. The main liquid pipe connects the conventional jet reheat injection subcooler 10 and the outdoor heat exchanger 12, and the main electronic expansion valve 11 is connected to the main liquid pipe.

[0048] The cascade active jet reheat heat pump module includes a heat storage module gas pipe stop valve 31, an active jet reheat heat pump gas pipe stop valve 39 and an active jet reheat heat pump liquid pipe stop valve 38. The cascade active jet reheat heat pump module is connected to the outdoor unit module through an external connecting pipe. The heat storage module gas pipe stop valve 31 is connected to the gas pipe stop valve 7 of the low temperature heat pump in the outdoor unit module through a connecting pipe, the active jet reheat heat pump gas pipe stop valve 39 is connected to the outlet end of the oil separator 3 through a connecting pipe, and the active jet reheat heat pump liquid pipe stop valve 38 is connected to the liquid pipe stop valve 8 of the low temperature heat pump in the outdoor unit module through a connecting pipe.

[0049] The cascade active jet reheat heat pump module includes a cascade heat exchanger 36, a cascade heat pump solenoid valve 35, a high-temperature heat pump compressor 41, a high-temperature heat pump plate heat exchanger 43, a high-temperature heat pump main electronic expansion valve 44, an active jet reheat subcooling electronic expansion valve 45, an active jet reheat subcooler 46 and a high-temperature heat pump water pump 49.

[0050] The cascade heat exchanger 36, the cascade heat pump solenoid valve 35, the high-temperature heat pump compressor 41, the high-temperature heat pump plate heat exchanger 43, and the high-temperature heat pump main electronic expansion valve 44 participate in the high-temperature heat pump cycle. The high-temperature heat pump exhaust pipe 42 of the high-temperature heat pump compressor 41 is connected to the inlet pipe of the high-temperature heat pump plate heat exchanger 43, and the outlet pipe of the high-temperature heat pump plate heat exchanger 43 is connected to the inlet pipe of the high-temperature heat pump main electronic expansion valve 44 and the cascade heat exchanger 36 in sequence, and the outlet pipe of the cascade heat exchanger 36 is connected to the return air pipe 13 of the high-temperature heat pump compressor 41. The hot water inlet pipe and the hot water outlet pipe of the high-temperature plate heat exchanger are respectively connected to the load side 48, and the hot water outlet pipe is installed with a high-temperature heat pump water pump 49, and the high-temperature heat pump water pump 49 pumps hot water to circulate between the high-temperature heat pump plate heat exchanger 43 and the load side 48.

[0051] The active jet enthalpy-added subcooling electronic expansion valve 45 and the active jet enthalpy-added subcooler 46 participate in the active jet enthalpy-added heat pump cycle. One end of the active jet enthalpy-added subcooling electronic expansion valve 45 is connected to the outlet pipe of the high-temperature heat pump plate heat exchanger 43, and the other end of the active jet enthalpy-added subcooling electronic expansion valve 45 is connected to the active jet enthalpy-added inlet pipe of the active jet enthalpy-added subcooler 46. The active jet enthalpy-added jet pipe 47 of the active jet enthalpy-added subcooler 46 is connected to the high-temperature heat pump compressor 41. The heating hot water inlet pipe and the heating hot water outlet pipe of the active jet enthalpy-added subcooler 46 are respectively connected to the hot water storage tank 50 of the heat storage module, and the heat storage module can be used as an external heat source of the active jet enthalpy-added subcooler 46.

[0052] The active jet enthalpy heat pump gas pipe stop valve 39 is connected to the cascade heat pump solenoid valve 35, the heat storage module gas pipe stop valve 31 is connected to the refrigerant inlet pipe of the heat storage module plate heat exchanger 33 through the heat storage module solenoid valve 32, the outlet pipe of the heat storage module solenoid valve 32 is connected to the inlet end of the heat storage module plate heat exchanger 33, and the refrigerant outlet pipe of the heat storage module plate heat exchanger 33 is connected to the pipeline between the one-way valve 37 and the active jet enthalpy heat pump liquid pipe stop valve 38. The heat storage module plate heat exchanger 33 is connected with a heat storage hot water inlet pipe and a heat storage hot water outlet pipe, and the heat storage hot water inlet pipe and the heat storage hot water outlet pipe are connected to the heat storage water tank 50 to store heat.

[0053] The heat storage module includes a heat storage module solenoid valve 32, a heat storage module plate heat exchanger 33, a heat storage water tank 50, a heat storage hot water pump 51, an active jet enthalpy increase water pump 52 and a water temperature sensor 53 for the heat storage water tank. The heat storage water tank 50 is connected with a heat storage hot water inlet pipe, a heat storage hot water outlet pipe, a heating hot water inlet pipe and a heating hot water outlet pipe. The heat storage hot water pump 51 pumps hot water through the heat storage hot water inlet pipe and the heat storage hot water outlet pipe to circulate between the heat storage module plate heat exchanger 33 and the heat storage water tank 50, so as to realize heat storage when the heat pump system is in heating operation. The active jet enthalpy increase water pump 52 pumps hot water to circulate between the active jet enthalpy increase subcooler 46 and the heat storage water tank 50, and uses the heat storage module as an external heat source for active jet enthalpy increase, and converts the heat of the external heat source into heating capacity in the form of jet enthalpy difference, which greatly improves the performance of the unit, obtains ultra-high energy efficiency, and solves the technical bottleneck that the heat pump cannot be used in an extremely low temperature environment.

[0054] The cycles of the cascade active jet enthalpy heat pump system in this embodiment include: 1. Cascade heat pump cycle; 2. Active jet enthalpy heat pump cycle; 3. Heat pump heat storage cycle; 4. Cascade heat pump cycle and heat pump heat storage cycle; 5. Defrosting cycle. In order to clearly introduce the operating cycle principle of this application, the following is introduced in combination with the flow diagram according to the operating cycle mode:

[0055] 1. Cascade heat pump cycle:

[0056] See also Figure 2 The cascade heat pump cycle includes a low-temperature heat pump cycle and a high-temperature heat pump cycle. It should be noted that the low-temperature heat pump cycle and the high-temperature heat pump cycle cannot operate independently, and both need to work synchronously. For ease of understanding, the low-temperature heat pump cycle and the high-temperature heat pump cycle are introduced separately in this application.

[0057] (1) Low temperature heat pump cycle

[0058] In the low-temperature heat pump cycle, the cascade heat exchanger 36 acts as a condenser, and the refrigerant in the low-temperature heat pump cycle transfers heat to the refrigerant in the high-temperature heat pump cycle and condenses, and then passes through the main electronic expansion valve 11 for throttling, and returns to the low-temperature heat pump compressor 1 after absorbing air energy through the outdoor heat exchanger, and re-enters the cascade heat exchanger 36 after being compressed by the low-temperature heat pump compressor 1. The specific cycle process is as follows:

[0059] Please refer to the flow diagram Figure 2 The high-temperature and high-pressure refrigerant discharged from the low-temperature heat pump compressor 1 passes through the oil separator 3, and then passes through the active jet enthalpy heat pump gas pipe stop valve 39 and the cascade heat pump solenoid valve 35 to enter the cascade heat exchanger 36. In the cascade heat exchanger 36, it exchanges heat with the refrigerant circulating in the high-temperature heat pump and then condenses. It passes through the one-way valve 37, the active jet enthalpy heat pump liquid pipe stop valve 38, and the low-temperature heat pump liquid pipe stop valve 8 to enter the conventional jet enthalpy heat pump outdoor unit. A part of the refrigerant in the liquid pipe passes through the conventional The main liquid pipe of the conventional jet reheat-added subcooler 10, the main electronic expansion valve 11, the outdoor heat exchanger 12, the c pipe of the four-way valve 5, and the s pipe of the four-way valve 5 return to the suction port of the low-temperature heat pump compressor 1 after passing through the gas-liquid separator 14; the other part of the refrigerant in the liquid pipe enters the conventional jet reheat-added subcooler 10 after throttling by the conventional jet reheat-added subcooling electronic expansion valve 15 to exchange heat with the refrigerant in the main liquid pipe, and then is injected to the injection port of the low-temperature heat pump compressor 1 through the conventional jet reheat-added injection main pipe 16.

[0060] (2) High temperature heat pump cycle

[0061] In the high-temperature heat pump cycle, the refrigerant circulating in the low-temperature heat pump transfers heat to the evaporation side of the high-temperature heat pump. The cascade heat exchanger 36 serves as the evaporator of the high-temperature heat pump, so that the refrigerant circulating in the high-temperature stage absorbs heat from the refrigerant circulating in the low-temperature stage. The specific cycle process is as follows:

[0062] Please refer to the flow diagram Figure 2The refrigerant circulating in the high temperature stage is compressed by the high temperature stage heat pump compressor 41, and enters the high temperature stage heat pump plate heat exchanger 43 through the high temperature stage heat pump exhaust pipe 42 of the high temperature stage heat pump compressor 41. The high temperature stage heat pump water pump 49 pumps hot water to circulate in the load side 48 and the high temperature stage heat pump plate heat exchanger 43, so that the hot water absorbs the heat of the refrigerant in the high temperature stage heat pump plate heat exchanger 43 and supplies the heat to the load side 48. After the refrigerant flows out of the high temperature stage heat pump plate heat exchanger 43, it is throttled by the high temperature stage heat pump main electronic expansion valve 44 and enters the cascade heat exchanger 36. In the cascade heat exchanger 36, the refrigerant circulating in the low temperature stage heat pump transfers heat to the refrigerant circulating in the high temperature stage heat pump, and then the refrigerant circulating in the high temperature stage heat pump returns to the high temperature stage heat pump compressor 41.

[0063] 2. Active jet enthalpy-increasing heat pump cycle

[0064] Please refer to the flow diagram Figure 3 The refrigerant circulating in the high-temperature stage is compressed by the high-temperature stage heat pump compressor 41, and enters the high-temperature stage heat pump plate heat exchanger 43 through the high-temperature stage heat pump exhaust pipe 42 of the high-temperature stage heat pump compressor 41. The high-temperature stage heat pump water pump 49 pumps hot water to circulate between the high-temperature stage heat pump plate heat exchanger 43 and the load side 48, so that the hot water absorbs the heat of the refrigerant in the high-temperature stage heat pump plate heat exchanger 43, and supplies the hot water to the load side 48. After the refrigerant flows out of the high-temperature heat pump plate heat exchanger 43, it is throttled by the high-temperature heat pump main electronic expansion valve 44 and enters the cascade heat exchanger 36. In the cascade heat exchanger 36, the refrigerant circulating in the low-temperature heat pump transfers heat to the refrigerant circulating in the high-temperature heat pump, and then the refrigerant circulating in the high-temperature heat pump returns to the high-temperature heat pump compressor 41; another part of the refrigerant passes through the active jet reheat-increasing subcooling electronic expansion valve 45 and enters the active jet reheat-increasing subcooler 46. The active jet reheat-increasing water pump 52 pumps the hot water in the hot water storage tank 50 to exchange heat with the refrigerant entering the active jet reheat-increasing subcooler 46. The jet refrigerant absorbs the heat provided by the hot water and returns to the high-temperature heat pump compressor 41 through the active jet reheat-increasing injection pipe 47.

[0065] 3. Heat Pump Thermal Storage Cycle

[0066] Please refer to the flow diagram Figure 4The gaseous refrigerant discharged from the low-temperature heat pump compressor 1 passes through the oil separator 3, the main solenoid valve 4, the d pipe of the four-way valve 5, the e pipe of the four-way valve 5, and then passes through the heat storage module gas pipe stop valve 31 and the heat storage module solenoid valve 32 and enters the heat storage module plate heat exchanger 33. The heat storage hot water pump 51 pumps the hot water in the heat storage water tank 50 to circulate. The hot water absorbs the heat released by the refrigerant flowing through the heat storage module plate heat exchanger 33 and is stored in the heat storage water tank 50. The refrigerant condenses after passing through the heat storage module plate heat exchanger 33, and enters the low-temperature heat pump main unit through the active jet reheat heat pump liquid pipe stop valve 38 and the liquid pipe stop valve 8 of the low-temperature heat pump. A part of the refrigerant in the liquid pipe passes through the main liquid pipe of the conventional jet reheat subcooler 10, the main electronic expansion valve 11, the outdoor heat exchanger 12, the c pipe of the four-way valve 5, and the s pipe of the four-way valve 5, and returns to the suction port of the low-temperature heat pump compressor 1 after passing through the gas-liquid separator 14; another part of the refrigerant in the liquid pipe enters the conventional jet reheat subcooler 10 after throttling through the conventional jet reheat subcooling electronic expansion valve 15, exchanges heat with the refrigerant in the main liquid pipe, and then is sprayed to the injection port of the low-temperature heat pump compressor 1 through the conventional jet reheat injection main pipe 16.

[0067] 4. Cascade heat pump cycle and heat pump thermal storage cycle

[0068] Please refer to the flow diagram Figure 5 The gaseous refrigerant discharged from the low-temperature heat pump compressor 1 is divided into two paths after passing through the oil separator 3, one path participates in the cascade heat pump cycle, and the other path participates in the heat pump heat storage cycle.

[0069] 5. Defrost cycle

[0070] When entering the defrost cycle, the four-way valve 5 is reversed, the low-temperature heat pump enters the refrigeration operation mode, the high-temperature heat pump system does not participate in defrosting, and maintains heating operation. The low-temperature heat pump uses the stored heat for heat storage defrosting. During the defrosting process, conventional jet enthalpy is increased to increase the refrigerant circulation volume of the defrosting operation, increase the system low pressure, speed up the defrosting speed, improve the defrosting effect, and increase the compressor exhaust superheat during the defrosting process to avoid compressor damage due to liquid return during the defrosting process. The specific cycle process is as follows:

[0071] Please refer to the flow diagram Figure 6The refrigerant discharged from the low-temperature heat pump compressor 1 passes through the d pipe of the four-way valve 5, the c pipe of the four-way valve 5, the outdoor heat exchanger 12, the high-pressure liquid storage tank 9, the liquid pipe stop valve 8 of the low-temperature heat pump, and the liquid pipe stop valve 38 of the active jet enthalpy increase heat pump, and then enters the heat storage module plate heat exchanger 33. At this time, the heat storage hot water pump 51 pumps the hot water in the heat storage water tank 50 to circulate and transfers heat to the refrigerant flowing through the heat storage module plate heat exchanger 33. The refrigerant returns to the low-temperature heat pump compressor 1 after passing through the heat storage module solenoid valve 32, the heat storage module gas pipe stop valve 31, the low-temperature heat pump gas pipe stop valve 7, the e pipe of the four-way valve 5, the s pipe of the four-way valve 5, and the gas-liquid separator 14. During the defrosting process, the conventional jet reheat-added subcooling electronic expansion valve 15 is opened, and a part of the refrigerant enters the conventional jet reheat-added subcooling device 10 through the conventional jet reheat-added subcooling electronic expansion valve 15, exchanges heat with the refrigerant in the main liquid pipe passing through the conventional jet reheat-added subcooling device 10, and then is injected into the intermediate pressure chamber of the low-temperature stage heat pump compressor 1 through the conventional jet reheat-added injection main pipe 16.

[0072] A cascade active jet enthalpy-increasing heat pump control method, such as Figure 8 As shown, it includes step S1, step S2, step S3, and step S4. In this embodiment, it mainly includes five operation modes: thermal storage hot water production operation mode, cascade heat pump heating operation mode, thermal storage hot water production operation + cascade heat pump heating operation mode, cascade active jet enthalpy increase heat pump heating operation mode, and defrosting operation mode.

[0073] Step S1A: a preset start-up condition for producing thermal storage hot water is configured. When the start-up condition for producing thermal storage hot water is met, the control for producing thermal storage hot water is started;

[0074] Step S1B: a preset shutdown condition for producing thermal storage hot water is configured. When the shutdown condition for producing thermal storage hot water is met, the thermal storage hot water production operation control is shut down;

[0075] Step S2A: a preset cascade heat pump heating operation start condition is configured, and when the cascade heat pump heating operation start condition is met, the cascade heat pump heating operation control is started;

[0076] Step S2B: a preset cascade heat pump heating operation shut-down condition is configured, and when the cascade heat pump heating operation shut-down condition is met, the cascade heat pump heating operation control is shut down;

[0077] Step S3A: a preset cascade active jet enthalpy heat pump heating operation start-up condition is configured, and when the cascade active jet enthalpy heat pump heating operation start-up condition is met, the cascade active jet enthalpy heat pump heating operation is started;

[0078] Step S3B: a preset cascade active jet enthalpy heat pump heating operation shutdown condition and a heat pump heating shutdown condition are configured. When the cascade active jet enthalpy heat pump heating operation shutdown condition is met, the cascade active jet enthalpy heat pump heating operation is shut down, and the cascade heat pump heating operation control is performed. When the heat pump heating shutdown condition is met, the cascade active jet enthalpy heat pump module is shut down;

[0079] Step S4A: a preset defrost operation start condition is configured, and when the defrost operation start condition is met, the defrost operation control is started;

[0080] Step S4B: a preset defrost operation closing condition is configured, and when the defrost operation closing condition is met, the defrost operation control is closed.

[0081] The following describes the control contents in detail according to the operation mode.

[0082] 1. Thermal storage hot water operation mode: corresponds to the heat pump thermal storage cycle mentioned above

[0083] 1.1 Enabling conditions

[0084] In the system shutdown state, the thermal storage hot water production operation start condition is configured with a preset outdoor ambient temperature threshold and a water temperature setting target value. When the outdoor ambient temperature is detected to be lower than the preset ambient temperature threshold T ao,set1 And the duration reaches the preset duration, and it is detected that when the actual stored water temperature T tank,cur Lower than the water temperature setting target value T tank,set The temperature difference ΔT from the preset first water storage temperature tank,set1 If the difference between the outdoor temperature and the setting temperature T is greater than the setting temperature T, the condition for starting the operation of hot water storage is met. ao,set1 ℃, for 30 seconds; and the current actual stored water temperature T tank,cur Lower than the water temperature setting target value T tank,set - Storage water temperature differential temperature ΔT tank,set1 , ΔT tank,set1 Set to 1°C, duration to 30 seconds, and heat storage operation starts.

[0085] 1.2 Control content

[0086] The low temperature heat pump compressor is set according to the target value T of the stored water temperature. tank,set Adjustment is performed when the actual stored water temperature T tank,cur Lower than the target value T of the stored water temperature tank,set - Storage water temperature differential temperature ΔT tank,set1 , the low temperature heat pump compressor increases the frequency of operation; when the actual storage water temperature T tank,cur Higher than the target value T of the stored water temperaturetank,set + Storage water temperature differential temperature ΔT tank,set1 , the low temperature heat pump compressor reduces the frequency of operation, when the stored water temperature T tank,cur Between the target value of the hot water temperature T tank,set - Storage water temperature differential temperature ΔT tank,set1 and the target value of the stored water temperature T tank,set + Storage water temperature differential temperature ΔT tank,set1 In between, the low temperature stage heat pump compressor maintains frequency operation.

[0087] 1.3 Closing conditions

[0088] The thermal storage hot water production operation shutdown condition is configured with a preset second thermal storage hot water temperature return difference temperature. When the actual thermal storage hot water temperature T tank,cur Higher than the water temperature setting target value T tank,set The temperature difference with the second water storage water temperature ΔT tank,set2 When the sum of the actual thermal storage hot water temperature T tank,cur Higher than the target value T of the stored water temperature tank,set +ΔT tank,set2 When the heat storage stops, the low temperature stage heat pump compressor stops running.

[0089] 2. Cascade heat pump heating operation mode: corresponding to the cascade heat pump cycle mentioned above

[0090] 2.1 Enabling conditions

[0091] The cascade high-temperature heat pump is connected to a wire controller, and the wire controller receives a heating start command. The cascade heat pump heating operation start condition is configured with a preset return water temperature target value and a preset first return water return temperature difference. When the detected return water temperature is less than the difference between the return water temperature target value and the first return water return temperature difference, and the duration reaches a preset time, it is considered that the cascade heat pump heating operation start condition is met. For example: the cascade high-temperature heat pump is connected to a wire controller, and the wire controller issues a start command. When the return water temperature sensor 60 detects a return water temperature T w,in,cur Less than the return water temperature target value T w,in,set -ΔT w,in,set1 ℃, ΔT w,in,set1 Set to 1°C for 30 seconds, the low-temperature heat pump starts running and the high-temperature heat pump starts at the same time.

[0092] 2.2 Control content

[0093] The low temperature heat pump is set according to a certain condensation temperature target value T con,set To adjust the low temperature heat pump compressor frequency, when the actual operating condensing temperature T con,cur Lower than the condensation temperature target value T con,set- Hysteresis value ΔT con,set , the low temperature heat pump compressor increases the frequency. When the actual operating condensing temperature T con,cur Higher than T con,setr + Hysteresis value ΔT con,set , the low temperature heat pump compressor reduces the frequency, when the actual condensing temperature is between the condensing temperature target value T con,tset - Hysteresis value ΔT con,set and condensation temperature target value T con,set + Hysteresis value ΔT con,set The frequency of the low temperature stage heat pump compressor remains unchanged.

[0094] The high temperature heat pump is set according to a certain return water temperature target value T w,in,set To adjust the frequency of the high-temperature heat pump compressor, when the actual operating return water temperature T w,in,set Lower than the return water temperature target value T w,in,set - Hysteresis value ΔT w,in,set1 , the high temperature heat pump compressor increases the frequency. When the actual operating return water temperature T w,in,cur Higher than the return water temperature target value T w,in,set + Hysteresis value ΔT w,in,set1 , the high temperature heat pump compressor reduces the frequency, when the actual return water temperature T w,in,cur Between the return water temperature target value T w,in,set - Hysteresis value ΔT w,in,set1 and return water temperature target value T w,in,set + Hysteresis value ΔT w,in,set1 The frequency of the high temperature stage heat pump compressor remains unchanged.

[0095] 2.3 Closing conditions

[0096] The cascade heat pump heating operation shutdown condition is configured with a preset second return water differential temperature. When the detected return water temperature is greater than the sum of the return water temperature target value and the preset second return water differential temperature, and the duration reaches a preset time, the cascade heat pump heating operation shutdown condition is considered to be met. That is: when the actual operating return water temperature T w,in,cur Higher than the return water temperature target value T w,in,set +ΔT w,in,set2 , and lasts for a preset time, such as ΔT w,in,set2 Set to 1°C for a preset duration of 30 seconds, the high-temperature heat pump stops running and the high-temperature heat pump compressor stops; at the same time, the low-temperature heat pump stops running and the low-temperature heat pump compressor stops.

[0097] 3. Cascade heat pump heating + thermal storage hot water operation mode: corresponding to the cascade heat pump and heat pump thermal storage cycle mentioned above

[0098] 3.1 Enabling conditions

[0099] At the same time, the start-up conditions of the thermal storage hot water operation mode and the start-up conditions of the cascade heat pump heating operation mode are met. For specific reference, please refer to the start-up conditions of 1.1 and 2.1.

[0100] 3.2 Control content

[0101] Thermal storage hot water operation and cascade heat pump heating operation are controlled independently, referring to the control contents of 1.2 and 2.2 respectively.

[0102] 3.3 Closing conditions

[0103] The shutdown of thermal storage hot water operation and the shutdown of cascade heat pump heating operation are judged independently, referring to the shutdown conditions of 1.3 and 2.3 respectively. Among them, when only the shutdown condition of 1.3 is met, the heat pump thermal storage cycle is stopped, and the unit performs the cascade heat pump cycle or the active jet enthalpy increase heat pump cycle; when only the shutdown condition of 2.3 is met, the cascade heat pump cycle is stopped, and the unit performs the heat pump thermal storage cycle; when the shutdown conditions of 1.3 and 2.3 are met at the same time, the cascade heat pump heating + thermal storage hot water operation mode is closed.

[0104] 4. Cascade active jet enthalpy heat pump heating operation mode: corresponding to the active jet enthalpy heat pump cycle mentioned above

[0105] 4.1 Enabling conditions

[0106] Based on the operation of the cascade heat pump heating mode, it is judged

[0107] The following conditions must be met at the same time:

[0108] 1) The above-mentioned cascade heat pump startup and operation conditions are met, that is,

[0109] The wire controller sends a power-on command. When the return water temperature sensor 60 detects the return water temperature T w,in,cur Less than the return water temperature target value T w,in,set - Hysteresis value ΔT w,in,set1 , for a preset duration, such as ΔT w,in,set1 Set to 1°C, and keep for 30 seconds, the low-temperature heat pump starts running, and the high-temperature heat pump starts at the same time.

[0110] 2) Outdoor ambient temperature T ao Lower than the set second ambient temperature threshold T ao,set2 , and the duration reaches the preset duration.

[0111] 3) The cascade heat pump is started and runs for a preset time, such as 5 minutes. The exhaust temperature and exhaust superheat are detected to ensure that the exhaust superheat ΔT d,cur Greater than the set first exhaust superheat target value ΔT d,set1The exhaust gas superheat is defined as the difference between the exhaust gas temperature detected by the high temperature stage heat pump exhaust gas temperature sensor 62 of the high temperature stage heat pump compressor 41 and the saturation temperature corresponding to the high pressure pressure detected by the high temperature stage heat pump high pressure sensor 61 .

[0112] 4) Simultaneously detect the temperature of the thermal storage hot water T tank,cur If the thermal storage hot water temperature T is detected tank,cur >The temperature T detected by the liquid pipe temperature sensor 58 liq + Thermal storage hot water temperature hysteresis threshold ΔT tank,liq [Set value], and the duration reaches the preset time, the active jet heat increase is turned on, and the corresponding subcooling electronic expansion valve 45 is opened, and the reference opening is V open1 [Set value], using the hot water in the water storage tank as the jet enthalpy heat source, the active jet enthalpy water pump 52 is turned on, and the water flow rate is constant at Y m 3 / h

set value

[0113] 4.2 Control content

[0114] The low temperature heat pump is set according to a certain condensation temperature target value T con,set To adjust the compressor frequency, when the actual operating condensing temperature T con,cur Lower than the condensation temperature target value T con,set - Hysteresis value ΔT con,set , the compressor increases the frequency. When the actual operating condensing temperature T con,cur Higher than T con,setr + Hysteresis value ΔT con,set , the compressor reduces the frequency. When the actual condensing temperature is between the condensing temperature target value T con,setr - Hysteresis value ΔT con,set and condensation temperature target value T con,setr + Hysteresis value ΔT con,set The compressor frequency remains unchanged.

[0115] The high temperature heat pump is set according to a certain return water temperature target value T w,in,set To adjust the compressor frequency, when the actual operating return water temperature T is detected w,in,cur Lower than the return water temperature target value T w,in,set - Hysteresis value ΔT w,in,set1 , the compressor increases the frequency. When the actual operating return water temperature T w,in,cur Higher than the return water temperature target value T w,in,set + Hysteresis value ΔT w,in,set1 , the compressor reduces the frequency, when the actual return water temperature T w,in,cur Between the return water temperature target value T w,in,set - Hysteresis value ΔT w,in,set1 and return water temperature target value T w,in,set + Hysteresis value ΔTw,in,set1 When the actual operating return water temperature T w,in,cur Higher than the return water temperature target value T w,in,set +ΔT w,in,set2 , and lasts for 30 seconds, the high-temperature heat pump stops running and the high-temperature compressor stops; at the same time, the low-temperature heat pump stops running and the low-temperature heat pump compressor stops.

[0116] When the active jet reheating start-up conditions are met, the active jet reheating water pump 52 is started and runs to pump hot water into the active jet reheating subcooler 46 according to the set flow rate.

[0117] Active jet enthalpy increase Active jet enthalpy increase The subcooling electronic expansion valve 45 is opened to the reference opening, and the initial opening is V open .

[0118] After 3 minutes, when the active jet enthalpy-increasing hot water inlet temperature T w,inj,in ≥Active jet enthalpy increase refrigerant outlet temperature T ref,inj,out + Hysteresis value setting value ΔT w-in,ref-out1 , and the outlet temperature of hot water with active jet enthalpy increase is T w,inj,out ≥Active jet enthalpy increase refrigerant inlet temperature T ref,inj,in + Hysteresis setting value ΔT w-out,ref-in1 , the opening of the subcooling electronic expansion valve with active jet enthalpy increase is adjusted.

[0119] According to the refrigerant injection superheat target value ΔT ref,inj,set Control and define the injection superheat ΔT ref,inj is the outlet temperature of the active jet enthalpy refrigerant T ref , inj,out Active jet enthalpy increase refrigerant inlet temperature T ref,inj,in When the actual injection superheat ΔT ref,inj_cur > Injection superheat target value ΔT ref,inj , set + Refrigerant injection hysteresis setting value ΔT ref,inj , the opening degree of the active jet enthalpy-increasing subcooling electronic expansion valve 45 is controlled to be widened; when the actual jet superheat ΔT ref,inj _cur<ΔT ref,inj _ set -Refrigerant injection differential setting value ΔT ref,inj , the opening degree of the active jet enthalpy-increasing subcooling electronic expansion valve 45 is controlled to be small; when ΔT ref,inj , set -Refrigerant injection differential setting value ΔT ref,inj ≤Actual injection superheat ΔT ref,inj_cur ≤ Injection superheat target value ΔT ref,inj _ set+ Refrigerant injection hysteresis setting value ΔT ref,inj, , the active jet enthalpy increase subcooling electronic expansion valve maintains the current opening unchanged.

[0120] 4.3 Closing conditions

[0121] When one of the following conditions is met, the active jet reheating stops, the active jet reheating water pump 52 stops running, and the active jet reheating subcooling electronic expansion valve 45 is closed.

[0122] 1) Outdoor ambient temperature T ao Higher than the set third ambient temperature threshold T ao,set3

[0123] 2) Exhaust superheat ΔT d,cur Less than the designed second exhaust gas superheat target value ΔT d,set2

[0124] 3) When the active jet enthalpy increase hot water inlet temperature T w,inj,in ≤Active jet enthalpy increase refrigerant outlet temperature T ref,inj,out + Hysteresis value setting value ΔT w-in,ref-out2 , or active jet enthalpy increase hot water outlet temperature T w,inj,out ≤Active jet enthalpy increase refrigerant inlet temperature T ref,inj,in + Hysteresis setting value ΔT w-out,ref-in2 .

[0125] When one of the above conditions is met, the active jet reheating stops, the active jet reheating water pump 52 stops running, the active jet reheating subcooling electronic expansion valve 45 is closed, and only the cascade heat pump heating operation is performed.

[0126] When the actual operating return water temperature T w,in,cur Higher than the return water temperature target value T w,in,set + set hysteresis value ΔT w,in,set2 , the high-temperature heat pump stops running and the high-temperature compressor stops; at the same time, the low-temperature heat pump stops running and the low-temperature heat pump compressor stops.

[0127] 5. Defrost operation mode: corresponds to the defrost cycle mentioned above

[0128] The defrosting entry judgment conditions, defrosting end judgment conditions and control logic have been given in Patent ZL201910300817.3, and will not be repeated again. The present invention provides the control logic of each component of the defrosting process.

[0129] When entering the defrost cycle, the high-temperature heat pump maintains heating operation, the high-temperature heat pump compressor 41 is turned on, and the operation is controlled according to the set return water temperature. The four-way valve 5 is reversed, the unit enters the cooling operation mode, the high-temperature heat pump system does not participate in defrosting, and maintains heating operation. The low-temperature heat pump uses the stored heat to perform heat storage defrosting. Conventional jet enthalpy increase is performed during the defrosting process. The conventional jet enthalpy increase subcooling electronic expansion valve 15 is opened to the preset opening, increasing the refrigerant circulation volume of the defrosting operation, increasing the system low pressure, accelerating the defrosting speed, and improving the defrosting effect. In addition, the compressor exhaust superheat can be increased during the defrosting process to avoid compressor damage caused by liquid return during the defrosting process.

[0130] At the same time, the solenoid valve 32 of the heat storage module is opened, and the heat storage hot water pump 51 is running to perform heat storage defrosting. The refrigerant in the defrosting cycle absorbs the heat of the heat storage hot water, which is conducive to rapid defrosting.

[0131] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A cascade active jet enthalpy-increasing heat pump system, characterized in that: It includes an outdoor unit module, a cascade active jet enthalpy-increasing heat pump module and a heat storage module, wherein the cascade active jet enthalpy-increasing heat pump module is connected to the outdoor unit module and the heat storage module through a pipeline; The outdoor unit module can perform outdoor unit module heating operation and outdoor unit module cooling operation; The cascade active jet enthalpy-increasing heat pump module comprises a cascade heat exchanger (36), a high-temperature heat pump compressor (41), a high-temperature heat pump plate heat exchanger (43), an active jet enthalpy-increasing subcooling electronic expansion valve (45), and an active jet enthalpy-increasing subcooler (46), wherein the cascade heat exchanger (36) and the outdoor unit module participate in a low-temperature heat pump cycle, the cascade heat exchanger (36), the high-temperature heat pump compressor (41), and the high-temperature heat pump plate heat exchanger (43) participate in a high-temperature heat pump cycle, and the high-temperature heat pump plate heat exchanger (43) is used to perform heat exchange with the load side. The heat storage module is used to store heat as an external heat source when the outdoor unit module is in heating operation, and the external heat source is used to perform heat exchange with the refrigerant flowing through the active jet enthalpy increase subcooler (46) when the outdoor unit module is in heating operation, or to perform heat exchange with the refrigerant flowing through the outdoor unit module when the outdoor unit module is in cooling operation.

2. The cascade active jet enthalpy-increasing heat pump system according to claim 1, characterized in that: The outdoor unit module comprises a low-temperature heat pump compressor (1), an oil separator (3), a four-way valve (5), a gas-liquid separator (14), an outdoor heat exchanger (12), and a main electronic expansion valve (11); the low-temperature heat pump exhaust pipe (2) of the low-temperature heat pump compressor (1) is connected to the d pipe of the four-way valve (5) through the oil separator (3); the e pipe of the four-way valve (5) is connected to the main air pipe (6); the c pipe of the four-way valve (5) is connected to one end of the outdoor heat exchanger (12); the s pipe of the four-way valve (5) is connected to the inlet pipe of the gas-liquid separator (14); the outlet pipe of the gas-liquid separator (14) is connected to the return air pipe (13) of the low-temperature heat pump compressor (1); the other end of the outdoor heat exchanger (12) is connected to the main electronic expansion valve (11) and the high-pressure liquid storage tank (9) in sequence; the other end of the high-pressure liquid storage tank (9) is connected to the liquid pipe stop valve (8) of the low-temperature heat pump; The cascade active jet enthalpy-increasing heat pump module comprises a cascade heat pump solenoid valve (35), a high-temperature heat pump main electronic expansion valve (44) and a high-temperature heat pump water pump (49); The high-temperature heat pump exhaust pipe (42) of the high-temperature heat pump compressor (41) is connected to the air inlet pipe of the high-temperature heat pump plate heat exchanger (43); the air outlet pipe of the high-temperature heat pump plate heat exchanger (43) is connected to the high-temperature heat pump main electronic expansion valve (44) and the air inlet pipe of the cascade heat exchanger (36) in sequence; the air outlet pipe of the cascade heat exchanger (36) is connected to the air return pipe (13) of the high-temperature heat pump compressor (41); the hot water inlet pipe and the hot water outlet pipe of the high-temperature heat pump plate heat exchanger (43) are respectively connected to the load side (48); a high-temperature heat pump water pump (49) is installed on the hot water outlet pipe; the high-temperature heat pump water pump (49) pumps hot water to circulate in the high-temperature heat pump plate heat exchanger (43) and the load side (48); One end of the active jet reheat-increasing subcooling electronic expansion valve (45) is connected to the outlet pipe of the high-temperature heat pump plate heat exchanger (43), and the other end of the active jet reheat-increasing subcooling electronic expansion valve (45) is connected to the active jet reheat-increasing inlet pipe of the active jet reheat-increasing subcooler (46). The active jet reheat-increasing injection pipe (47) of the active jet reheat-increasing subcooler (46) is connected to the jet reheat-increasing injection port of the high-temperature heat pump compressor (41), and the heating hot water inlet pipe and the heating hot water outlet pipe of the active jet reheat-increasing subcooler (46) are respectively connected to the heat storage module.

3. The cascade active jet enthalpy-increasing heat pump system according to claim 2 is characterized in that: The outdoor unit module further comprises a conventional jet enthalpy increase subcooler (10) and a conventional jet enthalpy increase subcooling electronic expansion valve (15), wherein the conventional jet enthalpy increase subcooler (10) is connected to a conventional jet enthalpy increase injection inlet pipe, a conventional jet enthalpy increase injection main pipe (16), a liquid storage tank outlet pipe, and a main liquid pipe, and the conventional jet enthalpy increase subcooling electronic expansion valve (15) is connected to the conventional jet enthalpy increase subcooler (10) via two pipelines, wherein the injection inlet pipe is connected to the inlet end of the conventional jet enthalpy increase subcooling electronic expansion valve (15) and the high-pressure liquid storage tank ( 9) and the liquid pipe section between the conventional jet enthalpy increase subcooler (10), the injection outlet pipe is connected between the outlet end of the conventional jet enthalpy increase subcooler electronic expansion valve (15) and the conventional jet enthalpy increase subcooler (10), the conventional jet enthalpy increase injection main pipe (16) is connected to the injection port of the low-temperature stage heat pump compressor (1) to inject refrigerant into the intermediate pressure chamber of the compressor, the main liquid pipe is connected to the conventional jet enthalpy increase subcooler (10) and the outdoor heat exchanger (12), and the main electronic expansion valve (11) is connected to the main liquid pipe.

4. The cascade active jet enthalpy-increasing heat pump system according to claim 2, characterized in that: The heat storage module comprises a heat storage module solenoid valve (32), a heat storage module plate heat exchanger (33), a heat storage tank (50), a heat storage hot water pump (51), an active jet enthalpy increase pump (52) and a water temperature sensor (53) for the heat storage tank. The heat storage tank (50) is connected with a heat storage hot water return pipe, a heat storage hot water outlet pipe, a heating hot water return pipe and a heating hot water outlet pipe. The heat storage hot water pump (51) pumps hot water through the heat storage hot water return pipe and the heat storage hot water outlet pipe to circulate between the heat storage module plate heat exchanger (33) and the heat storage tank (50). The active jet enthalpy increase pump (52) pumps hot water through the heating hot water return pipe and the heating hot water outlet pipe to circulate between the heat storage tank (50) and the active jet enthalpy increase subcooler (46).

5. The cascade active jet enthalpy-increasing heat pump system according to claim 2, characterized in that: The heat storage tank also includes a temperature detection module, the temperature detection module including a water temperature sensor (53) for a hot water storage tank, a jet enthalpy water inlet temperature sensor (54), a jet enthalpy water outlet temperature sensor (55), a jet enthalpy refrigerant inlet temperature sensor (56), a jet enthalpy refrigerant outlet temperature sensor (57), a liquid pipe temperature sensor (58), a hot water outlet temperature sensor (59) generated by a heat pump, and a return water temperature sensor (60). The hot water storage tank water temperature sensor (53) is used to detect the actual hot water temperature T in the hot water storage tank (50). tank,cur The jet enthalpy increase water inlet temperature sensor (54) is used to detect the active jet enthalpy increase hot water inlet temperature T w,inj,in The jet enthalpy increased water outlet temperature sensor (55) is used to detect the active jet enthalpy increased hot water outlet temperature T w,inj,out The jet enthalpy refrigerant inlet temperature sensor (56) is used to detect the active jet enthalpy refrigerant inlet temperature T ref,inj,in The jet enthalpy refrigerant outlet temperature sensor (57) is used to detect the active jet enthalpy refrigerant outlet temperature T ref,inj,out The liquid pipe temperature sensor (58) is used to detect the liquid pipe temperature T liq The return water temperature sensor (60) is used to detect the return water temperature T w,in,cur .

6. A cascade active jet enthalpy-increasing heat pump control method, applied to the cascade active jet enthalpy-increasing heat pump system as claimed in any one of claims 1 to 5, characterized in that: include: Step S1A: a preset start-up condition for producing thermal storage hot water is configured. When the start-up condition for producing thermal storage hot water is met, the control for producing thermal storage hot water is started; Step S1B: a preset shutdown condition for producing thermal storage hot water is configured. When the shutdown condition for producing thermal storage hot water is met, the thermal storage hot water production operation control is shut down; Step S2A: a preset cascade heat pump heating operation start condition is configured, and when the cascade heat pump heating operation start condition is met, the cascade heat pump heating operation control is started; Step S2B: a preset cascade heat pump heating operation shut-down condition is configured, and when the cascade heat pump heating operation shut-down condition is met, the cascade heat pump heating operation control is shut down; Step S3A: a preset cascade active jet enthalpy heat pump heating operation start-up condition is configured, and when the cascade active jet enthalpy heat pump heating operation start-up condition is met, the cascade active jet enthalpy heat pump heating operation is started; Step S3B: The preset cascade active jet enthalpy heat pump heating operation shutdown conditions and heat pump heating shutdown conditions are configured. When the cascade active jet enthalpy heat pump heating operation shutdown conditions are met, the cascade active jet enthalpy heat pump heating operation is shut down, and the cascade heat pump heating operation control is performed. When the heat pump heating shutdown conditions are met, the cascade active jet enthalpy heat pump module is shut down.

7. The control method of the cascade active jet enthalpy-increasing heat pump according to claim 6, characterized in that: In step S1A, the thermal storage hot water production operation start condition is configured with a preset first ambient temperature threshold and a water temperature setting target value. When it is detected that the outdoor ambient temperature is lower than the preset first ambient temperature threshold and the duration reaches the preset duration, and when it is detected that the actual stored water temperature is lower than the difference between the water temperature setting target value and the preset first stored water temperature return difference temperature and the duration reaches the preset duration, it is considered that the thermal storage hot water production operation start condition is met; In step S1B, the thermal storage hot water production operation shut-down condition is configured with a preset second thermal storage water temperature hysteresis temperature. When it is detected that the actual thermal storage hot water temperature is higher than the sum of the water temperature setting target value and the second thermal storage water temperature hysteresis temperature, and the duration reaches a preset time, the thermal storage hot water production operation shut-down condition is deemed to be met.

8. The control method of the cascade active jet enthalpy-increasing heat pump according to claim 6, characterized in that: In step S2A, the cascade heat pump heating operation start-up condition is configured with a preset return water temperature target value and a preset first return water return temperature difference. When the detected return water temperature is less than the difference between the return water temperature target value and the first return water return temperature difference, and the duration reaches a preset time, the cascade heat pump heating operation start-up condition is deemed to be met; In step S2B, the cascade heat pump heating operation shutdown condition is configured with a preset second return water return temperature difference. When the detected return water temperature is greater than the sum of the return water temperature target value and the preset second return water return temperature difference, and the duration reaches a preset time, the cascade heat pump heating operation shutdown condition is deemed to be met.

9. The control method of the cascade active jet enthalpy-increasing heat pump according to claim 6, characterized in that: The exhaust gas superheat is defined as the difference between the exhaust gas temperature detected by the high-temperature heat pump exhaust gas temperature sensor (62) of the high-temperature heat pump compressor (41) and the saturation temperature corresponding to the high pressure detected by the high-temperature heat pump high-pressure sensor (61); In step S3A, the cascade active jet enthalpy heat pump heating operation start-up condition is configured with a preset second ambient temperature threshold, a first exhaust superheat target value, and a thermal storage hot water temperature hysteresis setting threshold. When it is detected that the outdoor ambient temperature is lower than the second ambient temperature threshold, and the cascade heat pump is turned on and runs for more than a preset running time, it is detected that the exhaust superheat is greater than the preset first exhaust superheat target value, and it is detected that the thermal storage hot water temperature is greater than the sum of the liquid pipe temperature and the thermal storage hot water temperature hysteresis setting threshold and the duration exceeds a preset time, it is deemed that the cascade active jet enthalpy heat pump heating operation start-up condition is met; In step S3B, the cascade active jet enthalpy heat pump heating operation shutdown condition is configured with a third ambient temperature threshold, a second exhaust superheat target value and a hysteresis setting value. When it is detected that the outdoor ambient temperature is higher than the third ambient temperature threshold, or the exhaust superheat is less than the preset second exhaust superheat target value, or when the active jet enthalpy hot water inlet temperature is less than or equal to the sum of the active jet enthalpy refrigerant outlet temperature and the hysteresis setting value, or the active jet enthalpy hot water outlet temperature is less than or equal to the sum of the active jet enthalpy refrigerant inlet temperature and the hysteresis setting value, the cascade active jet enthalpy heat pump heating operation shutdown condition is deemed to be met; In step S3B, the heat pump heating shutdown condition is configured with a return water temperature target value and a return water temperature hysteresis threshold. When the return water temperature is detected to be higher than the sum of the return water temperature target value and the return water temperature hysteresis threshold, the heat pump heating shutdown condition is deemed to be met.

10. The control method of the cascade active jet enthalpy-increasing heat pump according to claim 6, characterized in that: The method further comprises step S4A: configuring a preset defrost operation start condition, and starting the defrost operation control when the defrost operation start condition is met; Step S4B: a preset defrost operation closing condition is configured, and when the defrost operation closing condition is met, the defrost operation control is closed.

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