Two-stage enthalpy-increasing heat pump system and control method

Abstract

The present application relates to the technical field of heat pump, and provides a two-stage enthalpy-increasing heat pump system and a control method, the two-stage enthalpy-increasing heat pump system comprising: a compressor, an indoor heat exchanger, an outdoor heat exchanger and a two-stage enthalpy-increasing assembly; the indoor heat exchanger and the outdoor heat exchanger are connected with the compressor respectively; the two-stage enthalpy-increasing assembly comprises: a primary heat exchanger, a secondary heat exchanger and an ejector; a primary enthalpy-increasing main path and a primary enthalpy-increasing auxiliary path of the primary heat exchanger are connected with the indoor heat exchanger respectively, and a first throttling device is arranged between the primary enthalpy-increasing auxiliary path and the indoor heat exchanger; a secondary enthalpy-increasing main path and a secondary enthalpy-increasing auxiliary path of the secondary heat exchanger are connected with the primary enthalpy-increasing main path respectively, and the secondary enthalpy-increasing main path is connected with the outdoor heat exchanger, and a second throttling device is arranged between the secondary enthalpy-increasing auxiliary path and the primary enthalpy-increasing main path; the ejector is connected with the primary enthalpy-increasing auxiliary path, the secondary enthalpy-increasing auxiliary path and the compressor respectively. The present application can fully recycle the heat of the heat pump system itself, and improve the heating and refrigeration energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and in particular to a two-stage enthalpy-increasing heat pump system and its control method. Background Technology

[0002] Among related technologies, vapor injection enthalpy enhancement technology is a commonly used efficiency-enhancing technology for air source heat pump systems. However, in current enthalpy-enhancing heat pump systems, the subcooling of the refrigerant liquid in the circuit during heating operation is insufficient, and the temperature of the refrigerant liquid before the expansion valve is still very high. This part of the heat is directly wasted after it enters the expansion valve for expansion and cooling, resulting in low energy efficiency of the heat pump system. Summary of the Invention

[0003] This invention provides a two-stage enthalpy-increasing heat pump system and control method, which can fully recover the heat of the heat pump system itself and maximize the utilization of heat, thereby improving the heating and cooling efficiency of the heat pump system.

[0004] This invention provides a two-stage enthalpy-increasing heat pump system, comprising:

[0005] compressor;

[0006] The indoor heat exchanger and the outdoor heat exchanger are respectively connected to the compressor;

[0007] A two-stage enthalpy-increasing assembly includes: a primary heat exchanger, a secondary heat exchanger, and an ejector. The primary enthalpy-increasing main path and the primary enthalpy-increasing auxiliary path of the primary heat exchanger are respectively connected to the indoor heat exchanger, and a first throttling device is provided between the primary enthalpy-increasing auxiliary path and the indoor heat exchanger.

[0008] The secondary enthalpy-increasing main circuit and the secondary enthalpy-increasing auxiliary circuit of the secondary heat exchanger are respectively connected to the primary enthalpy-increasing main circuit, and the secondary enthalpy-increasing main circuit is connected to the outdoor heat exchanger. A second throttling device is provided between the secondary enthalpy-increasing auxiliary circuit and the primary enthalpy-increasing main circuit.

[0009] The ejector is connected to the primary enthalpy-increasing auxiliary circuit, the secondary enthalpy-increasing auxiliary circuit, and the compressor, respectively.

[0010] According to a two-stage enthalpy-increasing heat pump system provided by the present invention, the two-stage enthalpy-increasing assembly further includes:

[0011] The third throttling device is located between the secondary enthalpy-increasing main circuit and the outdoor heat exchanger.

[0012] According to the present invention, a two-stage enthalpy-increasing heat pump system is provided, wherein the third throttling device is a first electronic expansion valve.

[0013] According to the present invention, a two-stage enthalpy-increasing heat pump system is provided, wherein the inlet ends of the primary enthalpy-increasing main circuit and the primary enthalpy-increasing auxiliary circuit are connected to a first common node, and a first on / off valve is provided between the first common node and the indoor heat exchanger.

[0014] A second on / off valve is provided between the secondary enthalpy-increasing main circuit and the outdoor heat exchanger.

[0015] According to a two-stage enthalpy-increasing heat pump system provided by the present invention, the two-stage enthalpy-increasing assembly further includes:

[0016] The first branch has a first end connected between the indoor heat exchanger and the first on / off valve, a second end connected between the secondary enthalpy-increasing main branch and the second on / off valve, and the first branch is provided with a third on / off valve.

[0017] The second branch has a first end connected between the primary enthalpy-increasing main branch and the first common node, and a second end connected between the second on / off valve and the outdoor heat exchanger. The second branch is also equipped with a fourth on / off valve.

[0018] According to a two-stage enthalpy-increasing heat pump system provided by the present invention, the compressor is connected to the indoor heat exchanger and the outdoor heat exchanger via a four-way valve.

[0019] According to a two-stage enthalpy-increasing heat pump system provided by the present invention, a liquid storage tank is provided between the indoor heat exchanger and the first-stage heat exchanger.

[0020] According to the present invention, a two-stage enthalpy-increasing heat pump system is provided, wherein the first throttling device is a second electronic expansion valve and the second throttling device is a capillary tube.

[0021] The present invention also provides a control method for the above-mentioned two-stage enthalpy-increasing heat pump system, comprising:

[0022] Obtain the operating mode of the two-stage enthalpy-increasing heat pump system;

[0023] In response to the operating mode, the four-way valve is controlled to switch direction and the opening and closing of the first on / off valve, the second on / off valve, the third on / off valve and the fourth on / off valve are controlled.

[0024] According to a control method for a two-stage enthalpy-increasing heat pump system provided by the present invention, the step of controlling the switching of the four-way valve and the on / off states of the first, second, third, and fourth on / off valves in response to the operating mode includes:

[0025] The operating mode is determined to be the heating mode. The four-way valve is controlled to switch, so that the compressor exhausts gas to the indoor heat exchanger and returns gas through the outdoor heat exchanger. The first on-off valve and the second on-off valve are controlled to open, and the third on-off valve and the fourth on-off valve are controlled to close.

[0026] The operating mode is determined to be cooling mode. The four-way valve is controlled to switch, so that the compressor exhausts gas to the outdoor heat exchanger and returns gas through the indoor heat exchanger. The first and second on-off valves are controlled to close, while the third and fourth on-off valves are opened.

[0027] The two-stage enthalpy-increasing heat pump system and control method provided by this invention connects an indoor heat exchanger and an outdoor heat exchanger to a compressor. The two-stage enthalpy-increasing assembly includes a primary heat exchanger, a secondary heat exchanger, and an ejector. The primary enthalpy-increasing main circuit and the primary enthalpy-increasing auxiliary circuit of the primary heat exchanger are connected to the indoor heat exchanger, and a first throttling device is provided between the primary enthalpy-increasing auxiliary circuit and the indoor heat exchanger. The secondary enthalpy-increasing main circuit and the secondary enthalpy-increasing auxiliary circuit of the secondary heat exchanger are connected to the primary enthalpy-increasing main circuit, and the secondary enthalpy-increasing main circuit is connected to the outdoor heat exchanger. A second throttling device is provided between the secondary enthalpy-increasing auxiliary circuit and the primary enthalpy-increasing main circuit. The ejector is connected to the primary enthalpy-increasing auxiliary circuit, the secondary enthalpy-increasing auxiliary circuit, and the compressor. This system can fully recover the heat of the heat pump system itself and maximize the utilization of heat, thereby improving the heating efficiency of the heat pump system. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the two-stage enthalpy-increasing heat pump system provided by the present invention;

[0030] Figure 2 This is a schematic diagram of the heating principle of the two-stage enthalpy-increasing heat pump system provided by the present invention;

[0031] Figure 3 This is the heating pressure-enthalpy diagram of the two-stage enthalpy-increasing heat pump system provided by the present invention;

[0032] Figure 4 This is a schematic diagram of the refrigeration principle of the two-stage enthalpy-increasing heat pump system provided by the present invention;

[0033] Figure 5 This is the refrigeration pressure-enthalpy diagram of the two-stage enthalpy-increasing heat pump system provided by the present invention;

[0034] Figure 6 This is a flowchart illustrating the control method for the two-stage enthalpy-increasing heat pump system provided by the present invention.

[0035] Figure label:

[0036] 1: Compressor; 2: Indoor heat exchanger; 3: Outdoor heat exchanger; 4: Two-stage enthalpy-increasing assembly;

[0037] 401: Primary heat exchanger; 4011: Primary enthalpy-increasing main circuit; 4012: Primary enthalpy-increasing auxiliary circuit;

[0038] 402: Secondary heat exchanger; 4021: Secondary enthalpy-increasing main circuit; 4022: Secondary enthalpy-increasing auxiliary circuit;

[0039] 403: Ejector; 404: First throttling device; 405: Second throttling device;

[0040] 406: Third throttling device; 407: First on / off valve; 408: Second on / off valve;

[0041] 409: First branch; 410: Third shut-off valve; 411: Second branch;

[0042] 412: Fourth shut-off valve; 5: Four-way valve; 6: Liquid reservoir. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] In the description of the embodiments of the present invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0047] The following is combined with Figures 1-6 The present invention describes a two-stage enthalpy-increasing heat pump system and its control method.

[0048] According to an embodiment of the first aspect of the present invention, referring to Figure 1 As shown, the two-stage enthalpy-increasing heat pump system provided by the present invention mainly includes: a compressor 1, an indoor heat exchanger 2, an outdoor heat exchanger 3, and a two-stage enthalpy-increasing assembly 4. The compressor 1 is used to generate a high-temperature, high-pressure gaseous refrigerant; the indoor heat exchanger 2 and the outdoor heat exchanger 3 are respectively connected to the compressor 1.

[0049] The two-stage enthalpy-increasing assembly 4 includes: a primary heat exchanger 401, a secondary heat exchanger 402, and an ejector 403. The primary heat exchanger 401 is provided with a primary enthalpy-increasing main path 4011 and a primary enthalpy-increasing auxiliary path 4012. The inlet ends of the primary enthalpy-increasing main path 4011 and the primary enthalpy-increasing auxiliary path 4012 are respectively connected to the indoor heat exchanger 2. The refrigerant in the primary enthalpy-increasing main path 4011 can exchange heat with the refrigerant in the primary enthalpy-increasing auxiliary path 4012. Furthermore, a first throttling device 404 is provided between the primary enthalpy-increasing auxiliary path 4012 and the indoor heat exchanger 2. The first throttling device 404 is located at the inlet end of the primary enthalpy-increasing auxiliary path 4012, and throttling, pressure reduction, and temperature reduction are achieved through the first throttling device 404.

[0050] The secondary heat exchanger 402 is provided with a secondary enthalpy-increasing main circuit 4021 and a secondary enthalpy-increasing auxiliary circuit 4022. The inlet ends of the secondary enthalpy-increasing main circuit 4021 and the secondary enthalpy-increasing auxiliary circuit 4022 are respectively connected to the outlet end of the primary enthalpy-increasing main circuit 4011. The refrigerant in the secondary enthalpy-increasing main circuit 4021 can exchange heat with the refrigerant in the secondary enthalpy-increasing auxiliary circuit 4022. The outlet end of the secondary enthalpy-increasing main circuit 4021 is connected to the outdoor heat exchanger 3. A second throttling device 405 is provided between the secondary enthalpy-increasing auxiliary circuit 4022 and the primary enthalpy-increasing main circuit 4011. The second throttling device 405 is located at the inlet end of the secondary enthalpy-increasing auxiliary circuit 4022, and throttling, pressure reduction and temperature reduction are achieved through the second throttling device 405.

[0051] The ejector 403 is connected to the primary enthalpy-increasing auxiliary path 4012, the secondary enthalpy-increasing auxiliary path 4022, and the compressor 1, respectively. Specifically, the injection inlet of the ejector 403 is connected to the primary enthalpy-increasing auxiliary path 4012, the ejection inlet of the ejector 403 is connected to the secondary enthalpy-increasing auxiliary path 4022, and the outlet of the ejector 403 is connected to the enthalpy-increasing suction port of the compressor 1.

[0052] When the heat pump system is in heating mode, the high-temperature and high-pressure exhaust gas from compressor 1 enters the indoor heat exchanger 2 for condensation and heat release. The cooled liquid refrigerant is divided into two paths and enters the primary heat exchanger 401. One path directly enters the primary enthalpy-increasing main path 4011, while the other path is throttled and cooled by the first throttling device 404, becoming a gas-liquid two-phase refrigerant that enters the primary enthalpy-increasing auxiliary path 4012. Since the temperature of the gas-liquid two-phase refrigerant is lower than that of the liquid refrigerant entering the primary enthalpy-increasing main path 4011, the gas-liquid two-phase refrigerant in the primary enthalpy-increasing auxiliary path 4012 can absorb the heat from the liquid refrigerant in the primary enthalpy-increasing main path 4011, and transform into a dry pure gaseous refrigerant that enters the injection inlet of ejector 403, forming a high-speed jet of airflow.

[0053] Simultaneously, the liquid refrigerant in the primary enthalpy-increasing main path 4011 of the primary heat exchanger 401 is cooled by the primary enthalpy-increasing auxiliary path 4012. The cooled liquid refrigerant then splits into two paths: one directly enters the secondary enthalpy-increasing main path 4021 of the secondary heat exchanger 402, and the other is throttled and depressurized by the second throttling device 405 before entering the secondary enthalpy-increasing auxiliary path 4022. At this point, due to the high-speed jetting of gas from the primary enthalpy-increasing auxiliary path 4012 within the ejector 403, a negative pressure is formed under the Venturi effect, causing a decrease in pressure in the secondary enthalpy-increasing auxiliary path 4022 of the secondary heat exchanger 402. This decrease in evaporation pressure leads to a temperature drop, causing the second throttling device... After being throttled and cooled at 405, the refrigerant flashes into a gas-liquid two-phase state. Since the temperature of the gas-liquid two-phase refrigerant entering the secondary enthalpy-increasing auxiliary circuit 4022 is lower than the temperature of the liquid refrigerant entering the secondary enthalpy-increasing main circuit 4021, the gas-liquid two-phase refrigerant in the secondary enthalpy-increasing auxiliary circuit 4022 can absorb the heat of the liquid refrigerant in the secondary enthalpy-increasing main circuit 4021 and change phase to dry pure gaseous refrigerant, which enters the ejector inlet of ejector 403. After the temperature of the liquid refrigerant in the secondary enthalpy-increasing main circuit 4021 decreases, it enters the outdoor heat exchanger 3 to absorb heat and evaporate into gaseous refrigerant, which then flows back to the compressor.

[0054] Furthermore, the source gas from the primary enthalpy-increasing auxiliary path 4012 entering the ejector 403 mixes with the entrained gas from the secondary enthalpy-increasing auxiliary path 4022 entering the ejector 403 to become a dry saturated gaseous refrigerant that flows back to the enthalpy-increasing suction port of the compressor 1.

[0055] The two-stage enthalpy-increasing heat pump system provided in this embodiment of the invention adopts a two-stage enthalpy-increasing design. When the refrigerant liquid outlet of the primary enthalpy-increasing main circuit 4011 of the primary heat exchanger 401 still has a high temperature and enters the secondary heat exchanger 402, the primary enthalpy-increasing gas discharged from the primary enthalpy-increasing auxiliary circuit 4012 is injected into the ejector 403 for high-speed ejection. Based on the Venturi principle of the ejector 403, the intermediate evaporation pressure of the secondary enthalpy-increasing circuit in the secondary heat exchanger 402 is reduced, and the refrigerant liquid outlet temperature of the secondary enthalpy-increasing main circuit 4021 is further reduced, so that the refrigerant liquid is fully subcooled, and the heat recovery and utilization are maximized, thereby achieving efficient circulation and improving the heating energy efficiency of the heat pump system.

[0056] According to one embodiment of the present invention, referring to Figure 1 As shown, the two-stage enthalpy-increasing assembly of the present invention further includes a third throttling device 406. The third throttling device 406 is disposed between the secondary enthalpy-increasing main circuit 4021 and the outdoor heat exchanger 3. It is used to throttle and reduce the pressure of the refrigerant liquid discharged from the secondary enthalpy-increasing main circuit 4021 into a gas-liquid two-phase refrigerant with a lower temperature, and then send it to the outdoor heat exchanger 3 to absorb heat. This effectively improves the heat absorption and evaporation capacity of the outdoor heat exchanger 3, thereby further improving the energy efficiency of the heat pump system.

[0057] According to one embodiment of the present invention, the third throttling device 406 is a first electronic expansion valve.

[0058] According to one embodiment of the present invention, referring to Figure 1 As shown, the inlet ends of the primary enthalpy-increasing main path 4011 and the primary enthalpy-increasing auxiliary path 4012 are connected to the first common node. A first on / off valve 407 is provided between the first common node and the indoor heat exchanger 2. A second on / off valve 408 is provided between the secondary enthalpy-increasing main path 4021 and the outdoor heat exchanger 3. The second on / off valve 408 is specifically located between the third throttling device 406 and the outdoor heat exchanger 3. The first on / off valve 407 and the second on / off valve 408 are used to control the on / off of the corresponding flow paths.

[0059] Furthermore, the entrance ends of the secondary enthalpy-increasing main road 4021 and the secondary enthalpy-increasing auxiliary road 4022 are connected to the second common node, and the second common node is connected to the exit end of the primary enthalpy-increasing main road 4011.

[0060] According to one embodiment of the present invention, the two-stage enthalpy-increasing assembly 4 further includes: a first branch 409 and a second branch 411. The first end of the first branch 409 is connected between the indoor heat exchanger 2 and the first on / off valve 407, and the second end of the first branch 409 is connected between the secondary enthalpy-increasing main line 4021 and the second on / off valve 408. The first branch 409 is provided with a third on / off valve 410 for controlling the on / off state of the first branch 409. The first end of the second branch 411 is connected between the primary enthalpy-increasing main line 4011 and the first common node, and the second end of the second branch 411 is connected between the second on / off valve 408 and the outdoor heat exchanger 3. The second branch 411 is provided with a fourth on / off valve 412 for controlling the on / off state of the second branch 411.

[0061] When the heat pump system operates in heating mode, the first on / off valve 407 and the second on / off valve 408 are opened, while the third on / off valve 410 and the fourth on / off valve 412 are closed. Figure 2 As shown; when the heat pump system operates in cooling mode, it controls the first on / off valve 407 and the second on / off valve 408 to close, while the third on / off valve 410 and the fourth on / off valve 412 open, as follows. Figure 4 As shown. The specific principles are explained later.

[0062] According to one embodiment of the present invention, referring to Figure 1 As shown, compressor 1 is connected to indoor heat exchanger 2 and outdoor heat exchanger 3 through four-way valve 5. By controlling the reversal of four-way valve 5, the operating mode of the heat pump system can be switched.

[0063] Specifically, the first end of the four-way valve 5 is connected to the exhaust port of the compressor 1, the second end of the four-way valve 5 is connected to the indoor heat exchanger 2, the third end of the four-way valve 5 is connected to the outdoor heat exchanger 3, and the fourth end of the four-way valve 5 is connected to the return port of the compressor 1.

[0064] When the heat pump system is in heating mode, the first end of the four-way valve 5 is connected to the second end, and the third end is connected to the fourth end. The compressor 1 exhausts gas into the indoor heat exchanger 2 and returns gas through the outdoor heat exchanger 3. When the heat pump system is in cooling mode, the first end of the four-way valve 5 is connected to the third end, and the second end is connected to the fourth end. The compressor 1 exhausts gas into the outdoor heat exchanger 3 and returns gas through the indoor heat exchanger 2.

[0065] According to one embodiment of the present invention, referring to Figure 1 As shown, a liquid storage tank 6 is provided between the indoor heat exchanger 2 and the primary heat exchanger 401.

[0066] Specifically, the two ends of the liquid reservoir 6 are connected to the indoor heat exchanger 2 and the first on / off valve 407, respectively. The first end of the first branch 409 is connected between the liquid reservoir 6 and the first on / off valve 407, and the second end of the first branch 409 is connected between the third throttling device 406 and the second on / off valve 408.

[0067] By setting up a liquid receiver 6, the liquid refrigerant in the indoor heat exchanger 2 can be quickly and timely discharged into the liquid receiver 6 during winter heating, avoiding occupying the heat exchange body of the indoor heat exchanger 2, thereby maintaining the heat exchange area of ​​the indoor heat exchanger 2 in real time and improving the heat exchange effect.

[0068] According to one embodiment of the present invention, the first throttling device 404 is a second electronic expansion valve, and the second throttling device 405 is a capillary tube.

[0069] Furthermore, the indoor heat exchanger 2 is a shell-and-tube heat exchanger, into which circulating water can be introduced to heat or cool down using the refrigerant; the outdoor heat exchanger 3 is a finned heat exchanger; and the primary heat exchanger 401 and the secondary heat exchanger 402 are plate heat exchangers.

[0070] The working principle of the two-stage enthalpy-increasing heat pump system provided by this invention is described below with specific examples, mainly including winter heating mode and summer cooling mode. The refrigerant flow direction is shown below. Figure 2 and Figure 4 The direction indicated by the middle arrow.

[0071] Winter heating mode: Refer to Figure 2 and Figure 3 As shown, when the heat pump system is running in heating mode, the first end of the four-way valve 5 is connected to the second end, and the third end is connected to the fourth end; and the first on-off valve 407 and the second on-off valve 408 are open, while the third on-off valve 410 and the fourth on-off valve 412 are closed.

[0072] The high-temperature exhaust from compressor 1 enters the indoor heat exchanger 2 through the four-way valve 5 for condensation. During condensation, a 40°C gas-liquid two-phase refrigerant is formed. After cooling, it becomes a 38°C liquid refrigerant and is discharged. At the same time, the circulating water in the indoor heat exchanger 2 is heated from 36°C to 41°C. The cooled 38°C liquid refrigerant passes through the liquid receiver 6 and splits into two paths. One path, still a 38°C liquid refrigerant, enters the primary enthalpy-increasing main path 4011 of the primary heat exchanger 401. The other path, after being throttled and cooled by the second electronic expansion valve, becomes a 13°C gas-liquid two-phase refrigerant and enters the primary enthalpy-increasing auxiliary path 4012 of the primary heat exchanger 401. The primary enthalpy-increasing auxiliary path 4012 absorbs heat from the primary enthalpy-increasing main path 4011 and changes phase to 13°C dry pure gaseous refrigerant, which enters the injection inlet of the ejector 403, forming a high-speed jet of air.

[0073] Simultaneously, the 38°C liquid refrigerant in the primary enthalpy-increasing main path 4011 is cooled to 15°C by the primary enthalpy-increasing auxiliary path 4012, and then splits into two paths: one directly enters the secondary enthalpy-increasing main path 4021 of the secondary heat exchanger 402, and the other enters the secondary enthalpy-increasing auxiliary path 4022 of the secondary heat exchanger 402 after pressure reduction via a capillary tube. At this time, due to the high-speed injection of gas from the primary enthalpy-increasing auxiliary path 4012 into the ejector 403, a negative pressure is formed under the Venturi effect, thereby reducing the pressure in the secondary enthalpy-increasing auxiliary path 4022 of the secondary heat exchanger 402. The decrease in evaporation pressure leads to a decrease in temperature, causing the refrigerant after capillary throttling to flash. -7°C gas-liquid two-phase refrigerant enters the secondary enthalpy-increasing auxiliary circuit 4022. The -7°C gas-liquid two-phase refrigerant in the secondary enthalpy-increasing auxiliary circuit 4022 absorbs heat from the 15°C liquid refrigerant in the secondary enthalpy-increasing main circuit 4021, and changes phase to -7°C dry pure gaseous refrigerant, which enters the ejector inlet of ejector 403. The 15°C liquid refrigerant in the secondary enthalpy-increasing main circuit 4021 is further cooled to -5°C by the -7°C gas-liquid two-phase refrigerant. After being depressurized by the first electronic expansion valve, it becomes a -18°C gas-liquid two-phase refrigerant, enters the outdoor heat exchanger 3, absorbs heat, and becomes a -16°C dry gas, and then returns to the compressor 1 through the four-way valve 5.

[0074] Furthermore, the 13°C ejector source gas discharged from the primary enthalpy-increasing auxiliary path 4012 and the -7°C ejected gas discharged from the secondary enthalpy-increasing auxiliary path 4022 are mixed in the ejector 403 and become 4°C dry saturated gas, which returns to the enthalpy-increasing suction port of the compressor 1.

[0075] like Figure 3 As shown, the outlet liquid temperature of the indoor heat exchanger 2, originally 38℃, is continuously cooled to -5℃ by two stages of enthalpy enhancement. The temperature before the expansion valve is even lower, resulting in sufficient subcooling. This leads to a lower enthalpy value of the refrigerant entering the outdoor heat exchanger 3, and a greater heat absorption capacity of the outdoor heat exchanger 3, thereby increasing the energy efficiency of the main circuit. At the same time, because of the secondary enthalpy enhancement auxiliary circuit 4022, the evaporation temperature of the primary enthalpy enhancement auxiliary circuit 4012 can be appropriately increased. For example, by increasing the opening of the second electronic expansion valve, the flow rate of the primary enthalpy enhancement auxiliary circuit 4012 can be increased, and the evaporation temperature can be raised, thereby improving the energy efficiency of the primary enthalpy enhancement auxiliary circuit 4012 and thus improving the overall energy efficiency. Furthermore, the evaporation temperature of the secondary enthalpy enhancement auxiliary circuit 4022 is still much higher than the evaporation temperature of the main circuit, so the energy efficiency of the secondary enthalpy enhancement auxiliary circuit 4022 is still higher than that of the main circuit.

[0076] Therefore, this invention not only improves the energy efficiency of the main circuit, but also introduces two high-efficiency enthalpy-increasing auxiliary circuits, thereby significantly improving the energy efficiency and capacity of the entire heat pump system.

[0077] Summer cooling mode: Refer to Figure 4 and Figure 5As shown, when the heat pump system is running in cooling mode, the first end of the four-way valve 5 is connected to the third end, and the second end is connected to the fourth end; and the first on-off valve 407 and the second on-off valve 408 are closed, while the third on-off valve 410 and the fourth on-off valve 412 are open.

[0078] The 85°C gaseous refrigerant discharged from compressor 1 enters the outdoor heat exchanger 3 through the four-way valve 5 for condensation. During the condensation process, it forms a 43°C gas-liquid two-phase refrigerant. After cooling, it becomes a 40°C liquid refrigerant and is discharged. It is then split into two paths through the second branch 411. One path, still a 40°C liquid refrigerant, enters the primary enthalpy-increasing main path 4011 of the primary heat exchanger 401. The other path, after being throttled and cooled by the second electronic expansion valve, becomes a 15°C gas-liquid two-phase refrigerant and enters the primary enthalpy-increasing auxiliary path 4012 of the primary heat exchanger 401. The primary enthalpy-increasing auxiliary path 4012 absorbs the heat from the primary enthalpy-increasing main path 4011 and changes phase to 15°C dry pure gaseous refrigerant, which enters the injection inlet of ejector 403, forming a high-speed jet of airflow.

[0079] Simultaneously, the 40°C liquid refrigerant in the primary enthalpy-increasing main path 4011 is cooled to 17°C by the primary enthalpy-increasing auxiliary path 4012, and then splits into two paths: one directly enters the secondary enthalpy-increasing main path 4021 of the secondary heat exchanger 402, and the other enters the secondary enthalpy-increasing auxiliary path 4022 of the secondary heat exchanger 402 after being depressurized by a capillary tube. At this time, due to the high-speed injection of gas in the primary enthalpy-increasing auxiliary path 4012 into the ejector 403, a negative pressure is formed under the Venturi effect, thereby reducing the pressure in the secondary heat exchanger 402. The decrease in evaporation pressure leads to a decrease in temperature, causing the refrigerant after capillary throttling to flash into a 5°C gas-liquid two-phase refrigerant, which then enters the secondary enthalpy-increasing auxiliary path 4022. 022, the 5°C gas-liquid two-phase refrigerant in the secondary enthalpy-increasing auxiliary circuit 4022 absorbs heat from the 17°C liquid refrigerant in the secondary enthalpy-increasing main circuit 4021, and changes phase to 5°C dry pure gaseous refrigerant. It enters the ejector inlet of the ejector 403. The 17°C liquid refrigerant in the secondary enthalpy-increasing main circuit 4021 is further cooled to 6°C by the 5°C gas-liquid two-phase refrigerant. After being depressurized by the first electronic expansion valve, it becomes a 2°C gas-liquid two-phase refrigerant. It enters the indoor heat exchanger 2 through the first branch circuit 409 and the liquid receiver 6, absorbs heat and evaporates, and becomes a 6°C dry gas. Then it returns to the compressor 1 through the four-way valve 5. At the same time, the circulating water entering the indoor heat exchanger 2 is cooled from 12°C to 7°C.

[0080] Furthermore, the 15°C ejector source gas discharged from the primary enthalpy-increasing auxiliary path 4012 and the 5°C ejected gas discharged from the secondary enthalpy-increasing auxiliary path 4022 are mixed in the ejector 403 and become 12°C dry saturated gas, which returns to the enthalpy-increasing suction port of the compressor 1.

[0081] like Figure 5As shown, the outlet liquid temperature of the outdoor heat exchanger 3 was originally 40℃, but it was continuously cooled to 6℃ by two stages of enthalpy enhancement, which further reduced the temperature after the expansion valve to 2℃. This resulted in a lower refrigerant enthalpy value entering the indoor heat exchanger 2, and a greater heat absorption capacity of the indoor heat exchanger 2, thereby effectively improving the cooling efficiency.

[0082] Therefore, the two-stage enthalpy-increasing heat pump system of the present invention can still function during summer cooling, which can greatly improve the cooling capacity and energy efficiency of the heat pump system in summer.

[0083] The control method of the two-stage enthalpy-increasing heat pump system provided by the present invention will be described below. The control method of the two-stage enthalpy-increasing heat pump system described below can be referred to in correspondence with the two-stage enthalpy-increasing heat pump system described above.

[0084] According to an embodiment of the second aspect of the present invention, referring to Figure 6 As shown, the present invention also provides a control method for the two-stage enthalpy-increasing heat pump system of the above embodiments, which mainly includes the following steps:

[0085] S100: Obtain the operating mode of the two-stage enthalpy-increasing heat pump system.

[0086] S200, in response to the operating mode, controls the reversal of the four-way valve 5 and the opening and closing of the first on-off valve 407, the second on-off valve 408, the third on-off valve 410 and the fourth on-off valve 412.

[0087] When the operating mode is determined to be heating mode, the four-way valve 5 is switched, causing the compressor 1 to discharge gas to the indoor heat exchanger 2 and return gas through the outdoor heat exchanger 3. Simultaneously, the first and second on-off valves 407 and 408 are opened, while the third and fourth on-off valves 410 and 412 are closed. When the operating mode is determined to be cooling mode, the four-way valve 5 is switched, causing the compressor 1 to discharge gas to the outdoor heat exchanger 3 and return gas through the indoor heat exchanger 2. Simultaneously, the first and second on-off valves 407 and 408 are closed, while the third and fourth on-off valves 410 and 412 are opened. The specific process is described above and will not be repeated here.

[0088] In summary, this invention can significantly increase the flow rate of the enthalpy-enhancing auxiliary circuit, allowing the liquid refrigerant before the main circuit valve to be fully subcooled, thus achieving efficient circulation. Furthermore, during winter heating or summer cooling, the simultaneous activation of the dual-stage ejector enthalpy enhancement can greatly improve the heating or cooling efficiency of the heat pump system.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A two-stage enthalpy-increasing heat pump system, characterized in that, include: compressor; The indoor heat exchanger and the outdoor heat exchanger are respectively connected to the compressor; A two-stage enthalpy-increasing assembly includes: a primary heat exchanger, a secondary heat exchanger, and an ejector. The primary enthalpy-increasing main path and the primary enthalpy-increasing auxiliary path of the primary heat exchanger are respectively connected to the indoor heat exchanger, and a first throttling device is provided between the primary enthalpy-increasing auxiliary path and the indoor heat exchanger. The secondary enthalpy-increasing main circuit and the secondary enthalpy-increasing auxiliary circuit of the secondary heat exchanger are respectively connected to the primary enthalpy-increasing main circuit, and the secondary enthalpy-increasing main circuit is connected to the outdoor heat exchanger. A second throttling device is provided between the secondary enthalpy-increasing auxiliary circuit and the primary enthalpy-increasing main circuit. The ejector is connected to the primary enthalpy-increasing auxiliary circuit, the secondary enthalpy-increasing auxiliary circuit, and the compressor, respectively. The inlet ends of the primary enthalpy-increasing main circuit and the primary enthalpy-increasing auxiliary circuit are connected to the first common node, and a first on / off valve is provided between the first common node and the indoor heat exchanger. A second on / off valve is provided between the secondary enthalpy-increasing main circuit and the outdoor heat exchanger; The entrance ends of the secondary enthalpy-increasing main road and the secondary enthalpy-increasing auxiliary road are connected to the second common node, and the second common node is connected to the exit end of the primary enthalpy-increasing main road. The two-stage enthalpy-increasing assembly also includes: The third throttling device is installed between the secondary enthalpy-increasing main circuit and the outdoor heat exchanger; The two-stage enthalpy-increasing assembly also includes: The first branch has a first end connected between the indoor heat exchanger and the first on / off valve, a second end connected between the secondary enthalpy-increasing main branch and the second on / off valve, and the first branch is provided with a third on / off valve. The second branch has a first end connected between the primary enthalpy-increasing main branch and the first common node, and a second end connected between the second on / off valve and the outdoor heat exchanger. The second branch is also equipped with a fourth on / off valve. The compressor is connected to the indoor heat exchanger and the outdoor heat exchanger via a four-way valve.

2. The two-stage enthalpy-increasing heat pump system according to claim 1, characterized in that, The third throttling device is the first electronic expansion valve.

3. The two-stage enthalpy-increasing heat pump system according to claim 1, characterized in that, A liquid storage tank is provided between the indoor heat exchanger and the primary heat exchanger.

4. The two-stage enthalpy-increasing heat pump system according to any one of claims 1-3, characterized in that, The first throttling device is a second electronic expansion valve, and the second throttling device is a capillary tube.

5. A control method for a two-stage enthalpy-increasing heat pump system according to claim 1, characterized in that, include: Obtain the operating mode of the two-stage enthalpy-increasing heat pump system; In response to the operating mode, the four-way valve is controlled to switch direction and the opening and closing of the first on / off valve, the second on / off valve, the third on / off valve and the fourth on / off valve are controlled.

6. The control method for the two-stage enthalpy-increasing heat pump system according to claim 5, characterized in that, The step of controlling the switching of the four-way valve and the on / off states of the first, second, third, and fourth on / off valves in response to the operating mode includes: The operating mode is determined to be the heating mode. The four-way valve is controlled to switch, so that the compressor exhausts gas to the indoor heat exchanger and returns gas through the outdoor heat exchanger. The first on-off valve and the second on-off valve are controlled to open, and the third on-off valve and the fourth on-off valve are controlled to close. The operating mode is determined to be cooling mode. The four-way valve is controlled to switch, so that the compressor exhausts gas to the outdoor heat exchanger and returns gas through the indoor heat exchanger. The first and second on-off valves are controlled to close, while the third and fourth on-off valves are opened.

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